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Document Type:Latin Dissertation
Language of Document:English
Record Number:55054
Doc. No:TL25008
Call number:‭3279745‬
Main Entry:Mohammad Ismail Talukder
Title & Author:Implantable neural stimulation and neural response reading microsystems design for wireless retinal and auditory prosthesesMohammad Ismail Talukder
College:Wayne State University
Date:2007
Degree:Ph.D.
student score:2007
Page No:227
Abstract:There are over 10 million peoples in the world who are blind for retinal diseases. On the other hand, 300,000 people are profoundly deaf in America. This dissertation is undertaken to help these people and contribute to the development of neural prosthesis. Research are carried out in two important areas—(1) designing electrode array which is the best and the most effective in building interface between the microsystem and the neurons, and (2) developing implantable microsystem which is capable of processing wireless digital signals, generate modulated biphasic pulses based on signal, and map it on an electrode array to stimulate the neurons. Threshold for stimulation reported by various papers varies widely (0.15μA to 1121μA). A comprehensive investigation is carried out to reduce this diversity, and design probe that has higher resolution, deeper penetration and offer least resistance to the stimulating current. The designed CMOS-based donut probe offers 33% better resolution and 44% less resistance. A methodology is developed to design probes that can optimize threshold, resolution, penetration, and geometry of the probe. In-vivo test of the fabricated probes shows that neurons can be stimulated with as little as 10μA current. In second part of my research, I have designed two different types of microsystem—one for sequential stimulation and another for parallel stimulation. Sequential stimulation is good for smaller electrodes array like cochlear implant while parallel stimulation is required for large number of electrodes array—like retinal implant. Two neural stimulators—one for 5x5 array and another for 32x32 array—are designed for sequential stimulation using well-known multiplexing technique with only a few components. These stimulators can communicate data in both the directions and don't need address of any probe to excite it. The clock is performing the address decoding and saving us from the wireless address transmission overhead. Tests confirm their functionalities. For larger array parallel multiplexing technique is applied. A scaleable 5x5 array neural implant chip is designed and fabricated in 3mmx3mm die to demonstrate the idea. It is designed with CMOS-based onboard flat donut probes to eliminate the need of wiring the probes from the chip. The chip has only four wires (data, clock, Vdd, Vss) to interface with the wireless receiver. Its data rate is only limited by the external clock. High-resolution programmable biphasic width controller and current stimulator have made it possible to tune the chip for a wide range of patients. Tests verify its capabilities. To monitor the effectiveness of neural prosthesis after implant, a multi-channel neural response reading system is designed, fabricated and tested. It can capture action potential in high resolution and high sampling rate. This device can also be used to control the prosthetic limbs by reading the neural activity generated by thoughts in the brain.
Subject:Applied sciences; Auditory prostheses; Electrode array; Implantable; Microsystems; Neural stimulation; Retinal prostheses; Biomedical research; Electrical engineering; 0541:Biomedical research; 0544:Electrical engineering
Added Entry:P. Siy
Added Entry:Wayne State University