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Barth K, Schmitz C, Jochum T, Viventi J. Intan Technologies integrated circuits can produce analog-to-digital conversion artifacts that affect neural signal acquisition. J Neural Eng 2024; 21:044001. [PMID: 38865993 DOI: 10.1088/1741-2552/ad5762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 06/12/2024] [Indexed: 06/14/2024]
Abstract
Objective.Intan Technologies' integrated circuits (ICs) are valuable tools for neurophysiological data acquisition, providing signal amplification, filtering, and digitization from many channels (up to 64 channels/chip) at high sampling rates (up to 30 kSPS) within a compact package (⩽9× 7 mm). However, we found that the analog-to-digital converters (ADCs) in the Intan RHD2000 series ICs can produce artifacts in recorded signals. Here, we examine the effects of these ADC artifacts on neural signal quality and describe a method to detect them in recorded data.Approach.We identified two types of ADC artifacts produced by Intan ICs: 1) jumps, resulting from missing output codes, and 2) flatlines, resulting from overrepresented output codes. We identified ADC artifacts in neural recordings acquired with Intan RHD2000 ICs and tested the repeated performance of 17 ICsin vitro. With the on-chip digital-signal-processing disabled, we detected the ADC artifacts in each test recording by examining the distribution of unfiltered ADC output codes.Main Results.We found larger ADC artifacts in recordings using the Intan RHX data acquisition software versions 3.0-3.2, which did not run the necessary ADC calibration command when the inputs to the Intan recording controller were rescanned. This has been corrected in the Intan RHX software version 3.3. We found that the ADC calibration routine significantly reduced, but did not fully eliminate, the occurrence and size of ADC artifacts as compared with recordings acquired when the calibration routine was not run (p< 0.0001). When the ADC calibration routine was run, we found that the artifacts produced by each ADC were consistent over time, enabling us to sort ICs by performance.Significance.Our findings call attention to the importance of evaluating signal quality when acquiring electrophysiological data using Intan Technologies ICs and offer a method for detecting ADC artifacts in recorded data.
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Affiliation(s)
- Katrina Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Cecilia Schmitz
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Thomas Jochum
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, United States of America
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC, United States of America
- Department of Neurology, Duke University School of Medicine, Durham, NC, United States of America
- Duke Comprehensive Epilepsy Center, Duke University School of Medicine, Durham, NC, United States of America
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2
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Silva AB, Littlejohn KT, Liu JR, Moses DA, Chang EF. The speech neuroprosthesis. Nat Rev Neurosci 2024; 25:473-492. [PMID: 38745103 DOI: 10.1038/s41583-024-00819-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2024] [Indexed: 05/16/2024]
Abstract
Loss of speech after paralysis is devastating, but circumventing motor-pathway injury by directly decoding speech from intact cortical activity has the potential to restore natural communication and self-expression. Recent discoveries have defined how key features of speech production are facilitated by the coordinated activity of vocal-tract articulatory and motor-planning cortical representations. In this Review, we highlight such progress and how it has led to successful speech decoding, first in individuals implanted with intracranial electrodes for clinical epilepsy monitoring and subsequently in individuals with paralysis as part of early feasibility clinical trials to restore speech. We discuss high-spatiotemporal-resolution neural interfaces and the adaptation of state-of-the-art speech computational algorithms that have driven rapid and substantial progress in decoding neural activity into text, audible speech, and facial movements. Although restoring natural speech is a long-term goal, speech neuroprostheses already have performance levels that surpass communication rates offered by current assistive-communication technology. Given this accelerated rate of progress in the field, we propose key evaluation metrics for speed and accuracy, among others, to help standardize across studies. We finish by highlighting several directions to more fully explore the multidimensional feature space of speech and language, which will continue to accelerate progress towards a clinically viable speech neuroprosthesis.
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Affiliation(s)
- Alexander B Silva
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA
- Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA
| | - Kaylo T Littlejohn
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA
- Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Jessie R Liu
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA
- Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA
| | - David A Moses
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA
- Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA
| | - Edward F Chang
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA.
- Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA.
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3
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Huo J, Zhang L, Luo X, Rao Y, Cao P, Hou X, He J, Mu J, Geng W, Cui H, Cheng R, Chou X. Motor Behavior Regulation of Rat Robots Using Integrated Electrodes Stimulated by Micro-Nervous System. MICROMACHINES 2024; 15:587. [PMID: 38793158 PMCID: PMC11123150 DOI: 10.3390/mi15050587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 04/16/2024] [Accepted: 04/26/2024] [Indexed: 05/26/2024]
Abstract
As a cutting-edge technology, animal robots based on living organisms are being extensively studied, with potential for diverse applications in the fields of neuroscience, national security, and civil rescue. However, it remains a significant challenge to reliably control the animal robots with the objective of protecting their long-term survival, and this has seriously hindered their practical implementation. To address this issue, this work explored the use of a bio-friendly neurostimulation system that includes integrated stimulation electrodes together with a remote wireless stimulation circuit to control the moving behavior of rat robots. The integrated electrodes were implanted simultaneously in four stimulation sites, including the medial forebrain bundle (MFB) and primary somatosensory cortex, barrel field (S1BF). The control system was able to provide flexibility in adjusting the following four stimulation parameters: waveform, amplitude, frequency, and duration time. The optimized parameters facilitated the successful control of the rat's locomotion, including forward movement and left and right turns. After training for a few cycles, the rat robots could be guided along a designated route to complete the given mission in a maze. Moreover, it was found that the rat robots could survive for more than 20 days with the control system implanted. These findings will ensure the sustained and reliable operation of the rat robots, laying a robust foundation for advances in animal robot regulation technology.
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Affiliation(s)
- Jiabing Huo
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Le Zhang
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Xiangyu Luo
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Yongkang Rao
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Peili Cao
- Fifth Clinical Medical School, Shanxi Medical University, Taiyuan 030012, China
- Department of Neurosurgery, Shanxi Provincial People’s Hospital, Taiyuan 030012, China
| | - Xiaojuan Hou
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Jian He
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Jiliang Mu
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Wenping Geng
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Haoran Cui
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
| | - Rui Cheng
- Department of Neurosurgery, Shanxi Provincial People’s Hospital, Taiyuan 030012, China
| | - Xiujian Chou
- Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
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4
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Palopoli-Trojani K, Trumpis M, Chiang CH, Wang C, Williams AJ, Evans CL, Turner DA, Viventi J, Hoffmann U. High-density cortical µECoG arrays concurrently track spreading depolarizations and long-term evolution of stroke in awake rats. Commun Biol 2024; 7:263. [PMID: 38438529 PMCID: PMC10912118 DOI: 10.1038/s42003-024-05932-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 02/18/2024] [Indexed: 03/06/2024] Open
Abstract
Spreading depolarizations (SDs) are widely recognized as a major contributor to the progression of tissue damage from ischemic stroke even if blood flow can be restored. They are characterized by negative intracortical waveforms of up to -20 mV, propagation velocities of 3 - 6 mm/min, and massive disturbance of membrane ion homeostasis. High-density, micro-electrocorticographic (μECoG) epidural electrodes and custom, DC-coupled, multiplexed amplifiers, were used to continuously characterize and monitor SD and µECoG cortical signal evolution in awake, moving rats over days. This highly innovative approach can define these events over a large brain surface area (~ 3.4 × 3.4 mm), extending across the boundaries of the stroke, and offers sufficient electrode density (60 contacts total per array for a density of 5.7 electrodes / mm2) to measure and determine the origin of SDs in relation to the infarct boundaries. In addition, spontaneous ECoG activity can simultaneously be detected to further define cortical infarct regions. This technology allows us to understand dynamic stroke evolution and provides immediate cortical functional activity over days. Further translational development of this approach may facilitate improved treatment options for acute stroke patients.
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Affiliation(s)
| | | | | | - Charles Wang
- Biomedical Engineering, Duke University, Durham, NC, USA
| | | | - Cody L Evans
- Center for Perioperative Organ Protection, Department of Anesthesiology, Duke University, Durham, USA
| | - Dennis A Turner
- Biomedical Engineering, Duke University, Durham, NC, USA
- Neurosurgery, Neurobiology, Duke University, Durham, USA
- Research and Surgery Services, Durham VAMC, Durham, USA
| | | | - Ulrike Hoffmann
- Center for Perioperative Organ Protection, Department of Anesthesiology, Duke University, Durham, USA.
