Droplet Microsensors Based on GaN Diode Optopairs

In this work, the fabrication of a compact GaN-based droplet microsensor is demonstrated. The monolithic integration design of GaN diode optopairs provides the sensor with attractive properties such as miniaturization, robustness, low cost, and suitability for mass production. The sliding of water droplets across the device results in significant photocurrent changes, and the microsensor can respond to water droplet frequencies up to 3 Hz. The microsensor exhibits lightweight, low-cost, and rapid response, and has a high potential for tracking droplets in practical applications.