1
|
Schiavone G, Vachicouras N, Vyza Y, Lacour SP. Dimensional scaling of thin-film stimulation electrode systems in translational research. J Neural Eng 2021; 18. [PMID: 33831857 DOI: 10.1088/1741-2552/abf607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/08/2021] [Indexed: 12/20/2022]
Abstract
Objective.Electrical stimulation of biological tissue is an established technique in research and clinical practice that uses implanted electrodes to deliver electrical pulses for a variety of therapies. Significant research currently explores new electrode system technologies and stimulation protocols in preclinical models, aiming at both improving the electrode performance and confirming therapeutic efficacy. Assessing the scalability of newly proposed electrode technology and their use for tissue stimulation remains, however, an open question.Approach.We propose a simplified electrical model that formalizes the dimensional scaling of stimulation electrode systems. We use established equations describing the electrode impedance, and apply them to the case of stimulation electrodes driven by a voltage-capped pulse generator.Main results.We find a hard, intrinsic upward scalability limit to the electrode radius that largely depends on the conductor technology. We finally provide a simple analytical formula predicting the maximum size of a stimulation electrode as a function of the stimulation parameters and conductor resistance.Significance.Our results highlight the importance of careful geometrical and electrical designs of electrode systems based on novel thin-film technologies and that become particularly relevant for their translational implementation with electrode geometries approaching clinical human size electrodes and interfacing with voltage-capped neurostimulation systems.
Collapse
Affiliation(s)
- Giuseppe Schiavone
- 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, 1202 Geneva, Switzerland
| | - Nicolas Vachicouras
- 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, 1202 Geneva, Switzerland
| | - Yashwanth Vyza
- 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, 1202 Geneva, Switzerland
| | - Stéphanie P Lacour
- 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, 1202 Geneva, Switzerland
| |
Collapse
|
2
|
Egunov AI, Dou Z, Karnaushenko DD, Hebenstreit F, Kretschmann N, Akgün K, Ziemssen T, Karnaushenko D, Medina-Sánchez M, Schmidt OG. Impedimetric Microfluidic Sensor-in-a-Tube for Label-Free Immune Cell Analysis. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2002549. [PMID: 33448115 DOI: 10.1002/smll.202002549] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Analytical platforms based on impedance spectroscopy are promising for non-invasive and label-free analysis of single cells as well as of their extracellular matrix, being essential to understand cell function in the presence of certain diseases. Here, an innovative rolled-up impedimetric microfulidic sensor, called sensor-in-a-tube, is introduced for the simultaneous analysis of single human monocytes CD14+ and their extracellular medium upon liposaccharides (LPS)-mediated activation. In particular, rolled-up platinum microelectrodes are integrated within for the static and dynamic (in-flow) detection of cells and their surrounding medium (containing expressed cytokines) over an excitation frequency range from 102 to 5 × 106 Hz. The correspondence between cell activation stages and the electrical properties of the cell surrounding medium have been detected by electrical impedance spectroscopy in dynamic mode without employing electrode surface functionalization or labeling. The designed sensor-in-a-tube platform is shown as a sensitive and reliable tool for precise single cell analysis toward immune-deficient diseases diagnosis.
Collapse
Affiliation(s)
- Aleksandr I Egunov
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Zehua Dou
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Dmitriy D Karnaushenko
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Franziska Hebenstreit
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Nicole Kretschmann
- Center of Clinical Neuroscience, Multiple Sklerose Zentrum Dresden, University Hospital Carl Gustav Carus at Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
| | - Katja Akgün
- Center of Clinical Neuroscience, Multiple Sklerose Zentrum Dresden, University Hospital Carl Gustav Carus at Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
| | - Tjalf Ziemssen
- Center of Clinical Neuroscience, Multiple Sklerose Zentrum Dresden, University Hospital Carl Gustav Carus at Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
| | - Daniil Karnaushenko
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Mariana Medina-Sánchez
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Oliver G Schmidt
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, Str. der Nationen 62, 09111, Chemnitz, Germany
- Nanophysics, Dresden University of Technology, Haeckelstraße 3, 01069, Dresden, Germany
| |
Collapse
|
3
|
Schiavone G, Kang X, Fallegger F, Gandar J, Courtine G, Lacour SP. Guidelines to Study and Develop Soft Electrode Systems for Neural Stimulation. Neuron 2020; 108:238-258. [PMID: 33120021 DOI: 10.1016/j.neuron.2020.10.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/23/2020] [Accepted: 10/08/2020] [Indexed: 12/13/2022]
Abstract
Electrical stimulation of nervous structures is a widely used experimental and clinical method to probe neural circuits, perform diagnostics, or treat neurological disorders. The recent introduction of soft materials to design electrodes that conform to and mimic neural tissue led to neural interfaces with improved functionality and biointegration. The shift from stiff to soft electrode materials requires adaptation of the models and characterization methods to understand and predict electrode performance. This guideline aims at providing (1) an overview of the most common techniques to test soft electrodes in vitro and in vivo; (2) a step-by-step design of a complete study protocol, from the lab bench to in vivo experiments; (3) a case study illustrating the characterization of soft spinal electrodes in rodents; and (4) examples of how interpreting characterization data can inform experimental decisions. Comprehensive characterization is paramount to advancing soft neurotechnology that meets the requisites for long-term functionality in vivo.
