Spatial Thermal Gradient Mapping Micro-Machined Accelerometer Arrays
Spatial thermal gradient mapping in micro-machined accelerometer arrays decouples linear motion from external board heat using differential thermopile matrices.
Substrate Conduction
Thermal Leakage
Heat transfer through the physical mounting or base material of a sensing element affects the temperature of the active region. This process, known as substrate conduction, draws heat away from or introduces heat to the sensing zone, which distorts the measured temperature. The magnitude of this thermal path depends on the material’s thermal conductivity and thickness.
It is particularly pronounced in compact designs where the sensing element is close to the housing.
Measurement Error
The deviation caused by this heat path creates an offset between the sensor temperature and the medium temperature. This offset increases when there is a large temperature difference between the medium and the mounting wall. The resulting error can exceed several degrees in high-temperature or high-vacuum applications.
Isolation Design
Designers minimize this unwanted heat flow by using low-conductivity mounting materials or by extending the immersion length of the sensor. These techniques ensure that the active area of the sensor remains in thermal equilibrium with the medium. Extending the lead wires also helps to isolate the sensor from the cold mounting wall.
Verification Method
Testing the sensor in a controlled temperature bath allows technicians to measure the immersion depth sensitivity. The output is monitored as the sensor is gradually withdrawn from the bath to determine the point where heat leakage begins to affect the reading. This test establishes the minimum insertion depth required for accurate operation.