A 16x16-pixel pulse-frequency-modulation based image sensor for retinal prosthesis

Furumiya, Tetsuo; Ng, David C.; Yasuoka, Koutaro; Shiraishi, Fuyuka; Kagawa, Keiichiro; Tokuda, Takashi; Ohta, Jun; Nunoshita, Masahiro

doi:10.1109/icsens.2004.1426155

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…When light enters the photodiode, the voltage node of V X drops because the parasitic capacitor C P is discharged by the dark current. In previous studies, the node of V X was directly connected to a Schmitt trigger [ 18 ] or an inverter [ 19 ] for digitization. However, the discharging speed is not sufficient to drive the Schmitt trigger or comparator, thereby generating slow-speed pulse trains at the PFM output.…”

Section: Methodsmentioning

confidence: 99%

Integrated Low-Voltage Compliance and Wide-Dynamic Stimulator Design for Neural Implantable Devices

Hong

Kim

2023

Sensors

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In this study, a pulse frequency modulation (PFM)-based stimulator is proposed for use in biomedical implantable devices. Conventionally, functional electrical stimulation (FES) techniques have been used to reinforce damaged nerves, such as retina tissue and brain tissue, by injecting a certain amount of charge into tissues. Although several design methods are present for implementing FES devices, an FES stimulator for retinal implants is difficult to realize because of the chip area, which needs to be inserted in a fovea, sized 5 mm x 5 mm, and power limitations to prevent the heat generation that causes tissue damage. In this work, we propose a novel stimulation structure to reduce the compliance voltage during stimulation, which can result in high-speed and low-voltage operation. A new stimulator that is composed of a modified high-speed PFM, a 4-bit counter, a serializer, a digital controller, and a current driver is designed and verified using a DB HiTek standard 0.18 μm process. This proposed stimulator can generate a charge up to 130 nC, consumes an average power of 375 µW during a stimulation period, and occupies a total area of 700 µm × 68 µm.

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Section: Methodsmentioning

confidence: 99%

Integrated Low-Voltage Compliance and Wide-Dynamic Stimulator Design for Neural Implantable Devices

Hong

Kim

2023

Sensors

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“…Works that are closer to our aim are the ones using PFM: bioinspired systems, such as retinomorphic sensors [ 19 ], prosthetic feedback [ 20 ], neuro-inspired controller [ 21 ] or spike-based PID controllers [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Low-Cost Servomotor Driver for PFM Control

Aragon-Jurado

Morgado-Estevez

Perez-Peña

2017

Sensors

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Servomotors have already been around for some decades and they are extremely popular among roboticists due to their simple control technique, reliability and low-cost. They are usually controlled by using Pulse Width Modulation (PWM) and this paper aims to keep the idea of simplicity and low-cost, while introducing a new control technique: Pulse Frequency Modulation (PFM). The objective of this paper is to focus on our development of a low-cost servomotor controller which will allow the research community to use them with PFM. A low-cost commercial servomotor is used as the base system for the development: a small PCB that fits inside the case and allocates all the electronic components to control the motor has been designed to replace the original. The potentiometer is retained as the feedback sensor and a microcontroller is responsible for controlling the position of the motor. The paper compares the performance of a PWM and a PFM controlled servomotor. The comparison shows that the servomotor with our controller achieves a faster mechanism for switching targets and a lower latency. This controller can be used with neuromorphic systems to remove the conversion from events to PWM.

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A 0.6V CMOS Image Sensor with in-pixel biphasic current driver for biomedical application

Lee

Hsieh

2011

2011 IEEE International Symposium of Circuits and Systems (ISCAS)

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A 16x16-pixel pulse-frequency-modulation based image sensor for retinal prosthesis

Cited by 3 publications

References 5 publications

Integrated Low-Voltage Compliance and Wide-Dynamic Stimulator Design for Neural Implantable Devices

Integrated Low-Voltage Compliance and Wide-Dynamic Stimulator Design for Neural Implantable Devices

Low-Cost Servomotor Driver for PFM Control

A 0.6V CMOS Image Sensor with in-pixel biphasic current driver for biomedical application

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