Potassium selective chemically modified field effect transistors based on AlGaN/GaN two-dimensional electron gas heterostructures

We investigate the use of the AlGaN/GaN high electron mobility transistor (HEMT) as a novel transducer for the development of ion-selective chemically modified HEMT sensors (ChemHEMTs). For this, polyvinyl chloride (PVC) membrane doped with ion-selective ionophores is deposited onto the area of the gate for the chemical recognition step, while the AlGaN/GaN HEMT is used as the transducer. In particular, the use of a valinocycin doped membrane with thickness of 50 μm generates a sensor with excellent analytical characteristics for the monitoring of K+. The K+-ChemHEMT has sensitivity of 52.4 mV/pK+in the linear range of 10−5 to 10−2 M, while the detection limit is in the order of 3.1 × 10−6 M. Also, the sensor shows selectivity similar to valinomycin-based ISEs, while the signal stability over time and the measurement to measurement reproducibility are very good.