Implementation of polyaniline in biocompatible supports for sensing and energy storage

Conductive polymers represent an affordable and reliable answer to the stiffness of conventional electronics. Polyaniline (PANI) in particular shows a peculiar doping/dedoping process, with high conductivity and exceptional tuneability. On the other hand, this material is fragile and not flexible. Different supports can enhance the mechanical properties of PANI, donating resilience, tenacity, and flexibility. This contribution would like to study the composite material based on PANI and paper or hydrogel and to report the fabrication of two different biocompatible devices, respectively a paper-like sensor for humidity1 and an all-in-one supercapacitor (SC)2. PANI was polymerized with poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) for a more mechanically stable structure. With the addition of PAMPSA, the emeraldine state of PANI is achieved, providing enhanced conductivity. For the fabrication of conductive paper, the polymerization was conducted in situ on cellulose fibres, which were then dried and consequently pressed. Humidity sensors were fabricated by cutting the obtained sheets in rectangles. Due to humidity (RH%), cellulose/PANI-PAMPSA conductivity increases and the considered analytical signal is the measured current flow through the material by applying a constant voltage. Another interesting application is in the medical field, as a breath or ECG sensor. We then investigated the insertion of PANI-PAMPSA in polyvinyl alcohol (PVA) hydrogel systems. PVA powder was dissolved in PANI-PAMPSA solution, inducing a physical crosslinking through freeze-thaw cycles and providing a self-healing ability to the SC. Since PANI-based hydrogel partially functions as an electrode, the need of an electrolyte is covered by PVA-H2SO4 hydrogel, with a high adhesion between the layers. The resulting structure composes the all-in-one supercapacitor. References: [1] Ragazzini, I.; Gualandi, I.; D’Altri, G.; Di Matteo, V.; Yeasmin, L.; Cassani, M. C.; Scavetta, E.; Bernardi, E.; Ballarin, B., Carbohydr Polym 2023, 316, 121079. [2] D’Altri, G.; Yeasmin, L.; Di Matteo, V.; Scurti, S.; Giovagnoli, A.; Di Filippo, M. F.; Gualandi, I.; Cassani, M. C.; Caretti, D.; Panzavolta, S.; Scavetta, E.; Rea, M.; Ballarin, B., ACS Omega 2024, 6391-6402.