Piezoelectric material could revolutionise sensors, imaging and energy harvesting

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A new, highly efficient piezoelectric material has been successfully integrated into a silicon MEMS system, paving the way for significant advances in sensing, imaging and energy harvesting.

Researchers from University of Wisconsin-Madison have collaborated with scientists at the National Institute of Standards and Technology (NIST) on the project. A piezoelectric material expands slightly when fed electricity and, conversely, generates an electric charge when squeezed. Piezoelectric materials are used in sensors, sonar and ultrasound systems, which use the same principle in reverse to translate sound waves into images of, among other things, fetuses in utero and fish under the water. The researchers sought to find or invent new piezoelectric materials that expand more and more forcefully and produce stronger electrical signals, enabling new technologies such as energy harvesting. A new material, PMN-PT, was integrated into tiny 'diving board like' cantilevers on a silicon base, a typical material for MEMS construction. Compared to rival materials, the researchers demonstrated that PMN-PT could deliver two to four times more movement with stronger force, while using only 3 volts. It also generated a similarly strong electric charge when compressed, making it suitable for sensing and energy harvesting markets. Vladimir Aksyuk, NIST researcher developed engineering models of the cantilevers to confirm that the experimental observations were due to the piezolelectric's performance and to estimate how much they would bend – and at what voltage. Further performance measures were made in comparison to silicon systems that achieve similar effects using electrostatic attraction. "Silicon is good for these systems, but it is passive and can only move if heated or using electrostatics, which requires high voltage or large dissipated power," said Aksyuk. "Our work shows definitively that the addition of PMN-PT to MEMS designed for sensing or as energy harvesters will provide a tremendous boost to their sensitivity and efficiency. A much bigger 'bend for your buck,' I guess you could say." Other participants included researchers from Penn State University; the University of California, Berkeley; the University of Michigan; Cornell University; and Argonne National Laboratory.