The position-sensing sheet relies on two types of flexible electronics. Using a technique similar to silk screening, the researchers printed an array of copper coils 10 millimeters in diameter. In addition, they used a modified inkjet printer to print an array of organic transistors. Both devices are thin and flexible enough to bend with a sheet of plastic.
Gadgets would need to be equipped with a coil and special power-harvesting circuitry to use the power pad.
Still, the flexible electronics used to make this prototype is still in its infancy. "There's a lot of space to improve," Someya says. The devices aren't quite reliable enough. They change their characteristics in a period of months, he says, due to oxygen and humidity, which attack organic semiconductors and electrodes. However, he says, he is optimistic because some commercial displays, called organic electroluminescence (OEL) displays, use similar materials, and in recent years the display market has helped drive improvements in these organic devices.
Someya estimates that it will take about five years to overcome the remaining technical issues. Ultimately, he hopes to create a rollable, portable, and reliable power system that could be built into furniture and homes. "Our final goal is to implement the device as infrastructure," he says, "embedded [in walls and tables] from the beginning." Imagine, he says, moving a flat-screen television from wall to wall, without needing to worry about plugging it into an electrical outlet.