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5
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Ahn SH, Koh CS, Park M, Jun SB, Chang JW, Kim SJ, Jung HH, Jeong J. Liquid Crystal Polymer-Based Miniaturized Fully Implantable Deep Brain Stimulator. Polymers (Basel) 2023; 15:4439. [PMID: 38006163 PMCID: PMC10675735 DOI: 10.3390/polym15224439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/22/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
A significant challenge in improving the deep brain stimulation (DBS) system is the miniaturization of the device, aiming to integrate both the stimulator and the electrode into a compact unit with a wireless charging capability to reduce invasiveness. We present a miniaturized, fully implantable, and battery-free DBS system designed for rats, using a liquid crystal polymer (LCP), a biocompatible and long-term reliable material. The system integrates the simulator circuit, the receiver coil, and a 20 mm long depth-type microelectrode array in a dome-shaped LCP package that is 13 mm in diameter and 5 mm in height. Wireless powering and control via an inductive link enable device miniaturization, allowing for full implantation and, thus, the free behavior of untethered animals. The eight-channel stimulation electrode array was microfabricated on an LCP substrate to form a multilayered system substrate, which was monolithically encapsulated by a domed LCP lid using a specialized spot-welding process. The device functionality was validated via an in vivo animal experiment using a neuropathic pain model in rats. This experiment demonstrated an increase in the mechanical withdrawal threshold of the rats with microelectrical stimulation delivered using the fully implanted device, highlighting the effectiveness of the system.
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Affiliation(s)
- Seung-Hee Ahn
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Chin Su Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Minkyung Park
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Sang Beom Jun
- Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jin Woo Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyun Ho Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, Pusan National University, Yangsan 50612, Republic of Korea
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6
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Duraivel S, Rahimpour S, Chiang CH, Trumpis M, Wang C, Barth K, Harward SC, Lad SP, Friedman AH, Southwell DG, Sinha SR, Viventi J, Cogan GB. High-resolution neural recordings improve the accuracy of speech decoding. Nat Commun 2023; 14:6938. [PMID: 37932250 PMCID: PMC10628285 DOI: 10.1038/s41467-023-42555-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 10/13/2023] [Indexed: 11/08/2023] Open
Abstract
Patients suffering from debilitating neurodegenerative diseases often lose the ability to communicate, detrimentally affecting their quality of life. One solution to restore communication is to decode signals directly from the brain to enable neural speech prostheses. However, decoding has been limited by coarse neural recordings which inadequately capture the rich spatio-temporal structure of human brain signals. To resolve this limitation, we performed high-resolution, micro-electrocorticographic (µECoG) neural recordings during intra-operative speech production. We obtained neural signals with 57× higher spatial resolution and 48% higher signal-to-noise ratio compared to macro-ECoG and SEEG. This increased signal quality improved decoding by 35% compared to standard intracranial signals. Accurate decoding was dependent on the high-spatial resolution of the neural interface. Non-linear decoding models designed to utilize enhanced spatio-temporal neural information produced better results than linear techniques. We show that high-density µECoG can enable high-quality speech decoding for future neural speech prostheses.
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Affiliation(s)
| | - Shervin Rahimpour
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA
- Department of Neurosurgery, Clinical Neuroscience Center, University of Utah, Salt Lake City, UT, USA
| | - Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Michael Trumpis
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Charles Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Katrina Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Stephen C Harward
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, USA
| | - Shivanand P Lad
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA
| | - Allan H Friedman
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA
| | - Derek G Southwell
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, USA
- Department of Neurobiology, Duke School of Medicine, Durham, NC, USA
| | - Saurabh R Sinha
- Penn Epilepsy Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA.
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, USA.
- Department of Neurobiology, Duke School of Medicine, Durham, NC, USA.
| | - Gregory B Cogan
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, USA.
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, USA.
- Department of Neurology, Duke School of Medicine, Durham, NC, USA.
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA.
- Center for Cognitive Neuroscience, Duke University, Durham, NC, USA.
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7
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Hu J, Hossain RF, Navabi ZS, Tillery A, Laroque M, Donaldson PD, Swisher SL, Kodandaramaiah SB. Fully desktop fabricated flexible graphene electrocorticography (ECoG) arrays. J Neural Eng 2023; 20:10.1088/1741-2552/acae08. [PMID: 36548995 PMCID: PMC10027363 DOI: 10.1088/1741-2552/acae08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/22/2022] [Indexed: 12/24/2022]
Abstract
Objective:Flexible Electrocorticography (ECoG) electrode arrays that conform to the cortical surface and record surface field potentials from multiple brain regions provide unique insights into how computations occurring in distributed brain regions mediate behavior. Specialized microfabrication methods are required to produce flexible ECoG devices with high-density electrode arrays. However, these fabrication methods are challenging for scientists without access to cleanroom fabrication equipment.Results:Here we present a fully desktop fabricated flexible graphene ECoG array. First, we synthesized a stable, conductive ink via liquid exfoliation of Graphene in Cyrene. Next, we established a stencil-printing process for patterning the graphene ink via laser-cut stencils on flexible polyimide substrates. Benchtop tests indicate that the graphene electrodes have good conductivity of ∼1.1 × 103S cm-1, flexibility to maintain their electrical connection under static bending, and electrochemical stability in a 15 d accelerated corrosion test. Chronically implanted graphene ECoG devices remain fully functional for up to 180 d, with averagein vivoimpedances of 24.72 ± 95.23 kΩ at 1 kHz. The ECoG device can measure spontaneous surface field potentials from mice under awake and anesthetized states and sensory stimulus-evoked responses.Significance:The stencil-printing fabrication process can be used to create Graphene ECoG devices with customized electrode layouts within 24 h using commonly available laboratory equipment.
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Affiliation(s)
- Jia Hu
- Department of Mechanical Engineering, University of Minnesota Twin Cities
| | | | - Zahra S. Navabi
- Department of Mechanical Engineering, University of Minnesota Twin Cities
| | | | - Michael Laroque
- Department of Mechanical Engineering, University of Minnesota Twin Cities
| | - Preston D. Donaldson
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities
| | - Sarah L. Swisher
- Department of Electrical and Computer Engineering, University of Minnesota Twin Cities
| | - Suhasa B. Kodandaramaiah
- Department of Mechanical Engineering, University of Minnesota Twin Cities
- Department of Biomedical Engineering, University of Minnesota Twin Cities
- Department of Neuroscience, University of Minnesota Twin Cities
- Send manuscript correspondence to: Suhasa B. Kodandaramaiah, Department of Mechanical Engineering, University of Minnesota, Twin Cities, Address: 111 Church St SE, Room 303, Minneapolis, MN 55455,
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8
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Witham NS, Reiche CF, Odell T, Barth K, Chiang CH, Wang C, Dubey A, Wingel K, Devore S, Friedman D, Pesaran B, Viventi J, Solzbacher F. Flexural bending to approximate cortical forces exerted by electrocorticography (ECoG) arrays. J Neural Eng 2022; 19:10.1088/1741-2552/ac8452. [PMID: 35882223 PMCID: PMC10002477 DOI: 10.1088/1741-2552/ac8452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/26/2022] [Indexed: 11/11/2022]
Abstract
Objective.The force that an electrocorticography (ECoG) array exerts on the brain manifests when it bends to match the curvature of the skull and cerebral cortex. This force can negatively impact both short-term and long-term patient outcomes. Here we provide a mechanical characterization of a novel liquid crystal polymer (LCP) ECoG array prototype to demonstrate that its thinner geometry reduces the force potentially applied to the cortex of the brain.Approach.We built a low-force flexural testing machine to measure ECoG array bending forces, calculate their effective flexural moduli, and approximate the maximum force they could exerted on the human brain.Main results.The LCP ECoG prototype was found to have a maximal force less than 20% that of any commercially available ECoG arrays that were tested. However, as a material, LCP was measured to be as much as 24× more rigid than silicone, which is traditionally used in ECoG arrays. This suggests that the lower maximal force resulted from the prototype's thinner profile (2.9×-3.25×).Significance.While decreasing material stiffness can lower the force an ECoG array exhibits, our LCP ECoG array prototype demonstrated that flexible circuit manufacturing techniques can also lower these forces by decreasing ECoG array thickness. Flexural tests of ECoG arrays are necessary to accurately assess these forces, as material properties for polymers and laminates are often scale dependent. As the polymers used are anisotropic, elastic modulus cannot be used to predict ECoG flexural behavior. Accounting for these factors, we used our four-point flexure testing procedure to quantify the forces exerted on the brain by ECoG array bending. With this experimental method, ECoG arrays can be designed to minimize force exerted on the brain, potentially improving both acute and chronic clinical utility.
