Download or read book Microelectrode Arrays for Retinal Cell Stimulation written by Arti Patel and published by . This book was released on 2002 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterizing the Material Properties of Polymer Based Microelectrode Arrays for Retinal Prosthesis written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication techniques to increase the number of electrodes and integrate electronics. After the initial designs were fabricated and tested in acute implantation, it became obvious that there was a need to characterize and understand the mechanical and electrical properties of these new structures. This knowledge would be imperative in gaining credibility for polymer microfabrication and optimizing the designs. Thin composite microfabricated devices are challenging to characterize because they are difficult to handle, and exhibit non-linear, viscoelastic, and anisotropic properties. The objective of this research is to device experiments and protocols, develop an analytical model to represent the composite behavior, design and fabricate test structures, and conduct experimental testing to determine the mechanical and electrical properties of PDMS-metal composites. Previous uniaxial stretch tests show an average of 7% strain before failure on resistive heaters of similar dimensions deposited on PDMS. Lack of background information and questionable human accuracy demands a more sophisticated and thorough testing method. An Instron tensile testing machine was set up to interface with a digital multiplexor and computer interface to simultaneously record and graph position, load, and resistance across devices. With a compliant load cell for testing polymers and electrical interconnect grips designed and fabricated to interface the sample to the electronics, real-time resistance measurements were taken. Wafers of test structures were fabricated with variables such as lead width, pad to lead interface shape, PDMS thickness, metal (Ti and Au) thickness, and lead shape. Results showed that the serpentine shaped leads were 70% more effective, and that thicker adhesion layers of Ti were too brittle for testing. The other variables did not produce significant results.

Download or read book Optical and Electrical Stimulation of Retinal Ganglion Cells on a CMOS Microelectrode Array written by Ian Lloyd Jones and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Micro Electro Mechanical Systems written by Qing-An Huang and published by Springer. This book was released on 2018-05-04 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook volume aims to provide a comprehensive, self-contained, and authoritative reference in MEMS. It covers the theoretical and practical aspects including but not limited to sensors, actuators, RF MEMS, micro fluids and bio MEMS systems. It is particularly recommended to undergraduates, postgraduates, researchers, scientists, and field experts. This comprehensive summary will provide a solid knowledge background and inspire innovations in this highly interdisciplinary field. The handbook series consists of 5 volumes: Micro/nano fabrication technology, MEMS, Nanomaterial, Nanomedicine and Applications of micro-/nanotechnologies in IT. Experienced researchers and experts are invited to contribute in each of these areas.The series is published under Springer Major Reference works, which allows continuous online update and publication. These features allow newcomers and other readers to keep in touch with the most up-to-date information in micro-/nanotechnologies.It presents an overview of the knowledge base, as well as selected topics and provides comprehensive and authoritative information on the field for researchers, engineers, scientists and graduate students who are involved in different aspects of micro-/nanotechnologies.This publication will provide inspiration for innovative research and application ideas for continued growth of the field.

Download or read book Modeling and Simulation of Microelectrode Retina Interactions written by and published by . This book was released on 2002 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of the retinal prosthesis project is the development of an implantable microelectrode array that can be used to supply visually-driven electrical input to cells in the retina, bypassing nonfunctional rod and cone cells, thereby restoring vision to blind individuals. This goal will be achieved through the study of the fundamentals of electrical engineering, vision research, and biomedical engineering with the aim of acquiring the knowledge needed to engineer a high-density microelectrode-tissue hybrid sensor that will restore vision to millions of blind persons. The modeling and simulation task within this project is intended to address the question how best to stimulate, and communicate with, cells in the retina using implanted microelectrodes.

Download or read book Microfabrication of an Implantable Silicone Microelectrode Array for an Epiretinal Prosthesis written by Mariam Nader Maghribi and published by . This book was released on 2003 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Brain and Human Body Modeling 2020 written by Sergey N. Makarov and published by Springer Nature. This book was released on 2021 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 41st Annual International Conference of the IEEE EMBS, took place between July 23 and 27, 2019, in Berlin, Germany. The focus was on "Biomedical engineering ranging from wellness to intensive care." This conference provided an opportunity for researchers from academia and industry to discuss a variety of topics relevant to EMBS and hosted the 4th Annual Invited Session on Computational Human Models. At this session, a bevy of research related to the development of human phantoms was presented, together with a substantial variety of practical applications explored through simulation.

