Browsing by Author "Kuo, Po-Han"

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A CMOS 256-pixel Photovoltaics-powered Implantable Chip with Active Pixel Sensors and Iridium-oxide Electrodes for Subretinal Prostheses
(2018-01-01)
Wu, Chung-Yu
;
Kuo, Po-Han
;
Lin, Po-Kang
;
Chen, Po-Chun
;
Sung, Wei-Jie
A CMOS implantable chip with 256 active pixel sensors (APSs), on-chip photovoltaic cells, and iridium-oxide (IrOx) electrodes is proposed and designed for subretinal prostheses. In the proposed chip, the on-chip electrode surface is deposited with IrOx by RF sputtering and photolithography patterning. The divisional power supply scheme (DPSS) is adopted to generate sufficient stimulation current whereas the APS is used to enhance the image sensitivity. The proposed chip consists of a 16 x 16 photodiode array with 8 DPSS divisions, control signal generator circuits, and photovoltaic cells. It is designed and fabricated into 180 nm CMOS image sensor (CIS) technology and postprocessed with an IrOx coating. From the electrical measurement results, the fabricated chip has a peak output stimulation current of 16.7 mu A under the equivalent electrode impedance load. The stimulation frequency is 30.2 Hz and the amount of injected charges at each pixel is 3.5 nC. Both image light sensitivity and injection charges are significantly improved. The surface morphology, crystallinity, charge storage capacity, and biocompatibility of sputtering iridium oxide film (SIROF) were investigated. As a result, the SIROF has desirable physical and electrochemical properties that make it suitable for the neurostimulation electrodes on the 256-pixel implantable chip. The 7-month biocompatibility and charge delivery capability of the fabricated chip have been confirmed by electroretinography (ERG) measurement on a Lanyu minipig in in vivo animal tests.
Improved Charge Pump Design and Ex Vivo Experimental Validation of CMOS 256-Pixel Photovoltaic-Powered Subretinal Prosthetic Chip
(2020-05-01)
Kuo, Po-Han
;
Wong, Oi-Ying
;
Tzeng, Chi-Kuan
;
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.
Printable Graphene Oxide Micropatterns for a Bio-Subretinal Chip
(2018-09-19)
Yang, Jia-Wei
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Tseng, Ming-Liang
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Fu, Yu-Min
;
Kang, Che-Hao
;
Cheng, Yu-Ting
Recently, implantable artificial subretinal chips using electronic components have replaced photoreceptors to serve as the most feasible treatment for retinal diseases. As such a chip that is meant to be implanted and used for very long periods, growing retinal cells on it to improve the electrical stimulation efficiency and attraction of neuronal elements remains a challenge. Here, an inkjet printing technology is employed to create graphene oxide (GO) micropatterns onto microelectrodes of a photovoltaic-powered implantable retinal chip. These GO micropatterns allow human retinal pigment epithelium (RPE) cells to specially attach and grow in each microelectrode. In addition, the cell proliferation, viability, and tight junction of RPE cells are improved during culturing. The development of a simple surface-coating technology would pave the way for the development of the first fully integrated and encapsulated retinal prostheses with biocompatible on-chip microelectrodes for long-term implantation, which could be effectively applied in retina tissue engineering and therapy.
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
;
Lin, Po-Kang
;
Wu, Chung-Yu
;
Chiao, Chuan-Chin
Self-Powered Subretinal Prosthetic Devices Using Optoelectronic Technologies
(2016)
Wu, Chung-Yu
;
Kuo, Po-Han
;
Tzeng, Chi-Kuan
;
Chiao, Chuan-Chin
;
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.
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
;
Sung, Wei-Jie
;
Kuo, Po-Han
;
Tzeng, Chi-Kuan
;
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.