System design of a 16-channel microstimulator with programmable controller in artificial eye
| Autor: | Yu-Shian Lin, 林育鮮 |
|---|---|
| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 93 Age-related macular degeneration (AMD) and retinitis pigmentosa (RP), which are among the leading causes of blindness.The major cause of blindness is photoreceptors loss.The demonstration that direct electrical stimulation of retinal bipolar or ganglion cells can create visual sensation in patients has been shown clinically. Up to now, there are two main ways of stimulation in the visual prosthesis : the sub-retinal, advantages is easy to implant and use simply components ; disadvantage will be hold back nutrient transmission .another method is epi-retinal, it will not hold back nutrient transmission but it use complex components and difficult to fix chip in the retina. so we have brought up a new idea in order to overcome the defect and improve the overall performance - the sandwich-type approach, which has higher resolution and lower power consumption than the two previous ways. An artificial eye should contain the four parts of 1) the image capturing and processing, 2) the coding, modulating and wireless transmission, 3) the retinal chip(including the chips of programmed-controlled chip and micro-stimulator), and 4) the microelectrodes. The purpose of this thesis is using sandwich-type approach to design a system by mixed-signal process which includes a programmed-controlled chip which has the great ability to decode the encoded data and correct the errors in transmission. They are all based on the retina micro-stimulator which has been developed in our Lab because of the requirement in linkage for artificial eye. The prototype chip was fabricated by UMC in 0.18μm CMOS technology. The experimental results have met the desired specifications. With 10 KΩ retinal load, the retina chip can generate the programmed stimulus waveform with good linearity. The differential nonlinearity is less than 0.6 LSB and the integral nonlinearity is less than 1 LSB. The maximum output of the biphasic current is 102 uA with 3.3 uA step. It can also sequentially stimulate 16 channels to make up frames. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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