Fig. 3: Images of the MEMS differential thermopile-based H2 sensor. | Microsystems & Nanoengineering

Fig. 3: Images of the MEMS differential thermopile-based H2 sensor.

From: 1ppm-detectable hydrogen gas sensors by using highly sensitive P+/N+ single-crystalline silicon thermopiles

Fig. 3

a SEM image of the differential thermopile H2 sensor, showing the sensing thermopile loaded with catalyst, while the reference thermopile is left blank. b, c Optical images of differential thermopiles wire-bonded to a PCB. d, e Optical images of the differential thermopiles, showing the details of hot junctions, cold junctions, thermocouples, heating resistors, sensing output, and reference output electrodes. f–h Cross-sectional view of the suspended thermopiles over the insulation cavity, with magnified views of the thermocouples underneath the supporting SiNx membrane. i, j TEM images showing the morphology of Pt nanoparticles grown on Al2O3 nanosheets. k EDS characterization showing Pt NPs@Al2O3 as the catalyst for H2 detection

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