Micromachines

Editorial

6 pages, 175 KiB

Open AccessEditorial

Editorial for the Special Issue on Neural Electrodes: Design and Applications

by Joseph J. Pancrazio^* and Stuart F. Cogan^*

Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, BSB 13.633, Richardson, TX 75080, USA

Micromachines 2019, 10(7), 466; https://doi.org/10.3390/mi10070466 - 12 Jul 2019

Cited by 4 | Viewed by 2898

Abstract

Neural electrodes enable the recording and stimulation of bioelectrical activity from the nervous system [...] Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

Research

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15 pages, 3563 KiB

Open AccessArticle

Dextran as a Resorbable Coating Material for Flexible Neural Probes

by Dries Kil^1,*

, Marta Bovet Carmona², Frederik Ceyssens¹, Marjolijn Deprez³, Luigi Brancato¹

, Bart Nuttin³, Detlef Balschun² and Robert Puers¹

¹ ESAT-MICAS, KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium

² Laboratory for Biological Psychology, Brain & Cognition, KU Leuven, Tiensestraat 102, 3000 Leuven, Belgium

³ Experimental Neurosurgery and Neuroanatomy, UZ Herestraat 49 box 7003, 3000 Leuven, Belgium

Micromachines 2019, 10(1), 61; https://doi.org/10.3390/mi10010061 - 17 Jan 2019

Cited by 31 | Viewed by 5947

Abstract

In the quest for chronically reliable and bio-tolerable brain interfaces there has been a steady evolution towards the use of highly flexible, polymer-based electrode arrays. The reduced mechanical mismatch between implant and brain tissue has shown to reduce the evoked immune response, which [...] Read more.

In the quest for chronically reliable and bio-tolerable brain interfaces there has been a steady evolution towards the use of highly flexible, polymer-based electrode arrays. The reduced mechanical mismatch between implant and brain tissue has shown to reduce the evoked immune response, which in turn has a positive effect on signal stability and noise. Unfortunately, the low stiffness of the implants also has practical repercussions, making surgical insertion extremely difficult. In this work we explore the use of dextran as a coating material that temporarily stiffens the implant, preventing buckling during insertion. The mechanical properties of dextran coated neural probes are characterized, as well as the different parameters which influence the dissolution rate. Tuning parameters, such as coating thickness and molecular weight of the used dextran, allows customization of the stiffness and dissolution time to precisely match the user’s needs. Finally, the immunological response to the coated electrodes was analyzed by performing a histological examination after four months of in vivo testing. The results indicated that a very limited amount of glial scar tissue was formed. Neurons have also infiltrated the area that was initially occupied by the dissolving dextran coating. There was no noticeable drop in neuron density around the site of implantation, confirming the suitability of the coating as a temporary aid during implantation of highly flexible polymer-based neural probes. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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18 pages, 5870 KiB

Open AccessArticle

Remote Stimulation of Sciatic Nerve Using Cuff Electrodes and Implanted Diodes

by Arati Sridharan

, Sanchit Chirania, Bruce C. Towe and Jit Muthuswamy^*

School of Biological & Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State University, Tempe, AZ 85287, USA

Micromachines 2018, 9(11), 595; https://doi.org/10.3390/mi9110595 - 14 Nov 2018

Cited by 6 | Viewed by 7447

Abstract

We demonstrate a method of neurostimulation using implanted, free-floating, inter-neural diodes. They are activated by volume-conducted, high frequency, alternating current (AC) fields and address the issue of instability caused by interconnect wires in chronic nerve stimulation. The aim of this study is to [...] Read more.

We demonstrate a method of neurostimulation using implanted, free-floating, inter-neural diodes. They are activated by volume-conducted, high frequency, alternating current (AC) fields and address the issue of instability caused by interconnect wires in chronic nerve stimulation. The aim of this study is to optimize the set of AC electrical parameters and the diode features to achieve wireless neurostimulation. Three different packaged Schottky diodes (1.5 mm, 500 µm and 220 µm feature sizes) were tested in vivo (n = 17 rats). A careful assessment of sciatic nerve activation as a function of diode–dipole lengths and relative position of the diode was conducted. Subsequently, free-floating Schottky microdiodes were implanted in the nerve (n = 3 rats) and stimulated wirelessly. Thresholds for muscle twitch responses increased non-linearly with frequency. Currents through implanted diodes within the nerve suffer large attenuations (~100 fold) requiring 1–2 mA drive currents for thresholds at 17 µA. The muscle recruitment response using electromyograms (EMGs) is intrinsically steep for subepineurial implants and becomes steeper as diode is implanted at increasing depths away from external AC stimulating electrodes. The study demonstrates the feasibility of activating remote, untethered, implanted microscale diodes using external AC fields and achieving neurostimulation. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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21 pages, 4762 KiB

Open AccessArticle

Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes

by Malgorzata M. Straka^1,*, Benjamin Shafer², Srikanth Vasudevan²

, Cristin Welle³ and Loren Rieth^1,4

¹ Center for Bioelectronic Medicine, Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY 11030, USA

² U.S. Food and Drug Administration, Center for Devices and Radiological Health (CDRH), Office of Science and Engineering Laboratory (OSEL), Division of Biomedical Physics (DBP), Silver Spring, MD 20993, USA

³ Departments of Neurosurgery and Bioengineering, University of Colorado, Aurora, CO 80045, USA

⁴ Departments of Electrical Engineering and Bioengineering, University of Utah, Salt Lake City, UT 84112, USA

Micromachines 2018, 9(11), 587; https://doi.org/10.3390/mi9110587 - 12 Nov 2018

Cited by 28 | Viewed by 5198

Abstract

Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to false [...] Read more.

Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to false positives. We implanted cohorts of five iridium oxide (IrOx) and six platinum (Pt) Utah arrays into the sciatic nerve of rats, and collected the electrochemical impedance spectroscopy (EIS) up to 12 weeks or until array failure. We developed a method to classify the shapes of the magnitude and phase spectra, and correlated the classifications to circuit models and electrochemical processes at the interface likely responsible. We found categories of EIS characteristic of iridium oxide tip metallization, platinum tip metallization, tip metal degradation, encapsulation degradation, and wire breakage in the lead. We also fitted the impedance spectra as features to a fine-Gaussian support vector machine (SVM) algorithm for both IrOx and Pt tipped arrays, with a prediction accuracy for categories of 95% and 99%, respectively. Together, this suggests that these simple and computationally efficient algorithms are sufficient to explain the majority of variance across a wide range of EIS data describing Utah arrays. These categories were assessed over time, providing insights into the degradation and failure mechanisms for both the electrode–tissue interface and wire bundle. Methods developed in this study will allow for a better understanding of how EIS can characterize the physical changes to electrodes in vivo. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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16 pages, 3306 KiB

Open AccessFeature PaperArticle

A Mechanically-Adaptive Polymer Nanocomposite-Based Intracortical Probe and Package for Chronic Neural Recording

by Allison Hess-Dunning^1,2,*

and Dustin J. Tyler^1,2,3

¹ Rehabilitation Research and Development, Louis Stokes Cleveland VA Medical Center, Cleveland, OH 44106, USA

² Advanced Platform Technology Center, Cleveland, OH 44106, USA

³ Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA

Micromachines 2018, 9(11), 583; https://doi.org/10.3390/mi9110583 - 8 Nov 2018

Cited by 25 | Viewed by 4431

Abstract

Mechanical, materials, and biological causes of intracortical probe failure have hampered their utility in basic science and clinical applications. By anticipating causes of failure, we can design a system that will prevent the known causes of failure. The neural probe design was centered [...] Read more.

Mechanical, materials, and biological causes of intracortical probe failure have hampered their utility in basic science and clinical applications. By anticipating causes of failure, we can design a system that will prevent the known causes of failure. The neural probe design was centered around a bio-inspired, mechanically-softening polymer nanocomposite. The polymer nanocomposite was functionalized with recording microelectrodes using a microfabrication process designed for chemical and thermal process compatibility. A custom package based upon a ribbon cable, printed circuit board, and a 3D-printed housing was designed to enable connection to external electronics. Probes were implanted into the primary motor cortex of Sprague-Dawley rats for 16 weeks, during which regular recording and electrochemical impedance spectroscopy measurement sessions took place. The implanted mechanically-softening probes had stable electrochemical impedance spectra across the 16 weeks and single units were recorded out to 16 weeks. The demonstration of chronic neural recording with the mechanically-softening probe suggests that probe architecture, custom package, and general design strategy are appropriate for long-term studies in rodents. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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Graphical abstract

15 pages, 3395 KiB

Open AccessFeature PaperArticle

Integrity Assessment of a Hybrid DBS Probe that Enables Neurotransmitter Detection Simultaneously to Electrical Stimulation and Recording

by Danesh Ashouri Vajari^1,2,*, Maria Vomero^1,2, Johannes B. Erhardt^1,2, Ali Sadr¹, Juan S. Ordonez^1,3, Volker A. Coenen^2,5,6

and Thomas Stieglitz^1,2,4

¹ Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Kohler-Allee 102, 79110 Freiburg, Germany

² BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Georges-Kohler-Allee 79, 79110 Freiburg, Germany

³ Indigo Diabetes N.V., Bollebergen 2B box 5, B-9052 Gent, Belgium

⁴ Bernstein Center Freiburg, University of Freiburg, Hansastrasse 9a, 79104 Freiburg, Germany

⁵ Department of Stereotactic and Functional Neurosurgery, University Medical Center Freiburg, Breisacher Strasse 64, 79106 Freiburg, Germany

⁶ Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany

Micromachines 2018, 9(10), 510; https://doi.org/10.3390/mi9100510 - 10 Oct 2018

Cited by 15 | Viewed by 7328

Abstract

Deep brain stimulation (DBS) is a successful medical therapy for many treatment resistant neuropsychiatric disorders such as movement disorders; e.g., Parkinson’s disease, Tremor, and dystonia. Moreover, DBS is becoming more and more appealing for a rapidly growing number of patients with other neuropsychiatric [...] Read more.

Deep brain stimulation (DBS) is a successful medical therapy for many treatment resistant neuropsychiatric disorders such as movement disorders; e.g., Parkinson’s disease, Tremor, and dystonia. Moreover, DBS is becoming more and more appealing for a rapidly growing number of patients with other neuropsychiatric diseases such as depression and obsessive compulsive disorder. In spite of the promising outcomes, the current clinical hardware used in DBS does not match the technological standards of other medical applications and as a result could possibly lead to side effects such as high energy consumption and others. By implementing more advanced DBS devices, in fact, many of these limitations could be overcome. For example, a higher channels count and smaller electrode sites could allow more focal and tailored stimulation. In addition, new materials, like carbon for example, could be incorporated into the probes to enable adaptive stimulation protocols by biosensing neurotransmitters in the brain. Updating the current clinical DBS technology adequately requires combining the most recent technological advances in the field of neural engineering. Here, a novel hybrid multimodal DBS probe with glassy carbon microelectrodes on a polyimide thin-film device assembled on a silicon rubber tubing is introduced. The glassy carbon interface enables neurotransmitter detection using fast scan cyclic voltammetry and electrophysiological recordings while simultaneously performing electrical stimulation. Additionally, the presented DBS technology shows no imaging artefacts in magnetic resonance imaging. Thus, we present a promising new tool that might lead to a better fundamental understanding of the underlying mechanism of DBS while simultaneously paving our way towards better treatments. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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14 pages, 6071 KiB

Open AccessArticle

Chronic Intracortical Recording and Electrochemical Stability of Thiol-ene/Acrylate Shape Memory Polymer Electrode Arrays

by Allison M. Stiller^1,*

, Joshua Usoro¹

, Christopher L. Frewin¹, Vindhya R. Danda^1,2, Melanie Ecker³

, Alexandra Joshi-Imre¹

, Kate C. Musselman¹, Walter Voit^2,3, Romil Modi²

, Joseph J. Pancrazio¹ and Bryan J. Black¹

¹ Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA

² Qualia, Inc., Dallas, TX 75252, USA

³ Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA

Micromachines 2018, 9(10), 500; https://doi.org/10.3390/mi9100500 - 29 Sep 2018

Cited by 50 | Viewed by 6553

Abstract

Current intracortical probe technology is limited in clinical implementation due to the short functional lifetime of implanted devices. Devices often fail several months to years post-implantation, likely due to the chronic immune response characterized by glial scarring and neuronal dieback. It has been [...] Read more.

