New Flexible Electronic Sensor Is Lightest And Thinnest Yet

Flexible electronics that adhere to patients’ bodies and monitor health or form touch-sensitive robot “skin” have long been on scientists’ wish lists. Some bendable circuits, fabricated on thin polymer or steel sheets, have materialized in recent years. But a brand-new version is thinner and more lightweight than ever before. Siegfried Bauer of Johannes Kepler University, in Austria; Martin Kaltenbrunner and Takao Someya of the University of Tokyo; and colleagues designed the record-breaking device, which is one-fifth the thickness of plastic kitchen wrap and one-thirtieth the weight of a sheet of office paper (Nature 2013, DOI: 10.1038/nature12314). To make the bendable circuit, the team began with a 1-µm-thick polyethylene naphthalate “foil” and added to it an insulating layer of aluminum oxide. Because the foil has a rough surface, the team developed a room-temperature electrochemical process for depositing the oxide film onto it uniformly. After further surface treatment, the researchers laid down arrays of organic-semiconductor-based transistors and gold resistor pads. When stuck to a person’s skin, the flexible sheet can detect pressure changes. And it’s so bendable that it can be crumpled into a ball without losing function.