Thin Film / Thick Film Processing

Giant Piezoelectric Effect to Improve MEMS Devices

Researchers in the Department of Materials Science and Engineering and the Materials Research Institute at Penn State are part of a multidisciplinary team of researchers from universities and national laboratories across the U.S. who have fabricated piezoelectric thin films with record-setting properties. These engineered films have great potential for energy harvesting applications, as well as in micro-electro-mechanical-systems (MEMS), micro actuators, and sensors for a variety of miniaturized systems, such as ultrasound imaging, microfluidics, and mechanical sensing.

Piezoelectric materials can transform electrical energy into mechanical energy and vice versa. Most MEMS utilize silicon, the standard material for semiconductor electronics, as the substrate. Integrating piezoelectric thin films onto silicon-based MEMS devices with dimensions from micrometers to a few millimeters in size will add an active component that can take advantage of motion, such as a footstep or a vibrating motor, to generate electric current, or use a small applied voltage to create micron level motion, such as in focusing a digital camera.

Previously, the best piezoelectric MEMS devices were made with layers of silicon and lead zirconium titanate (PZT) films. Recently, a team led by Chang-Beom Eom of University of Wisconsin-Madison synthesized a lead magnesium niobate-lead titanate (PMN-PT) thin film integrated on a silicon substrate.

The Penn State team, led by Susan Trolier-McKinstry, professor of ceramic science and engineering, and including research associate Srowthi Bharadwaja, PhD, measured the electrical and piezoelectric performance of the thin films and compared the PMN-PT films against the reported values of other micromachined actuator materials to show the potential of PMN-PT for actuator and energy harvesting applications.