The shadow-effect energy generator (SEG), developed in Singapore, makes use of the contrast in illumination between lit and shadowed areas to generate electricity. The low-cost flexible device, which powered a watch in experiments, even gives an advantage over commercially available solar cells by operating in dark areas.A wearable SEG could make use of ambient light to potentially improve the versatility of devices such as smartphones and smartwatches.A team from the NUS Department of Materials Science and Engineering as well as NUS Department of Physics created a device called a shadow effect energy generator (SEG), which makes use of the contrast in illumination between lit and shadowed areas to generate electricity. Their research breakthrough was reported in scientific journal Energy & Environmental Science on 15 April 2020. “Shadows are omnipresent, and we often take them for granted. In conventional photovoltaic or optoelectronic applications where a steady source of light is used to power devices, the presence of shadows is undesirable, since it degrades the performance of devices. In this work, we capitalized on the illumination contrast caused by shadows as an indirect source of power. The contrast in illumination induces a voltage difference between the shadow and illuminated sections, resulting in an electric current. This novel concept of harvesting energy in the presence of shadows is unprecedented,” explained research team leader Assistant Professor Tan Swee Ching, who is from NUS Materials Science and Engineering.Along with being able to power small gadgets under less-than-optimal lighting, SEGs could also serve as motion sensors – when a moving object casts a shadow across one of the devices, it causes a detectable electrical current to be generated. The scientists are now looking into replacing the gold with a cheaper material, in order to further reduce the cost of the technology.