University of Tokyo and RIKEN in Japan have developed a sensory device which works on solar power or artificial bright light. They were then able to measure the heartbeats of rats and humans under bright light conditions. Now, to overcome the challenge of measuring heartrate or brain function poses a challenge of battery which needs constant charging as well as intrusive and bulky. To overcome, a chargeable sensory device as watch can be used a nano-grating surface on the light absorbers of the solar cell, allowing for high photo-conversion efficiency (PCE) and light angle independency.
To make thing further easier, the is also a digital silicon-based portion which will facilitate data transfer.