It Comes at the Right Time
Smartphones, e-watches, and other mobile electronic devices all need a continuous and efficient power supply. Since these are devices people use both indoors and outdoors, the need for wearable power sources becomes apparent. Sure, solar cells are doing a fantastic job outdoors, but because of shadow persistence, their efficiency drops significantly under indoor conditions. This new discovery is both incredibly exciting and very timely.
Generating Electricity Through the ‘Shadow-Effect’
The team at NUS from the Department of Physics and the Department of Materials Science and Engineering developed a device called SEG (shadow-effect energy generator). The device uses the contrast in illumination between shadowed and lit areas to generate electricity. A series of laboratory experiments conducted under conditions of shifting shadows, proved that the four-cell SEG is actually twice as efficient as commercial silicon solar cells. The SEG can also serve a second purpose. It can be a self-powered sensor for tracking moving objects as they cast an intermittent shadow on the SEG whenever they pass by it. This, in turn, triggers the device’s sensor to record the presence of moving objects.
How the Gadget Works
The device is made up of a set of SEG cells placed on a transparent and flexible plastic film. Each SEG cell represents a silicon wafer with a thin film of gold on top of it. Compared to commercial silicon solar cells, the SEG can actually be fabricated at a much lower cost. According to its creators at NUS, the optimum efficiency of the SEG comes when half of it is illuminated, and the other half of the cell is in shadow.