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

Abstract

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 μA/pH; pH 7.4–9 sensitivity is 51.073 μA/pH; and K+ sensitivity is 4.94 μA/lgαK+), 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.

Point-of-care and self-testing for potassium: recent advances

“…Liu et al (2020) improved on this by developing a wearable detection platform based on high-electron-mobility transistors for monitoring of potassium and pH. 66 Real-time monitoring of subjects who exercised for 33 minutes was performed. A photo of the sensor attached to a forehead is shown in Fig.…”

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

“…[24][25][26][27][28][29] Above all, the two-dimensional electron gas (2DEG) in the AlGaN/GaN HEMT sensor is a located in close proximity to the surface, rendering it highly responsive to variations in surface potential. In recent years, AlGaN/GaN HEMT sensors have been successfully employed for the detection of proteins (biomarkers, antigens), [30][31][32] ions, 29,[33][34][35][36] DNA hybridization, 37 and pH [38][39][40][41] in solution or serum samples due to their various advantages mentioned above. However, challenges such as skin compatibility issues, 39 bulky test devices, 42,43 and limited integration with sweat collection and transport systems 44 have consistently hindered these biosensors from evolving into a truly wearable sweat sensing platform.…”

“…In recent years, AlGaN/GaN HEMT sensors have been successfully employed for the detection of proteins (biomarkers, antigens), 30–32 ions, 29,33–36 DNA hybridization, 37 and pH 38–41 in solution or serum samples due to their various advantages mentioned above. However, challenges such as skin compatibility issues, 39 bulky test devices, 42,43 and limited integration with sweat collection and transport systems 44 have consistently hindered these biosensors from evolving into a truly wearable sweat sensing platform.…”

Field effect transistor based wearable biosensors for healthcare monitoring

“…c Potassium ion-selective membrane modified on the GaN surface (reprinted with permission from Ref. [ 127 ] Copyright 2019 Wiley). d 3D-EMG-ISFETs with Al 2 O 3 as pH sensing dielectric, functionalized with ion selective membranes for Na + ,K + , and Ca 2+ sensing (reprinted with permission from Ref.…”