Transduction Principle
Microfabricated pressure transducers utilize a thin, flexible diaphragm positioned above a fixed backplate to measure environmental force. A standard capacitive pressure sensor translates physical deformation of this diaphragm into a measurable change in electrical capacitance. The resulting electrical signal varies inversely with the distance between the two conductive plates.
Signal Quality
Dynamic response and noise levels depend directly on the mechanical stiffness of the diaphragm and the gap size. High-resolution devices operate with sub-micron gaps to maximize the nominal capacitance and the sensitivity to minor force changes. This layout reduces the impact of external electromagnetic fields on the measurement accuracy.
Environmental Drift
Temperature variations introduce thermal expansion mismatch between the silicon diaphragm and the substrate materials. This physical shift alters the baseline gap size and generates a temperature-dependent drift in the measured capacitance. Sensor assemblies minimize this error by incorporating reference capacitors on the same chip to subtract common-mode thermal behavior.
The reference capacitors are designed to be immune to external pressure changes while experiencing identical thermal gradients, which allows for precise real-time compensation.
Calibration Check
Production testing requires applying a controlled pressure sweep while monitoring the capacitance output. This procedure establishes the characteristic curve of the sensor and determines the linearity of its response across the specified operating band. Automated calibration systems perform these checks under controlled thermal conditions to verify the temperature compensation algorithms.