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Affiliation(s)
- Nicholas S Witham
- The University of Utah, Salt Lake City, UT, United States of America
| | | | - Thomas Odell
- The University of Utah, Salt Lake City, UT, United States of America
| | - Katrina Barth
- Duke University, Durham, NC, United States of America
| | | | - Charles Wang
- Duke University, Durham, NC, United States of America
| | - Agrita Dubey
- New York University Grossman School of Medicine, New York City, NY, United States of America
| | - Katie Wingel
- New York University Grossman School of Medicine, New York City, NY, United States of America
| | - Sasha Devore
- New York University Grossman School of Medicine, New York City, NY, United States of America
| | - Daniel Friedman
- New York University Grossman School of Medicine, New York City, NY, United States of America
| | - Bijan Pesaran
- New York University, New York City, NY, United States of America
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9
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Mariello M, Kim K, Wu K, Lacour SP, Leterrier Y. Recent Advances in Encapsulation of Flexible Bioelectronic Implants: Materials, Technologies, and Characterization Methods. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201129. [PMID: 35353928 DOI: 10.1002/adma.202201129] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/13/2022] [Indexed: 06/14/2023]
Abstract
Bioelectronic implantable systems (BIS) targeting biomedical and clinical research should combine long-term performance and biointegration in vivo. Here, recent advances in novel encapsulations to protect flexible versions of such systems from the surrounding biological environment are reviewed, focusing on material strategies and synthesis techniques. Considerable effort is put on thin-film encapsulation (TFE), and specifically organic-inorganic multilayer architectures as a flexible and conformal alternative to conventional rigid cans. TFE is in direct contact with the biological medium and thus must exhibit not only biocompatibility, inertness, and hermeticity but also mechanical robustness, conformability, and compatibility with the manufacturing of microfabricated devices. Quantitative characterization methods of the barrier and mechanical performance of the TFE are reviewed with a particular emphasis on water-vapor transmission rate through electrical, optical, or electrochemical principles. The integrability and functionalization of TFE into functional bioelectronic interfaces are also discussed. TFE represents a must-have component for the next-generation bioelectronic implants with diagnostic or therapeutic functions in human healthcare and precision medicine.
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Affiliation(s)
- Massimo Mariello
- Laboratory for Processing of Advanced Composites (LPAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Kyungjin Kim
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Kangling Wu
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Stéphanie P Lacour
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Yves Leterrier
- Laboratory for Processing of Advanced Composites (LPAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
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10
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Cappotto D, Kang H, Li K, Melloni L, Schnupp J, Auksztulewicz R. Simultaneous mnemonic and predictive representations in the auditory cortex. Curr Biol 2022; 32:2548-2555.e5. [PMID: 35487221 DOI: 10.1016/j.cub.2022.04.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/03/2022] [Accepted: 04/08/2022] [Indexed: 11/26/2022]
Abstract
Recent studies have shown that stimulus history can be decoded via the use of broadband sensory impulses to reactivate mnemonic representations.1-4. However, memories of previous stimuli can also be used to form sensory predictions about upcoming stimuli.5,6 Predictive mechanisms allow the brain to create a probable model of the outside world, which can be updated when errors are detected between the model predictions and external inputs. 7-10 Direct recordings in the auditory cortex of awake mice established neural mechanisms for how encoding mechanisms might handle working memory and predictive processes without "overwriting" recent sensory events in instances where predictive mechanisms are triggered by oddballs within a sequence.11 However, it remains unclear whether mnemonic and predictive information can be decoded from cortical activity simultaneously during passive, implicit sequence processing, even in anesthetized models. Here, we recorded neural activity elicited by repeated stimulus sequences using electrocorticography (ECoG) in the auditory cortex of anesthetized rats, where events within the sequence (referred to henceforth as "vowels," for simplicity) were occasionally replaced with a broadband noise burst or omitted entirely. We show that both stimulus history and predicted stimuli can be decoded from neural responses to broadband impulses, at overlapping latencies but based on independent and uncorrelated data features. We also demonstrate that predictive representations are dynamically updated over the course of stimulation.
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Affiliation(s)
- Drew Cappotto
- Department of Neuroscience, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong Kong.
| | - HiJee Kang
- Department of Neuroscience, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong Kong
| | - Kongyan Li
- Department of Neuroscience, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong Kong
| | - Lucia Melloni
- Neural Circuits, Consciousness and Cognition Research Group, Max Planck Institute for Empirical Aesthetics, Grüneburgweg 14, 60322 Frankfurt am Main, Germany
| | - Jan Schnupp
- Department of Neuroscience, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong Kong
| | - Ryszard Auksztulewicz
- Department of Neuroscience, City University of Hong Kong, 31 To Yuen Street, Kowloon Tong, Hong Kong; Neural Circuits, Consciousness and Cognition Research Group, Max Planck Institute for Empirical Aesthetics, Grüneburgweg 14, 60322 Frankfurt am Main, Germany; European Neuroscience Institute Göttingen: A Joint Initiative of the University Medical Center Göttingen and the Max Planck Society, Grisebachstraße 5, 37077 Göttingen, Germany
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11
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Yun S, Koh CS, Seo J, Shim S, Park M, Jung HH, Eom K, Chang JW, Kim SJ. A Fully Implantable Miniaturized Liquid Crystal Polymer (LCP)-Based Spinal Cord Stimulator for Pain Control. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22020501. [PMID: 35062462 PMCID: PMC8778878 DOI: 10.3390/s22020501] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 05/09/2023]
Abstract
Spinal cord stimulation is a therapy to treat the severe neuropathic pain by suppressing the pain signal via electrical stimulation of the spinal cord. The conventional metal packaged and battery-operated implantable pulse generator (IPG) produces electrical pulses to stimulate the spinal cord. Despite its stable operation after implantation, the implantation site is limited due to its bulky size and heavy weight. Wireless communications including wireless power charging is also restricted, which is mainly attributed to the electromagnetic shielding of the metal package. To overcome these limitations, here, we developed a fully implantable miniaturized spinal cord stimulator based on a biocompatible liquid crystal polymer (LCP). The fabrication of electrode arrays in the LCP substrate and monolithically encapsulating the circuitries using LCP packaging reduces the weight (0.4 g) and the size (the width, length, and thickness are 25.3, 9.3, and 1.9 mm, respectively). An inductive link was utilized to wirelessly transfer the power and the data to implanted circuitries to generate the stimulus pulse. Prior to implantation of the device, operation of the pulse generator was evaluated, and characteristics of stimulation electrode such as an electrochemical impedance spectroscopy (EIS) were measured. The LCP-based spinal cord stimulator was implanted into the spared nerve injury rat model. The degree of pain suppression upon spinal cord stimulation was assessed via the Von Frey test where the mechanical stimulation threshold was evaluated by monitoring the paw withdrawal responses. With no spinal cord stimulation, the mechanical stimulation threshold was observed as 1.47 ± 0.623 g, whereas the stimulation threshold was increased to 12.7 ± 4.00 g after spinal cord stimulation, confirming the efficacy of pain suppression via electrical stimulation of the spinal cord. This LCP-based spinal cord stimulator opens new avenues for the development of a miniaturized but still effective spinal cord stimulator.
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Affiliation(s)
- Seunghyeon Yun
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Chin Su Koh
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Jungmin Seo
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Minkyung Park
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Hyun Ho Jung
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
- Correspondence: (K.E.); (J.W.C.)
| | - Jin Woo Chang
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
- Correspondence: (K.E.); (J.W.C.)
