Toward an optoelectronic-based visual prosthesis: control unit design and validation

• Published in: Analog integrated circuits and signal processing 2019-02, Vol.98 (2), p.311-320
• Main Authors: Ben Ayed, Hanen, Ali, Mohamed, Saha, Sreenil, Masmoudi, Mohamed, Sawan, Mohamad
• Format: Article
• Language: English
• Subjects: Artificial vision; Circuits and Systems; CMOS; Digital cameras; Electrical Engineering; Engineering; Image quality; Laser arrays; Nerves; Neural prostheses; Optoelectronic devices; Prostheses; Retina; Sensor arrays; Signal,Image and Speech Processing; Stimulation; Voltage controlled oscillators
• ISSN: 0925-1030; 1573-1979
• DOI: 10.1007/s10470-018-1294-2

We propose a control unit intended for light stimulation of optical nerves (LiSON), which is an optoelectronic-based visual prosthesis. The device is composed of an image sensor array to capture the scene and a miniaturized laser array to stimulate the neural cells forming the optic nerve. The adopted optical stimulation technique is intended to avoid the signal overlapping caused by conventional direct stimulation pathways, and thus improve the image quality. The presented control unit consists of averaging and subtracting the received optical data to reproduce the behavior of bipolar cells, followed by a voltage-controlled oscillator acting as ganglion cells used to transform the signal in a pulse train. The control unit prototype contains an image sensor of 9 × 9 pixels array to validate the operation principles of the proposed system. The chip was fabricated in 0.13 µm CMOS standard technology, and the measurements meet the expectation.