Miniaturized Dual-Axis Electrolytic Tilt Sensor

The electrolytic tilt sensor operates by measuring the change of conductance between detecting electrodes immersed in an electrolyte. Previously reported electrolytic tilt sensors detect an inclination only on one axis owing to the structural limit for symmetric formation of the detecting electrodes with a fiducial electrode as the reference on the same substrate. In this paper, we report the design and fabrication of a micro-electro-mechanical-system (MEMS)-based dual-axis electrolytic tilt sensor. The proposed tilt sensor has overcome its structural limit by placing the fiducial common electrode at the bottom of the electrolyte cavity for contact with the electrolyte through a via-hole. The proposed tilt sensor shows approximately 50 mV of change in the output voltage per degree of inclination angle in an operating angle range of $\pm 70$°.