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
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12
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Schweigmann M, Caudal LC, Stopper G, Scheller A, Koch KP, Kirchhoff F. Versatile Surface Electrodes for Combined Electrophysiology and Two-Photon Imaging of the Mouse Central Nervous System. Front Cell Neurosci 2021; 15:720675. [PMID: 34447299 PMCID: PMC8383317 DOI: 10.3389/fncel.2021.720675] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/19/2021] [Indexed: 11/23/2022] Open
Abstract
Understanding and modulating CNS function in physiological as well as pathophysiological contexts remains a significant ambition in research and clinical applications. The investigation of the multifaceted CNS cell types including their interactions and contributions to neural function requires a combination of the state-of-the-art in vivo electrophysiology and imaging techniques. We developed a novel type of liquid crystal polymer (LCP) surface micro-electrode manufactured in three customized designs with up to 16 channels for recording and stimulation of brain activity. All designs include spare central spaces for simultaneous 2P-imaging. Nanoporous platinum-plated contact sites ensure a low impedance and high current transfer. The epidural implantation of the LCP micro-electrodes could be combined with standard cranial window surgery. The epidurally positioned electrodes did not only display long-term biocompatibility, but we also observed an additional stabilization of the underlying CNS tissue. We demonstrate the electrode’s versatility in combination with in vivo 2P-imaging by monitoring anesthesia-awake cycles of transgenic mice with GCaMP3 expression in neurons or astrocytes. Cortical stimulation and simultaneous 2P Ca2+ imaging in neurons or astrocytes highlighted the astrocytes’ integrative character in neuronal activity processing. Furthermore, we confirmed that spontaneous astroglial Ca2+ signals are dampened under anesthesia, while evoked signals in neurons and astrocytes showed stronger dependency on stimulation intensity rather than on various levels of anesthesia. Finally, we show that the electrodes provide recordings of the electrocorticogram (ECoG) with a high signal-to noise ratio and spatial signal differences which help to decipher brain activity states during experimental procedures. Summarizing, the novel LCP surface micro-electrode is a versatile, convenient, and reliable tool to investigate brain function in vivo.
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Affiliation(s)
- Michael Schweigmann
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.,Department of Electrical Engineering, Trier University of Applied Sciences, Trier, Germany
| | - Laura C Caudal
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Gebhard Stopper
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Klaus P Koch
- Department of Electrical Engineering, Trier University of Applied Sciences, Trier, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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13
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Chiang CH, Won SM, Orsborn AL, Yu KJ, Trumpis M, Bent B, Wang C, Xue Y, Min S, Woods V, Yu C, Kim BH, Kim SB, Huq R, Li J, Seo KJ, Vitale F, Richardson A, Fang H, Huang Y, Shepard K, Pesaran B, Rogers JA, Viventi J. Development of a neural interface for high-definition, long-term recording in rodents and nonhuman primates. Sci Transl Med 2021; 12:12/538/eaay4682. [PMID: 32269166 DOI: 10.1126/scitranslmed.aay4682] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 02/28/2020] [Indexed: 12/25/2022]
Abstract
Long-lasting, high-resolution neural interfaces that are ultrathin and flexible are essential for precise brain mapping and high-performance neuroprosthetic systems. Scaling to sample thousands of sites across large brain regions requires integrating powered electronics to multiplex many electrodes to a few external wires. However, existing multiplexed electrode arrays rely on encapsulation strategies that have limited implant lifetimes. Here, we developed a flexible, multiplexed electrode array, called "Neural Matrix," that provides stable in vivo neural recordings in rodents and nonhuman primates. Neural Matrix lasts over a year and samples a centimeter-scale brain region using over a thousand channels. The long-lasting encapsulation (projected to last at least 6 years), scalable device design, and iterative in vivo optimization described here are essential components to overcoming current hurdles facing next-generation neural technologies.
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Affiliation(s)
- Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
| | - Sang Min Won
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Amy L Orsborn
- Center for Neural Science, New York University, New York, NY 10003, USA.,Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195, USA.,Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Ki Jun Yu
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Michael Trumpis
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Brinnae Bent
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Charles Wang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Yeguang Xue
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Seunghwan Min
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Virginia Woods
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Chunxiu Yu
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.,Department of Biological Science, Michigan Technological University, Houghton, MI 49931, USA
| | - Bong Hoon Kim
- Department of Organic Materials and Fiber Engineering, Soongsil University, Seoul 06978, Republic of Korea.,Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University, Seoul 06978, Republic of Korea
| | - Sung Bong Kim
- Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Rizwan Huq
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Jinghua Li
- Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Department of Materials Science and Engineering, Center for Chronic Brain Injury, The Ohio State University, Columbus, OH 43210, USA
| | - Kyung Jin Seo
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA
| | - Flavia Vitale
- Department of Neurology, Department of Bioengineering, Department of Physical Medicine & Rehabilitation, Center for Neuroengineering and Therapeutics, University of Pennsylvania, PA 19104, USA.,Center of Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA 19104, USA
| | - Andrew Richardson
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hui Fang
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115, USA
| | - Yonggang Huang
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA.,Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Center for Bio-integrated Electronics, Northwestern University, Evanston, IL 60208, USA
| | - Kenneth Shepard
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA.,Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - Bijan Pesaran
- Center for Neural Science, New York University, New York, NY 10003, USA. .,Department of Neurology, NYU Langone Health, New York, NY 10016, USA
| | - John A Rogers
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA. .,Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA.,Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Center for Bio-integrated Electronics, Northwestern University, Evanston, IL 60208, USA.,Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.,Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA. .,Department of Neurobiology, Duke University, Durham, NC 27708, USA.,Department of Neurosurgery, Duke University, Durham, NC 27708, USA
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14
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Chiang CH, Wang C, Barth K, Rahimpour S, Trumpis M, Duraivel S, Rachinskiy I, Dubey A, Wingel KE, Wong M, Witham NS, Odell T, Woods V, Bent B, Doyle W, Friedman D, Bihler E, Reiche CF, Southwell DG, Haglund MM, Friedman AH, Lad SP, Devore S, Devinsky O, Solzbacher F, Pesaran B, Cogan G, Viventi J. Flexible, high-resolution thin-film electrodes for human and animal neural research. J Neural Eng 2021; 18:10.1088/1741-2552/ac02dc. [PMID: 34010815 PMCID: PMC8496685 DOI: 10.1088/1741-2552/ac02dc] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 05/19/2021] [Indexed: 11/11/2022]
Abstract
Objective.Brain functions such as perception, motor control, learning, and memory arise from the coordinated activity of neuronal assemblies distributed across multiple brain regions. While major progress has been made in understanding the function of individual neurons, circuit interactions remain poorly understood. A fundamental obstacle to deciphering circuit interactions is the limited availability of research tools to observe and manipulate the activity of large, distributed neuronal populations in humans. Here we describe the development, validation, and dissemination of flexible, high-resolution, thin-film (TF) electrodes for recording neural activity in animals and humans.Approach.We leveraged standard flexible printed-circuit manufacturing processes to build high-resolution TF electrode arrays. We used biocompatible materials to form the substrate (liquid crystal polymer; LCP), metals (Au, PtIr, and Pd), molding (medical-grade silicone), and 3D-printed housing (nylon). We designed a custom, miniaturized, digitizing headstage to reduce the number of cables required to connect to the acquisition system and reduce the distance between the electrodes and the amplifiers. A custom mechanical system enabled the electrodes and headstages to be pre-assembled prior to sterilization, minimizing the setup time required in the operating room. PtIr electrode coatings lowered impedance and enabled stimulation. High-volume, commercial manufacturing enables cost-effective production of LCP-TF electrodes in large quantities.Main Results. Our LCP-TF arrays achieve 25× higher electrode density, 20× higher channel count, and 11× reduced stiffness than conventional clinical electrodes. We validated our LCP-TF electrodes in multiple human intraoperative recording sessions and have disseminated this technology to >10 research groups. Using these arrays, we have observed high-frequency neural activity with sub-millimeter resolution.Significance.Our LCP-TF electrodes will advance human neuroscience research and improve clinical care by enabling broad access to transformative, high-resolution electrode arrays.
