A new device can produce electricity using shadows
Someday, shadows and light could team up to provide power. A new device exploits the contrast between bright spots and shade to create a current that can power small electronics. “We can harvest energy anywhere on Earth, not just open spaces,” says Swee Ching Tan, a materials scientist at the National University of Singapore. Tan and his team created the device, called a shadow-effect energy generator, by placing a superthin coating of gold on silicon, a typical solar cell material. Like in a solar cell, light shining on silicon energizes its electrons. With the gold layer, the shadow-effect energy generator produces an electric current when part of the device lies in shadow. The excited electrons jump from the silicon to the gold. With part of the device shaded, the voltage of the illuminated metal increases relative to the dark area and electrons in the generator flow from high to low voltage. Sending them through an external circuit creates a current that can power a gadget, Tan’s...