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 x 1 x 0.2 mm(3) 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 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.