Browsing by Author "Sung, Wei-Jie"

Now showing 1 - 2 of 2

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.
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.