Piezoelectric materials hold great promise as sensors and as energy harvesters but are normally much less effective at high temperatures, limiting their use in environments such as engines or space exploration. A new piezoelectric device was developed that remains highly effective at elevated temperatures.
Piezoelectric materials generate an electric charge when rapidly compressed by a mechanical force during vibrations or motion such as from machinery or an engine. This can serve as a sensor to measure changes in pressure, temperature, strain, or acceleration. Potentially, piezoelectrics could power a range of devices from personal electronics like wristband devices to bridge stability sensors.
Researchers integrated the material into a version of a piezoelectric energy harvester technology called a bimorph that enables the device to act as a sensor, an energy harvester, or an actuator. A bimorph has two piezoelectric layers shaped and assembled to maximize efficient energy harvesting. Sensors and energy harvesters, while bending the bimorph structure, generate an electrical signal for measurement or act as a power source.
Unfortunately, these functions work less effectively in high-temperature environments. Current state-of-the-art piezoelectric energy harvesters are normally limited to a maximum effective operating temperature range of 176 °F (80 °C) to 248 °F (120 °C).
The new piezoelectric material composition showed a near-constant efficient performance at temperatures up to 482 °F (250 °C). In addition, while there was a gradual dropoff in performance above 482 °F (250 °C), the material remained effective as an energy harvester or sensor at temperatures to well above 572 °F.
Another benefit of the material was an unexpectedly high level of electricity production. While at present, piezoelectric energy harvesters are not at the level of more efficient power producers such as solar cells, the new material’s performance was strong enough to open possibilities for other applications; for example, as a continuous, battery-free power supply in dark or concealed environments such as inside an automotive system or even the human body.