Collapse
Affiliation(s)
- Giuseppe Schiavone
- 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, 1202 Geneva, Switzerland
| | - Xiaoyang Kang
- 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, 1202 Geneva, Switzerland
| | - Florian Fallegger
- 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, 1202 Geneva, Switzerland
| | - Jérôme Gandar
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Grégoire Courtine
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Defitech Center for Interventional Neurotherapies (NeuroRestore), Department of Neurosurgery, University Hospital of Lausanne (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Stéphanie P Lacour
- 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, 1202 Geneva, Switzerland.
| |
Collapse
|
4
|
Merletti R, Cerone GL. Tutorial. Surface EMG detection, conditioning and pre-processing: Best practices. J Electromyogr Kinesiol 2020; 54:102440. [PMID: 32763743 DOI: 10.1016/j.jelekin.2020.102440] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/13/2020] [Accepted: 06/20/2020] [Indexed: 10/24/2022] Open
Abstract
This tutorial is aimed primarily to non-engineers, using or planning to use surface electromyography (sEMG) as an assessment tool for muscle evaluation in the prevention, monitoring, assessment and rehabilitation fields. The main purpose is to explain basic concepts related to: (a) signal detection (electrodes, electrode-skin interface, noise, ECG and power line interference), (b) basic signal properties, such as amplitude and bandwidth, (c) parameters of the front-end amplifier (input impedance, noise, CMRR, bandwidth, etc.), (d) techniques for interference and artifact reduction, (e) signal filtering, (f) sampling and (g) A/D conversion, These concepts are addressed and discussed, with examples. The second purpose is to outline best practices and provide general guidelines for proper signal detection, conditioning and A/D conversion, aimed to clinical operators and biomedical engineers. Issues related to the sEMG origin and to electrode size, interelectrode distance and location, have been discussed in a previous tutorial. Issues related to signal processing for information extraction will be discussed in a subsequent tutorial.
Collapse
Affiliation(s)
- R Merletti
- LISiN - Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications - Politecnico di Torino, Turin, Italy.
| | - G L Cerone
- LISiN - Laboratory for Engineering of the Neuromuscular System, Department of Electronics and Telecommunications - Politecnico di Torino, Turin, Italy
| |
Collapse
|
5
|
Maldari M, Albatat M, Bergsland J, Haddab Y, Jabbour C, Desgreys P. Wide Frequency Characterization of Intra-Body Communication for Leadless Pacemakers. IEEE Trans Biomed Eng 2020; 67:3223-3233. [PMID: 32167883 DOI: 10.1109/tbme.2020.2980205] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Leadless Cardiac Pacemakers (LCP) have the potential to revolutionize Cardiac Rhythm Management (CRM). Current LCPs can only pace a single location of the heart limiting their use to patients requiring single-chamber stimulation. A Multi-node system of synchronized LCPs could be used in a significantly larger patient population. Synchronization using standard communication techniques involves high power consumption decreasing the longevity of the device. In this work, we investigate Galvanic Intra Body Communication (IBC) as a method to synchronize multi-node LCP systems. First, an accurate computational torso model was used for quasi-static simulations to estimate channel pathloss in the frequency range [40 kHz-20 MHz]. The model was then verified with in-vivo measurements using a novel experimental setup, where two LCP devices were placed in the right atrium, right ventricle and left ventricle. All channels involved in a potential multi-node LCP system were characterized. The orientation of the transducers relative to each other had a great impact on the results, with the attenuation level ranging between 55 dB and 70 dB between the best and worst orientations. The best results were achieved in the MHz range. Coupled with the fact that it does not require additional electrodes, this study suggests Galvanic IBC be superior to conventional communication methods for LCP devices. This analysis defines a methodology for galvanic IBC channel characterization for LCP systems, which is an important step for the design of efficient transceivers for IBC applications. More experiments with larger datasets are needed to bring this method to practice.
