A wearable mask sensor based on polyaniline/CNT nanocomposites for monitoring ammonia gas and human breathing

Flexible gas sensors have been widely used in environmental and human health monitoring due to their flexibility and compatibility with electronic device substrates. Herein, we prepared a porous polypropylene/carbon nanotube/polyaniline (p-PP/CNT/PANI) nanocomposite gas sensor using disposable surgical masks as a flexible substrate. The CNT aqueous solution with a surfactant was drop-coated on the porous polypropylene fibers (p-PP) of the mask, followed by in-situ polymerization of aniline on the p-PP/CNT composite. The fabricated flexible p-PP/CNT/PANI gas sensor exhibited fast response (93 s) and recovery times (36 s), low detection limit (500 ppb), high response value (452% towards 70 ppm NH3), and good stability at room temperature. The excellent sensing performance was mainly attributed to the p-PP/CNT/PANI network with a higher specific surface area and their conductive channels. Moreover, the composite sensor in a disposal mask can detect breathing patterns in real-time for potential noninvasive monitoring of respiratory rate.