AlGaN/GaN Hetrojunction pH Sensors with μL Level Trace Detection Based on PDMS Microfluidic Chips

Trace measurement of pH value is of great significance in modern fields such as industry, agriculture, medicine, environmental science, and bioengineering. Microfluidic chips that combine polydimethylsiloxane (PDMS) with gallium nitride high-electron-mobility transistors (GaN HEMTs) provide an effective method for the trace detection of hydrogen ion concentration in solutions. Based on AlGaN/GaN high-electron-mobility transistors, this study conducts a systematic analysis by comparing sensors packaged with PDMS for devices with a width-to-length ratio (W/L) of 800/400 μm and those with traditional packaging. It is found that the sensor packaged with PDMS has a current sensitivity slightly higher than that of the traditionally packaged sensor, reaching 139.92 μA/pH (134.6 μA/pH for the traditional package), and its voltage sensitivity is also slightly higher than the latter, standing at 49.95 mV/pH (44.77 mV/pH for the traditional package). In addition, on the premise of ensuring sensing performance, detection can be completed with only 5 μL of solution. Therefore, the application of the microfluidic chip system can not only improve the sensitivity and response speed of the sensor but also significantly reduce the experimental cost.