Current intracortical probe technology is limited in clinical implementation due to the short functional lifetime of implanted devices. Devices often fail several months to years post-implantation, likely due to the chronic immune response characterized by glial scarring and neuronal dieback. It has been demonstrated that this neuroinflammatory response is influenced by the mechanical mismatch between stiff devices and the soft brain tissue, spurring interest in the use of softer polymer materials for probe encapsulation. Here, we demonstrate stable recordings and electrochemical properties obtained from fully encapsulated shape memory polymer (SMP) intracortical electrodes implanted in the rat motor cortex for 13 weeks. SMPs are a class of material that exhibit modulus changes when exposed to specific conditions. The formulation used in these devices softens by an order of magnitude after implantation compared to its dry, room-temperature modulus of ~2 GPa. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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18 pages, 3890 KiB

Open AccessCommunication

Design Choices for Next-Generation Neurotechnology Can Impact Motion Artifact in Electrophysiological and Fast-Scan Cyclic Voltammetry Measurements

by Evan N. Nicolai¹, Nicholas J. Michelson^2,3

, Megan L. Settell¹, Seth A. Hara⁴

, James K. Trevathan¹

, Anders J. Asp¹, Kaylene C. Stocking², J. Luis Lujan^5,6

, Takashi D.Y. Kozai^{2,7,8,9,10,*,†}

and Kip A. Ludwig^11,12,*,†

¹ Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA

² Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA

³ Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 1Z3, Canada

⁴ Division of Engineering, Mayo Clinic, Rochester, MN 55905, USA

⁵ Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA

⁶ Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA

⁷ Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA 15213, USA

⁸ McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA

⁹ NeuroTech Center of the University of Pittsburgh Brain Institute, Pittsburgh, PA 15213, USA

¹⁰ Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15213, USA

¹¹ Department of Bioengineering, University of Wisconsin, Madison, WI 53706, USA

¹² Department of Neurological Surgery, University of Wisconsin, Madison, WI 53706, USA

^† These authors have contributed equally to this work.

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Micromachines 2018, 9(10), 494; https://doi.org/10.3390/mi9100494 - 27 Sep 2018

Cited by 17 | Viewed by 6212

Abstract

Implantable devices to measure neurochemical or electrical activity from the brain are mainstays of neuroscience research and have become increasingly utilized as enabling components of clinical therapies. In order to increase the number of recording channels on these devices while minimizing the immune [...] Read more.

Implantable devices to measure neurochemical or electrical activity from the brain are mainstays of neuroscience research and have become increasingly utilized as enabling components of clinical therapies. In order to increase the number of recording channels on these devices while minimizing the immune response, flexible electrodes under 10 µm in diameter have been proposed as ideal next-generation neural interfaces. However, the representation of motion artifact during neurochemical or electrophysiological recordings using ultra-small, flexible electrodes remains unexplored. In this short communication, we characterize motion artifact generated by the movement of 7 µm diameter carbon fiber electrodes during electrophysiological recordings and fast-scan cyclic voltammetry (FSCV) measurements of electroactive neurochemicals. Through in vitro and in vivo experiments, we demonstrate that artifact induced by motion can be problematic to distinguish from the characteristic signals associated with recorded action potentials or neurochemical measurements. These results underscore that new electrode materials and recording paradigms can alter the representation of common sources of artifact in vivo and therefore must be carefully characterized. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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18 pages, 3727 KiB

Open AccessArticle

Characterization of the Neuroinflammatory Response to Thiol-ene Shape Memory Polymer Coated Intracortical Microelectrodes

by Andrew J. Shoffstall^1,2, Melanie Ecker^2,3

, Vindhya Danda^3,4,5,6, Alexandra Joshi-Imre⁴

, Allison Stiller⁵

, Marina Yu^1,2, Jennifer E. Paiz^1,2, Elizabeth Mancuso^1,2, Hillary W. Bedell¹, Walter E. Voit^3,4,5,6, Joseph J. Pancrazio⁵ and Jeffrey R. Capadona^1,2,*

¹ Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA

² Advanced Platform Technology Center, Rehabilitation Research and Development, Louis Stokes Cleveland Department of Veteran Affairs Medical Center, Cleveland, OH, USA

³ Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, USA

⁴ Center for Engineering Innovation, The University of Texas at Dallas, Richardson, TX, USA

⁵ Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA

⁶ Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX, USA

Micromachines 2018, 9(10), 486; https://doi.org/10.3390/mi9100486 - 24 Sep 2018

Cited by 26 | Viewed by 5294

Abstract

Thiol-ene based shape memory polymers (SMPs) have been developed for use as intracortical microelectrode substrates. The unique chemistry provides precise control over the mechanical and thermal glass-transition properties. As a result, SMP substrates are stiff at room temperature, allowing for insertion into the [...] Read more.

