Graphene Nanoplatelets–PVDF Stretchable Sensors for Tactile Interaction: From Grasp Detection to Morse Code Communication

Abstract

Conductive flexible pressure sensors based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) doped with graphene nanoplatelets (GNPs) were fabricated via solvent casting, targeting tactile sensing applications. The electrical behavior of the sensors was assessed via direct current (DC) and alternating current (AC) analysis, identifying the percolation threshold at 2.78 wt.%, with a 2D network, and outstanding stability with frequency. Pressure response was evaluated across microscale and macroscales using a microdurometer and calibrated weights. Notably, higher sensitivity was observed at the macroscale, attributed to greater network alteration, reaching a maximum sensitivity of 3.14 ± 0.15 kPa−1 at 6 wt.% GNP. This optimal formulation was further explored through proof-of-concept tactile demonstrations, including Morse code communication and grasp detection tasks. These tests revealed a strong correlation between electrical output and mechanical stimuli, underscoring the sensor's high sensitivity, responsiveness, and potential for integration into wearable human–machine interface systems.