Browsing by Author "Chiao, Chuan-Chin"

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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
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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 Rabbit Retinal Ganglion Cells to Subretinal Electrical Stimulation Using a Silicon-Based Microphotodiode Array
(2011-12-01)
Yang, Ya-Ting
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Lin, Po-Kang
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Wan, Chen
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Yang, Wen-Chia
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Lin, Li-Ju
PURPOSE. With subretinal prostheses, retinal ganglion cells (RGCs) are activated by electrical stimulation of the retinal neural network. The aim of this study was to evaluate the efficacy of silicon-based solar cells in evoking RGC responses by electrically stimulating the photoreceptor side of an isolated retina. METHODS. A light-bleached retina of an adult New Zealand White rabbit was placed with its photoreceptor side down onto a silicon chip that consisted of a 4 x 4 microphotodiode array (MPDA). The stimulating current was elicited by activating the solar cell with a 532-nm laser light source. Responses of the ON and OFF alpha RGCs on electrical stimulation were recorded extracellularly. Recorded RGCs were then injected with 4% N-(2-aminoethyl)-biotinamide hydrochloride to allow cell type identification. RESULTS. Using a design that includes a circumvented ground electrode, the authors successfully evoked spiking responses by the ON and OFF alpha RGCs in an isolated rabbit retina using low light power to activate the MPDA (equivalent to 39 mu C/cm(2)). The charge density-dependent response and the frequency-dependent pair-pulse suppression were characterized. The spike latency of the RGC responses triggered by electrical stimulation was equivalent to the latency of its light response, which supports the hypothesis that the activation is mediated by the retinal neural network. CONCLUSIONS. Reliable activation of RGCs by electrical stimulation in vitro using an MPDA demonstrates the feasibility of developing solar cell-based subretinal prostheses that potentially could be developed into a power-free device able to restore vision. (Invest Ophthalmol Vis Sci. 2011; 52: 9353-9361) DOI: 10.1167/iovs.11-7808
Responses of retinal ganglion cells to electrical stimulation of photovoltaic-powered sub-retinal prosthesis in vitro
(2019-07-01)
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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電機學院
Responses of retinal ganglion cells to electrical stimulation with a subretinal photovoltaic prosthesis
(2015-06-01)
Tsai, Yueh-Chun
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Kuo, Po-Han
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Lin, Po-Kang
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Wu, Chung-Yu
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Chiao, Chuan-Chin
Self-Powered Subretinal Prosthetic Devices Using Optoelectronic Technologies
(2016)
Wu, Chung-Yu
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Kuo, Po-Han
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Tzeng, Chi-Kuan
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Chiao, Chuan-Chin
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Pan, Jui-Wen
The design of subretinal prosthetic devices including a self-powered implantable chip and an extraocular optical goggle is presented. Various optoelectronic and biological technologies are adopted in the device design to enhance both performance and biocompatibility. Experimental results and initial animal test results are described. Future development are also discussed.
Spatiotemporal integration of visual stimuli and its relevance to the use of a divisional power supply scheme for retinal prosthesis
(2020-02-21)
Tsai, Yueh-Chun
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Wu, Jose Jiun-Shian
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Lin, Po-Kang
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Lin, Bo-Jyun
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Wang, Pin-Shiou
A wireless photovoltaic retinal prosthesis is currently being studied with the aim of providing prosthetic vision to patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The major challenge of a photovoltaic device is its limited power efficiency. Our retinal prosthetic design implements a unique divisional power supply scheme (DPSS) system that provides the electrical power generated by all of the solar cells to only a subset of electrodes at any moment in time. The aim of the present study was to systematically characterize the spatiotemporal integration performance of the system under various DPSS conditions using human subjects and a psychophysical approach. A 16x16 pixels LED array controlled by Arduino was used to simulate the output signal of the DPSS design, and human performance under different visual stimulations at various update frequencies was then used to assess the spatiotemporal capability of retinal prostheses. The results showed that the contrast polarity of the image, image brightness, and division number influenced the lower limit of the update frequency of the DPSS system, while, on the other hand, visual angle, ambient light level, and stimulation order did not affect performance significantly. Pattern recognition by visual persistence with spatiotemporal integration of multiple frames of sparse dots is a feasible approach in retinal prosthesis design. These findings provide an insight into how to optimize a photovoltaic retinal prosthesis using a DPSS design with an appropriate update frequency for reliable pattern recognition. This will help the development of a wireless device able to restore vision to RP and AMD patients in the future.
Temporal integration of repeated electrical stimuli in the pulse number modulation of retinal prosthesis
(2018-07-01)
Chiao, Chuan-Chin
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Tsai, Yueh-Chun
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Wu, Chung-Yu
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電子工程學系及電子研究所
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生醫電子轉譯研究中心
The Design of CMOS Self-Powered 256-Pixel Implantable Chip with On-Chip Photovoltaic Cells and Active Pixel Sensors for Subretinal Prostheses
(2015-01-01)
Wu, Chung-Yu
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Sung, Wei-Jie
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Kuo, Po-Han
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Tzeng, Chi-Kuan
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Chiao, Chuan-Chin
A photovoltaic-cell-powered CMOS 256-pixel implantable chip is proposed for subretinal prostheses. In the proposed chip, the divisional power supply scheme (DPSS) and the active pixel sensor (APS) are adopted to improve the efficiency of output stimulation currents and the image sensitivity. The proposed chip consists of a 16x16 photodiode array with 8 DPSS divisions, control signal generator circuits, and photovoltaic cells. It is designed and fabricated in 180-nm CMOS image sensor (CIS) technology. The chip size is 3mm x 3mm. The measured frequency of eight-phase control signals is 47.68 Hz under signal light intensity of 5 mW/cm(2) and background IR intensity of 80 mW/cm(2). The measured output stimulation current is 19.9 mu A under 10-k Omega load. Under the equivalent electrode impedance load, the measured frequency of eight-phase control signals is 45.45 Hz. The measured peak output stimulation current is 19.52 mu A and the amount of injected charges per pixel is 4.03nC. The measurement results have verified the correct function of the proposed subretinal implant chip.