Researchers at Princeton University have demonstrated that high performance piezoelectric ceramics can be transferred onto rubber or plastic, rendering them flexible without sacrificing energy efficiency.

“The human body is a ideal source of power if we can harness our body motion such as walking, finger typing or breathing. This would be especially convenient for implantable medical devices such as pacemakers, since surgeries are now required to replace dead batteries. If we could replace those batteries with power directly harvested from the continual motion of the lungs, it could significantly improve the quality of life for patients,” said Michael McAlpine, assistant professor of mechanical and aerospace engineering at Princeton University, in an interview with Nanowerk.

McAlpine and his team have fabricated biocompatible power-generating rubber films. By successfully combining silicone with nanoribbons of piezoelectric ceramics, the team created an implantable ‘piezo–rubber’ that could harness natural body movements to power electronic devices.

The team has also successfully shown that it can transfer highly crystalline piezoelectric ribbons in high yields and over large areas onto rubber substrates.

Growth conditions for ceramic crystals are critical for achieving high piezoelectric performance – high temperatures and a carefully chosen growth substrate are required – both incompatible with flexible rubbers or plastics. The way McAlpine’s team solved the problem was to first fabricate lead zirconate titanate (PZT) nanoribbons and then, in a separate process under ambient conditions, print the nanoribbons onto silicone rubber.

“First, PZT films were grown on a cleaved magnesium oxide crystal substrate and postannealed to form a perovskite crystal structure. Second, the structure, composition, and piezoelectric response of the films were characterized to ensure optimal performance. Next, the films were patterned into nanothick ribbons and printed onto clear sheets of silicone rubber (PDMS) via dry transfer. Finally, the fundamental piezoelectric properties were characterized on the rubber substrate using a nanoscale characterization method, piezoresponse force microscopy,” McAlpine said.

The findings were published in the January 26 online issue of Nano Letters.