Quasi-monolithic heat flux microsensor based on porous silicon boxes

A new generation of heat flux microsensors manufactured in CMOS silicon technology with high sensitivities is presented. Incident heat flux is converted into periodic superficial temperature gradients by an array of porous silicon boxes processed onto the substrate. A planar thermopile built up of doped polysilicon/gold thermocouples converts this temperature field into an electromotive force (e.m.f.). A sensitivity of 6.6 μV/(W/m2) was measured for a 5 mm × 5 mm sensor. Low thickness and high thermal conductivity of the devices result in low disturbances in the thermal environment. These microsensors have expanding opportunities in a wide range of applications such as contactless temperature or phase change enthalpy measurement, regulation systems for home or industry heating–cooling equipments.