A Chip-Scale GaN-Based Optical Pressure Sensor With Microdome-Patterned Polydimethylsiloxane (PDMS)

In this letter, a novel integration of GaN chip with microdome-patterned polydimethylsiloxane (PDMS) film for pressure sensing is demonstrated. The compact $1\times {1}\times {0.2}$ mm3 GaN-on-sapphire chip consisting of light emitter and photodetector is formed through wafer-scale, high-throughput microfabrication processes. The integration of deformable dome-shaped PDMS enables the GaN chip to respond to the pressure variation effectively. The sensor exhibits a sensitivity of $0.989~\mu \text{A}$ /kPa for a wide pressure range of 0–50 kPa. In addition to the optical and electrical characteristics of the sensor, its prominent sensing performances of high repeatability and stability to dynamic pressure changes are studied through a range of experiments. The compact assembly scheme has advantages in manufacturing cost, compactness, and robustness, which is of great value for real-time pressure monitoring in a wide range of practical applications.