Polypyrrole coated nonwoven fabric as a piezoresistive sensing material: a multifunctional study on physicochemical, electromechanical, and biological assessment.

Textile-based pressure sensors for wearable applications require simple fabrication methods, long-term durability, and biocompatibility for skin contact, yet existing sensors often lack comprehensive validation. This study fabricates piezoresistive pressure sensors by depositing polypyrrole (PPy) on polypropylene nonwoven fabric via in situ chemical polymerization. This work combines simple fabrication with comprehensive electromechanical and biological validation. Material characterization using XRD, FTIR, Raman, SEM/EDX, and AFM confirmed uniform PPy coatings. The sensors show piezoresistive response across 0.6-6.1 kPa, with quasi-linear voltage increase and exponential resistance decrease under pressure. Voltage response followed a linear fit (sensitivity 0.47 V/kPa, R 2 = 0.993), while resistance response followed an exponential decay fit (R 2 = 0.998). Performance testing revealed 1000-cycle durability, one-hour stability (voltage drift -1.64%), temperature-dependent resistance response evaluated over an extended 30 °C-100 °C range for material-level characterization (NTC coefficient -0.941%/°C), and functionality retention over 7 washing cycles. Hysteresis measured 8.68% of full-scale output. Biocompatibility testing (ISO 10993-5) showed cell viability maintained above 70% at all concentrations up to 100 μg/mL, and antibacterial testing (AATCC 147) showed zones of 37-40 mm against E. coli and 38-42 mm against S. aureus. Overall, these laboratory-scale results indicate that PPy-coated nonwoven fabric is a promising material for durable, biocompatible pressure sensors.