The Main Sensor Types and What Each One Measures
Selecting sensors requires matching physical transduction principles to measurands while accounting for thermal drift, noise floor, and fab availability.
Magnetoresistance
Material Property
Material properties of a conductor or semiconductor describe the change in electrical resistance in response to an external magnetic field. Variations in magnetoresistance allow for the creation of non-contact sensors that detect position or rotation. Anisotropic and giant variants of the effect offer different levels of sensitivity for industrial applications.
The resistance typically decreases as the magnetic field aligns with the internal magnetization of the material.
Sensor Application
Solid-state bridges utilize this effect to measure small changes in magnetic flux with high resolution. While Hall effect sensors measure voltage, devices based on magnetoresistance monitor the change in current flow through the sensing element. This characteristic makes them suitable for high-speed encoding in automotive and industrial drives.
They are often packaged with integrated permanent magnets to detect the movement of ferrous gear teeth.
Temperature Sensitivity
Internal resistance changes with thermal fluctuations and requires active compensation to maintain accuracy. The coefficients of magnetoresistance are often non-linear and vary between material batches. Signal conditioning electronics typically include a temperature sensor to apply real-time corrections.
Calibration ensures that the output remains stable even as the sensor body warms during operation.
Saturation Limit
Performance degrades once the external field strength exceeds the level needed to fully align the internal magnetic moments.