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This paper reports a flexible optical pressure sensor based on a porous structured elastomer and its application to a wearable human motion detecting device, which is operated in a self-power-generating way by integrating with an organic photovoltaic cell. Complete investigation of material characteristics and sensing performances as well as optical simulation for understanding the sensing mechanism have been produced. Finally, a self-power-generating wearable motion sensing device was demonstrated as a sensor for detection of flexion and extension motion of a human finger.

This paper reports a novel flexible optical pressure sensor based on a porous elastomer film as a light transmission medium with ultra-high sensitivity and simplicity. The pore-closing behavior under external pressure and corresponding change of light transmittance of porous elastomer film were investigated. The porous elastomer film based optical pressure sensor showed highly sensitive and stable performance with the sensitivity of 2.177 kPa−1 over the pressure range of 0–10 kPa. Finally, the optical pressure sensor was integrated with thin film solar cell to modulate the generated electrical current towards self-powered sensing platform.

We have developed a self-powered gas sensor operating without external power under a light source, unlike a sensor that requires an external power source, such as a chemiresistive gas sensor or an electrochemical gas sensor. The sensor consists of a colorimetric film and an organic solar cell. The sensor uses a color change caused by the reaction of the N, N,N',N'-tetramethyl-p-phenylenediamine (TMPD) with NO 2 gas. The color change caused by the redox reaction of the colorimetric material does not require a separate light source and photodetector, unlike the conventional colorimetric sensor, because it directly changes the output of the solar cell by changing the transmittance of the film. Using this sensor, 1, 5, 10, 20ppm NO 2 gas was detected without external power source, and the performance of the gas sensor could be improved by using microstructure. This work is the first demonstration of self-powered gas sensor based on the combination of photovoltaic cell and microstructured colorimetric film.