Human physiological motion detection by a blend of polyaniline-polyvinyl alcohol semi-conductive ink deposited on flexible cellulose substrate

Polyaniline-polyvinyl alcohol (PANI-PVA) semiconducting ink systems have been developed and reported in this article. First, polyaniline in its emeraldine salt form was synthesized by the in-situ polymerization method and then the polyaniline (PANI) powder was mixed with polyvinyl alcohol (PVA) until the formation of a viscous homogenous solution. Both the prepared ink systems were found to be crystalline as well as microporous as revealed by X-ray diffraction measurements and SEM micrographs respectively. The XRD reveals an extremely intense peak at 2θ= 22.5° is caused by reflections from the (020) Miller plane of PANI. UV–vis–NIR spectroscopy measurements reveal their energy bands at 315 and 610 nm. This work reports on the resistive response of the PANI-PVA semiconducting ink systems deposited on flexible cellulose substrate under various stresses and strains developed in the human body due to its movement. The changing stress and strain field affects the polaron hopping barrier and as a result, the effective conductivity of the inks is adjusted. The stress and strain field developed due to various physiological movements is thus accountable for the observed variation in electrical properties. The experimental findings demonstrate that the proposed flexible, high-endurance polymeric systems can be a promising candidate for wearable electronics and real-time monitoring of human physiological motions. A relative pressure sensitivity of 3.16 × 10⁻³ Torr⁻¹ has been obtained for PANI-PVA ink in the pressure range of 750–970.05 Torr. Under a 750–823.50 Torr pressure range, PANI ink showed response and recovery times of 0.321 and 0.132 seconds, respectively, compared to 0.278 and 0.252 seconds for the PANI-PVA ink system.