A wireless-transfer-based hydrogen gas sensing system with a Pd/AlGaN/GaN heterostructure field-effect transistor (HFET)

In this paper, a wireless hydrogen sensing system using a Pd/AlGaN/GaN heterostructure field-effect transistor (HFET) is developed and demonstrated. This HFET device shows good hydrogen sensing performance, including higher drain current variation (0.17 mA @ 1 ppm H₂/air gas), fast response speed, and superior repeatability behaviors. For the sensing application, a readout circuit is designed to display the value of hydrogen concentration. Then, these data are fed into single chip microprocessor for later processing and wireless transmission. In addition, a grey polynomial differential model algorithm is employed to significantly reduce the redundant data for alleviate the wireless transmission load. The wireless monitoring of hydrogen concentration in a remote site longer than 50 m in distance is successfully demonstrated. From the experimental results, the proposed wireless hydrogen sensing system shows the advantages of high hydrogen sensing performance, easy operation, low cost, high portability, and effective wireless transmission.