# Capacitive carbon-nanotube composite eye tracking sensor for non-human primate oculomotor research

> **NIH NIH R21** · UNIVERSITY OF WASHINGTON · 2021 · $222,008

## Abstract

Project Summary/Abstract
The accuracy and timely execution of rapid saccadic eye movements are crucial for effective vision.
Therefore, an accurate measure of where the eye is aimed is required to understand not only the effect on
visual processing but also the neuronal mechanisms that underlie the generation of the eye movements
themselves. For more than 40 years, much of our understanding of the oculomotor system has relied on the
scleral search coil system. This system has the advantages of operating in real time and having low noise and
high accuracy. However, it requires an invasive surgery to implant the eye coil and bulky high power AC
electromagnetic field coils. Unfortunately, as far as we are aware, there are no longer manufacturers that
supply the scleral search coil system. The shifting focus of the electronics industry toward digital switching
technology obsoletes most linear parts required to build the power oscillator that feeds the field coils and the
detector. The optical eye movement transducers, which do not require attachment to the eye, are limited by
the long latency of their video processing. Also, the fast high-end devices suffer from ringing artifacts at the
end of a saccade that may mislead the interpretation of saccade kinematics. These problems could be a
barrier for a new oculomotor neurophysiology lab.
 With the recent development of optogenetics, a technique that allows light to manipulate the activity of
specific neurons with high temporal precision and then examine the effects on eye movements, the availability
of an eye tracking device with a real-time characteristics is necessary. This real-time, low latency requirement
is necessary in a closed-loop optogenetics experiment in which the laser light pulse is triggered and modulated
by the kinematics of the eye movement while a saccade is unfolding.
 To address the need for a non-contact eye movement transducer with high spatial and temporal
resolution, we propose to develop an eye tracking device that senses the asymmetric geometry of the ocular
globe. The device will be based on a capacitive sensor that measures the proximity between the globe and the
sensor. A capacitive proximity sensor has a wide bandwidth in excess of 1MHz and the signal processing
stage can be designed using small-signal analog/digital circuits that allow for real-time operation. The
capacitance sensor is composed of a fractured carbon nanotube-paper composite (CPC). Unlike other planar
capacitive sensors, the fractured CPC relies on the total surface area resulting from the stretching of numerous
multi-walled carbon nanotubes (MWCNTs). The surface area of MWCNT networks can be large enough to
provide measurements that are orders of magnitude more sensitive than that of planar capacitors. The
performance of the proposed sensor will be evaluated in a non-human primate and compared to that of a
scleral search coil system.

## Key facts

- **NIH application ID:** 10222711
- **Project number:** 5R21EY031768-02
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Jae-Hyun Chung
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $222,008
- **Award type:** 5
- **Project period:** 2020-08-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10222711

## Citation

> US National Institutes of Health, RePORTER application 10222711, Capacitive carbon-nanotube composite eye tracking sensor for non-human primate oculomotor research (5R21EY031768-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10222711. Licensed CC0.

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