Wearable Multiparameter Platform Based on AlGaN/GaN High‐electron‐mobility Transistors for Real‐time Monitoring of pH and Potassium Ions in Sweat

Biosensors based on field-effect transistor (FET) structures have attracted considerable attention because they offer rapid, inexpensive parallel sensing and ultrasensitive label-free detection. However, long-term repeatable detection cannot be performed, and Ag/AgCl reference electrode design is complicated, which has hindered FET biosensors from becoming truly wearable health-monitoring platforms. In this paper, we propose a novel wearable detection platform based on AlGaN/GaN high-electron-mobility transistors (HEMTs). In this platform, a sweatband was used to continuously collect sweat, and a pH detecting unit and a potassium ion detecting unit were formed by modifying different sensitive films to realize the long-term stable and repeatable detection of pH and potassium ions. Experimental data show that the wearable detection platform based on AlGaN/GaN HEMTs has good sensitivity (pH 3-7 sensitivity is 45.72 mu A/pH; pH 7.4-9 sensitivity is 51.073 mu A/pH; and K+ sensitivity is 4.94 mu A/lg alpha(+)(K)), stability (28 days) and repeatability (the relative standard deviation (RSD) of pH 3-7 sensitivity is 2.6 %, the RSD of pH 7.4-9 sensitivity is 2.1 %, and the RSD of K+ sensitivity is 7.3 %). Our newly proposed wearable platform has excellent potential for predictive analytics and personalized medical treatment.