Polypyrrole-coated fiber-scaffolds: Concurrent linear actuation and sensing

Conducting polymers such as polypyrrole (PPy) can be deposited on various substrates to obtain conductive electroactive coatings. While electrochemical coatings are generally considered to be more effective, chemical coatings are more industrially suitable, especially on complex substrates. In this work, we aimed to explore the electro-chemo-mechanical response of conductive fiber scaffolds (CFS) prepared by coating PPy (chemically) on glucose-gelatin nanofibre scaffolds. Electroactivity was readily observed in both aqueous and propylene carbonate solutions of lithium bis(trifluoromethanesulfonyl)imide, with mainly anion activity in both cases. A higher actuation response was achieved in the aqueous solutions with strain in the range of 1.2% and stress in the range of 3 kPa. Under both cyclic voltammetry and square wave potential steps driving, stable actuation for over 100 cycles was maintained. In addition to actuation, the CFS samples exhibited concurrent sensory properties, in sensing current densities and mechanical load. The PPy-coated CFS material functioning as both an actuator and a sensor is envisaged to have potential applications in smart materials, soft robotics or e-skin. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48533.