This second power-supplying sheet has an array of switches and copper coils. The switches, made of silver and plastic, turn the electric current on and off, mediating its flow to the adjacent copper coil.
When a laptop is placed on the combined sheets, its position is sensed, and current flows through a coil, enabling electromagnetic induction. The flow of the current creates a magnetic field. If a laptop with a power-harvesting coil comes close enough to the field, it will induce an electric current to flow through the laptop’s coil, wirelessly supplying power.
The researchers’ combining of a number of types of flexible electronics is notable, says John Rogers, professor of materials science at the University of Illinois. Rogers is a pioneer in the field of flexible and stretchable electronics. The new system “appears to represent a very interesting and new application of organic or flexible electronics,” he says.
The sheet of power is research that’s “well worth highlighting,” says Sigurd Wagner, professor of electrical engineering at Princeton. Someya is taking advantage of technology that allows electronics to be printed on a sheet with a large area, he says, and in a way that lets large amounts of power transmit to a selectively small area when needed.
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.