Alignment of Multiple Electrospun Piezoelectric Fiber Bundles Across Serrated Gaps at an Incline: A Method to Generate Textile Strain Sensors

In this paper, we report a new type of electrospinning collector that allows simultaneous collection and alignment of multiple poly(vinylidene fluoride-trifluoroethylene) piezoelectric fiber bundles with a controlled separation. The key enabling feature is the serrated teeth along the edges across an inclined gap as a part of the conductive collector. As a result, the electrical field across the gap is shaped to direct the electrospun fibers to merge into multiple bundles. The sharp points on the serrated teeth provide favorable charge dissipation points and thus fibers are preferentially formed bridging two closest sharp points across the gap. To investigate the effectiveness of serrated teeth on the formation of multiple fiber bundles, three-dimensional finite element simulations are conducted. The corresponding collectors are implemented to experimentally study the resulting electrospun fibers. Both simulation and experimental results suggest that multiple fiber bundles can be formed under the condition of a low teeth pitch to gap distance ratio. Furthermore, a sharper tooth angle results in a higher preferential formation of fiber bundles. Finally, the total electrospinning time should be less than 60 seconds to maintain favorable electric field profile. We also demonstrate that these piezoelectric fiber bundles can serve as ultra-flexible textile sensors.