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Jain T, Tantisuwanno C, Paul A, Takmakov P, Joy A, Isayeva I, Simon DD. Accelerated in vitro oxidative degradation testing of polypropylene surgical mesh. J Biomed Mater Res B Appl Biomater 2023; 111:2064-2076. [PMID: 37596906 DOI: 10.1002/jbm.b.35308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/14/2023] [Accepted: 08/01/2023] [Indexed: 08/21/2023]
Abstract
Polypropylene (PP) surgical mesh had reasonable success in repair of hernia and treatment of stress urinary incontinence (SUI); however, their use for the repair of pelvic organ prolapse (POP) resulted in highly variable results with lifelong complications in some patients. One of several factors that could be associated with mesh-related POP complications is changes in the properties of the implanted surgical mesh due to oxidative degradation of PP in vivo. Currently, there are no standardized in vitro bench testing methods available for assessing the susceptibility to oxidative degradation and estimating long-term in vivo stability of surgical mesh. In this work, we adapted a previously reported automated reactive accelerated aging (aRAA) system, which uses elevated temperatures and high concentrations of hydrogen peroxide (H2 O2 ), for accelerated bench-top oxidative degradation testing of PP surgical mesh. Since H2 O2 is highly unstable at elevated temperatures and for prolonged periods, the aRAA system involves a feedback loop based on electrochemical detection methods to maintain consistent H2 O2 concentration in test solutions. Four PP mesh samples with varying mesh knit designs, filament diameter, weight, and % porosity, were selected for testing using aRAA up to 4 weeks and characterized using thermal analysis, Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM). Additionally, the oxidation index (OI) values were calculated based on the FTIR-ATR spectra to estimate the oxidative degradation and oxidation reaction kinetics of PP surgical mesh. The OI values and surface damage in the form of surface flaking, peeling, and formation of transverse cracks increased with aRAA aging time. The aRAA test method introduced here could be used to standardize the assessment of long-term stability of surgical mesh and may also be adopted for accelerated oxidative degradation testing of other polymer-based medical devices.
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Affiliation(s)
- Tanmay Jain
- Division of Biology, Chemistry and Materials Science, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Silver Spring, Maryland, USA
| | | | - Arindam Paul
- Division of Biology, Chemistry and Materials Science, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Silver Spring, Maryland, USA
| | - Pavel Takmakov
- Division of Biology, Chemistry and Materials Science, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Silver Spring, Maryland, USA
| | - Abraham Joy
- Department of Polymer Science, The University of Akron, Akron, Ohio, USA
| | - Irada Isayeva
- Division of Biology, Chemistry and Materials Science, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Silver Spring, Maryland, USA
| | - David D Simon
- Division of Biology, Chemistry and Materials Science, U.S. Food and Drug Administration, Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Silver Spring, Maryland, USA
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2
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Liu DX, Lam DV, Gao Y, LeBlanc RC, Usab AA, Fielding ES, Brunkalla CL, Yang K, Shoffstall AJ. Characterization of a Temporary Peripheral Nerve Stimulation Electrode Utilizing a Bioabsorbable Suture Substrate. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:5094-5098. [PMID: 36086486 PMCID: PMC10369404 DOI: 10.1109/embc48229.2022.9871604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Electrical stimulation after peripheral nerve injury (PNI) has the potential to promote more rapid and complete recovery of damaged fiber tracts. While permanently implanted devices are commonly used to treat chronic or persistent conditions, they are not ideal solutions for transient medical therapies due to high costs, increased risk of surgical injury, irritation, infection, and persistent inflammation at the site of the implant. Furthermore, removal of temporary leads placed on or around peripheral nerves may have unacceptable risk for nerve injury, which is counterproductive in developing therapies for PNI treatment. Transient devices which provide effective clinical stimulation while being capable of harmless bioabsorption may overcome key challenges in these areas. However, current bioabsorbable devices are limited in their robustness and require complex fabrication strategies and novel materials which may complicate their clinical translation pathway. In this study, we present a simple bioabsorbable / biodegradable electrode fabricated by modifying standard absorbable sutures, and we present data characterizing our prototype's stability in vitro and in vivo.
