MEMS and sensors

What is the detection principle of semiconductor gas sensors using tin oxide or similar materials?

  1. AThe gas temperature causes light emission
  2. BThe gas changes a sound
  3. CThe target gas adsorbs and reacts on the surface, changing the electrical resistance of the sensor material
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Answer: C. The target gas adsorbs and reacts on the surface, changing the electrical resistance of the sensor material

In a semiconductor gas sensor, oxygen adsorbed on the surface of heated tin oxide captures electrons, keeping the resistance high. When combustible gases are present, they react with the adsorbed oxygen and the electrons return, lowering the resistance. This change in resistance is used to detect the gas.

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