Conference Proceeding

Towards High - resolution Retinal Prostheses with Direct Optical Addressing and Inductive Telemetry

Dr. Sohmyung Ha,
New York university Abu Dhabi, UAE

Sohmyung Ha is an assistant professor of electrical and computer engineering at New York University Abu Dhabi. He received the B.S. degree summa cum laude and the M.S. degree in Electrical Engineering from the Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, in 2004 and 2006, respectively. From 2006 to 2010, he worked as an analog and mixed-signal circuit designer at Samsung Electronics, Yongin, Korea, where he was a part of the engineering team responsible for several of the world best-selling multimedia devices, smartphones and TVs. After an extended career in industry, he returned to academia as a Fulbright Scholar, and obtained the M.S. and Ph.D. degrees with the best Ph.D. thesis award for biomedical engineering from the Department of Bioengineering, University of California San Diego, La Jolla, CA, USA, in 2015 and 2016, respectively. His research aims at advancing the engineering and applications of silicon integrated technology interfacing with biology in a variety of forms ranging from implantable biomedical devices to unobtrusive wearable sensors. The engineering advances in the design of integrated circuits and system components target high performance, miniature form factor, and power autonomy in fully integrated interfaces. Targeted applications include self-powered biosensors for wearable health monitoring, subcutaneous glucose sensors for continuous monitoring in diabetes patients, scalable high-resolution retinal prostheses, and minimally invasive brain-computer interfaces for closed-loop remediation of neurological disorders such as epilepsy and Parkinson’s disease. Since 2016, he has been with New York University Abu Dhabi.

Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. The hybrid optical addressability and electronic powering scheme provides for separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for the common voltage stimulation. A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.

Published: 27 April 2017