Circuits that are thin, lightweight, and bendable hold promise for a wide variety of applications, particularly artificial skin, implantable sensors, and other biomedical devices. Giovanni Salvatore and colleagues in the Wearable Computing Group at ETH Zürich have now demonstrated an extremely versatile technique for fabricating flexible circuits. Starting with an ordinary wafer, the researchers deposit a thin, sacrificial polymer layer that can be easily dissolved. Next they add an insoluble thin film that will serve as the ultimate substrate for the final deposition step—the electronic circuitry. Dissolving the bottom polymer film frees the circuit-topped insoluble film, at which point it can be transferred to its intended destination.
This photo highlights one appeal of the technique: extreme flexibility and conformability. These thin-film transistors lie on a 1-µm film of the biocompatible polymer parylene that’s been draped across human hairs about 100 µm in diameter. Despite the film’s strong curvature, the transistor...
