Novel Hybrid Pressure Sensor Based on Electrospun Spandex-Polyvinylidene Fluoride Composite Nanofiber Webs

In this study, the mixture solution of Spandex and polyvinylidene fluoride (PVDF) was electrospun under controlled compositions to obtain Spandex-PVDF hybrid nanofiber webs. Their physico-mechanical and piezo-responsive behaviors were investigated. When the dynamically changing force was applied to this hybrid sensor, dynamic pressure could be measured through the electric current generated by the orientational change of C-F dipoles in the PVDF part of the composite nanoweb as a function of time. When the static force was applied to this hybrid sensor, static pressure could be measured through the increasing capacitance value caused by the decreasing thickness of the composite nanoweb rather than the piezoelectric current. The piezoelectric and piezocapacitive properties of this hybrid sensor could be measured simultaneously using a piezoelectric amplifier and an LCR meter, respectively. Overall, 25–50 wt.% addition of PVDF in Spandex greatly enhanced the piezoelectric output signal as well as reduced pressure-capacitance hysteresis and higher capacitance change with the applied pressure due to the rubbery Spandex of this hybrid sensor. Moreover, AgNO3, which acts as a precursor of silver nano-particle (AgNP) formed in the electrospun PVDF nanoweb, was added into the PVDF/Spandex electrospun solution to get enhanced piezoelectric performance of the hybrid sensor caused by the preferential formation of β-phase of PVDF. The results are reported in detail.