Technology for Motion and Pressure

"A sensor is the gateway between the three-dimensional world and an information system. You can't measure 3D-phenomena efficiently and accurately without resorting to 3D-technology. This is why VTI has created 3D MEMS for its motion and pressure sensors."

Heikki Kuisma, Vice President, Research
heikki.kuisma@vti.fi

VTI's silicon capacitive sensor is made of single crystal silicon and glass. This design ensures exceptional reliability, unprecedented accuracy and excellent stability over time and temperature. The 3D MEMS technology provides thick, robust sensor structures that are very sensitive to inertial forces and pressure but are insensitive to other environmental variables and causes of failure.

The capacitive detection principle is simple and stable. It is based on the variation of the distance between two surfaces. The capacitance or charge storage capacity of a pair of surfaces depends on their distance and on the overlapping surface area.

VTI's 3D MEMS are capped, i.e. inherently hermetically sealed for reduced packaging requirements. No particles or chemicals can enter the capped sensor, a fact that ensures reliability.

The dual capacitor structure and its symmetry improve zero stability, linearity and cross-axis sensitivity of the 3D MEMS accelerometer. Temperature dependence is typically less than 0.05FS/ºC and cross-axis sensitivity typically less than 3%.

Depending on the needs of the application the accelerometer element can be tuned for a specific sensitivity and frequency response. Elements are available for both in-plane and z-axis measurement as well as for 3-axis sensing. Flexible 2-chip or 3-chip solution enables customised sensors.

Capacitive absolute pressure sensors are highly stable and very insensitive to mounting stress. Depending on environmental condition, calibration, linearization and thermal compensation, accuracies in the range of 0.01...0.5 %/FS can typically be obtained.