Piezoresistive polypropylene–carbon nanofiber composites as mechanical transducers

Abstract

This paper describes a strain sensor based on a polypropylene-carbon nanofiber (PP-CNF) composite film, fabricated by twin screw extrusion and compression molding, which is an inexpensive industrial polymer production technique. Its working principle is based on the piezoresistive effect showed by this kind of composites. Strain sensing by variation of the electrical resistance of the sensor was tested by a four-point bending method. Furthermore, the dependence of the gauge factor as a function of the deformation and velocity of deformation was calculated. The reproducibility of the electrical response of the material was also tested by applying up to forty loading-unloading cycles. The experimental results showed that PP-CNF films have an overall appropriate response for being used as piezoresistive deformation sensors, with a small non-linear response, typical of composites within the percolation threshold. Finally, electrical equivalent model of the sensor was developed and the experimental data was tested against it, showing good agreement.

Development of inkjet printed strain sensors

“…Furthermore, the sensors show a GF of ∼2.48 ± 2.6%, as calculated following equation ( 2) with a procedure similar to the one shown in figure 5(c). The values of the GF indicate the contribution of the intrinsic piezoelectric effect of the polymer layer over the geometrical factors [29].…”