Accelerometers

The MultiMEMS MPW process allows designs for various inertial devices, such as accelerometers, force sensors, inclinometers, angular rate sensors, energy harvesters.

The simplified cross-section of a typical MultiMEMS accelerometer is illustrated below. Though not recommended because of the severe undercutting of the convex corners, the mass of the inertial devices can also be manufactured with full-wafer thickness.

Cross-Sectional View:

Accelerometer [Hide] [Show]

The most relevant features of the accelerometers, i.e. main sensitivity, resonance frequencies, cross-axis sensitivity, linearity, sensitivity to package-related stress, depend on the number and geometry of the beams used as suspension system.

Examples of Accelerometers

The four-beam accelerometer pictured below has been developed by SINTEF to be used as micro-balance in pharmaceutical applications. The device is very sensitive to the weight of materials placed on top of its inertial mass.

Micro-balance designed by SINTEF and manufactured in the MultiMEMS MPW

The four-beam accelerometers pictured below have been developed by Vestfold University College for medical applications. The devices, while still robust to package-related stress, are single-axis acceleration sensing elements with practically no cross-axis sensitivity.

Accelerometers designed by Vestfold UC and manufactured in the MultiMEMS MPW

The two-beam accelerometer pictured below has been developed by SensoNor for automotive applications. The SA30 crash sensor^[1], based on a thermally excited, acceleration-sensitive resonant structure, features self-test and self-calibration functions.

Schematic view of SensoNor's SA30 patented crash sensor

References

1. "Force Sensor", U.S. Patent 5,834,646 (1998), European Patent EP 0737864 B1 (2000).