Collapse
|
6
|
A Novel Method for Humidity-Dependent Through-Plane Impedance Measurement for Proton Conducting Polymer Membranes. MEMBRANES 2019; 9:membranes9050062. [PMID: 31067800 PMCID: PMC6571940 DOI: 10.3390/membranes9050062] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 11/17/2022]
Abstract
In this study, we introduce a through-plane electrochemical measurement cell for proton conducting polymer membranes (PEM) with the ability to vary temperature and humidity. Model Nafion and 3M membranes, as well as anisotropic composite membranes, were used to compare through plane and in plane conductivity. Electrochemical impedance spectroscopy (EIS) was applied to evaluate the proton conductivity of bare proton exchange membranes. In the Nyquist plots, all membranes showed a straight line with an angle of 60–70 degrees to the Z’-axis. Equivalent circuit modeling and linear extrapolation of the impedance data were compared to extract the membrane resistance. System and cell parameters such as high frequency inductance, contact resistance and pressure, interfacial capacitance were observed and instrumentally minimized. Material-related effects, such as swelling of the membranes and indentation of the platinum mesh electrodes were examined thoroughly to receive a reliable through-plane conductivity. The received data for model Nafion and 3M membranes were in accordance with literature values for in-plane and through-plane conductivity of membrane electrode assemblies. Anisotropic composite membranes underlined the importance of a sophisticated measurement technique that is able to separate the in-plane and through-plane effects in polymer electrolytes.
Collapse
|
7
|
Afsharipour B, Soedirdjo S, Merletti R. Two-dimensional surface EMG: The effects of electrode size, interelectrode distance and image truncation. Biomed Signal Process Control 2019. [DOI: 10.1016/j.bspc.2018.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
8
|
Michelson NJ, Eles JR, Vazquez AL, Ludwig KA, Kozai TDY. Calcium activation of cortical neurons by continuous electrical stimulation: Frequency dependence, temporal fidelity, and activation density. J Neurosci Res 2018; 97:620-638. [PMID: 30585651 DOI: 10.1002/jnr.24370] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/20/2018] [Accepted: 11/28/2018] [Indexed: 01/18/2023]
Abstract
Electrical stimulation of the brain has become a mainstay of fundamental neuroscience research and an increasingly prevalent clinical therapy. Despite decades of use in basic neuroscience research and the growing prevalence of neuromodulation therapies, gaps in knowledge regarding activation or inactivation of neural elements over time have limited its ability to adequately interpret evoked downstream responses or fine-tune stimulation parameters to focus on desired responses. In this work, in vivo two-photon microscopy was used to image neuronal calcium activity in layer 2/3 neurons of somatosensory cortex (S1) in male C57BL/6J-Tg(Thy1-GCaMP6s)GP4.3Dkim/J mice during 30 s of continuous electrical stimulation at varying frequencies. We show frequency-dependent differences in spatial and temporal somatic responses during continuous stimulation. Our results elucidate conflicting results from prior studies reporting either dense spherical activation of somas biased toward those near the electrode, or sparse activation of somas at a distance via axons near the electrode. These findings indicate that the neural element specific temporal response local to the stimulating electrode changes as a function of applied charge density and frequency. These temporal responses need to be considered to properly interpret downstream circuit responses or determining mechanisms of action in basic science experiments or clinical therapeutic applications.
Collapse
Affiliation(s)
- Nicholas J Michelson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
| | - James R Eles
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Alberto L Vazquez
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kip A Ludwig
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, Wisconsin.,Department of Neurological Surgery, University of Wisconsin Madison, Madison, Wisconsin
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, Pennsylvania.,Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.,NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, Pennsylvania
| |
Collapse
|
9
|
Kumar R, Kant R. Experimental corroboration of general phenomenological theory for dynamics of EDL in viscous medium on rough heterogeneous electrode. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.10.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
10
|
Sadeghi S, Fooladi E, Malekaneh M. A New Amperometric Benzaldhyde Biosensor Based on Aldehyde Oxidase Immobilized on Fe3O4-GrapheneOxide/Polyvinylpyrrolidone/Polyaniline Nanocomposite. ELECTROANAL 2014. [DOI: 10.1002/elan.201400420] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
11
|
Yaeli S, Binyamin E, Shoham S. Form-function relations in cone-tipped stimulating microelectrodes. FRONTIERS IN NEUROENGINEERING 2009; 2:13. [PMID: 19680467 PMCID: PMC2726034 DOI: 10.3389/neuro.16.013.2009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 07/20/2009] [Indexed: 11/30/2022]
Abstract
Metal microelectrodes are widely used in neuroscience research, and could potentially replace macroelectrodes in various neuro-stimulation applications where their small size, specificity, and their ability to also measure unit activity are desirable. The design of stimulating microelectrodes for specific applications requires knowledge on how tip geometry affects function, but several fundamental aspects of this relationship are not yet well understood. This study uses a combined experimental and physical finite elements simulation approach to formulate three new relationships between the geometrical and electrical properties of stimulating cone-tipped tungsten microelectrodes: (1) The empirical relationship between microelectrode 1-kHz impedance and the exposed tip surface area is best approximated by an inverse square-root function (as expected for a cone-tipped resistive interface). (2) Tip angle plays a major role in determining current distribution along the tip, and as a consequence crucially affects the charge injection capacity of a microelectrode. (3) The critical current for the onset of corrosion is independent of tip surface area in sharp microelectrodes.
