Semitransparent Image Sensors for Eye-Tracking Applications

Due to their ability to capture vast amounts of information, traditional image sensors play a pivotal role in today’s society. However, the opaque nature of both their pixels and stacked read-out electronics can be a limiting factor in applications such as human–computer interfaces, smart displays, and both augmented and virtual reality. In this paper, we present the development and analysis of the first semitransparent image sensor and its applicability as an eye-tracking device. Consisting of an 8 × 8 array of semitransparent photodetectors and electrodes deposited on a fully transparent substrate, the sensor’s pixels achieve an optical transparency of 85–95% and high sensitivity, with more than 90% of these pixels demonstrating a noise equivalent irradiance <10^–4 W/m² for wavelengths of 637 nm. The fabrication of such sensors represents a fundamental shift in how we think about cameras and imaging as these devices can be concealed in plain sight.