Thiol-ene based shape memory polymers (SMPs) have been developed for use as intracortical microelectrode substrates. The unique chemistry provides precise control over the mechanical and thermal glass-transition properties. As a result, SMP substrates are stiff at room temperature, allowing for insertion into the brain without buckling and subsequently soften in response to body temperatures, reducing the mechanical mismatch between device and tissue. Since the surface chemistry of the materials can contribute significantly to the ultimate biocompatibility, as a first step in the characterization of our SMPs, we sought to isolate the biological response to the implanted material surface without regards to the softening mechanics. To accomplish this, we tightly controlled for bulk stiffness by comparing bare silicon ‘dummy’ devices to thickness-matched silicon devices dip-coated with SMP. The neuroinflammatory response was evaluated after devices were implanted in the rat cortex for 2 or 16 weeks. We observed no differences in the markers tested at either time point, except that astrocytic scarring was significantly reduced for the dip-coated implants at 16 weeks. The surface properties of non-softening thiol-ene SMP substrates appeared to be equally-tolerated and just as suitable as silicon for neural implant substrates for applications such as intracortical microelectrodes, laying the groundwork for future softer devices to improve upon the prototype device performance presented here. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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14 pages, 2422 KiB

Open AccessArticle

Amorphous Silicon Carbide Platform for Next Generation Penetrating Neural Interface Designs

by Felix Deku^1,*

, Christopher L. Frewin¹, Allison Stiller¹

, Yarden Cohen², Saher Aqeel¹, Alexandra Joshi-Imre¹

, Bryan Black¹, Timothy J. Gardner², Joseph J. Pancrazio¹ and Stuart F. Cogan¹

¹ Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA

² Department of Biology and Biomedical Engineering, Boston University, Boston, MA 02215, USA

Micromachines 2018, 9(10), 480; https://doi.org/10.3390/mi9100480 - 20 Sep 2018

Cited by 25 | Viewed by 5437

Abstract

Microelectrode arrays that consistently and reliably record and stimulate neural activity under conditions of chronic implantation have so far eluded the neural interface community due to failures attributed to both biotic and abiotic mechanisms. Arrays with transverse dimensions of 10 µm or below [...] Read more.

Microelectrode arrays that consistently and reliably record and stimulate neural activity under conditions of chronic implantation have so far eluded the neural interface community due to failures attributed to both biotic and abiotic mechanisms. Arrays with transverse dimensions of 10 µm or below are thought to minimize the inflammatory response; however, the reduction of implant thickness also decreases buckling thresholds for materials with low Young’s modulus. While these issues have been overcome using stiffer, thicker materials as transport shuttles during implantation, the acute damage from the use of shuttles may generate many other biotic complications. Amorphous silicon carbide (a-SiC) provides excellent electrical insulation and a large Young’s modulus, allowing the fabrication of ultrasmall arrays with increased resistance to buckling. Prototype a-SiC intracortical implants were fabricated containing 8 - 16 single shanks which had critical thicknesses of either 4 µm or 6 µm. The 6 µm thick a-SiC shanks could penetrate rat cortex without an insertion aid. Single unit recordings from SIROF-coated arrays implanted without any structural support are presented. This work demonstrates that a-SiC can provide an excellent mechanical platform for devices that penetrate cortical tissue while maintaining a critical thickness less than 10 µm. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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22 pages, 6027 KiB

Open AccessFeature PaperArticle

Acquisition of Neural Action Potentials Using Rapid Multiplexing Directly at the Electrodes

by Mohit Sharma^1,*, Avery Tye Gardner¹, Hunter J. Strathman², David J. Warren², Jason Silver¹ and Ross M. Walker^1,*

¹ Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA

² Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA

Micromachines 2018, 9(10), 477; https://doi.org/10.3390/mi9100477 - 20 Sep 2018

Cited by 43 | Viewed by 7335

Abstract

Neural recording systems that interface with implanted microelectrodes are used extensively in experimental neuroscience and neural engineering research. Interface electronics that are needed to amplify, filter, and digitize signals from multichannel electrode arrays are a critical bottleneck to scaling such systems. This paper [...] Read more.

Neural recording systems that interface with implanted microelectrodes are used extensively in experimental neuroscience and neural engineering research. Interface electronics that are needed to amplify, filter, and digitize signals from multichannel electrode arrays are a critical bottleneck to scaling such systems. This paper presents the design and testing of an electronic architecture for intracortical neural recording that drastically reduces the size per channel by rapidly multiplexing many electrodes to a single circuit. The architecture utilizes mixed-signal feedback to cancel electrode offsets, windowed integration sampling to reduce aliased high-frequency noise, and a successive approximation analog-to-digital converter with small capacitance and asynchronous control. Results are presented from a 180 nm CMOS integrated circuit prototype verified using in vivo experiments with a tungsten microwire array implanted in rodent cortex. The integrated circuit prototype achieves <0.004 mm² area per channel, 7 µW power dissipation per channel, 5.6 µV_rms input referred noise, 50 dB common mode rejection ratio, and generates 9-bit samples at 30 kHz per channel by multiplexing at 600 kHz. General considerations are discussed for rapid time domain multiplexing of high-impedance microelectrodes. Overall, this work describes a promising path forward for scaling neural recording systems to numbers of electrodes that are orders of magnitude larger. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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12 pages, 3951 KiB

Open AccessCommunication

Genetic Modulation at the Neural Microelectrode Interface: Methods and Applications

by Bailey M. Winter¹, Samuel R. Daniels¹, Joseph W. Salatino¹

and Erin K. Purcell^1,2,*

¹ Department of Biomedical Engineering, Michigan State University, East Lansing, MI 48824, USA

² Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA

Micromachines 2018, 9(10), 476; https://doi.org/10.3390/mi9100476 - 20 Sep 2018

Cited by 9 | Viewed by 4060

Abstract

The use of implanted microelectrode arrays (MEAs), in the brain, has enabled a greater understanding of neural function, and new treatments for neurodegenerative diseases and psychiatric disorders. Glial encapsulation of the device and the loss of neurons at the device-tissue interface are widely [...] Read more.

The use of implanted microelectrode arrays (MEAs), in the brain, has enabled a greater understanding of neural function, and new treatments for neurodegenerative diseases and psychiatric disorders. Glial encapsulation of the device and the loss of neurons at the device-tissue interface are widely believed to reduce recording quality and limit the functional device-lifetime. The integration of microfluidic channels within MEAs enables the perturbation of the cellular pathways, through defined vector delivery. This provides new approaches to shed light on the underlying mechanisms of the reactive response and its contribution to device performance. In chronic settings, however, tissue ingrowth and biofouling can obstruct or damage the channel, preventing vector delivery. In this study, we describe methods of delivering vectors through chronically implanted, single-shank, “Michigan”-style microfluidic devices, 1–3 weeks, post-implantation. We explored and validated three different approaches for modifying gene expression at the device-tissue interface: viral-mediated overexpression, siRNA-enabled knockdown, and cre-dependent conditional expression. We observed a successful delivery of the vectors along the length of the MEA, where the observed expression varied, depending on the depth of the injury. The methods described are intended to enable vector delivery through microfluidic devices for a variety of potential applications; likewise, future design considerations are suggested for further improvements on the approach. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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14 pages, 6091 KiB

Open AccessArticle

LED Optrode with Integrated Temperature Sensing for Optogenetics

by S. Beatriz Goncalves^1,2

, José M. Palha²

, Helena C. Fernandes²

, Márcio R. Souto²

, Sara Pimenta²

, Tao Dong^1,3

, Zhaochu Yang¹

, João F. Ribeiro²

and José H. Correia^1,2,*

¹ Institute of Applied Micro-Nano Science and Technology—IAMNST, Chongqing Key Laboratory of Colleges and Universities on Micro-Nano Systems Technology and Smart Transducing, Chongqing Engineering Laboratory for Detection, Control and Integrated System, National Research Base of Intelligent Manufacturing Service, Chongqing Technology and Business University, Nan’an District, Chongqing 400067, China

² CMEMS-UMinho, Department of Industrial Electronics, University of Minho, Guimaraes 4800-058, Portugal

³ Institute for Microsystems-IMS, Faculty of Technology, Natural Sciences and Maritime Sciences, University of South-Eastern Norway (USN), Postboks 235, 3603 Kongsberg, Norway

Micromachines 2018, 9(9), 473; https://doi.org/10.3390/mi9090473 - 17 Sep 2018

Cited by 28 | Viewed by 8255

Abstract

In optogenetic studies, the brain is exposed to high-power light sources and inadequate power density or exposure time can cause cell damage from overheating (typically temperature increasing of 2

^{\circ}

C). In order to overcome overheating issues in optogenetics, this paper presents a [...] Read more.

In optogenetic studies, the brain is exposed to high-power light sources and inadequate power density or exposure time can cause cell damage from overheating (typically temperature increasing of 2

^{\circ}

C). In order to overcome overheating issues in optogenetics, this paper presents a neural tool capable of assessing tissue temperature over time, combined with the capability of electrical recording and optical stimulation. A silicon-based 8 mm long probe was manufactured to reach deep neural structures. The final proof-of-concept device comprises a double-sided function: on one side, an optrode with LED-based stimulation and platinum (Pt) recording points; and, on the opposite side, a Pt-based thin-film thermoresistance (RTD) for temperature assessing in the photostimulation site surroundings. Pt thin-films for tissue interface were chosen due to its biocompatibility and thermal linearity. A single-shaft probe is demonstrated for integration in a 3D probe array. A 3D probe array will reduce the distance between the thermal sensor and the heating source. Results show good recording and optical features, with average impedance magnitude of 371 k

Ω

, at 1 kHz, and optical power of 1.2 mW·mm

^{- 2}

(at 470 nm), respectively. The manufactured RTD showed resolution of 0.2

^{\circ}

C at 37

^{\circ}

C (normal body temperature). Overall, the results show a device capable of meeting the requirements of a neural interface for recording/stimulating of neural activity and monitoring temperature profile of the photostimulation site surroundings, which suggests a promising tool for neuroscience research filed. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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9 pages, 1589 KiB

Open AccessArticle

A Meta-Analysis of Intracortical Device Stiffness and Its Correlation with Histological Outcomes

by Allison M. Stiller^*

, Bryan J. Black, Christopher Kung, Aashika Ashok, Stuart F. Cogan, Victor D. Varner and Joseph J. Pancrazio

Department of Bioengineering, The University of Texas at Dallas, 800W. Campbell Rd., Richardson, TX 75080, USA

Micromachines 2018, 9(9), 443; https://doi.org/10.3390/mi9090443 - 6 Sep 2018

Cited by 55 | Viewed by 5429

Abstract

Neural implants offer solutions for a variety of clinical issues. While commercially available devices can record neural signals for short time periods, they fail to do so chronically, partially due to the sustained tissue response around the device. Our objective was to assess [...] Read more.

Neural implants offer solutions for a variety of clinical issues. While commercially available devices can record neural signals for short time periods, they fail to do so chronically, partially due to the sustained tissue response around the device. Our objective was to assess the correlation between device stiffness, a function of both material modulus and cross-sectional area, and the severity of immune response. Meta-analysis data were derived from nine previously published studies which reported device material and geometric properties, as well as histological outcomes. Device bending stiffness was calculated by treating the device shank as a cantilevered beam. Immune response was quantified through analysis of immunohistological images from each study, specifically looking at fluorescent markers for neuronal nuclei and astrocytes, to assess neuronal dieback and gliosis. Results demonstrate that the severity of the immune response, within the first 50 µm of the device, is highly correlated with device stiffness, as opposed to device modulus or cross-sectional area independently. In general, commercially available devices are around two to three orders of magnitude higher in stiffness than devices which induced a minimal tissue response. These results have implications for future device designs aiming to decrease chronic tissue response and achieve increased long-term functionality. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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21 pages, 3796 KiB

Open AccessFeature PaperArticle

Scalable, Modular Three-Dimensional Silicon Microelectrode Assembly via Electroless Plating

by Jörg Scholvin¹, Anthony Zorzos¹, Justin Kinney¹, Jacob Bernstein¹, Caroline Moore-Kochlacs^1,2, Nancy Kopell², Clifton Fonstad¹ and Edward S. Boyden^1,*

¹ Massachusetts Institute of Technology, Cambridge, MA 02139, USA

² Department of Mathematics, Boston University, Boston, MA 02215, USA

Micromachines 2018, 9(9), 436; https://doi.org/10.3390/mi9090436 - 30 Aug 2018

Cited by 5 | Viewed by 6349

Abstract

We devised a scalable, modular strategy for microfabricated 3-D neural probe synthesis. We constructed a 3-D probe out of individual 2-D components (arrays of shanks bearing close-packed electrodes) using mechanical self-locking and self-aligning techniques, followed by electroless nickel plating to establish electrical contact [...] Read more.

We devised a scalable, modular strategy for microfabricated 3-D neural probe synthesis. We constructed a 3-D probe out of individual 2-D components (arrays of shanks bearing close-packed electrodes) using mechanical self-locking and self-aligning techniques, followed by electroless nickel plating to establish electrical contact between the individual parts. We detail the fabrication and assembly process and demonstrate different 3-D probe designs bearing thousands of electrode sites. We find typical self-alignment accuracy between shanks of <0.2° and demonstrate orthogonal electrical connections of 40 µm pitch, with thousands of connections formed electrochemically in parallel. The fabrication methods introduced allow the design of scalable, modular electrodes for high-density 3-D neural recording. The combination of scalable 3-D design and close-packed recording sites may support a variety of large-scale neural recording strategies for the mammalian brain. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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20 pages, 5266 KiB

Open AccessArticle

Development, Modeling, Fabrication, and Characterization of a Magnetic, Micro-Spring-Suspended System for the Safe Electrical Interconnection of Neural Implants

by Katharina Hoch¹, Frederick Pothof¹, Felix Becker¹, Oliver Paul^1,2 and Patrick Ruther^1,2,*

¹ Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, Germany

² BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, 79110 Freiburg, Germany

Micromachines 2018, 9(9), 424; https://doi.org/10.3390/mi9090424 - 23 Aug 2018

Cited by 3 | Viewed by 5125

Abstract

The development of innovative tools for neuroscientific research is based on in vivo tests typically applied to small animals. Most often, the interfacing of neural probes relies on commercially available connector systems which are difficult to handle during connection, particularly when freely behaving [...] Read more.

The development of innovative tools for neuroscientific research is based on in vivo tests typically applied to small animals. Most often, the interfacing of neural probes relies on commercially available connector systems which are difficult to handle during connection, particularly when freely behaving animals are involved. Furthermore, the connectors often exert high mechanical forces during plugging and unplugging, potentially damaging the fragile bone structure. In order to facilitate connector usage and increase the safety of laboratory animals, we developed a new magnetic connector system circumventing the drawbacks of existing tools. The connector system uses multiple magnet pairs and spring-suspended electrical contact pads realized using micro-electromechanical systems (MEMS) technologies. While the contact pad suspension increases the system tolerance in view of geometrical variations, we achieved a reliable self-alignment of the connector parts at ±50 µm provided by the specifically oriented magnet pairs and without the need of alignment pins. While connection forces are negligible, we can adjust the forces during connector release by modifying the magnet distance. With the connector test structures developed here, we achieved an electrical connection yield of 100%. Based on these findings, we expect that in vivo experiments with freely behaving animals will be facilitated with improved animal safety. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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12 pages, 2151 KiB

Open AccessFeature PaperArticle

Liquid Crystal Elastomer-Based Microelectrode Array for In Vitro Neuronal Recordings

by Rashed T. Rihani^†

, Hyun Kim^†, Bryan J. Black, Rahul Atmaramani, Mohand O. Saed, Joseph J. Pancrazio and Taylor H. Ware^*

¹ Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA

^† These authors contributed equally to this work.

Micromachines 2018, 9(8), 416; https://doi.org/10.3390/mi9080416 - 20 Aug 2018

Cited by 28 | Viewed by 7285

Abstract

Polymer-based biomedical electronics provide a tunable platform to interact with nervous tissue both in vitro and in vivo. Ultimately, the ability to control functional properties of neural interfaces may provide important advantages to study the nervous system or to restore function in patients [...] Read more.

Polymer-based biomedical electronics provide a tunable platform to interact with nervous tissue both in vitro and in vivo. Ultimately, the ability to control functional properties of neural interfaces may provide important advantages to study the nervous system or to restore function in patients with neurodegenerative disorders. Liquid crystal elastomers (LCEs) are a class of smart materials that reversibly change shape when exposed to a variety of stimuli. Our interest in LCEs is based on leveraging this shape change to deploy electrode sites beyond the tissue regions exhibiting inflammation associated with chronic implantation. As a first step, we demonstrate that LCEs are cellular compatible materials that can be used as substrates for fabricating microelectrode arrays (MEAs) capable of recording single unit activity in vitro. Extracts from LCEs are non-cytotoxic (>70% normalized percent viability), as determined in accordance to ISO protocol 10993-5 using fibroblasts and primary murine cortical neurons. LCEs are also not functionally neurotoxic as determined by exposing cortical neurons cultured on conventional microelectrode arrays to LCE extract for 48 h. Microelectrode arrays fabricated on LCEs are stable, as determined by electrochemical impedance spectroscopy. Examination of the impedance and phase at 1 kHz, a frequency associated with single unit recording, showed results well within range of electrophysiological recordings over 30 days of monitoring in phosphate-buffered saline (PBS). Moreover, the LCE arrays are shown to support viable cortical neuronal cultures over 27 days in vitro and to enable recording of prominent extracellular biopotentials comparable to those achieved with conventional commercially-available microelectrode arrays. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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18 pages, 1718 KiB

Open AccessArticle

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

by Evans K. Bernardin¹

, Christopher L. Frewin², Richard Everly³, Jawad Ul Hassan⁴

and Stephen E. Saddow^5,*

¹ Department of Biomedical Engineering, University of South Florida, Tampa, FL 33620, USA

² Department of Bioengineering, University of Texas at Dallas, Dallas, TX 75080, USA

³ Nanotechnology Research and Education Center @ USF, Tampa, FL 33617, USA

⁴ Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden

⁵ Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA

Micromachines 2018, 9(8), 412; https://doi.org/10.3390/mi9080412 - 18 Aug 2018

Cited by 26 | Viewed by 5807 | Correction

Abstract

Intracortical neural interfaces (INI) have made impressive progress in recent years but still display questionable long-term reliability. Here, we report on the development and characterization of highly resilient monolithic silicon carbide (SiC) neural devices. SiC is a physically robust, biocompatible, and chemically inert [...] Read more.

