Investigation of electromechanical properties of as-electrospun polystyrene fiber mat via sequential approaching/loading technique

Abstract

Electromechanically active submicron/micron polymer fibers are promising building blocks for biological/soft-robotic motion sensors and pressure sensors. In particular, mats of the fibers produced by electrospinning demonstrated distinct direct/converse electromechanical properties compared to those of films. Although several studies have demonstrated the direct electromechanical characteristics of the electromechanically active electrospun fiber mats, detailed investigation of the characteristics when the testing probe starts to contact the fiber mats, in addition to the effect on the preloading value, have not been reported. In this study, a sequential approaching/loading electromechanical testing technique has been proposed for a detailed investigation of the electromechanical properties of the fiber mats, in particular, near the contact between the testing electrode and the fiber mats. The results demonstrate that the preload and load values significantly affect the measured values of the apparent piezoelectric d constant (dapp). Therefore, careful determination of the applied preload and load values was a prerequisite for measuring the dapp of the very soft fiber mats. The present technique also demonstrates that the measured value of the capacitance of the fiber mat is significantly affected by the value of the applied load; therefore, a careful determination of the loading value is indispensable for measuring the capacitance of the fiber mats. The proposed technique can pave the way for a deep understanding of the direct electromechanical characteristics of a variety of significantly soft submicron/micron fiber mats and can aid the exploration of strategies to develop advanced biological/soft-robotic motion sensors and pressure sensors employing these mats.