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Han M, Yildiz E, Kaleli HN, Karaz S, Eren GO, Dogru‐Yuksel IB, Senses E, Şahin A, Nizamoglu S. Tissue-Like Optoelectronic Neural Interface Enabled by PEDOT:PSS Hydrogel for Cardiac and Neural Stimulation. Adv Healthc Mater 2022; 11:e2102160. [PMID: 34969168 DOI: 10.1002/adhm.202102160] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/29/2021] [Indexed: 01/01/2023]
Abstract
Optoelectronic biointerfaces have made a significant impact on modern science and technology from understanding the mechanisms of the neurotransmission to the recovery of the vision for blinds. They are based on the cell interfaces made of organic or inorganic materials such as silicon, graphene, oxides, quantum dots, and π-conjugated polymers, which are dry and stiff unlike a cell/tissue environment. On the other side, wet and soft hydrogels have recently been started to attract significant attention for bioelectronics because of its high-level tissue-matching biomechanics and biocompatibility. However, it is challenging to obtain optimal opto-bioelectronic devices by using hydrogels requiring device, heterojunction, and hydrogel engineering. Here, an optoelectronic biointerface integrated with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, hydrogel that simultaneously achieves efficient, flexible, stable, biocompatible, and safe photostimulation of cells is demonstrated. Besides their interfacial tissue-like biomechanics, ≈34 kPa, and high-level biocompatibility, hydrogel-integration facilitates increase in charge injection amounts sevenfolds with an improved responsivity of 156 mA W-1 , stability under mechanical bending , and functional lifetime over three years. Finally, these devices enable stimulation of individual hippocampal neurons and photocontrol of beating frequency of cardiac myocytes via safe charge-balanced capacitive currents. Therefore, hydrogel-enabled optoelectronic biointerfaces hold great promise for next-generation wireless neural and cardiac implants.
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Affiliation(s)
- Mertcan Han
- Department of Electrical and Electronics Engineering Koç University Istanbul 34450 Turkey
| | - Erdost Yildiz
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
| | - Hümeyra Nur Kaleli
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
| | - Selcan Karaz
- Department of Chemical and Biological Engineering Koç University Istanbul 34450 Turkey
| | - Guncem Ozgun Eren
- Graduate School of Biomedical Science and Engineering Koç University Istanbul 34450 Turkey
| | | | - Erkan Senses
- Department of Chemical and Biological Engineering Koç University Istanbul 34450 Turkey
| | - Afsun Şahin
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
- Department of Ophthalmology Medical School Koç University Istanbul 34450 Turkey
| | - Sedat Nizamoglu
- Department of Electrical and Electronics Engineering Koç University Istanbul 34450 Turkey
- Graduate School of Biomedical Science and Engineering Koç University Istanbul 34450 Turkey
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4
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Mobini S, González MU, Caballero-Calero O, Patrick EE, Martín-González M, García-Martín JM. Effects of nanostructuration on the electrochemical performance of metallic bioelectrodes. NANOSCALE 2022; 14:3179-3190. [PMID: 35142756 DOI: 10.1039/d1nr06280h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The use of metallic nanostructures in the fabrication of bioelectrodes (e.g., neural implants) is gaining attention nowadays. Nanostructures provide increased surface area that might benefit the performance of bioelectrodes. However, there is a need for comprehensive studies that assess electrochemical performance of nanostructured surfaces in physiological and relevant working conditions. Here, we introduce a versatile scalable fabrication method based on magnetron sputtering to develop analogous metallic nanocolumnar structures (NCs) and thin films (TFs) from Ti, Au, and Pt. We show that NCs contribute significantly to reduce the impedance of metallic surfaces. Charge storage capacity of Pt NCs is remarkably higher than that of Pt TFs and that of the other metals in both morphologies. Circuit simulations of the electrode/electrolyte interface show that the signal delivered in voltage-controlled systems is less filtered when nanocolumns are used. In a current-controlled system, simulation shows that NCs provide safer stimulation conditions compared to TFs. We have assessed the durability of NCs and TFs for potential use in vivo by reactive accelerated aging test, mimicking one-year in vivo implantation. Although each metal/morphology reveals a unique response to aging, NCs show overall more stable electrochemical properties compared to TFs in spite of their porous structure.
