Polyelectrolyte-graphite grafted polymer composite sensors with high voltage sensitivity and output current density

Poly (vinylidene fluoride) (PVDF)–based composites are highly desirable for diverse applications, including wearable devices, energy harvesting, smart skin robotics, and health monitoring devices. However, enhancing the voltage sensitivity and output current density of PVDF-based composites remains critical for their practical use in energy harvesting and wearable device applications. To enhance the voltage sensitivity and output current density, polystyrene sulfonic acid (PSSA) ionic filler, and graphite (Gr) electronic filler are incorporated into a PVDF matrix, leading to the development of a polar (β)–phase-based polymer composite sensor (PCS). The PVDF/PSSA/Gr-based PCS with an optimized blend ratio of 80/05/15 exhibits a high sensitivity of 0.6 V/N, which is nearly 105 times higher than that of the pure PVDF sensor. Due to the high ionic-electronic conduction in PCS, the 80/05/15-based PCS generates an enhanced output current density of 0.02 A/cm² with a tapping force of 7.8 N at frequency of 0.1 Hz, which is 1.5 × 10⁶ times higher than that of the pure PVDF sensor. After being worn on the finger, the PCS successfully detects finger bending and generates an output voltage of up to 5 V. The study demonstrates the potential of PVDF/PSSA/Gr composite–based sensors for wearable sensing and energy harvesting applications.