Integrated CMOS MEMS liquid capacitive inclinometer

This paper reports a miniaturized CMOS MEMS capacitive inclinometer with dielectric liquid sensing medium in the reservoir on top of the CMOS substrate. A DFR/glass cap is bonded to the CMOS chip to form a reservoir for the sensing liquid. Rotating/tilting the sensor changes the electrode area covered by the liquid and leads to a change of capacitance. The packaged sensor had a dimension of 2.4×2.4×1.2 mm
³
. Experimental results obtained by the on-chip readout circuit showed the proposed inclinometer had a sensitivity of 0.48 mV/deg in the linear range between ±60°. With proper calibration, the linear range can be extended to ±90°.