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Affiliation(s)
- Sahba Mobini
- Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC), Isaac Newton 8, E-28760, Tres Cantos, Madrid, Spain.
| | - María Ujué González
- Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC), Isaac Newton 8, E-28760, Tres Cantos, Madrid, Spain.
| | - Olga Caballero-Calero
- Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC), Isaac Newton 8, E-28760, Tres Cantos, Madrid, Spain.
| | - Erin E Patrick
- Department of Electrical and Computer Engineering, University of Florida, Center Drive 968, Gainesville, FL 32603, USA
| | - Marisol Martín-González
- Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC), Isaac Newton 8, E-28760, Tres Cantos, Madrid, Spain.
| | - José Miguel García-Martín
- Instituto de Micro y Nanotecnología, IMN-CNM, CSIC (CEI UAM+CSIC), Isaac Newton 8, E-28760, Tres Cantos, Madrid, Spain.
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Oldroyd P, Malliaras GG. Achieving long-term stability of thin-film electrodes for neurostimulation. Acta Biomater 2022; 139:65-81. [PMID: 34020055 DOI: 10.1016/j.actbio.2021.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/06/2021] [Accepted: 05/06/2021] [Indexed: 12/17/2022]
Abstract
Implantable electrodes that can reliably measure brain activity and deliver an electrical stimulus to a target tissue are increasingly employed to treat various neurological diseases and neuropsychiatric disorders. Flexible thin-film electrodes have gained attention over the past few years to minimise invasiveness and damage upon implantation. Research has previously focused on optimising the electrode's electrical and mechanical properties; however, their chronic stability must be validated to translate electrodes from a research to a clinical application. Neurostimulation electrodes, which actively inject charge, have yet to reliably demonstrate continuous functionality for ten years or more in vivo, the accepted metric for clinical viability. Long-term stability can only be achieved if the focus switches to investigating how and why such devices fail. Unfortunately, there is a field-wide reluctance to investigate device stability and failures, which hinders device optimisation. This review surveys thin-film electrode designs with a focus on adhesion between electrode layers and the interactions with the surrounding environment. A comprehensive summary of the abiotic failure modes faced by such electrodes is presented, and to encourage investigation, systematic methods for analysing their origin are recommended. Finally, approaches to reducing the likelihood of device failure are offered. STATEMENT OF SIGNIFICANCE: Neural electrodes that can deliver an electrical stimulus to a target tissue are widely used to treat various neurological diseases. Essential to the function of these electrodes is the ability to safely stimulate the target tissue for extended periods (> 10 years); however, this has not yet been clinically achieved. The key to achieving long-term stability is an increased understanding of electrode interactions with the surrounding tissue and subsequent systematic analysis of their failure modes. This review highlights the need for a change in the approach to investigating electrode failure, and in doing so summarizes the common ways in which neural electrodes fail, methods for identifying them and approaches to preventing them.
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6
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Doering M, Kieninger J, Urban G, Weltin A. Electrochemical microelectrode degradation monitoring: in situ investigation of platinum corrosion at neutral pH. J Neural Eng 2022; 19. [PMID: 34983028 DOI: 10.1088/1741-2552/ac47da] [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: 11/23/2021] [Accepted: 01/04/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The stability of platinum and other noble metal electrodes is critical for neural implants, electrochemical sensors, and energy sources. Beyond the acidic or alkaline environment found in most electrochemical studies, the investigation of electrode corrosion in neutral pH and chloride containing electrolytes is essential, particularly regarding the long-term stability of neural interfaces, such as brain stimulation electrodes or cochlear implants. In addition, the increased use of microfabricated devices demands the investigation of thin-film electrode stability. APPROACH We developed a procedure of electrochemical methods for continuous tracking of electrode degradation in situ over the complete life cycle of platinum thin-film microelectrodes in a unique combination with simultaneous chemical sensing. We used chronoamperometry and cyclic voltammetry to measure electrode surface and analyte redox processes, together with accelerated electrochemical degradation. MAIN RESULTS We compared degradation between thin-film microelectrodes and bulk electrodes, neutral to acidic pH, different pulsing schemes, and the presence of the redox active species oxygen and hydrogen peroxide. Results were confirmed by mechanical profilometry and microscopy to determine material changes on a nanometer scale. We found that electrode degradation is mainly driven by repeated formation and removal of the platinum surface oxide, also within the electrochemical stability window of water. There was no considerable difference between thin-film micro- and macroscopic bulk electrodes or in the presence of reactive species, whereas acidic pH or extending the potential window led to increased degradation. SIGNIFICANCE Our results provide valuable fundamental information on platinum microelectrode degradation under conditions found in biomedical applications. For the first time, we deployed a unified method to report quantitative data on electrode degradation up to a defined endpoint. Our method is a widely applicable framework for comparative long-term studies of sensor and neural interface stability.
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Affiliation(s)
- Moritz Doering
- University of Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, Baden-Württemberg, 79110, GERMANY
| | - Jochen Kieninger
- University of Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, Baden-Württemberg, 79110, GERMANY
| | - Gerald Urban
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, 79110, GERMANY
| | - Andreas Weltin
- IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, 79110, GERMANY
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7
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Ikeda K, Tajima K, Tanabe Y, Poon ASY, Kajimura S. Activation of UCP1-Independent Ca 2+ Cycling Thermogenesis by Wireless Optogenetics. Methods Mol Biol 2022; 2448:131-139. [PMID: 35167095 PMCID: PMC9087983 DOI: 10.1007/978-1-0716-2087-8_9] [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] [Indexed: 06/14/2023]
Abstract
The identification of non-canonical UCP1-independent thermogenic mechanisms offers new opportunities to target such pathways to improve metabolic health. Based on our recent studies on Ca2+ futile cycling thermogenesis in beige fat, we applied the newly developed implantable wireless optogenetic system to activate Ca2+ cycling in an adipocyte-specific manner without external stimuli, i.e., fat-specific cold mimetics. Here, we describe the detailed methodology and application to the prevention of obesity.
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Affiliation(s)
- Kenji Ikeda
- Department of Molecular Endocrinology and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kazuki Tajima
- Department of Endocrinology and Metabolism, Yokohama Medical Center, Yokohama, Japan
| | - Yuji Tanabe
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Ada S Y Poon
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
| | - Shingo Kajimura
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Harvard, MA, USA.
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8
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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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9
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Abstract
Peripheral nerve interfaces (PNIs) record and/or modulate neural activity of nerves, which are responsible for conducting sensory-motor information to and from the central nervous system, and for regulating the activity of inner organs. PNIs are used both in neuroscience research and in therapeutical applications such as precise closed-loop control of neuroprosthetic limbs, treatment of neuropathic pain and restoration of vital functions (e.g. breathing and bladder management). Implantable interfaces represent an attractive solution to directly access peripheral nerves and provide enhanced selectivity both in recording and in stimulation, compared to their non-invasive counterparts. Nevertheless, the long-term functionality of implantable PNIs is limited by tissue damage, which occurs at the implant-tissue interface, and is thus highly dependent on material properties, biocompatibility and implant design. Current research focuses on the development of mechanically compliant PNIs, which adapt to the anatomy and dynamic movements of nerves in the body thereby limiting foreign body response. In this paper, we review recent progress in the development of flexible and implantable PNIs, highlighting promising solutions related to materials selection and their associated fabrication methods, and integrated functions. We report on the variety of available interface designs (intraneural, extraneural and regenerative) and different modulation techniques (electrical, optical, chemical) emphasizing the main challenges associated with integrating such systems on compliant substrates.
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Affiliation(s)
- Valentina Paggi
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Centre for Neuroprosthetics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1202 Geneva, Switzerland. Equally contributing authors
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10
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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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11
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Stability Performance Analysis of Various Packaging Materials and Coating Strategies for Chronic Neural Implants under Accelerated, Reactive Aging Tests. MICROMACHINES 2020; 11:mi11090810. [PMID: 32858951 PMCID: PMC7570179 DOI: 10.3390/mi11090810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 12/13/2022]
Abstract
Reliable packaging for implantable neural prosthetic devices in body fluids is a long-standing challenge for devices’ chronic applications. This work studied the stability of Parylene C (PA), SiO2, and Si3N4 packages and coating strategies on tungsten wires using accelerated, reactive aging tests in three solutions: pH 7.4 phosphate-buffered saline (PBS), PBS + 30 mM H2O2, and PBS + 150 mM H2O2. Different combinations of coating thicknesses and deposition methods were studied at various testing temperatures. Analysis of the preliminary data shows that the pinholes/defects, cracks, and interface delamination are the main attributes of metal erosion and degradation in reactive aging solutions. Failure at the interface of package and metal is the dominating factor in the wire samples with open tips.