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Affiliation(s)
- Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
- These authors contributed equally to this work
| | - Charles Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
- These authors contributed equally to this work
| | - Katrina Barth
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Shervin Rahimpour
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
| | - Michael Trumpis
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | | | - Iakov Rachinskiy
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Agrita Dubey
- Center for Neural Science, New York University, NY, NY, United States of America
| | - Katie E Wingel
- Center for Neural Science, New York University, NY, NY, United States of America
| | - Megan Wong
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Nicholas S Witham
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States of America
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Thomas Odell
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Virginia Woods
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Brinnae Bent
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
| | - Werner Doyle
- Department of Neurosurgery, NYU Langone Medical Center, New York City, NY, United States of America
| | - Daniel Friedman
- Department of Neurology, NYU Grossman School of Medicine, NY, NY, United States of America
| | | | - Christopher F Reiche
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Derek G Southwell
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
| | - Michael M Haglund
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
| | - Allan H Friedman
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
| | - Shivanand P Lad
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
| | - Sasha Devore
- Department of Neurology, NYU Grossman School of Medicine, NY, NY, United States of America
| | - Orrin Devinsky
- Department of Neurosurgery, NYU Langone Medical Center, New York City, NY, United States of America
- Department of Neurology, NYU Grossman School of Medicine, NY, NY, United States of America
- Comprehensive Epilepsy Center, NYU Langone Health, NY, NY, United States of America
| | - Florian Solzbacher
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States of America
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States of America
- Department of Materials Science & Engineering, University of Utah, Salt Lake City, UT, United States of America
| | - Bijan Pesaran
- Center for Neural Science, New York University, NY, NY, United States of America
- Department of Neurology, NYU Grossman School of Medicine, NY, NY, United States of America
| | - Gregory Cogan
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
- Department of Psychology and Neuroscience, Duke University, Durham, NC, United States of America
- Center for Cognitive Neuroscience, Duke University, Durham, NC, United States of America
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, United States of America
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
- Department of Neurosurgery, Duke School of Medicine, Durham, NC, United States of America
- Department of Neurobiology, Duke School of Medicine, Durham, NC, United States of America
- Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC, United States of America
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15
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Cappotto D, Auksztulewicz R, Kang H, Poeppel D, Melloni L, Schnupp J. Decoding the Content of Auditory Sensory Memory Across Species. Cereb Cortex 2021; 31:3226-3236. [PMID: 33625488 DOI: 10.1093/cercor/bhab002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/08/2020] [Accepted: 01/03/2021] [Indexed: 02/06/2023] Open
Abstract
In contrast to classical views of working memory (WM) maintenance, recent research investigating activity-silent neural states has demonstrated that persistent neural activity in sensory cortices is not necessary for active maintenance of information in WM. Previous studies in humans have measured putative memory representations indirectly, by decoding memory contents from neural activity evoked by a neutral impulse stimulus. However, it is unclear whether memory contents can also be decoded in different species and attentional conditions. Here, we employ a cross-species approach to test whether auditory memory contents can be decoded from electrophysiological signals recorded in different species. Awake human volunteers (N = 21) were exposed to auditory pure tone and noise burst stimuli during an auditory sensory memory task using electroencephalography. In a closely matching paradigm, anesthetized female rats (N = 5) were exposed to comparable stimuli while neural activity was recorded using electrocorticography from the auditory cortex. In both species, the acoustic frequency could be decoded from neural activity evoked by pure tones as well as neutral frozen noise burst stimuli. This finding demonstrates that memory contents can be decoded in different species and different states using homologous methods, suggesting that the mechanisms of sensory memory encoding are evolutionarily conserved across species.
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Affiliation(s)
- Drew Cappotto
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Ryszard Auksztulewicz
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong.,Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, 60322 Frankfurt am Main, Germany
| | - HiJee Kang
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - David Poeppel
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, 60322 Frankfurt am Main, Germany
| | - Lucia Melloni
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, 60322 Frankfurt am Main, Germany
| | - Jan Schnupp
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
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16
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Evaluation methods for long-term reliability of polymer-based implantable biomedical devices. Biomed Eng Lett 2021; 11:97-105. [PMID: 34150346 DOI: 10.1007/s13534-021-00188-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/24/2021] [Accepted: 04/05/2021] [Indexed: 01/04/2023] Open
Abstract
Long-term reliability of implantable biomedical devices is a critical issue for their practical usefulness and successful translation into clinical application. Reliability is particularly of great concern for recently demonstrated devices based on new materials typically relying on polymeric thin films and microfabrication process. While reliability testing protocol has been well-established for traditional metallic packages, common evaluation methods for polymer-based microdevices has yet to be agreed upon, even though various testing methods have been proposed. This article is aiming to summarize the evaluation methods on long-term reliability of emerging biomedical implants based on polymeric thin-films in terms of their theories and implementation with specific focus on difference from the traditional metallic packages.
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17
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Kaiju T, Inoue M, Hirata M, Suzuki T. High-density mapping of primate digit representations with a 1152-channel µECoG array. J Neural Eng 2021; 18. [PMID: 33530064 DOI: 10.1088/1741-2552/abe245] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/02/2021] [Indexed: 12/11/2022]
Abstract
Objective.Advances in brain-machine interfaces (BMIs) are expected to support patients with movement disorders. Electrocorticogram (ECoG) measures electrophysiological activities over a large area using a low-invasive flexible sheet placed on the cortex. ECoG has been considered as a feasible signal source of the clinical BMI device. To capture neural activities more precisely, the feasibility of higher-density arrays has been investigated. However, currently, the number of electrodes is limited to approximately 300 due to wiring difficulties, device size, and system costs.Approach.We developed a high-density recording system with a large coverage (14 × 7 mm2) and using 1152 electrodes by directly integrating dedicated flexible arrays with the neural-recording application-specific integrated circuits and their interposers.Main results.Comparative experiments with a 128-channel array demonstrated that the proposed device could delineate the entire digit representation of a nonhuman primate. Subsampling analysis revealed that higher-amplitude signals can be measured using higher-density arrays.Significance.We expect that the proposed system that simultaneously establishes large-scale sampling, high temporal-precision of electrophysiology, and high spatial resolution comparable to optical imaging will be suitable for next-generation brain-sensing technology.
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Affiliation(s)
- Taro Kaiju
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan
| | - Masato Inoue
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.,Department of Neurological Diagnosis and Restoration, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Masayuki Hirata
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.,Department of Neurological Diagnosis and Restoration, Osaka University Graduate School of Medicine, Osaka, Japan
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18
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Kang H, Auksztulewicz R, An H, Abi Chacra N, Sutter ML, Schnupp JWH. Neural Correlates of Auditory Pattern Learning in the Auditory Cortex. Front Neurosci 2021; 15:610978. [PMID: 33790730 PMCID: PMC8005649 DOI: 10.3389/fnins.2021.610978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 02/23/2021] [Indexed: 11/13/2022] Open
Abstract
Learning of new auditory stimuli often requires repetitive exposure to the stimulus. Fast and implicit learning of sounds presented at random times enables efficient auditory perception. However, it is unclear how such sensory encoding is processed on a neural level. We investigated neural responses that are developed from a passive, repetitive exposure to a specific sound in the auditory cortex of anesthetized rats, using electrocorticography. We presented a series of random sequences that are generated afresh each time, except for a specific reference sequence that remains constant and re-appears at random times across trials. We compared induced activity amplitudes between reference and fresh sequences. Neural responses from both primary and non-primary auditory cortical regions showed significantly decreased induced activity amplitudes for reference sequences compared to fresh sequences, especially in the beta band. This is the first study showing that neural correlates of auditory pattern learning can be evoked even in anesthetized, passive listening animal models.
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Affiliation(s)
- Hijee Kang
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Ryszard Auksztulewicz
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong.,Neuroscience Department, Max Planck Institute for Empirical Aesthetics, Frankfurt, Germany
| | - Hyunjung An
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Nicolas Abi Chacra
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Mitchell L Sutter
- Center for Neuroscience and Section of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Jan W H Schnupp
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
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19
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Trumpis M, Chiang CH, Orsborn AL, Bent B, Li J, Rogers JA, Pesaran B, Cogan G, Viventi J. Sufficient sampling for kriging prediction of cortical potential in rat, monkey, and human µECoG. J Neural Eng 2021; 18. [PMID: 33326943 DOI: 10.1088/1741-2552/abd460] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 12/16/2020] [Indexed: 12/22/2022]
Abstract
Objective. Large channel count surface-based electrophysiology arrays (e.g. µECoG) are high-throughput neural interfaces with good chronic stability. Electrode spacing remains ad hoc due to redundancy and nonstationarity of field dynamics. Here, we establish a criterion for electrode spacing based on the expected accuracy of predicting unsampled field potential from sampled sites.Approach. We applied spatial covariance modeling and field prediction techniques based on geospatial kriging to quantify sufficient sampling for thousands of 500 ms µECoG snapshots in human, monkey, and rat. We calculated a probably approximately correct (PAC) spacing based on kriging that would be required to predict µECoG fields at≤10% error for most cases (95% of observations).Main results. Kriging theory accurately explained the competing effects of electrode density and noise on predicting field potential. Across five frequency bands from 4-7 to 75-300 Hz, PAC spacing was sub-millimeter for auditory cortex in anesthetized and awake rats, and posterior superior temporal gyrus in anesthetized human. At 75-300 Hz, sub-millimeter PAC spacing was required in all species and cortical areas.Significance. PAC spacing accounted for the effect of signal-to-noise on prediction quality and was sensitive to the full distribution of non-stationary covariance states. Our results show that µECoG arrays should sample at sub-millimeter resolution for applications in diverse cortical areas and for noise resilience.
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Affiliation(s)
- Michael Trumpis
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America
| | - Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America
| | - Amy L Orsborn
- Center for Neural Science, New York University, New York, NY 10003, United States of America.,Department of Electrical & Computer Engineering, University of Washington, Seattle, WA 98195, United States of America.,Department of Bioengineering, University of Washington, Seattle, Washington 98105, United States of America.,Washington National Primate Research Center, Seattle, Washington 98195, United States of America
| | - Brinnae Bent
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America
| | - Jinghua Li
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States of America.,Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210, United States of America.,Chronic Brain Injury Program, The Ohio State University, Columbus, OH 43210, United States of America
| | - John A Rogers
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States of America.,Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, United States of America.,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, United States of America.,Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America
| | - Bijan Pesaran
- Center for Neural Science, New York University, New York, NY 10003, United States of America
| | - Gregory Cogan
- Department of Neurosurgery, Duke School of Medicine, Durham, NC 27710, United States of America.,Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, United States of America.,Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, United States of America.,Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC 27710, United States of America
| | - Jonathan Viventi
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America.,Department of Neurosurgery, Duke School of Medicine, Durham, NC 27710, United States of America.,Duke Comprehensive Epilepsy Center, Duke School of Medicine, Durham, NC 27710, United States of America.,Department of Neurobiology, Duke School of Medicine, Durham, NC 27710, United States of America
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Rihani R, Tasnim N, Javed M, Usoro JO, D'Souza TM, Ware TH, Pancrazio JJ. Liquid Crystalline Polymers: Opportunities to Shape Neural Interfaces. Neuromodulation 2021; 25:1259-1267. [PMID: 33501705 DOI: 10.1111/ner.13364] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/21/2020] [Accepted: 01/05/2021] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Polymers have emerged as constituent materials for the creation of microscale neural interfaces; however, limitations regarding water permeability, delamination, and material degradation impact polymeric device robustness. Liquid crystal polymers (LCPs) have molecular order like a solid but with the fluidity of a liquid, resulting in a unique material, with properties including low water permeability, chemical inertness, and mechanical toughness. The objective of this article is to review the state-of-the-art regarding the use of LCPs in neural interface applications and discuss challenges and opportunities where this class of materials can advance the field of neural interfaces. MATERIALS AND METHODS This review article focuses on studies that leverage LCP materials to interface with the nervous system in vivo. A comprehensive literature search was performed using PubMed, Web of Science (Clarivate Analytics), and Google Scholar. RESULTS There have been recent efforts to create neural interfaces that leverage the material advantages of LCPs. The literature offers examples of LCP as a basis for implantable medical devices and neural interfaces in the form of planar electrode arrays for retinal prosthetic, electrocorticography applications, and cuff-like structures for interfacing the peripheral nerve. In addition, there have been efforts to create penetrating intracortical devices capable of microstimulation and resolution of biopotentials. Recent work with a subclass of LCPs, namely liquid crystal elastomers, demonstrates that it is possible to create devices with features that deploy away from a central implantation site to interface with a volume of tissue while offering the possibility of minimizing tissue damage. CONCLUSION We envision the creation of novel microscale neural interfaces that leverage the physical properties of LCPs and have the capability of deploying within neural tissue for enhanced integration and performance.
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Affiliation(s)
- Rashed Rihani
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Nishat Tasnim
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Mahjabeen Javed
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Joshua O Usoro
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Tania M D'Souza
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA.,Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA.,Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Joseph J Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
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Ding D, Lu Y, Zhao R, Liu X, De-Eknamkul C, Ren C, Mehrsa A, Komiyama T, Kuzum D. Evaluation of Durability of Transparent Graphene Electrodes Fabricated on Different Flexible Substrates for Chronic In Vivo Experiments. IEEE Trans Biomed Eng 2020; 67:3203-3210. [PMID: 32191878 PMCID: PMC8560430 DOI: 10.1109/tbme.2020.2979475] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To investigate chronic durability of transparent graphene electrodes fabricated on polyethylene terephthalate (PET) and SU-8 substrates for chronic in vivo studies. METHODS We perform systematic accelerated aging tests to understand the chronic reliability and failure modes of transparent graphene microelectrode arrays built on PET and SU-8 substrates. We employ graphene microelectrodes fabricated on PET substrate in chronic in vivo experiments with transgenic mice. RESULTS Our results show that graphene microelectrodes fabricated on PET substrate work reliably after 30 days accelerated aging test performed at 87 °C, equivalent to 960 days in vivo lifetime. We demonstrate stable chronic recordings of cortical potentials in multimodal imaging/recording experiments using transparent graphene microelectrodes fabricated on PET substrate. On the other hand, graphene microelectrode arrays built on SU-8 substrate exhibit extensive crack formation across microelectrode sites and wires after one to two weeks, resulting in total failure of recording capability for chronic studies. CONCLUSION PET shows superior reliability as a substrate for graphene microelectrode arrays for chronic in vivo experiments. SIGNIFICANCE Graphene is a unique neural interface material enabling cross-talk free integration of electrical and optical recording and stimulation techniques in the same experiment. To date, graphene-based microelectrode arrays have been demonstrated in various multi-modal acute experiments involving electrophysiological sensing or stimulation, optical imaging and optogenetics stimulation. Understanding chronic reliability of graphene-based transparent interfaces is very important to expand the use of this technology for long-term behavioral studies with animal models.
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22
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Boehler C, Carli S, Fadiga L, Stieglitz T, Asplund M. Tutorial: guidelines for standardized performance tests for electrodes intended for neural interfaces and bioelectronics. Nat Protoc 2020; 15:3557-3578. [DOI: 10.1038/s41596-020-0389-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/28/2020] [Indexed: 01/22/2023]
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23
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França AS, van Hulten JA, Cohen MX. Low-cost and versatile electrodes for extracellular chronic recordings in rodents. Heliyon 2020; 6:e04867. [PMID: 32984592 PMCID: PMC7492997 DOI: 10.1016/j.heliyon.2020.e04867] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/04/2020] [Accepted: 09/04/2020] [Indexed: 11/19/2022] Open
Abstract
Electrophysiological data are used to investigate fundamental properties of brain function, its relation to cognition, and its dysfunction in diseases. The development of reliable and open-source systems for electrophysiological data acquisition is decreasing the total cost of constructing and operating an electrophysiology laboratory, and facilitates low-cost methods to extract and analyze the data (Siegle et al., 2017). Here we detail our method of building custom-designed low-cost electrodes. These electrodes can be customized and manufactured by any researcher to address a broad set of research questions, further decreasing the final cost of an implanted animal. Finally, we present data showing such an electrode has a good signal quality to record LFP.
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24
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Zhao J, Ghannam R, Htet KO, Liu Y, Law M, Roy VAL, Michel B, Imran MA, Heidari H. Self-Powered Implantable Medical Devices: Photovoltaic Energy Harvesting Review. Adv Healthc Mater 2020; 9:e2000779. [PMID: 32729228 DOI: 10.1002/adhm.202000779] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/09/2020] [Indexed: 12/21/2022]
Abstract
Implantable technologies are becoming more widespread for biomedical applications that include physical identification, health diagnosis, monitoring, recording, and treatment of human physiological traits. However, energy harvesting and power generation beneath the human tissue are still a major challenge. In this regard, self-powered implantable devices that scavenge energy from the human body are attractive for long-term monitoring of human physiological traits. Thanks to advancements in material science and nanotechnology, energy harvesting techniques that rely on piezoelectricity, thermoelectricity, biofuel, and radio frequency power transfer are emerging. However, all these techniques suffer from limitations that include low power output, bulky size, or low efficiency. Photovoltaic (PV) energy conversion is one of the most promising candidates for implantable applications due to their higher-power conversion efficiencies and small footprint. Herein, the latest implantable energy harvesting technologies are surveyed. A comparison between the different state-of-the-art power harvesting methods is also provided. Finally, recommendations are provided regarding the feasibility of PV cells as an in vivo energy harvester, with an emphasis on skin penetration, fabrication, encapsulation, durability, biocompatibility, and power management.
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Affiliation(s)
- Jinwei Zhao
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Rami Ghannam
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Kaung Oo Htet
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Yuchi Liu
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Man‐kay Law
- State Key Laboratory of Analog and Mixed‐Signal VLSI AMSV University of Macao Macao China
| | | | - Bruno Michel
- Smart System Integration IBM Research GmbH Rueschlikon CH‐8803 Switzerland
| | - Muhammad Ali Imran
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Hadi Heidari
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
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25
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Chiang CH, Lee J, Wang C, Williams AJ, Lucas TH, Cohen YE, Viventi J. A modular high-density μECoG system on macaque vlPFC for auditory cognitive decoding. J Neural Eng 2020; 17:046008. [PMID: 32498058 DOI: 10.1088/1741-2552/ab9986] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE A fundamental goal of the auditory system is to parse the auditory environment into distinct perceptual representations. Auditory perception is mediated by the ventral auditory pathway, which includes the ventrolateral prefrontal cortex (vlPFC). Because large-scale recordings of auditory signals are quite rare, the spatiotemporal resolution of the neuronal code that underlies vlPFC's contribution to auditory perception has not been fully elucidated. Therefore, we developed a modular, chronic, high-resolution, multi-electrode array system with long-term viability in order to identify the information that could be decoded from μECoG vlPFC signals. APPROACH We molded three separate μECoG arrays into one and implanted this system in a non-human primate. A custom 3D-printed titanium chamber was mounted on the left hemisphere. The molded 294-contact μECoG array was implanted subdurally over the vlPFC. μECoG activity was recorded while the monkey participated in a 'hearing-in-noise' task in which they reported hearing a 'target' vocalization from a background 'chorus' of vocalizations. We titrated task difficulty by varying the sound level of the target vocalization, relative to the chorus (target-to-chorus ratio, TCr). MAIN RESULTS We decoded the TCr and the monkey's behavioral choices from the μECoG signal. We analyzed decoding accuracy as a function of number of electrodes, spatial resolution, and time from implantation. Over a one-year period, we found significant decoding with individual electrodes that increased significantly as we decoded simultaneously more electrodes. Further, we found that the decoding for behavioral choice was better than the decoding of TCr. Finally, because the decoding accuracy of individual electrodes varied on a day-by-day basis, electrode arrays with high channel counts ensure robust decoding in the long term. SIGNIFICANCE Our results demonstrate the utility of high-resolution and high-channel-count, chronic µECoG recording. We developed a surface electrode array that can be scaled to cover larger cortical areas without increasing the chamber footprint.
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Affiliation(s)
- Chia-Han Chiang
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America. These authors contributed equally to this work
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26
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Chong H, Majerus SJ, Bogie KM, Zorman CA. Non‐hermetic packaging of biomedical microsystems from a materials perspective: A review. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/mds3.10082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Hao Chong
- Department of Electrical, Computer, and Systems Engineering Case Western Reserve University Cleveland OH USA
| | | | - Kath M. Bogie
- APT Center Louis Stokes VA Medical Center Cleveland OH USA
- Department of Orthopaedics Case Western Reserve University School of Medicine Cleveland OH USA
| | - Christian A. Zorman
- Department of Electrical, Computer, and Systems Engineering Case Western Reserve University Cleveland OH USA
- APT Center Louis Stokes VA Medical Center Cleveland OH USA
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27
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Fallegger F, Schiavone G, Lacour SP. Conformable Hybrid Systems for Implantable Bioelectronic Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903904. [PMID: 31608508 DOI: 10.1002/adma.201903904] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/20/2019] [Indexed: 05/27/2023]
Abstract
Conformable bioelectronic systems are promising tools that may aid the understanding of diseases, alleviate pathological symptoms such as chronic pain, heart arrhythmia, and dysfunctions, and assist in reversing conditions such as deafness, blindness, and paralysis. Combining reduced invasiveness with advanced electronic functions, hybrid bioelectronic systems have evolved tremendously in the last decade, pushed by progress in materials science, micro- and nanofabrication, system assembly and packaging, and biomedical engineering. Hybrid integration refers here to a technological approach to embed within mechanically compliant carrier substrates electronic components and circuits prepared with traditional electronic materials. This combination leverages mechanical and electronic performance of polymer substrates and device materials, respectively, and offers many opportunities for man-made systems to communicate with the body with unmet precision. However, trade-offs between materials selection, manufacturing processes, resolution, electrical function, mechanical integrity, biointegration, and reliability should be considered. Herein, prominent trends in manufacturing conformable hybrid systems are analyzed and key design, function, and validation principles are outlined together with the remaining challenges to produce reliable conformable, hybrid bioelectronic systems.
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Affiliation(s)
- Florian Fallegger
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
| | - Giuseppe Schiavone
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
| | - Stéphanie P Lacour
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne, 1202, Geneva, Switzerland
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28
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An H, Auksztulewicz R, Kang H, Schnupp JWH. Cortical mapping of mismatch responses to independent acoustic features. Hear Res 2020; 399:107894. [PMID: 31987647 DOI: 10.1016/j.heares.2020.107894] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 11/30/2022]
Abstract
Predictive coding is an influential theory of neural processing underlying perceptual inference. However, it is unknown to what extent prediction violations of different sensory features are mediated in different regions in auditory cortex, with different dynamics, and by different mechanisms. This study investigates the neural responses to synthesized acoustic syllables, which could be expected or unexpected, along several features. By using electrocorticography (ECoG) in rat auditory cortex (subjects: adult female Wistar rats with normal hearing), we aimed at mapping regional differences in mismatch responses to different stimulus features. Continuous streams of morphed syllables formed roving oddball sequences in which each stimulus was repeated several times (thereby forming a standard) and subsequently replaced with a deviant stimulus which differed from the standard along one of several acoustic features: duration, pitch, interaural level differences (ILD), or consonant identity. Each of these features could assume one of several different levels, and the resulting change from standard to deviant could be larger or smaller. The deviant stimuli were then repeated to form new standards. We analyzed responses to the first repetition of a new stimulus (deviant) and its last repetition in a stimulus train (standard). For the ECoG recording, we implanted urethane-anaesthetized rats with 8 × 8 surface electrode arrays covering a 3 × 3 mm cortical patch encompassing primary and higher-order auditory cortex. We identified the response topographies and latencies of population activity evoked by acoustic stimuli in the rat auditory regions, and mapped their sensitivity to expectation violations along different acoustic features. For all features, the responses to deviant stimuli increased in amplitude relative to responses to standard stimuli. Deviance magnitude did not further modulate these mismatch responses. Mismatch responses to different feature violations showed a heterogeneous distribution across cortical areas, with no evidence for systematic topographic gradients for any of the tested features. However, within rats, the spatial distribution of mismatch responses varied more between features than the spatial distribution of tone-evoked responses. This result supports the notion that prediction error signaling along different stimulus features is subserved by different cortical populations, albeit with substantial heterogeneity across individuals.
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Affiliation(s)
- HyunJung An
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong
| | - Ryszard Auksztulewicz
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong; Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Frankfurt, Germany
| | - HiJee Kang
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong
| | - Jan W H Schnupp
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong.
