Download or read book Mechanistic Electrochemical Characterization of Novel Microelectrode Arrays and Their Application in Mapping Brain Activity Across Species and Humans written by Mehran Ganji and published by . This book was released on 2019 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrocorticography (ECoG) arrays are used in clinical mapping for neurosurgical resection and hold the promise for less damaging brain-machine interfaces. Current clinical ECoG electrodes face physical limits to the number of contact sites, spatial resolution (centimeter scale), and contact diameter (millimeter scale), and thus cannot resolve the dynamically changing neural activity over sub-millimeter scales . In addition to these practical limitations, current clinical electrode arrays are constrained to non-conformal electrode-carriers/substrates and to less-optimal metal electrochemical interfaces. Increasing the flexibility of clinical electrodes may lead to higher signal-to-noise ratios as well as higher spatial specificity and this also requires overcoming substantial physical barriers due to the compromised metal electrochemical interface properties. The objectives of this thesis, described in seven chapters, are to develop high performance, safe, and durable neural electrode interfaces to yield stable, high signal-to-noise ratio cortical recordings in animal models as well as in humans. In the second chapter, we demonstrate that sterilization of PEDOT:PSS electrophysiology devices can be performed using an autoclave. We find that autoclaving is a viable sterilization method, leaving morphology unaltered and causing only minor changes in electrical properties. These results pave the way for the widespread utilization of PEDOT:PSS electrophysiology devices in the clinic. In the third chapter, we translate the use of robust PEDOT:PSS microelectrode arrays for safe intraoperative monitoring of the human brain. PEDOT:PSS micro-electrodes measured significant differential neural modulation under various clinically relevant conditions. We report the first evoked (stimulus-locked) cognitive activity with changes in amplitude across pial surface distances as small as 400 [mu]m, potentially enabling basic neurophysiology studies at the scale of neural micro-circuitry. In the fourth and fifth chapters, we present the first systematic study of scaling effects on the electrochemical properties of Pt and Au metallic and PEDOT:PSS organic electrodes from neural recording and stimulation perspectives. PEDOT:PSS coating reduced the impedances of metallic electrodes by up to 18X. The overall reduced noise of the PEDOT:PSS microelectrodes enable a lower noise floor for recording action-potentials with high fidelity. We observed a substantial enhancement in charge injection capacity up to 9.5X for PEDOT:PSS microelectrodes compared to metal ones and 88% lower required power for injecting the same charge density. These results permit quantitative optimization of contact material and diameter for different ECoG applications. In the sixth chapter, We report an effective method of mechanically anchoring the PEDOT within the Au nanorod (Au-nr) structure and demonstrate that it provides enhanced adhesion and overall PEDOT layer stability under various electrochemical (charge injection) and In vivo stability tests. In the seventh chapter, we report the fabrication of pure Pt nanorods (PtNRs) by utilizing low-temperature selective dealloying to develop scalable and biocompatible 1D platinum nanorod (PtNR) arrays that exhibit superb electrochemical properties at various length scales for high-performance neurotechnologies. PtNR arrays record brain activity with cellular resolution from the cortical surfaces in birds, mice, and non-human primates; demonstrating the PtNR microelectrode system as a robust system for high performance and stable neural electrode interfaces.