Download or read book High Density Microelectrode Arrays for In Vitro Retinal Studies written by Deborah Gunning and published by . This book was released on 2007 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electric Stimulation Parameters for an Epi retinal Prosthesis written by Andrew Eli Grumet and published by . This book was released on 1999 with total page 144 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 An Optoelectronic Retinal Prosthesis written by Alexander Forrest Albert Butterwick and published by . This book was released on 2008 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Curvable Silicon Retinal Implant written by Rostam Dinyari and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In age-related macular degeneration (AMD) and retinitis pigmentosa (RP), two leading causes of blindness, the photoreceptor layer of the retina is degenerated while the rest of the retina is well preserved. The function of the photoreceptors is very similar to that of solar cells. Upon receiving light, they activate the inner layers of the retina by producing electrical and chemical signals. These signals are then processed and compressed by a complex circuit of retinal neurons (horizontal cells, bipolar cells, amacrine cells, and ganglion cells) and sent to the brain. The brain perceives these data as sight. Electronic retinal implant systems seek to restore sight in AMD and RP by electrical stimulation of the surviving retinal neurons. Currently the more dominant systems consist of a microelectrode array, which is placed directly on the ganglion cells (epiretinal). In this approach, a camera mounted on goggles captures video which is then processed by a pocket computer. The power and data are then transmitted wirelessly to an extraocular receiver unit. Through an intraocular cable, the receiver unit sends appropriate electrical stimuli to the array of microelectrodes. The electrodes then stimulate the ganglion cells by passing current pulses through the tissue. These stimulations are perceived by the brain as spots of light. The epiretinal approach has some disadvantages. Because the electrodes directly stimulate the ganglion cells, the image processing and data compression capabilities of the retina are not utilized. Placing the extraocular receiver unit and connecting it via a cable to the microelectrode array significantly complicates the surgical procedure and increases the chance of post surgical complications. Additionally, the perceived images are independent of the eye movements. We have developed an integrated photovoltaic monolithic silicon retinal implant that requires no electrical power or data connection. In our design, a miniature camera captures video that is processed by a pocket computer before being projected into the eye at a near-infrared wavelength ([Lambda] = 905 nm) onto the silicon implant located in the subretinal space (area in the back of the retina). The implant consists of a two-dimensional array of photovoltaic pixels. The projected image is provided in pulsed fashion and each pixel element consists of up to three series-connected photovoltaic cells such that the pixels deliver current pulses that are sufficiently strong to stimulate the remaining functional neural cells. The current pulses are interpreted as visual images by the brain. Placing the implant in the subretinal space allows for utilization of the existing image processing and data compression functions of the retina. Each pixel receives both power and data directly through laser radiation. This eliminates the need for a separate wireless receiver unit and simplifies the surgical procedures and reduces the post-surgical risks. Additionally, in this approach, eye movements change the perceived images. The novelty of the work reported here is the integration of photovoltaic devices in a MEMS process that allows the implant to deform to the natural curvature of the eye, while also providing isolation between the bodies of the three series-connected subpixels that make up each pixel. This was achieved by patterning the implants into an array of pixels connected together by deformable silicon flexures. In addition, the trenches also provide electrical isolation between the three series-connected photovoltaic subpixels. Curving the implant is advantageous since the complete implant is in focus, resulting in optimum quality of vision perceived. Curved implants can also be substantially larger than planar implants and can hence cover a larger part of the field of view. A curvable implant also causes no mechanical strain or abnormality in the eye. Usage of three series-connected subpixels per pixel improves the impedance matching to the surrounding tissue and enhances the injected current per pixel allowing for higher resolution implants. Fabricated implant with a resolution of 64 pixels/mm2 can inject sufficient current for neural activation at safe optical intensities. Additionally, the exchange of nutrients and waste, which is necessary for the survival of the retinal cells, is provided by diffusion through the trenches that define the silicon devices.