Collapse
Affiliation(s)
- Steve Yaeli
- Faculty of Biomedical Engineering, Technion - Israel Institute of Technology Israel
| | | | | |
Collapse
|
12
|
|
13
|
Franks W, Schenker I, Schmutz P, Hierlemann A. Impedance Characterization and Modeling of Electrodes for Biomedical Applications. IEEE Trans Biomed Eng 2005; 52:1295-302. [PMID: 16041993 DOI: 10.1109/tbme.2005.847523] [Citation(s) in RCA: 469] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A low electrode-electrolyte impedance interface is critical in the design of electrodes for biomedical applications. To design low-impedance interfaces a complete understanding of the physical processes contributing to the impedance is required. In this work a model describing these physical processes is validated and extended to quantify the effect of organic coatings and incubation time. Electrochemical impedance spectroscopy has been used to electrically characterize the interface for various electrode materials: platinum, platinum black, and titanium nitride; and varying electrode sizes: 1 cm2, and 900 microm2. An equivalent circuit model comprising an interface capacitance, shunted by a charge transfer resistance, in series with the solution resistance has been fitted to the experimental results. Theoretical equations have been used to calculate the interface capacitance impedance and the solution resistance, yielding results that correspond well with the fitted parameter values, thereby confirming the validity of the equations. The effect of incubation time, and two organic cell-adhesion promoting coatings, poly-L-lysine and laminin, on the interface impedance has been quantified using the model. This demonstrates the benefits of using this model in developing better understanding of the physical processes occurring at the interface in more complex, biomedically relevant situations.
Collapse
Affiliation(s)
- Wendy Franks
- Physical Electronics Laboratory, ETH, Zurich 8093, Zurich, Switzerland.
| | | | | | | |
Collapse
|
14
|
Heer F, Franks W, Blau A, Taschini S, Ziegler C, Hierlemann A, Baltes H. CMOS microelectrode array for the monitoring of electrogenic cells. Biosens Bioelectron 2004; 20:358-66. [PMID: 15308242 DOI: 10.1016/j.bios.2004.02.006] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 02/04/2004] [Accepted: 02/05/2004] [Indexed: 10/26/2022]
Abstract
Signal degradation and an array size dictated by the number of available interconnects are the two main limitations inherent to standalone microelectrode arrays (MEAs). A new biochip consisting of an array of microelectrodes with fully-integrated analog and digital circuitry realized in an industrial CMOS process addresses these issues. The device is capable of on-chip signal filtering for improved signal-to-noise ratio (SNR), on-chip analog and digital conversion, and multiplexing, thereby facilitating simultaneous stimulation and recording of electrogenic cell activity. The designed electrode pitch of 250 microm significantly limits the space available for circuitry: a repeated unit of circuitry associated with each electrode comprises a stimulation buffer and a bandpass filter for readout. The bandpass filter has corner frequencies of 100 Hz and 50 kHz, and a gain of 1000. Stimulation voltages are generated from an 8-bit digital signal and converted to an analog signal at a frequency of 120 kHz. Functionality of the read-out circuitry is demonstrated by the measurement of cardiomyocyte activity. The microelectrode is realized in a shifted design for flexibility and biocompatibility. Several microelectrode materials (platinum, platinum black and titanium nitride) have been electrically characterized. An equivalent circuit model, where each parameter represents a macroscopic physical quantity contributing to the interface impedance, has been successfully fitted to experimental results.
