Enhancing wearable humidity sensing with conductive PANi-Coated polyurethane nanofibers

Abstract

This study presents a flexible nanofibrous humidity sensor for wearable applications and smart textiles. The methodology involved fabricating polyurethane (PU) nanofibers via electrospinning, followed by polyaniline (PANi) coating under varied synthesis conditions. Scanning electron microscopy (SEM) analysis revealed consistent diameter uniformity in the prepared PU nanofibers. Moreover, an increase in average nanofiber diameter (305 to 539 nm) was observed with rising polymer solution concentration (7% to 9%). Fourier-transform infrared spectroscopy (FT-IR) confirmed the physical presence of PANi on PU nanofiber surfaces without inducing structural changes. Additionally, the strength of PU nanofibrous samples, with or without PANi coating, increased proportionally with higher PANi and PU polymer concentrations. Electrical conductivity was measured using a four-point device, and surface resistance was assessed across varying humidity levels to study humidity’s impact on samples. Results exhibited a linear relationship between surface electrical resistance and relative humidity changes. Furthermore, the PU and PU/PANi nanofibers exhibit contact angles of 113° and 133°, respectively. The PANi-coated sample is more hydrophobic compared to the uncoated sample. In conclusion, these findings underscore the potential of the developed sensor as a responsive tool for monitoring humidity fluctuations in diverse applications.