Download or read book PEDOT PSS Parylene C ECoG Microelectrode Arrays for Multi Modal Recording of Brain Activity in Birds and Rodents written by Lorraine Amena Hossain and published by . This book was released on 2020 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding cognitive processing in intact brains is the subject of intense research efforts that aim to resolve individual and network activity of neuronal cells across different layers of the brain. While efforts to record a large number of individual cellular activity in intact brains are underway, the network-level coordinated activity of neurons result in long-range, low frequency oscillations that carry significant electrophysiological information and is the gold standard for recording neural correlates of cognition from animals and humans. Recently, recording of individual cellular activity, commonly referred to as single units, with high signal-to-noise ratio from the cortical surface was accomplished. Critical to this milestone in electrophysiology was the use of organic microelectrode arrays that (1) possess superior electrochemical junction characteristics enabling them to have contact diameters that are similar to neuronal sizes yet while maintaining low electrochemical impedances and low noise, and (2) enable conformal coverage of thin parylene C device carrier layers to the brain curvature. The small contact diameter, and therefore listening sphere, its low noise, and its intimate contact with the surface of the brain are all attributed as essential conditions to permit the recording of single unit activity from the brain's surface. This thesis appraises the development of novel microelectrode arrays that record single units from the brain's surface, and their application in recording brain activity from anesthetized and awake animal models. The first part of the dissertation discusses the application of Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, commonly known as PEDOT:PSS--a semiconductive polymer with excellent electrochemical properties--as well as microelectrode contacts that employ large surface area one-dimensional nanostructures, to the electrophysiological investigations in songbird experiments. Significantly, we observed strong correlation of surface-recorded single units with spectrotemporal features of replayed birdsongs across trials and that were also validated with simultaneously implanted depth electrodes. This finding has implications for minimally destructive brain-machine interfaces that can make use of surface-recorded units. Additionally, we carried out systematic investigations to understand the influence of the electrode contact diameter and the contact material on resolving single unit activity from the surface of the brain. Our initial results suggest that contacts with lower impedances result in higher signal amplitude as well as higher biological noise amplitude, due to their sensitivity and that amplitude of single units generally decreases with diameter. While acute recordings can streamline testing of neurotechnologies, chronic recordings are important for applications in which subjects can ultimately engage in behavioral experiments. To this end, the last part of this dissertation concerns with the development and optimization of a chronically stable device form factor. This device leverages the transparency of the parylene C substrate to perform simultaneous electrophysiological recording and multi-photon imaging of neuronal activity in awake mice. We recorded stimulus-evoked calcium indicator responses that correlated with local field potential (LFP) response and higher frequency multi- and single unit activity. This dissertation encompasses advances in the scalable, monolithic fabrication procedure for high-yield PEDOT:PSS microelectrode arrays on parylene C substrates and their utility of electrocorticography (ECoG) recording capability of neuronal activity from intact brains.
Download or read book Electrochemical Study and Characterization of Novel Microelectrode Materials written by Albert Brennsteiner and published by . This book was released on 19?? with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Engineering and Evaluation of a Novel Microgrid Electrode Array to Monitor the Electrical Activity on the Surface of the Cerebral Cortex written by Joseph Paul Kitzmiller and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The purpose of the study was to design and engineer a novel microdevice, a microgrid electrode array, that can further biomedical engineering research in the areas of neuroscience and neurology. Microfabrication techniques were developed to create the microdevice, which is capable of measuring electrical activity on the surface of the cerebral cortex at a greater level of spatial resolution than currently available for surface electrode grids. The device has been designed to detect the activity of individual cortical columns. Although penetrating microelectrodes are capable of detecting this level of detail, their invasiveness limits their use to human cortical tissue destined for surgical resection or strictly to animal studies. The development of a less-invasive non-penetrating microgrid electrode array suitable for human use would provide medical scientists with a unique and powerful tool for detailed brain mapping, gaining a better understanding of human cortical column function, as well as for exploring diseases and therapy options associated with the cerebral cortex. The fabrication protocol included several standard photolithography steps and many novel chemical and encapsulation methods. Characterization of the fabrication protocol steps and testing of the electrical connection integrity was performed using Scanning Electron Microscopy (SEM), optical microscopy, profilometery, and a microprobe station. Cyto-compatibility testing of the microgrid electrode with mammalian and human cortical cells consisted of qualitative and quantitative analyses. Evaluation with a porcine animal model consisted of collecting Visual Evoked Potentials (VEPs) from the primary visual cortex. Results from characterization of the fabrication process revealed that the desired geometries of the device were achieved. The resulting microgrid consisted of an array of surface contacts (200-micron platinum squares with bi-directional pitch of 400 microns) suspended in an insulating polydimethylsiloxane (PDMS) polymer. Cyto-compatibility testing with mammalian and human cells gave results that suggest that the device may be suitable for use with human patients. The results acquired from testing the device with an animal model revealed that the device was not only able to detect electrical activity from the cortex surface, but also suggests that activity corresponding to individual cortical columns can be acquired.
