Dew-point relative humidity CMOS microsensors

In this work we present the development of relative humidity (RH) microsensors in standard CMOS technology and bulk micromachining. Miniaturization of RH sensors allows reducing size, response times, power consumption and costs. Our device makes use of dew-point temperature detection approach, to achieve simple operation and high reproducibility. It is based on a suspended plate, anchored to the substrate by means of four arms. The thermoelectric Peltier effect is exploited to cool the plate until an interdigitated capacitor on top of the plate detects moisture and triggers the temperature measurements by means of thermocouples. By measuring dew-point and ambient temperatures, RH can be calculated through psycrometric charts. We report here the modeling, simulation, design and experimental characterization of CMOS RH microsensors.