Fig. 5: H2 sensing performance of MEMS differential thermopiles.

a–c Sensor response (Vdiff) to 1% H2 at different operating temperatures from 50 to 240 °C. An optimized working temperature of 120 °C is determined, with a power consumption of 40 mW. d–f Differential output vs. different hydrogen concentrations, showing a linear response within an H2 concentration range of 1 ppm to 2%. g Measured sensor response and recovery time (t90) of 1.9 and 1.4 s, respectively. h Zoomed-in view of the sensor response to continuously reduced H2 concentration down to 1 ppm