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Machnoor M, Shao X, Paknahad J, Humayun M, Lazzi G. On the Design of an Efficient Inductive Wireless Power Transfer for Passive Neurostimulation Systems. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:7497-7501. [PMID: 34892827 DOI: 10.1109/embc46164.2021.9630262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this paper, a minimally invasive wireless powered electronic lens (e-lens) with passive electrodes is presented for an ocular electrical stimulation. Previous research has focused on the differentiation property of the induction phenomenon and half wave rectifiers. However, these approaches are generally application specific, non efficient, suitable for low current, and deliver monophasic current stimulation. Existing rectifier-based techniques can lead to safety concerns as the offset voltage could change unpredictably. A new wireless power transfer circuit is presented for the design of an efficient system to wirelessly deliver charge-balanced biphasic waveforms through passive electrodes for transcorneal electrical stimulation. The absence of active components allows the development of a flexible e-lens system for therapeutic electrical stimulation of the eye.
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Liu X, Li J, Mao W, Chen Z, Chen Z, Wan P, Yu H. A Charge Balanced Neural Stimulator Silicon Chip for Human-Machine Interface. FRONTIERS IN ELECTRONICS 2021. [DOI: 10.3389/felec.2021.773812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This paper proposes a neural stimulator silicon chip design with an improved charge balancing technology. The proposed neural stimulation integrated circuit (IC) uses two charge balancing modules including synchronous charge detection module and short-time pulse insertion module. The synchronous charge detection module is designed based on a current splitter with ultra-small output current and an integrator circuit for neural stimulation pulse width control, which greatly reduces the residual charge remained on the electrode-tissue interface. The short-time pulse insertion module is designed based on the electrode voltage detection and compensation current control, which further reduces the accumulated residual charge and keeps the electrode voltage within a safety range of ±25 mV during multiple stimulation cycles. Finally, this neural stimulator is implemented in TSMC 0.18-μm CMOS process technology, and the chip function is tested and verified in both experiments with the electrode-tissue RC model and the PBS saline solution environment. The measurement result shows the neural stimulator chip achieves improved charge balancing with the residual charge smaller than 0.95 nC, which is the lowest compared to the traditional neural stimulator chips.
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Culaclii S, Wang PM, Taccola G, Yang W, Bailey B, Chen YP, Lo YK, Liu W. A Biomimetic, SoC-Based Neural Stimulator for Novel Arbitrary-Waveform Stimulation Protocols. Front Neurosci 2021; 15:697731. [PMID: 34393710 PMCID: PMC8358079 DOI: 10.3389/fnins.2021.697731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/07/2021] [Indexed: 11/15/2022] Open
Abstract
Novel neural stimulation protocols mimicking biological signals and patterns have demonstrated significant advantages as compared to traditional protocols based on uniform periodic square pulses. At the same time, the treatments for neural disorders which employ such protocols require the stimulator to be integrated into miniaturized wearable devices or implantable neural prostheses. Unfortunately, most miniaturized stimulator designs show none or very limited ability to deliver biomimetic protocols due to the architecture of their control logic, which generates the waveform. Most such designs are integrated into a single System-on-Chip (SoC) for the size reduction and the option to implement them as neural implants. But their on-chip stimulation controllers are fixed and limited in memory and computing power, preventing them from accommodating the amplitude and timing variances, and the waveform data parameters necessary to output biomimetic stimulation. To that end, a new stimulator architecture is proposed, which distributes the control logic over three component tiers - software, microcontroller firmware and digital circuits of the SoC, which is compatible with existing and future biomimetic protocols and with integration into implantable neural prosthetics. A portable prototype with the proposed architecture is designed and demonstrated in a bench-top test with various known biomimetic output waveforms. The prototype is also tested in vivo to deliver a complex, continuous biomimetic stimulation to a rat model of a spinal-cord injury. By delivering this unique biomimetic stimulation, the device is shown to successfully reestablish the connectivity of the spinal cord post-injury and thus restore motor outputs in the rat model.
