Relative humidity sensors based on porous polysilicon and porous silicon carbide

RH sensors have been made using porous polysilicon and porous SiC, both of which can also be made porous by electrochemical anodisation in HF, similarly to single crystal silicon. We show that polysilicon can be incorporated into a humidity sensor enabling a reduction (compared to single-crystal porous Si) of the effect of temperature on humidity measurements. We show that porous SiC can also be incorporated into a humidity sensor and that these sensors are able to withstand being subjected to harsh environments such as a high temperature and high RH chamber, and the outlet of a car exhaust.