A Low-cost Low-power Capacitive Humidity Sensor in CMOS technology

This paper presents a capacitive humidity sensor in CMOS technology. The humidity sensor element is implemented in standard CMOS technology without any further post-processing, which results in low fabrication cost. The sensor interface is based on a delta-sigma converter and can be easily reconfigured to compensate for process variation of the sensing element. The proposed humidity sensor is fabricated in 0.16 mu m standard CMOS process and the chip occupies 0.25mm(2). The measurement result shows that this humidity sensor acquires a resolution of 0.1% RH in the range of 20%RH to 90%RH. The interface achieves a 12.5-bits capacitance-to-digital conversion and consumes only 9.6 mu W power at 1.2V supply voltage.