Intracortical neural interfaces (INI) have made impressive progress in recent years but still display questionable long-term reliability. Here, we report on the development and characterization of highly resilient monolithic silicon carbide (SiC) neural devices. SiC is a physically robust, biocompatible, and chemically inert semiconductor. The device support was micromachined from p-type SiC with conductors created from n-type SiC, simultaneously providing electrical isolation through the resulting p-n junction. Electrodes possessed geometric surface area (GSA) varying from 496 to 500 K μm². Electrical characterization showed high-performance p-n diode behavior, with typical turn-on voltages of ~2.3 V and reverse bias leakage below 1 nArms. Current leakage between adjacent electrodes was ~7.5 nArms over a voltage range of −50 V to 50 V. The devices interacted electrochemically with a purely capacitive relationship at frequencies less than 10 kHz. Electrode impedance ranged from 675 ± 130 kΩ (GSA = 496 µm²) to 46.5 ± 4.80 kΩ (GSA = 500 K µm²). Since the all-SiC devices rely on the integration of only robust and highly compatible SiC material, they offer a promising solution to probe delamination and biological rejection associated with the use of multiple materials used in many current INI devices. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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Review

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19 pages, 1635 KiB

Open AccessReview

Progress in the Field of Micro-Electrocorticography

by Mehdi Shokoueinejad^1,2,†

, Dong-Wook Park^3,4,†, Yei Hwan Jung³

, Sarah K. Brodnick¹, Joseph Novello¹, Aaron Dingle⁵, Kyle I. Swanson², Dong-Hyun Baek¹, Aaron J. Suminski^1,2, Wendell B. Lake², Zhenqiang Ma^3,* and Justin Williams^1,2,*

¹ Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

² Department of Neurosurgery, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53792, USA

³ Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA

⁴ School of Electrical and Computer Engineering, University of Seoul, Seoul 02504, South Korea

⁵ Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Wisconsin-Madison, Madison, WI 53792, USA

^† These authors contributed equally to this work.

Micromachines 2019, 10(1), 62; https://doi.org/10.3390/mi10010062 - 17 Jan 2019

Cited by 45 | Viewed by 10419

Abstract

Since the 1940s electrocorticography (ECoG) devices and, more recently, in the last decade, micro-electrocorticography (µECoG) cortical electrode arrays were used for a wide set of experimental and clinical applications, such as epilepsy localization and brain–computer interface (BCI) technologies. Miniaturized implantable µECoG devices have [...] Read more.

Since the 1940s electrocorticography (ECoG) devices and, more recently, in the last decade, micro-electrocorticography (µECoG) cortical electrode arrays were used for a wide set of experimental and clinical applications, such as epilepsy localization and brain–computer interface (BCI) technologies. Miniaturized implantable µECoG devices have the advantage of providing greater-density neural signal acquisition and stimulation capabilities in a minimally invasive fashion. An increased spatial resolution of the µECoG array will be useful for greater specificity diagnosis and treatment of neuronal diseases and the advancement of basic neuroscience and BCI research. In this review, recent achievements of ECoG and µECoG are discussed. The electrode configurations and varying material choices used to design µECoG arrays are discussed, including advantages and disadvantages of µECoG technology compared to electroencephalography (EEG), ECoG, and intracortical electrode arrays. Electrode materials that are the primary focus include platinum, iridium oxide, poly(3,4-ethylenedioxythiophene) (PEDOT), indium tin oxide (ITO), and graphene. We discuss the biological immune response to µECoG devices compared to other electrode array types, the role of µECoG in clinical pathology, and brain–computer interface technology. The information presented in this review will be helpful to understand the current status, organize available knowledge, and guide future clinical and research applications of µECoG technologies. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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14 pages, 2746 KiB

Open AccessReview

A Bidirectional Neuromodulation Technology for Nerve Recording and Stimulation

by Jian Xu¹, Hongsun Guo¹, Anh Tuan Nguyen¹, Hubert Lim^1,2,3 and Zhi Yang^1,*

¹ Department of Biomedical Engineering, University of Minnesota, 312 Church Street SE, Minneapolis, MN 55455, USA

² Department of Otolaryngology, Head and Neck Surgery, University of Minnesota, 516 Delaware Street SE, Minneapolis, MN 55455, USA

³ Institute for Translational Neuroscience, University of Minnesota, 2101 6th Street SE, Minneapolis, MN 55455, USA

Micromachines 2018, 9(11), 538; https://doi.org/10.3390/mi9110538 - 23 Oct 2018

Cited by 19 | Viewed by 6468

Abstract

Electrical nerve recording and stimulation technologies are critically needed to monitor and modulate nerve activity to treat a variety of neurological diseases. However, current neuromodulation technologies presented in the literature or commercially available products cannot support simultaneous recording and stimulation on the same [...] Read more.

