The wearable sensor was jointly developed by a team at RIKEN and the University of Tokyo. A periodic nano-grating structure was achieved on an ultra-thin substrate with a thickness of 1 μm, a height of several tens of nm and a period of about 700 nm. This periodic nanograting structure adjusts the refractive index of light to reduce the reflection of light on the surface of the solar cell and at the same time enhances the light scattering inside the thin film and the surface plasmon resonance effect at the metal electrode. By integrating this ultra-thin type organic solar cell with an ultra-thin sensor of a skin pasting type utilizing an organic electrochemical transistor, a skin-pasted ECG measurement device was realized. When this was affixed to the skin of a human body, the electrocardiography measuring device was driven without external power supply, and signals were acquired with high precision at a signal-to-noise ratio of 25.9 decibels (dB).

RIKEN news release, September 27, 2018