Download or read book Artificial Vision written by Veit Peter Gabel and published by Springer. This book was released on 2016-11-24 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and analyses the most recent research dedicated to restoring vision in individuals who are severely impaired or blind from retinal disease or injury. It is written by the leading groups worldwide who are at the forefront of developing artificial vision. The book begins by discussing the difficulties in comparing and interpreting functional results in the area of very low vision and the principal prospects and limitations of spatial resolution with artificial tools. Further on, chapters are included by researchers who stimulate the surface or the pigment epithelial side of the retina and by experts who work on stimulating the optic nerve, the lateral geniculate body and the superficial layers of the visual cortex. Artificial Vision: A Clinical Guide collates the most recent work of key artificial vision research groups to explain in a comparable and stringent order their varying approaches, the clinical or preclinical outcomes and their achievements during the last years. Senior ophthalmic fellows and academic practitioners will find this guide to be an indispensable resource for understanding the current status of artificial vision.

Download or read book Handbook of Neuroengineering written by Nitish V. Thakor and published by Springer Nature. This book was released on 2023-02-02 with total page 3686 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Handbook serves as an authoritative reference book in the field of Neuroengineering. Neuroengineering is a very exciting field that is rapidly getting established as core subject matter for research and education. The Neuroengineering field has also produced an impressive array of industry products and clinical applications. It also serves as a reference book for graduate students, research scholars and teachers. Selected sections or a compendium of chapters may be used as “reference book” for a one or two semester graduate course in Biomedical Engineering. Some academicians will construct a “textbook” out of selected sections or chapters. The Handbook is also meant as a state-of-the-art volume for researchers. Due to its comprehensive coverage, researchers in one field covered by a certain section of the Handbook would find other sections valuable sources of cross-reference for information and fertilization of interdisciplinary ideas. Industry researchers as well as clinicians using neurotechnologies will find the Handbook a single source for foundation and state-of-the-art applications in the field of Neuroengineering. Regulatory agencies, entrepreneurs, investors and legal experts can use the Handbook as a reference for their professional work as well.​

Download or read book Bioelectricity written by Robert Plonsey and published by Springer Science & Business Media. This book was released on 1988-08-31 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vector analysis. Electrical sources and fields. Introduction to membrane biophysics. Action potentials. Propagation. Subthreshold stimuli. Extracelular fields. Membrane biophysics. The electrophysiology of the heart. The neuromuscular junction. Skeletal muscle. Functional neuromuscular stimulation.

Download or read book Patterned Electrical Stimulation of Primate Retina for the Development of Retinal Prostheses written by Lauren Hruby Jepson and published by . This book was released on 2012 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Epiretinal prostheses are designed to restore vision to people blinded by retinal degenerations, using electrical stimulation with an array of electrodes implanted on the surface of the retina to convey artificial visual signals to the brain. Current clinical prostheses provide limited visual function, in part because the activity that they generate is different from natural retinal responses to visual stimuli. An ideal retinal prosthesis would stimulate the retinal ganglion cells (RGCs) in a way that veridically recreates the precise, cell-type dependent spatiotemporal spiking patterns present in the retina. This requires RGC activation at the native temporal and spatial resolution of the retina. We sought to better understand how electrical stimulation with high-density electrode arrays can be used to control RGC activity using an in vitro retina preparation to simultaneously stimulate and record from primate RGCs. The five numerically dominant RGC types, the ON and OFF midget, ON and OFF parasol, and small bistratified cells, could be activated to fire single, precisely-timed spikes using brief current pulses that fell within established safe charge density limits. Single-cell activation, which would prevent the simultaneous activation of different RGC types, was possible in roughly half of the tested RGCs. We further investigated whether simultaneous patterned current injection through multiple electrodes could be used to improve spatial selectivity. The majority of RGC responses to simultaneous current injection through multiple electrodes could be described by a simple model in which currents from different electrodes combine linearly to produce RGC responses. Observed nonlinearities could be effectively captured by extending the model to include multiple regions of stimulus space, in which each region contained a different linear tradeoff between currents passed through the electrodes. The usefulness of the model for improving spatial selectivity was examined by using it to predict which combinations of currents would most selectively activate a cell. The selectivity of the pattern chosen using the model was much higher than with single-electrode stimulation, and was nearly identical to that of the optimal pattern. Collectively, these findings support the feasibility of using epiretinal stimulation to control retinal activity at or near its native spatial and temporal resolution, and suggest a strategy to improve spatial resolution beyond what can be achieved using individual electrodes.

Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: