Browsing by Author "Chu, Fang-Liang"

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A CMOS 256-Pixel Self-Photovoltaics-Powered Subretinal Prosthetic Chip with Wide Image Dynamic Range and Shared Electrodes and Its In Vitro Experimental Results on Rd1 Mice
(2019-01-01)
Wu, Chung-Yu
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Tzeng, Chi-Kuan
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Huang, Shih-Yun
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Chu, Fang-Liang
;
Chiao, Chuan-Chin
A self-photovoltaics-powered CMOS 256-pixel implantable chip with wide image dynamic range and shared electrodes is proposed and fabricated for subretinal prostheses. The infra-red (IR) light is incident only on photovoltaic cells of the chip whereas the visible light is mainly incident on pixels. The proposed adaptive background cancellation circuit (ABCC) is adopted to increase the image dynamic range so that the subretinal chip can adapt for different surrounding illuminances. Moreover, the bi-directional sharing electrodes (BDSEs) is used to increase electrode size under the same chip area and boost the stimulation charges to 11.4 nC. The functions of the chip have been successfully validated with both electrical measurement and in vitro patch clamp experiments with the retinas of Rd1 mice.
Improved Charge Pump Design and Ex Vivo Experimental Validation of CMOS 256-Pixel Photovoltaic-Powered Subretinal Prosthetic Chip
(2020-05-01)
Kuo, Po-Han
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Wong, Oi-Ying
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Tzeng, Chi-Kuan
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Wu, Pu-Wei
;
Chiao, Chuan-Chin
An improved design of CMOS 256-pixel photovoltaic-powered implantable chip for subretinal prostheses is presented. In the proposed subretinal chip, a high-efficiency fully-integrated 4x charge pump is designed and integrated with on-chip photovoltaic (PV) cells and a 256-pixel array with active pixel sensors (APS) for image light sensing, biphasic constant current stimulators, and electrodes. Thus the PV voltage generated by infrared (IR) light can be boosted to above 1V so that the charge injection is increased. The proposed chip adopts the 32-phase divisional power supply scheme (DPSS) to reduce the required supply current and thus the required area of the PV cells. The proposed chip is designed and fabricated in 180-nm CMOS image sensor (CIS) technology and post-processed with biocompatible IrOx electrodes and silicone packaging. From the electrical measurement results, the measured stimulation frequency is 28.3 Hz under the equivalent electrode impedance load. The measured maximum output stimulation current is 7.1 mu A and the amount of injected charges per pixel is 7.36 nC under image light intensity of 3200 lux and IR light intensity of 100 mW/cm(2). The function of the proposed chip has been further validated successfully with the ex vivo experimental results by recording the electrophysiological responses of retinal ganglion cells (RGCs) of retinas from retinal degeneration (rd1) mice with a multi-electrode array (MEA). The measured average threshold injected charge is about 3.97 nC which is consistent with that obtained from the patch clamp recording on retinas from wild type (C57BL/6) mice with a single electrode pair.
Interaction of electrical and light stimulations on the responses of retinal ganglion cells for sub-retinal prosthesis
(2020-06-01)
Chu, Fang-Liang
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Tsai, Yueh-Chun
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Wu, Chung-Yu
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Chiao, Chuan-Chin
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交大名義發表
Responses of retinal ganglion cells to electrical stimulation of photovoltaic-powered sub-retinal prosthesis in vitro
(2019-07-01)
Chu, Fang-Liang
;
Tsai, Yueh-Chun
;
Wu, Chung-Yu
;
Chiao, Chuan-Chin
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電機學院