Download or read book Microfluidic Brain Slice Chambers and Flexible Microelectrode Arrays for in Vitro Localized Stimulation and Spatial Mapping of Neural Activities written by Yujie Tang and published by . This book was released on 2012 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: In vitro neurobiological experiments using brain slices have played a key role in improving our understanding of the central nervous system. Microfabricated brain slice chambers and flexible semi-transparent multi-electrode arrays allow controlled local changes in the chemical environments as well as high resolution electrophysiology and optical recording of brain slices which would in turn provide further information of the complex neuronal system. In this study, we exploit the advantages of microfabricated devices, including a microfluidic brain slice chamber for localized chemical stimulation and a flexible microelectrode array for spatial mapping of neuronal activities, to investigate various biophysical properties of cortical spreading depression. First, a microfluidic brain slice chamber is designed and fabricated to permit localized chemical stimulation to specific brain slice cortical regions. We build a numerical finite element model to predict the injected plume shape and the resulting ion distributions in the stimulated brain slice. Various characterization methods, including particle tracking velocimetry, fluorescent imaging and tissue staining, are implemented to verify the fluid dynamics predicted by our model. With the ability to fine control the stimulation area, we vary the stimulation size as well as the extracellular potassium concentration ([K+]e) to study the conditions for the onset of cortical spreading depression. We find a strong correlation between the threshold concentration and the slice area exposed to the increased [K+]e. Our results show that CSD is inducible under the conditions expected in migraine aura. We then explore the use of a flexible microelectrode array to map spatiotemporal electrophysiological activities induced by localized chemical stimulation. We concurrently use the microfluidic device to initiate CSD in mice cortex and the electrode array to record electrical activities accompanying the spreading wave. Besides the consistency between optical and electrical recording, we observe the electrical responses similar to cortical spreading convulsion with a corresponding optical characteristic. In summary, the microfluidic brain slice chamber has been demonstrated with a localized stimulation capability and used to probe the cortical spreading depression initiation and propagation properties. The concurrent use of the microfluidic and microelectrode array techniques has been demonstrated and is shown to be promising in addressing scientific questions. Our work demonstrates a successful implementation of novel microfabricated tools for the neuroscience research.
Download or read book Design Fabrication and Characterization of Microelectrodes for Brain machine Interfaces written by Erin Patrick and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The long-term goal in the design of brain-machine interfaces (BMIs) is to restore communication and control of prosthetic devices to individuals with loss of motor function due to spinal cord injuries, amyotrophic lateral sclerosis, or muscular dystrophy, for example. One of the great challenges in this effort is to develop implantable systems that are capable of processing the activity of large ensembles of cortical neurons. This work presents the design, fabrication, characterization, and in vivo testing of a neural recording platform for a pre-clinical application. The recording platform is a flexible, polyimide-based microelectrode array that can be hybrid-packaged with custom electronics in a fully-implantable form factor. Results from the microelectrode array integrated with an amplifier integrated circuit include data from in vivo neural recordings showing consistent single-unit discrimination over 42 days. Moreover, results from the electrochemical assessment of the corrosion properties of the tungsten microwire electrodes used on the microelectrode array admonish the use of tungsten in long-term implants.
Download or read book Brief van C R J v d Water aan Nicolaas Anthony Donkersloot 1902 1965 written by and published by . This book was released on 1937 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Brain Activity Recorded by Micro ECoG Electrode Arrays written by Wang, Xi and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Tissue Reactivity to Microelectrode Arrays as a Function of Depth in the Rat Cerebral Cortex written by Tracy P. Williamson and published by . This book was released on 2006 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Network Electrophysiology written by Makoto Taketani and published by Springer Science & Business Media. This book was released on 2006-11-22 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Network Electrophysiology: Using Multi Electrode Arrays explores methods for using electrophysiological techniques for monitoring the concurrent activity of ensembles of single neurons. It reviews the recent progress in both electronics and computational tools developed to analyze the functional operations of large ensembles of neurons using multi-electrode arrays and in vitro preparations. In addition, it gives readers a sense of the applications made possible by these technological tools. This volume is the reference for researchers, industry, graduate students, and postdoctoral fellows in all areas of neuroscience, cognitive neuroscience, pharmaceutical science, and bioengineering.