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Affiliation(s)
- Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Po-Min Wang
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies, Trieste, Italy
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, United States
| | - William Yang
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Brett Bailey
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yan-Peng Chen
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yi-Kai Lo
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Niche Biomedical Inc., Los Angeles, CA, United States
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States
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Lyu H, John M, Burkland D, Greet B, Xi Y, Sampaio L, Taylor D, Razavi M, Babakhani A. A Multi-site Heart Pacing Study Using Wirelessly Powered Leadless Pacemakers. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:3434-3437. [PMID: 30441125 DOI: 10.1109/embc.2018.8512977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this work, we report an energy-efficient switched capacitor based millimeter-scale pacemaker (5 mm ×7.5 mm) and a multi-receiver wireless energy transfer system operating at around 200 MHz, and use them in a proof-of-concept multi-site heart pacing study. Two pacemakers were placed on two beating Langendorff rodent heart models separately. By utilizing a single transmitter positioned 20-30 cm away, both Langendorff hearts captured the stimuli simultaneously and were electromechanically coupled. This study provides an insight for future energy-efficient and distributed cardiac pacemakers that can offer cardiac resynchronization therapies.
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Ha S, Kim C, Park J, Cauwenberghs G, Mercier PP. A Fully Integrated RF-Powered Energy-Replenishing Current-Controlled Stimulator. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:191-202. [PMID: 30452378 DOI: 10.1109/tbcas.2018.2881800] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This paper presents a fully-integrated current-controlled stimulator that is powered directly from on-chip coil antenna and achieves adiabatic energy-replenishing operation without any bulky external components. Adiabatic supply voltages, which can reach a differential range of up to 7.2 V, are directly generated from an on-chip 190-MHz resonant LC tank via a self-cascading/folding rectifier network, bypassing the losses that would otherwise be introduced by the 0.8 V system supply-generating rectifier and regulator. The stimulator occupies 0.22 mm 2 in a 180 nm silicon-on-insulator process and produces differential currents up to 145 μA. Using a charge replenishing scheme, the stimulator redirects the charges accumulated across the electrodes to the system power supplies for 63.1% of stimulation energy recycling. To benchmark the efficiency of stimulation, a figure of merit termed the stimulator efficiency factor (SEF) is introduced. The adiabatic power rails and energy replenishment scheme enabled our stimulator to achieve an SEF of 6.0.
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Lyu H, Wang J, La JH, Chung JM, Babakhani A. An Energy-Efficient Wirelessly Powered Millimeter-Scale Neurostimulator Implant Based on Systematic Codesign of an Inductive Loop Antenna and a Custom Rectifier. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2018; 12:1131-1143. [PMID: 30040661 DOI: 10.1109/tbcas.2018.2852680] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, a switched-capacitor-based stimulator circuit that enables efficient energy harvesting for neurostimulation applications is presented, followed by the discussion on the optimization of the inductive coupling front-end through a codesign approach. The stimulator salvages input energy and stores it in a storage capacitor, and, when the voltage reaches a threshold, releases the energy as an output stimulus. The dynamics of the circuit are automatically enabled by a positive feedback, eliminating any stimulation control circuit blocks. The IC is fabricated in a 180 nm CMOS process and achieves a quiescent current consumption of 1.8 μA. The inductive coupling front-end is optimized as a loaded resonator, in which the input impedance of the custom rectifier directly loads the inductive loop antenna. The loaded quality factor and the rectifier's efficiency determine the reception sensitivity of the stimulator, while a balance should be achieved for the robustness of the system against dielectric medium variations by increasing the reception bandwidth. The finalized stimulator adopts a 4.9 mm × 4.9 mm inductive loop antenna and achieves an overall assembly dimension of 5 mm × 7.5 mm. Operating at the resonant frequency of 198 MHz, the stimulator works at a 14 cm distance from the transmitter in the air. An animal experiment was performed, in which a fully implanted stimulator excited the sciatic nerve of a rat that consequently triggered the movement of the limb.
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