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Shen K, Yau A, Panchavati S, Maharbiz MM. An Automated System for Reactive Accelerated Aging of Implant Materials with In-Situ Testing. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:4466-4469. [PMID: 33018986 DOI: 10.1109/embc44109.2020.9176443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The efficacy of implantable medical devices is limited by the longevity of devices in the body environment. Due to the aqueous and mobile-ion rich environment of tissue, robust and long-lasting encapsulation materials are critical for chronic implants. Assessing the reliability of medical devices is commonly performed through saline soak tests with reactive oxidative species at elevated temperatures and lifetime data are fit to an Arrhenius model to predict lifetime under physiological conditions. While effective, these systems often require frequent human involvement to maintain system temperature and reactive oxidative species concentration, as well as monitor sample lifetime, which makes long term testing of multiple samples difficult. Here we present an automated, low-cost, low-solution volume, and high-throughput reactive accelerated aging system to assay many thin film samples in an easy and low maintenance manner. The efficacy of up to 16 thin film coating samples can be assessed by our system through in-situ current leakage tests in a mock biological environment. We validate our system by aging thermal oxide and a-SiC thin films at 93 °C with 20 mM H2O2. Our system shows early failure of the thermal oxide compared to the a-SiC, in agreement with the current literature.
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13
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Wireless optogenetics protects against obesity via stimulation of non-canonical fat thermogenesis. Nat Commun 2020; 11:1730. [PMID: 32265443 PMCID: PMC7138828 DOI: 10.1038/s41467-020-15589-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 03/18/2020] [Indexed: 12/17/2022] Open
Abstract
Cold stimuli and the subsequent activation of β-adrenergic receptor (β-AR) potently stimulate adipose tissue thermogenesis and increase whole-body energy expenditure. However, systemic activation of the β3-AR pathway inevitably increases blood pressure, a significant risk factor for cardiovascular disease, and, thus, limits its application for the treatment of obesity. To activate fat thermogenesis under tight spatiotemporal control without external stimuli, here, we report an implantable wireless optogenetic device that bypasses the β-AR pathway and triggers Ca2+ cycling selectively in adipocytes. The wireless optogenetics stimulation in the subcutaneous adipose tissue potently activates Ca2+ cycling fat thermogenesis and increases whole-body energy expenditure without cold stimuli. Significantly, the light-induced fat thermogenesis was sufficient to protect mice from diet-induced body-weight gain. The present study provides the first proof-of-concept that fat-specific cold mimetics via activating non-canonical thermogenesis protect against obesity. Cardiovascular risks of cold exposure and the subsequent activation of the β3-AR pathway limit the application of beige fat thermogenesis for the treatment of obesity. Here, the authors show that optogenetics light-activated Ca2+ cycling in adipocytes triggers a fat-specific “cold-mimetic” thermogenesis response protecting mice against diet-induced obesity.
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14
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Characterization of Parylene-C degradation mechanisms: In vitro reactive accelerated aging model compared to multiyear in vivo implantation. Biomaterials 2020; 232:119731. [DOI: 10.1016/j.biomaterials.2019.119731] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 12/19/2019] [Accepted: 12/25/2019] [Indexed: 11/23/2022]
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15
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A review for the peripheral nerve interface designer. J Neurosci Methods 2019; 332:108523. [PMID: 31743684 DOI: 10.1016/j.jneumeth.2019.108523] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 12/11/2022]
Abstract
Informational density and relative accessibility of the peripheral nervous system make it an attractive site for therapeutic intervention. Electrode-based electrophysiological interfaces with peripheral nerves have been under development since the 1960s and, for several applications, have seen widespread clinical implementation. However, many applications require a combination of neural target resolution and stability which has thus far eluded existing peripheral nerve interfaces (PNIs). With the goal of aiding PNI designers in development of devices that meet the demands of next-generation applications, this review seeks to collect and present practical considerations and best practices which emerge from the literature, including both lessons learned during early PNI development and recent ideas. Fundamental and practical principles guiding PNI design are reviewed, followed by an updated and critical account of existing PNI designs and strategies. Finally, a brief survey of in vitro and in vivo PNI characterization methods is presented.
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16
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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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17
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Joshi-Imre A, Black BJ, Abbott J, Kanneganti A, Rihani R, Chakraborty B, Danda VR, Maeng J, Sharma R, Rieth L, Negi S, Pancrazio JJ, Cogan SF. Chronic recording and electrochemical performance of amorphous silicon carbide-coated Utah electrode arrays implanted in rat motor cortex. J Neural Eng 2019; 16:046006. [DOI: 10.1088/1741-2552/ab1bc8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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