Bi 2 S 3 /PVDF/Ppy-Based Freestanding, Wearable, Transient Nanomembrane for Ultrasensitive Pressure, Strain, and Temperature Sensing.

Flexible nanofiber-based composites have been widely explored because of their light weight, high surface area, scalability, and tunable physical and mechanical properties. In this work, we report electrospun 2D-Bi ₂ S ₃ incorporated PVDF/PPy nanofibers as a versatile platform for ultrasensitive pressure, strain, and temperature sensing. Detailed characterization studies revealed the formation of ultrathin nanofibers and characteristic Raman and IR vibration modes of PPy, 2D-Bi ₂ S ₃ , β-phased PVDF. The fabricated pressure sensor exhibited a sensitivity of 1.51 kPa ^-1 in the wide linear range of 1-50 kPa and a response time of 0.04 s. The practical ability of pressure sensor was tested by successfully detecting pulse rate of human radial arteries. Further, the BS- PVDF/PPy composite was employed as a strain sensor in the range of 3.1-61.5%, displayed a gauge factor (GF) of 45.45 and a response time of 0.1 s. The wearable sensor was capable of detecting minute changes in hand gestures by recognizing the microstrains applied to the device. The sensing mechanism can be attributed to the excellent piezoelectric property of β- phase PVDF, electron transport property of PPy nanoparticles and tensile strength of the BS nanoparticles embedded in the polymer matrix. When used as a wearable temperature sensor, the versatile device demonstrated a linear range of detection 24- 48 °C with a response time of 0.33 s and Temperature coefficient of resistance (TCR) of -0.1117 °C ^-1 that can be attributed to the phonon-assisted hoping mechanism. The nanofiber composite dissolved in volatile organic solvent acetone in 5 days with the least impact on the surrounding environment thus making this a promising strategy to develop transient technologies aimed at zero-waste, green electronics.