Stimulation and Recording Electrodes for Neural Prostheses

Aryan, Naser Pour; Kaim, Hans; Rothermel, Albrecht

doi:10.1007/978-3-319-10052-4

Cited by 16 publications

(6 citation statements)

References 23 publications

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“…For an excitable cell, this perturbation is above the threshold of what would be expected to elicit action potentials. To put the magnitude of these changes into context, we compare with recent studies of light-pulse irradiated organic donor-acceptor blends resulting in changes no higher than ±1 mV (18) or 80 mV, though this result was obtained with 72 mW/mm 2 (31). The efficiency of the capacitive coupling of our OEPC devices is therefore substantial.…”

Section: Photoinduced Membrane Potential Modulationmentioning

confidence: 84%

“…The growing field of neural prosthetics includes cochlear and artificial retina implants as well as brain stimulation electrodes for the treatment of Parkinson's disease, depression, etc. (1)(2)(3). As an alternative to conventional metal or semiconductor electrodes, light stimulation offers the potential of wireless, temporally and locally specific, minimally invasive manipulation of electrophysiological processes.…”

Section: Introductionmentioning

confidence: 99%

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Optoelectronic control of single cells using organic photocapacitors

et al. 2019

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Optical control of the electrophysiology of single cells can be a powerful tool for biomedical research and technology. Here, we report organic electrolytic photocapacitors (OEPCs), devices that function as extracellular capacitive electrodes for stimulating cells. OEPCs consist of transparent conductor layers covered with a donor-acceptor bilayer of organic photoconductors. This device produces an open-circuit voltage in a physiological solution of 330 mV upon illumination using light in a tissue transparency window of 630 to 660 nm. We have performed electrophysiological recordings on Xenopus laevis oocytes, finding rapid (time constants, 50 μs to 5 ms) photoinduced transient changes in the range of 20 to 110 mV. We measure photoinduced opening of potassium channels, conclusively proving that the OEPC effectively depolarizes the cell membrane. Our results demonstrate that the OEPC can be a versatile nongenetic technique for optical manipulation of electrophysiology and currently represents one of the simplest and most stable and efficient optical stimulation solutions.

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Section: Photoinduced Membrane Potential Modulationmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Optoelectronic control of single cells using organic photocapacitors

et al. 2019

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“…Fabrication of biodegradable metal electrodes -The electrodes are fabricated by evaporating magnesium (100 µm-thick electrode) on top of a 50 µm-thick polylactide layer (PLLA, Goodfellow) after having exposed the substrate surface to oxygen plasma. The electrodes are operated below the standard potential of -1.23 V (corresponding to the electrolysis of water) to avoid any unwanted redox reaction at the interface of Mg electrodes with body fluids and stay within the safe water window 28 .…”

Section: Sensor In Vivo Function and Biocompatibilitymentioning

confidence: 99%

A stretchable and biodegradable strain and pressure sensor for orthopaedic application

et al. 2018

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The ability to monitor, in real time, the mechanical forces on tendons after surgical repair could allow personalised rehabilitation programs to be developed for recovering patients. However, the development of devices capable of such measurements has been hindered by the strict requirements of biocompatible materials and the need for sensors with satisfactory performance. Here we report an implantable pressure and strain sensor made entirely of biodegradable materials. The sensor is designed to degrade after its useful lifetime, eliminating the need for a second surgery to remove the device. It can measure strain and pressure independently using two vertically isolated sensors capable of discriminating strain as small as 0.4% and the pressure exerted by a grain of salt (12 Pa) without interfering with one another. The device has minimal hysteresis, a response time in the millisecond range, and an excellent cycling stability for strain and pressure sensing, respectively. We have incorporated a biodegradable elastomer which was optimized to improve the strain cycling performances by 54%. An in vivo study shows that the sensor exhibits excellent biocompatibility and function in a rat model, illustrating the potential applicability of the device to the real-time monitoring of tendon healing. Text body In the U.S. alone, around 14 million people per year suffer from tendon, ligament, and joint injuries 1. After injury, tissues in the body undergo changes in their native biomechanical properties in order to repairs themselves. This is true for both hard tissues (bones) and soft tissues (tendons, skin, muscles). The objective of surgery and rehabilitation is to restore the tissues to their pre-injury function, with biomechanical properties as close as possible to native properties 2. A diagnostic tool that measures the biomechanical properties of the repair site in real-time would represent a significant step towards improved assessment of healing and the development of personalized rehabilitation strategies 3. Current clinical practice for monitoring tissue rehabilitation includes magnetic resonance imaging (MRI) or ultrasound, which provide a snapshot of tissue density and inflammation 4. Implantable sensors could give continuous information about tissue strain during rehabilitation protocols, as well as during the patient's daily activities, allowing activities to be tailored based on what the tissue can tolerate. Previously described implantable sensors have limited biocompatibility or have been designed for laboratory biomechanics studies rather than clinical practice 4,5 .

