Flexible sensor emits light when pressed

Discovery News : Flexible electronics and sensors are both made from crystalline materials. Because the different crystalline structures do not mesh well when combined on the same substrate layer, the creation of flexible sensor circuits has been a challenge. Now, Ali Javey of the University of California, Berkeley, and his colleagues have revealed two methods to create those circuits. They began with a layer of silicon substrate that they covered with a layer of a stretchable, flexible polymer called polymide. In the first of their techniques, they grew nanowire circuits on a cylinder by using cadmium selenide for the light sensors and germanium silicon for the transistors. They then rolled the cylinder on the polymide sheet to deposit the circuits. In the second technique, the circuits were grown on a flat surface and pressed directly onto the polymide. In both techniques, a second layer of polymide was applied on top. When the silicon layer was removed, what remained was a stretchable and flexible sheet of circuits that respond to pressure. The amount of light emitted by the device is directly related to the amount of pressure applied to each sensor. The photosensors were used to provide visual evidence of the sensor functionality, but Javey sees the technique being employed for different sorts of electronic device interfaces.