Sensitivity Parameter
Dimensionless sensitivity coefficients describe the ratio of fractional electrical resistance change to mechanical deformation in semiconductor structures. This behavior determines the piezoresistive strain sensitivity of a sensor, which can be orders of magnitude higher than that of metallic foil gauges. The parameter is primarily governed by the concentration and type of dopants introduced into the silicon crystal.
Measurement Drift
Environmental temperature fluctuations represent the primary source of instability, affecting both the base resistance and the sensitivity coefficient. In high-precision applications, piezoresistive strain sensitivity is measured against known strain fields on reference bending beams. Sourcing specifications detail this thermal coefficient of sensitivity to allow the system integrator to design appropriate electronic compensation.
Calibration Protocol
Metrological traceability requires that sensitivity factors are verified using standardized strain calibration rigs. A certificate of calibration lists the piezoresistive strain sensitivity across a specified strain range under controlled reference temperatures. Installers must account for adhesive shear lag, which reduces the strain transferred from the substrate to the sensor.
Material Physics
The physical origin of this behavior lies in the deformation-induced alteration of the semiconductor band structure, which redistributes charge carriers among different conduction valleys. Bandgap modification changes the mobility of holes or electrons, leading to the observed resistance variation. Because this effect is highly anisotropic, crystallographic orientation is critical during device fabrication to maximize the response.
Silicon sensors must be aligned precisely along the appropriate crystallographic axis to ensure that the measured piezoresistive strain sensitivity matches the theoretical values specified in the component datasheet.