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“…This general principle is one of the fundamental mechanisms behind electrochemistry (Zoski, 2007). Unless carefully and intentionally controlled, electrochemical reactions occurring at the metal-tissue interface are generally harmful to the body processes, causing pH changes, electrode corrosion with toxic byproducts, and bubble formation due to electrolysis (Brummer et al, 1983; Shannon, 1992; Merrill et al, 2005; Pour Aryan et al, 2014). For this reason, IPG designers are careful to avoid any unwanted electrochemical reactions when using bare metal electrodes to deliver current to the body.…”

Section: Enabling Technologymentioning

confidence: 99%

“…This can be accomplished in three ways: by decreasing the amount of time that the electrode is exposed to excess of electrons by reducing pulse duration; by limiting the amplitude of the current pulse that is delivered during this stimulation time and consequently the number of electrons that congregate at the electrode; and by increasing the surface area over which these electrons are distributed to reduce their density. IPGs typically use charge balanced biphasic pulses on the order of microseconds to milliseconds per phase to interact with neurons (Merrill et al, 2005; Pour Aryan et al, 2014). For the typical bare metal Pt electrodes, the safety criterion is 300 μC/cm 2 (Shannon, 1992; Merrill et al, 2005; Pour Aryan et al, 2014).…”

Section: Enabling Technologymentioning

confidence: 99%

Implantable Direct Current Neural Modulation: Theory, Feasibility, and Efficacy

Aplin

Fridman

2019

Front. Neurosci.

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Implantable neuroprostheses such as cochlear implants, deep brain stimulators, spinal cord stimulators, and retinal implants use charge-balanced alternating current (AC) pulses to recover delivered charge and thus mitigate toxicity from electrochemical reactions occurring at the metal-tissue interface. At low pulse rates, these short duration pulses have the effect of evoking spikes in neural tissue in a phase-locked fashion. When the therapeutic goal is to suppress neural activity, implants typically work indirectly by delivering excitation to populations of neurons that then inhibit the target neurons, or by delivering very high pulse rates that suffer from a number of undesirable side effects. Direct current (DC) neural modulation is an alternative methodology that can directly modulate extracellular membrane potential. This neuromodulation paradigm can excite or inhibit neurons in a graded fashion while maintaining their stochastic firing patterns. DC can also sensitize or desensitize neurons to input. When applied to a population of neurons, DC can modulate synaptic connectivity. Because DC delivered to metal electrodes inherently violates safe charge injection criteria, its use has not been explored for practical applicability of DC-based neural implants. Recently, several new technologies and strategies have been proposed that address this safety criteria and deliver ionic-based direct current (iDC). This, along with the increased understanding of the mechanisms behind the transcutaneous DC-based modulation of neural targets, has caused a resurgence of interest in the interaction between iDC and neural tissue both in the central and the peripheral nervous system. In this review we assess the feasibility of in-vivo iDC delivery as a form of neural modulation. We present the current understanding of DC/neural interaction. We explore the different design methodologies and technologies that attempt to safely deliver iDC to neural tissue and assess the scope of application for direct current modulation as a form of neuroprosthetic treatment in disease. Finally, we examine the safety implications of long duration iDC delivery. We conclude that DC-based neural implants are a promising new modulation technology that could benefit from further chronic safety assessments and a better understanding of the basic biological and biophysical mechanisms that underpin DC-mediated neural modulation.

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Stimulation and Recording Electrodes for Neural Prostheses

Cited by 16 publications

References 23 publications

Optoelectronic control of single cells using organic photocapacitors

Optoelectronic control of single cells using organic photocapacitors

A stretchable and biodegradable strain and pressure sensor for orthopaedic application

Implantable Direct Current Neural Modulation: Theory, Feasibility, and Efficacy

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