Download or read book Wearable Bioelectronics written by Anthony P.F. Turner and published by Elsevier. This book was released on 2019-11-26 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wearable Bioelectronics presents the latest on physical and (bio)chemical sensing for wearable electronics. It covers the miniaturization of bioelectrodes and high-throughput biosensing platforms while also presenting a systemic approach for the development of electrochemical biosensors and bioelectronics for biomedical applications. The book addresses the fundamentals, materials, processes and devices for wearable bioelectronics, showcasing key applications, including device fabrication, manufacturing, and healthcare applications. Topics covered include self-powering wearable bioelectronics, electrochemical transducers, textile-based biosensors, epidermal electronics and other exciting applications. Includes comprehensive and systematic coverage of the most exciting and promising bioelectronics, processes for their fabrication, and their applications in healthcare Reviews innovative applications, such as self-powering wearable bioelectronics, electrochemical transducers, textile-based biosensors and electronic skin Examines and discusses the future of wearable bioelectronics Addresses the wearable electronics market as a development of the healthcare industry
Download or read book Neuromorphic Olfaction written by Krishna C. Persaud and published by CRC Press. This book was released on 2016-04-19 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many advances have been made in the last decade in the understanding of the computational principles underlying olfactory system functioning. Neuromorphic Olfaction is a collaboration among European researchers who, through NEUROCHEM (Fp7-Grant Agreement Number 216916)-a challenging and innovative European-funded project-introduce novel computing p
Download or read book Neural Interface Engineering written by Liang Guo and published by Springer Nature. This book was released on 2020-05-04 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive reference to major neural interfacing technologies used to transmit signals between the physical world and the nervous system for repairing, restoring and even augmenting body functions. The authors discuss the classic approaches for neural interfacing, the major challenges encountered, and recent, emerging techniques to mitigate these challenges for better chronic performances. Readers will benefit from this book’s unprecedented scope and depth of coverage on the technology of neural interfaces, the most critical component in any type of neural prostheses. Provides comprehensive coverage of major neural interfacing technologies; Reviews and discusses both classic and latest, emerging topics; Includes classification of technologies to provide an easy grasp of research and trends in the field.
Download or read book Networks of the Brain written by Olaf Sporns and published by MIT Press. This book was released on 2016-02-12 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: An integrative overview of network approaches to neuroscience explores the origins of brain complexity and the link between brain structure and function. Over the last decade, the study of complex networks has expanded across diverse scientific fields. Increasingly, science is concerned with the structure, behavior, and evolution of complex systems ranging from cells to ecosystems. In Networks of the Brain, Olaf Sporns describes how the integrative nature of brain function can be illuminated from a complex network perspective. Highlighting the many emerging points of contact between neuroscience and network science, the book serves to introduce network theory to neuroscientists and neuroscience to those working on theoretical network models. Sporns emphasizes how networks connect levels of organization in the brain and how they link structure to function, offering an informal and nonmathematical treatment of the subject. Networks of the Brain provides a synthesis of the sciences of complex networks and the brain that will be an essential foundation for future research.
Download or read book Electrochemical Biosensors written by Serge Cosnier and published by CRC Press. This book was released on 2015-01-26 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since four decades, rapid detection and monitoring in clinical and food diagnostics and in environmental and biodefense have paved the way for the elaboration of electrochemical biosensors. Thanks to their adaptability, ease of use in relatively complex samples, and their portability, electrochemical biosensors now are one of the mainstays of analy
Download or read book Brain Computer Interfaces written by Jonathan Wolpaw and published by Oxford University Press. This book was released on 2012-01-24 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recognizable surge in the field of Brain Computer Interface (BCI) research and development has emerged in the past two decades. This book is intended to provide an introduction to and summary of essentially all major aspects of BCI research and development. Its goal is to be a comprehensive, balanced, and coordinated presentation of the field's key principles, current practice, and future prospects.
