Fully differential current-mode MEMS dual-axis optical inclination sensor

We demonstrate a tilt sensor fabricated in the MultiMEMS SensoNor process. The system uses an array of four photodiodes to determine the position of a bubble fluid pendulum and the tilt angle with respect to gravity. The entire sensing structure was manufactured in the commercial MultiMEMS process so it can be easily reproduced in large quantities. The device was tested across a range of inclinations to verify performance in sensing two axis tilt. Results for tilt measurements from −45° to +45° show correlation to expected values with an R2 value of 0.99595. The resolution of the device is 0.5° at zero degrees of inclination. The outputs of the sensor are mapped to a fit equation to allow calculation of inclination angle. The small size, simple structure, and minimal power consumption make it well-suited for a number of research and industrial applications.

► Design and testing of a MEMS inclination sensor.
► A fluid pendulum affects light transmission to photodiodes.
► Small size, robust operation, and straightforward post-processing.
► Four quadrant design leads to differential measurement and translinear readout.
► Commercial process and minimal post-processing allow for high volume production scaling.