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Yang W, Gong Y, Li W. A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants. Front Bioeng Biotechnol 2020; 8:622923. [PMID: 33585422 PMCID: PMC7873964 DOI: 10.3389/fbioe.2020.622923] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/10/2020] [Indexed: 01/28/2023] Open
Abstract
To date, a wide variety of neural tissue implants have been developed for neurophysiology recording from living tissues. An ideal neural implant should minimize the damage to the tissue and perform reliably and accurately for long periods of time. Therefore, the materials utilized to fabricate the neural recording implants become a critical factor. The materials of these devices could be classified into two broad categories: electrode materials as well as packaging and substrate materials. In this review, inorganic (metals and semiconductors), organic (conducting polymers), and carbon-based (graphene and carbon nanostructures) electrode materials are reviewed individually in terms of various neural recording devices that are reported in recent years. Properties of these materials, including electrical properties, mechanical properties, stability, biodegradability/bioresorbability, biocompatibility, and optical properties, and their critical importance to neural recording quality and device capabilities, are discussed. For the packaging and substrate materials, different material properties are desired for the chronic implantation of devices in the complex environment of the body, such as biocompatibility and moisture and gas hermeticity. This review summarizes common solid and soft packaging materials used in a variety of neural interface electrode designs, as well as their packaging performances. Besides, several biopolymers typically applied over the electrode package to reinforce the mechanical rigidity of devices during insertion, or to reduce the immune response and inflammation at the device-tissue interfaces are highlighted. Finally, a benchmark analysis of the discussed materials and an outlook of the future research trends are concluded.
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Affiliation(s)
- Weiyang Yang
- Microtechnology Lab, Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, United States
| | - Yan Gong
- Microtechnology Lab, Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, United States
| | - Wen Li
- Microtechnology Lab, Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, United States
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30
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Richner TJ, Brodnick SK, Thongpang S, Sandberg AA, Krugner-Higby LA, Williams JC. Phase relationship between micro-electrocorticography and cortical neurons. J Neural Eng 2019; 16:066028. [PMID: 31318702 DOI: 10.1088/1741-2552/ab335b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Electrocorticography (ECoG) is commonly used to map epileptic foci and to implement brain-computer interfaces. Understanding the spatiotemporal correspondence between potentials recorded from the brain's surface and the firing patterns of neurons within the cortex would inform the interpretation of ECoG signals and the design of (microfabricated) micro-ECoG electrode arrays. Based on the theory that synaptic potentials generated by neurons firing in synchrony superimpose to generate local field potentials (LFPs), we hypothesized that neurons in the cortex would fire at preferential phases of the micro-ECoG signal in a spatially dependent way. APPROACH We custom fabricated micro-ECoG electrode arrays with a small opening for silicon arrays (NeuroNexus) to be inserted into the cortex. MAIN RESULTS We found that the spectral coherence between micro-ECoG signals and intracortical LFPs decreased with distance and frequency, but the coherence with spiking units did not simply decrease over distance, likely due to the structure of the cortex. The majority of sorted units spiked during a preferred phase (usually downward) and frequency (usually below 20 Hz) of the micro-ECoG signal. Their preferred frequency decreased with administration of dexmeditomidine, a sedative commonly used for cortical mapping in patients with epilepsy prior to surgical resection. Dexmedetomidine concomitantly shifted the micro-ECoG spectral density towards lower frequencies. Therefore, the phase relationship between micro-ECoG signals and cortical spiking depends on the state of the brain, and spectrum shifts towards lower frequencies in the electrocorticography signal are a signature of increased spike-phase coupling. However, spike-phase coupling is not a static property since visual stimuli were found to modulate the magnitude of phase coupling at gamma frequency ranges (30-80 Hz), providing empirical evidence that neurons transiently phase-lock. SIGNIFICANCE The phase relationship between intracortical spikes and micro-ECoG signals depends on brain state, site separation, cortical structure, and external stimuli.
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Affiliation(s)
- Thomas J Richner
- Biomedical Engineering, 1550 Engineering Drive, University of Wisconsin, Madison, WI, United States of America
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31
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Ultra-Long-Term Reliable Encapsulation Using an Atomic Layer Deposited HfO2/Al2O3/HfO2 Triple-Interlayer for Biomedical Implants. COATINGS 2019. [DOI: 10.3390/coatings9090579] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Long-term packaging of miniaturized, flexible implantable medical devices is essential for the next generation of medical devices. Polymer materials that are biocompatible and flexible have attracted extensive interest for the packaging of implantable medical devices, however realizing these devices with long-term hermeticity up to several years remains a great challenge. Here, polyimide (PI) based hermetic encapsulation was greatly improved by atomic layer deposition (ALD) of a nanoscale-thin, biocompatible sandwich stack of HfO2/Al2O3/HfO2 (ALD-3) between two polyimide layers. A thin copper film covered with a PI/ALD-3/PI barrier maintained excellent electrochemical performance over 1028 days (2.8 years) during acceleration tests at 60 °C in phosphate buffered saline solution (PBS). This stability is equivalent to approximately 14 years at 37 °C. The coatings were monitored in situ through electrochemical impedance spectroscopy (EIS), were inspected by microscope, and were further analyzed using equivalent circuit modeling. The failure mode of ALD Al2O3, ALD-3, and PI soaking in PBS is discussed. Encapsulation using ultrathin ALD-3 combined with PI for the packaging of implantable medical devices is robust at the acceleration temperature condition for more than 2.8 years, showing that it has great potential as reliable packaging for long-term implantable devices.
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Ahn SH, Jeong J, Kim SJ. Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices. MICROMACHINES 2019; 10:E508. [PMID: 31370259 PMCID: PMC6723304 DOI: 10.3390/mi10080508] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/20/2019] [Accepted: 07/29/2019] [Indexed: 01/11/2023]
Abstract
The development of reliable long-term encapsulation technologies for implantable biomedical devices is of paramount importance for the safe and stable operation of implants in the body over a period of several decades. Conventional technologies based on titanium or ceramic packaging, however, are not suitable for encapsulating microfabricated devices due to their limited scalability, incompatibility with microfabrication processes, and difficulties with miniaturization. A variety of emerging materials have been proposed for encapsulation of microfabricated implants, including thin-film inorganic coatings of Al2O3, HfO2, SiO2, SiC, and diamond, as well as organic polymers of polyimide, parylene, liquid crystal polymer, silicone elastomer, SU-8, and cyclic olefin copolymer. While none of these materials have yet been proven to be as hermetic as conventional metal packages nor widely used in regulatory approved devices for chronic implantation, a number of studies have demonstrated promising outcomes on their long-term encapsulation performance through a multitude of fabrication and testing methodologies. The present review article aims to provide a comprehensive, up-to-date overview of the long-term encapsulation performance of these emerging materials with a specific focus on publications that have quantitatively estimated the lifetime of encapsulation technologies in aqueous environments.
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Affiliation(s)
- Seung-Hee Ahn
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea
| | - Joonsoo Jeong
- Department of Biomedical Engineering, School of Medicine, Pusan National University, Yangsan 50612, Korea.
| | - Sung June Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
- Institute of Aging, College of Medicine, Seoul National University, Seoul 08826, Korea.
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33
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Remote-Controlled Fully Implantable Neural Stimulator for Freely Moving Small Animal. ELECTRONICS 2019. [DOI: 10.3390/electronics8060706] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The application of a neural stimulator to small animals is highly desired for the investigation of electrophysiological studies and development of neuroprosthetic devices. For this purpose, it is essential for the device to be implemented with the capabilities of full implantation and wireless control. Here, we present a fully implantable stimulator with remote controllability, compact size, and minimal power consumption. Our stimulator consists of modular units of (1) a surface-type cortical array for inducing directional change of a rat, (2) a depth-type array for providing rewards, and (3) a package for accommodating the stimulating electronics, a battery and ZigBee telemetry, all of which are assembled after independent fabrication and implantation using customized flat cables and connectors. All three modules were packaged using liquid crystal polymer (LCP) to avoid any chemical reaction after implantation. After bench-top evaluation of device functionality, the stimulator was implanted into rats to train the animals to turn to the left (or right) following a directional cue applied to the barrel cortex. Functionality of the device was also demonstrated in a three-dimensional (3D) maze structure, by guiding the rats to better navigate in the maze. The movement of the rat could be wirelessly controlled by a combination of artificial sensation evoked by the surface electrode array and reward stimulation. We could induce rats to turn left or right in free space and help their navigation through the maze. The polymeric packaging and modular design could encapsulate the devices with strict size limitations, which made it possible to fully implant the device into rats. Power consumption was minimized by a dual-mode power-saving scheme with duty cycling. The present study demonstrated feasibility of the proposed neural stimulator to be applied to neuroprosthesis research.
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