Collapse
Affiliation(s)
- F Heer
- Physical Electronics Laboratory, ETH Zurich, 8093 Zurich, Switzerland.
| | | | | | | | | | | | | |
Collapse
|
15
|
Schimpf PH, Johnson G, Jorgenson DB, Haynor DR, Bardy GH, Kim Y. Effects of electrode interface impedance on finite element models of transvenous defibrillation. Med Biol Eng Comput 1995; 33:713-9. [PMID: 8523916 DOI: 10.1007/bf02510792] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- P H Schimpf
- Department of Electrical Engineering, University of Washington, Seattle 98195, USA
| | | | | | | | | | | |
Collapse
|
16
|
Stegeman DF, Gootzen TH, Theeuwen MM, Vingerhoets HJ. Intramuscular potential changes caused by the presence of the recording EMG needle electrode. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1994; 93:81-90. [PMID: 7512924 DOI: 10.1016/0168-5597(94)90070-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A comprehensive volume conductor study of single fiber needle EMG (SF EMG) has been made. The electrode shaft is described as a passive inhomogeneity in the volume conductor. The most important observation is a substantial increase in single fiber action potential (SFAP) amplitude (up to 70%) for muscle fibers observed from a short distance. For SFAPs from muscle fibers located on the back of the SF electrode a shadow effect occurs which can result in a maximal amplitude decrease of 50%. SFAP wave form changes were observed only in situations without practical consequences or beyond physical reality. The presence of the needle shaft causes an anisotropy-like behavior of the relation between leading-off point to muscle fiber distance. The observed amplification due to the presence of the needle cannula decreases faster in the direction parallel to the cannula than in the direction normal to it: due to the amplification of SFAPs from muscle fibers observed from a short distance, the maximal distance from which SFAPs are included in fiber density measurements (amplitude greater than 0.2 mV) is raised from 380 microns to 460 microns. Also, the consequences of the formation of an edematous layer around the needle cannula have been studied. It was shown that the effect of high conductive fluid around the needle electrode can counteract the effects caused by the presence of the electrical double layer.
Collapse
Affiliation(s)
- D F Stegeman
- Department of Clinical Neurophysiology, University of Nijmegen, The Netherlands
| | | | | | | |
Collapse
|
17
|
Theeuwen MM, Gootzen TH, Stegeman DF. Muscle electric activity. I: A model study on the effect of needle electrodes on single fiber action potentials. Ann Biomed Eng 1993; 21:377-89. [PMID: 8214822 DOI: 10.1007/bf02368630] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Needle recorded electromyographic signals can be expected to be influenced by the presence of the needle, the electrical double layer at the metal-electrolyte interface, and by an edematous layer around the needle electrode. The magnitude of each of these effects is derived from a cylinder symmetrical volume conductor model. Analytical solutions of Laplace's equation have been derived. These are used for simulating single muscle fiber action potentials (SFAPs) recorded by a typical single fiber electrode. The results indicate that there is no short-circuiting effect, in spite of the presence of a highly conducting needle shaft, which is due to the high impedance of the electrical double layer. The insulating properties of the double layer cause the SFAP amplitudes to increase, when the muscle fiber passes the electrode at the side of the leading-off point. The edematous layer counteracts this increase depending on the thickness and the conductivity of this layer. Only slight SFAP wave-form changes are found.
Collapse
Affiliation(s)
- M M Theeuwen
- Laboratory of Medical Physics and Biophysics, University of Nijmegen, The Netherlands
| | | | | |
Collapse
|
18
|
Beard RB, Hung BN, Schmukler R. Biocompatibility considerations at stimulating electrode interfaces. Ann Biomed Eng 1992; 20:395-410. [PMID: 1443832 DOI: 10.1007/bf02368539] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The choice of biocompatible stimulating electrodes for various biomedical applications varies with the type of electrode-tissue interface, biomolecules present, electrolyte background, preparation of electrode, interfacial potential, current density, electrode material, porosity, geometry, and inflammatory response. Illustrative examples are given to demonstrate the importance of these parameters. Topics discussed are: A) DC electrodes applied to partially keratinized epithelial membranes; B) Variation of the electrical impedance and biocompatibility of stimulating electrodes with electrode potential and surrounding pH; C) Influence of electrode geometry, porosity and pore size on biocompatibility; D) Body defense mechanisms at the sites of implantable stimulating electrodes; E) Thrombus formation at stimulating electrode interfaces and F) Sterilization of electrodes to ensure biocompatibility.
Collapse
Affiliation(s)
- R B Beard
- Biomedical Engineering and Science Institute, Drexel University, Philadelphia, PA 19104
| | | | | |
Collapse
|