Application of a Discrete AlGaN/GaN HEMT Sensor for In-Situ Regenerative Soot Particulate Detection

An in-situ regenerative soot particulate matter sensor for automotive exhaust systems based on a discrete AlGaN/GaN high electron mobility transistor (HEMT) was developed and tested, where charge-sensitive AlGaN/GaN HEMT was utilized to detect the signal variations caused by the presence of soot particulate matters, and the micro-hotplate serves as soot deposition, while the self-heating unit was used for sensing and in-situ regeneration. The two parts were connected for electrical signal transmission. Soot particulate were generated by a laminar diesel flame with an adsorption rate of 23.29 μg cm⁻² min⁻¹ on the sensor surface, resulting in 1.32% sensing response after 20 s deposition and reached saturation after a 12 minute deposition of soot. After soot deposition, the sensor was successfully regenerated when a voltage of 2 V was applied to the micro-hot plate, causing in-situ heat-up to reach 600°C for 30 seconds. Moreover, benefiting from the advantage of discrete structure, the sensor exhibited consistent and stable response characteristics even after undergoing more than 10 consecutive regeneration cycles, and the replaceable micro-hotplate could further extend the service life of the sensor. These results show that the discrete AlGaN/GaN HEMT sensor can be a promising soot particulate sensing platform for automotive exhaust systems.