Electrospun Nanofibers for Optimized Fiber-Shaped Wearable Sensors ^†

This work discusses the design of highly stretchable, piezoresistive, flexible sensors obtained by electrospun nanofibers collected on rotating flexible wires. The resulting nanostructured sensors have a fiber-shape due to the inner plastic core being in intimate contact with the nanofibers forming the outer shell. The final fiber-shape thus facilitates the integration of the sensor into soft electronic platforms. Composite nanofibers, made of polyethylene oxide and multiwall carbon nanotubes, were selected as the sensitive material that is able to combine an effective response to mechanical deformation with compatibility in contact with the human body. Two flexible wire collectors were selected: a plastic wire and a plastic hollow wire. We demonstrate that the collectors induce a partially ordered distribution of NFs with good percolation behavior. Piezoresistive characterization confirmed the increase in the nanofibers’ electrical resistance with increasing applied pressure. The dimensionless sensitivity |∆R/R0| was calculated and plotted as a function of the applied pressure, demonstrating the good behavior of the new fiber-shaped pressure sensors.