AC Excitation to Mitigate Drift in AlGaN/GaN HEMT-Based Sensors

An integrated wearable sticker based on extended-gate AlGaN/GaN high electron mobility transistors for real-time cortisol detection in human sweat

“…The measurement starts in PBS-only as a baseline, and then PBS-only or different concentration of cortisol in PBS was added each time for 2 min per injection. An initial drift of the baseline signal is often observed possibly due to ionic interactions at the gate or channel interfaces and the 1/ f noise, 52–54 which was stabilized in all the cases in less than 5 min. The tests were performed with a reservoir fixed on the sensor, exposing the sensor to 30 μL of solution at the fixed concentration after removing the previous solution.…”