Novel AlGaN/GaN HEMT pH Sensor for Real-Time Monitoring Based on Visible Light Communication Technology

This work reports a novel real-time high sensitivity pH monitoring system based on light signal acquisition of visible light communication technology (VLCT). The pH monitoring system is composed of LED as signal transmission and AlGaN/GaN high electron mobility transistor (HEMT) as pH sensor. The luminescence of LED is regulated by HEMT when monitoring pH. The luminescence intensity of the LED varies with the current change of sensor and it will be captured by CCD or optical power meter to realize pH monitoring. The sensor shows excellent sensing characteristics with a maximum sensitivity of $285.7 ~\mu \text{A}$ /pH and a resolution of 0.14 pH at the range of pH from 2 to 12.45.