Fast Response PDMS/GaN Optical Vacuum Microsensors

In this letter, we demonstrate a PDMS/GaN-based optical microsensor for measuring vacuum pressure. The submillimeter-sized GaN device responsible for optical emission and detection is fabricated through the wafer-scale process. The integration of low-cost porous PDMS film can provide significant reflection changes under atmospheric pressure and vacuum conditions, enabling the GaN device to sense pressure variations in 22–760 Torr. The attractive features of the sensor such as compactness, ease of operation, fast response of 1.0 s, small hysteresis of 1.3 %, and high stability make it suitable for wide applications of vacuum pressure sensing.