A mode localization based resonant MEMS tilt sensor with a linear measurement range of 360°

This paper reports a resonant MEMS tilt sensor based on mode localization phenomenon for the first time. The tilt sensor consists of two mode localization based accelerometers which are perpendicular to each other. The input tilt angle will cause dramatic changes of the mode shape of both accelerometers. Furthermore, the linear measurement range is extended to a full-range of [-90°, 90°] by alternatively measuring the shifts of the two amplitude ratios with a phase difference of 90°. Current test results show that the relative sensitivity based on the amplitude ratio is averagely 169 times higher than that of the frequency with a non-linearity of less than 4.5% in the range of [-90°, 90°]. The outputs of the input tilt angle (θ) from [90°, 270°] and [-90°, 90°] are axial symmetry about θ = 90°, so it is easy to extend the linear measurement range to 360°.