On the Sensing Strategy and Approaches of Liquid Sensors based on AlGaN/GaN HEMTs

This study conducts a comparative evaluation of gate-modulated and surface-functionahsed sensing techniques employing AlGaN/GaN High Electron Mobility Transistors for the detection of uric acid (UA) biomolecules. The sensing cavity is functionalised using a T-ZnO layer to enhance selectivity. The impact of UA charge concentrations (55 μM and 460 μM) on device performance is analyzed throng threshold voltage shift (ΔV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</inf>) and dram current change (ΔI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</inf>). The results demonstrate that surface-based sensing exhibits a superior threshold voltage sensitivity (0.425 mV/μM) compared to gate-based sensing (0.381 mV/μM) at 460 μM UA concentration. The findings suggest that surface-based sensing provides enhanced charge detection due to its reduced influence from the gate’s electric field, leading to improved sensitivity and reliability.