A 0.8-V 4096-Pixel CMOS Sense-and-Stimulus Imager for Retinal Prosthesis

Lee, Chih-Lin; Hsieh, Chih-Cheng

doi:10.1109/ted.2013.2238634

Cited by 22 publications

(14 citation statements)

References 16 publications

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“…When compared with the previous work with PFM image sensor [21], the 0.5 V PWM sensor reduces the number of in-pixel transistors and scales down the necessary voltage headroom of the analog circuit as shown in Fig. 2.…”

Section: Chip Architecture and Sas Pixelmentioning

confidence: 99%

“…However, the rest of the retinal neurons are still functional and actively connected to the brain. Artificial retina implant has been developed in hopes of restoring useful vision for people blinded by photoreceptor loss [5]- [21]. In the application of retinal prostheses, the implanted stimulator is placed underneath the retina (Sub-retinal) or upon the retina (Epi-retinal) through surgery.…”

Section: Introductionmentioning

confidence: 99%

“…However, the systems comprising a camera, a transceiver, and an implanted stimulator are bulky and not power-efficient. When compared with the implants with telemetry systems, other structures with integrated image sensor and in-pixel biphasic current stimulator were carried out in [16]- [21]. As a result, the concept of "sense-and-stimulus (SAS)" has been proposed for subretinal applications in [20] and [21].…”

Section: Introductionmentioning

confidence: 99%

“…When compared with the implants with telemetry systems, other structures with integrated image sensor and in-pixel biphasic current stimulator were carried out in [16]- [21]. As a result, the concept of "sense-and-stimulus (SAS)" has been proposed for subretinal applications in [20] and [21]. The reported pulse-frequency-modulation (PFM) based SAS imagers are used to replace the sensing capability of damaged neuron cells in the retina.…”

Section: Introductionmentioning

confidence: 99%

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A 0.5 V/1.8 V High Dynamic Range CMOS Imager for Artificial Retina Applications

Lee

Hsieh

2015

IEEE Sensors J.

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This paper presents a 0.5 V/1.8 V high dynamic range (HDR) sense-and-stimulus (SAS) CMOS imager with adaptive gain control for artificial retina applications. The proposed dual-supply SAS pixel consists of a 0.5 V HDR pulsewidth modulation image sensor (for sense) and a 1.8 V pulse-to-current stimulator (for stimulus) to achieve a highly integrated and lowpower solution. The 0.5 V operated HDR image sensor is adopted to reduce power consumption with dynamic range extension for in vivo requirement and mimicking the eyesight capability. The 1.8 V operated in-pixel pulse-to-current stimulator provides a biphasic current pulse with sufficient intensity to activate neuron cells for artificial vision recovery applications. The timeto-voltage conversion technique with a programmable gain is employed to achieve a reduced fixed-pattern-noise (FPN) and an adaptive sensitivity. A prototype chip has been implemented and verified with a sensing array of 40 × 40, a pixel size of 30 × 30 μm 2 , and a fill factor of 33.3%. The maximum driving capability of biphasic stimulation current is ±50 μA with a 7.5 k electrode model. The measurement results show an array FPN of 0.63% and a tunable dynamic range of 36 dB. The chip consumes a total power of 2.1 mW with current stimulator at 16.9 frame/s, which achieves an imager figure of merit of 77.7 nW/frame pixel.Index Terms-Artificial retina, CMOS, converter, dynamic range, gain control, image sensor, low power, pulse width modulation. 1530-437X

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Section: Chip Architecture and Sas Pixelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A 0.5 V/1.8 V High Dynamic Range CMOS Imager for Artificial Retina Applications

Lee

Hsieh

2015

IEEE Sensors J.

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“…(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) The stimulating electrodes of a subretinal implant are positioned under photoreceptors whereas those of an epiretinal implant are positioned above ganglion cells. In the subretinal implants, (8)(9)(10)(11)(12)(13)(14)(15) passive photodiode array, (9) active photodiode sensors with current amplifiers, (8,11,12) or active pixel circuits, (10,13) have been proposed. Most subretinal implants require a wire through the eyeball to provide power supply.…”

Section: Introductionmentioning

confidence: 99%

A CMOS 256-pixel Photovoltaics-powered Implantable Chip with Active Pixel Sensors and Iridium-oxide Electrodes for Subretinal Prostheses

Wu¹,

Kuo²,

Lin³

et al. 2018

Sensors and Materials

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Keywords: divisional power supply scheme, active pixel sensor, photovoltaic cell, CMOS image sensor, biocompatible package 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 × 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 μA 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.

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Multichannel Microstimulating SoC

Noorsal

Sooksood

et al. 2022

Handbook of Biochips

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A 0.8-V 4096-Pixel CMOS Sense-and-Stimulus Imager for Retinal Prosthesis

Cited by 22 publications

References 16 publications

A 0.5 V/1.8 V High Dynamic Range CMOS Imager for Artificial Retina Applications

A 0.5 V/1.8 V High Dynamic Range CMOS Imager for Artificial Retina Applications

A CMOS 256-pixel Photovoltaics-powered Implantable Chip with Active Pixel Sensors and Iridium-oxide Electrodes for Subretinal Prostheses

Multichannel Microstimulating SoC

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