High-repeatability macro-porous sponge piezoresistive pressure sensor with polydopamine/polypyrrole composite coating based on in situ polymerization method

High-stability piezoresistive sensors are an important part of smart wearable systems. In this study, an in situ polymerization method was used to polymerize a layer of polydopamine (PDA) and poly-pyrrole (PPy) on the surface of the macro-porous sponge (MPS). The deposition of PDA was done using para toluene sulfonic acid (p-TSA), the pH of the solution being used to control the thickness of the PDA, that followed by PPy coating. The thin layer of PDA effects to give better adherent in-between MPS surface and PPy coating. The morphology, chemical composition, and pressure-sensing properties of the fabricated PDA/PPy pressure sensors have been widely investigated. The experimental results show that the PDA/PPy-MPS pressure sensor with the concentration of p-TSA is 0.05 M with PDA coating shows better performance in the pressure range of 1–10 kPa. The pressure sensor performance of PDA (0.05 M p-TSA)/PPy-MPS near 1000 pressure cycles related to average sensitivity, hysteresis, and non-linear errors are 7.20 ± 2.46 kPa−1, 13.51 ± 0.03%, and 3.30 ± 0.59%, respectively. The repeatability error of up and down near conductive signals are reported as 2.70 ± 0.93% and 2.25 ± 0.63%. Its minimum resistance is reported as 9.94 Ω when the pressure increased up to 119 kPa. The developed applications of PDA/PPy-MPS show promising ability to use as a pressure sensor and switching element in smart wearable devices.