Meaning
Mechanical strain applied to certain semiconductor or metallic materials causes a measurable change in their electrical resistivity. This physical phenomenon, known as the piezoresistive effect, is the operating principle behind many industrial pressure sensors, accelerometers and strain gauges. It allows physical forces to be directly converted into electrical signals for monitoring and control systems.
Material Deformation
Under applied load, the crystal lattice of a piezoresistive material undergoes microscopic distortion. This distortion alters the energy bands and the mobility of charge carriers, leading to a shift in the electrical resistance of the material. In sensors utilizing the piezoresistive effect, this shift is highly linear over a wide operating range.
This linearity simplifies the design of the signal conditioning circuitry and improves measurement accuracy.
Sensor Sensitivity
The magnitude of the resistance change is determined by the material’s gauge factor. Silicon-based piezoresistive sensors exhibit much higher sensitivity than metal foil gauges, making them ideal for detecting minute pressure changes. This sensitivity is highly valued in high-precision aerospace and automotive applications.
However, silicon sensors are also sensitive to temperature changes, requiring active thermal compensation to prevent measurement drift. This compensation is typically integrated directly into the sensor package, combining the sensing element with a dedicated temperature sensor and correction circuit.
Industrial Application
Transducers using this technology are widely deployed in process industries to monitor pipeline pressures and fluid levels. Manufacturers of these sensors sell their products to system integrators under long-term supply agreements. These contracts specify performance parameters such as sensitivity, response time and operating temperature range, ensuring that the delivered sensors meet strict industrial standards.
