Simulation of a micro-fabricated inclinometer

A two-axis inclinometer has been simulated using the nodal analysis capabilities of T-Spice, The sensor was fabricated at the Fachhochschule Furtwangen using silicon bulk micromachining techniques. The sensor consists of a proof-mass which is suspended via four beams to a frame. Four resistors are implanted into the surface of the beams along each axis and are connected to form a Wheatstone bridge. The output voltage of the bridge is zeroed when the frame is not tilted. As the frame tilts, the proof-mass causes the beams to bend and the values of the resistors to change. The bridge output as a function of the inclination angle was calculated and found to be sinusoidal in agreement with the experimental results. The analysis indicated that by proper arrangement of the resistors, the sensor sensitivity could be improved from 0.34 mV to 1.25 mV per degree of inclination.