Meaning
Surface charge generation on certain crystalline materials in response to a change in temperature is used for thermal sensing. The pyroelectric effect is found in specific polymers like polyvinylidene fluoride, which are used to make infrared sensors. This phenomenon allows for the detection of heat without physical contact.
Charge Generation
As the temperature of the material changes, the molecular structure shifts and alters the internal electrical polarization. This movement creates a measurable voltage across the surfaces of the polymer film. The pyroelectric effect is temporary, as the charge eventually leaks away once the temperature stabilizes.
Rapid temperature changes produce a stronger signal than slow drifts, making the sensor ideal for detecting moving objects.
Sensor Application
Thin films of polarized polymer are used to create responsive and flexible thermal detectors. Because the pyroelectric effect is highly sensitive to small temperature variations, these sensors are ideal for motion detection and industrial process monitoring. They are often integrated into automated molding cells to detect the presence of hot parts.
Material Conditioning
To maximize the sensitivity of the polymer, it must be subjected to a strong electric field during the manufacturing process. This step aligns the molecular dipoles so that the pyroelectric effect is as strong as possible. Once conditioned, the material remains active unless it is heated above its Curie temperature.