Electrical nerve recording and stimulation technologies are critically needed to monitor and modulate nerve activity to treat a variety of neurological diseases. However, current neuromodulation technologies presented in the literature or commercially available products cannot support simultaneous recording and stimulation on the same nerve. To solve this problem, a new bidirectional neuromodulation system-on-chip (SoC) is proposed in this paper, which includes a frequency-shaping neural recorder and a fully integrated neural stimulator with charge balancing capability. In addition, auxiliary circuits consisting of power management and data transmission circuits are designed to provide the necessary power supply for the SoC and the bidirectional data communication between the SoC and an external computer via a universal serial bus (USB) interface, respectively. To achieve sufficient low input noise for sensing nerve activity at a sub-10

μ

V range, several noise reduction techniques are developed in the neural recorder. The designed SoC was fabricated in a 0.18

μ

m high-voltage Bipolar CMOS DMOS (BCD) process technology that was described in a previous publication and it has been recently tested in animal experiments that demonstrate the proposed SoC is capable of achieving reliable and simultaneous electrical stimulation and recording on the same nerve. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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14 pages, 1797 KiB

Open AccessReview

Chronically Implanted Intracranial Electrodes: Tissue Reaction and Electrical Changes

by Andrew Campbell^1,* and Chengyuan Wu²

¹ Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA

² Department of Neurological Surgery, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA

Micromachines 2018, 9(9), 430; https://doi.org/10.3390/mi9090430 - 25 Aug 2018

Cited by 102 | Viewed by 10815

Abstract

The brain-electrode interface is arguably one of the most important areas of study in neuroscience today. A stronger foundation in this topic will allow us to probe the architecture of the brain in unprecedented functional detail and augment our ability to intervene in [...] Read more.

The brain-electrode interface is arguably one of the most important areas of study in neuroscience today. A stronger foundation in this topic will allow us to probe the architecture of the brain in unprecedented functional detail and augment our ability to intervene in disease states. Over many years, significant progress has been made in this field, but some obstacles have remained elusive—notably preventing glial encapsulation and electrode degradation. In this review, we discuss the tissue response to electrode implantation on acute and chronic timescales, the electrical changes that occur in electrode systems over time, and strategies that are being investigated in order to minimize the tissue response to implantation and maximize functional electrode longevity. We also highlight the current and future clinical applications and relevance of electrode technology. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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19 pages, 1018 KiB

Open AccessFeature PaperReview

Opportunities and Challenges for Single-Unit Recordings from Enteric Neurons in Awake Animals

by Bradley B. Barth^1,*

, Hsin-I Huang², Gianna E. Hammer² and Xiling Shen¹

¹ Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA

² Department of Immunology, Duke University, Durham, NC 27710, USA

Micromachines 2018, 9(9), 428; https://doi.org/10.3390/mi9090428 - 25 Aug 2018

Cited by 6 | Viewed by 5546

Abstract

Advanced electrode designs have made single-unit neural recordings commonplace in modern neuroscience research. However, single-unit resolution remains out of reach for the intrinsic neurons of the gastrointestinal system. Single-unit recordings of the enteric (gut) nervous system have been conducted in anesthetized animal models [...] Read more.

Advanced electrode designs have made single-unit neural recordings commonplace in modern neuroscience research. However, single-unit resolution remains out of reach for the intrinsic neurons of the gastrointestinal system. Single-unit recordings of the enteric (gut) nervous system have been conducted in anesthetized animal models and excised tissue, but there is a large physiological gap between awake and anesthetized animals, particularly for the enteric nervous system. Here, we describe the opportunity for advancing enteric neuroscience offered by single-unit recording capabilities in awake animals. We highlight the primary challenges to microelectrodes in the gastrointestinal system including structural, physiological, and signal quality challenges, and we provide design criteria recommendations for enteric microelectrodes. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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1 pages, 155 KiB

Open AccessCorrection

Correction: Bernardin E.K.; et al. Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface. Micromachines, 2018, 9, 412

by Evans K. Bernardin¹

, Christopher L. Frewin², Richard Everly³, Jawad Ul Hassan⁴ and Stephen E. Saddow^5,*

¹ Department of Biomedical Engineering, University of South Florida, Tampa, FL 33620, USA

² Department of Bioengineering, University of Texas at Dallas, Dallas, TX 75080, USA

³ Nanotechnology Research and Education Center @ USF, Tampa, FL 33617, USA

⁴ Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden

⁵ Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA

Micromachines 2018, 9(9), 451; https://doi.org/10.3390/mi9090451 - 10 Sep 2018

Cited by 5 | Viewed by 2631

Abstract

The authors would like to indicate the following financial support they received to the Acknowledgement Section of their published paper [...] Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

17 pages, 1881 KiB

Open AccessPerspective

The History and Horizons of Microscale Neural Interfaces

by Takashi D. Y. Kozai^1,2,3,4,5

¹ Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA

² Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15213, USA

³ Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15261, USA

⁴ McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15212, USA

⁵ NeuroTech Center, University of Pittsburgh Brain Institute, Pittsburgh, PA 15260, USA

Micromachines 2018, 9(9), 445; https://doi.org/10.3390/mi9090445 - 6 Sep 2018

Cited by 18 | Viewed by 6967

Abstract

Microscale neural technologies interface with the nervous system to record and stimulate brain tissue with high spatial and temporal resolution. These devices are being developed to understand the mechanisms that govern brain function, plasticity and cognitive learning, treat neurological diseases, or monitor and [...] Read more.

Microscale neural technologies interface with the nervous system to record and stimulate brain tissue with high spatial and temporal resolution. These devices are being developed to understand the mechanisms that govern brain function, plasticity and cognitive learning, treat neurological diseases, or monitor and restore functions over the lifetime of the patient. Despite decades of use in basic research over days to months, and the growing prevalence of neuromodulation therapies, in many cases the lack of knowledge regarding the fundamental mechanisms driving activation has dramatically limited our ability to interpret data or fine-tune design parameters to improve long-term performance. While advances in materials, microfabrication techniques, packaging, and understanding of the nervous system has enabled tremendous innovation in the field of neural engineering, many challenges and opportunities remain at the frontiers of the neural interface in terms of both neurobiology and engineering. In this short-communication, we explore critical needs in the neural engineering field to overcome these challenges. Disentangling the complexities involved in the chronic neural interface problem requires simultaneous proficiency in multiple scientific and engineering disciplines. The critical component of advancing neural interface knowledge is to prepare the next wave of investigators who have simultaneous multi-disciplinary proficiencies with a diverse set of perspectives necessary to solve the chronic neural interface challenge. Full article

(This article belongs to the Special Issue Neural Microelectrodes: Design and Applications)

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