Pyroelectricity is generation of electric power with temperature variation of Pyroelectric crystals. The generated voltage is proportional to the temperature difference. The pyroelectric effect can be used for harvesting thermal energy during temperature increase (heating) and decrease (cooling) of pyroelectric crystals. Pyroelectricity should not be confused with thermoelectricity or piezoelectricity. The pyroelectric effect was discovered before the piezoelectric effect and is mainly used for pyroelectric infrared temperature detectors.

Pyroelectric Sensors/Detectors Operating Principle

The pyroelectric sensors are just like thermal (heat) conductors or heat pipes, they are used for coupling the heat source and heat sink devices. While heating or cooling, the heat is passed through the pyroelectric crystals, so that the flow of difference temperature is sensed and converted to voltage (electrical energy).

Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. The change in temperature slightly modifies the positions of the atoms within the crystal structure, such that the polarization of the material changes. This polarization change gives rise to a voltage across the crystal. If the temperature stays constant at its new value, the pyroelectric voltage gradually disappears due to leakage current (the leakage can be due to electrons moving through the crystal, ions moving through the air, current leaking through a voltmeter attached across the crystal, etc.).

Applications of Pyroelectric Sensors & Detectors

Pyroelectric energy conversion offers a novel approach for directly converting time-dependent temperature oscillations into electricity. It makes use of the pyroelectric effect to create a flow of charge to or from the surface of a material as a result of successive heating and cooling.

The power generated from pyroelectric effect is very small, but it is helpful in powering wireless (RF) sensors to operate independantly in a wireless network. Also, pyroelectric energy is sufficient for a MEMS temperature sensor to measure temperature oscillations and send the data wirelessly.