Highly hydrostable and flexible wearable sensors based on graphitic nanoreinforced PVDF-HFP for biomedical applications

Abstract

The development of highly hydrostable wearable sensors is critical for applications in medical and sports, where the sensing performance could be affected by varying environmental conditions. This study examines the design, characterization, and performance of piezoresistive strain sensors fabricated using Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) reinforced with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) after aging. These sensors were subjected to immersion tests (from 15 min to 2 months in deionized water) to simulate harsh humidity conditions, allowing for the evaluation of their water uptake, electrical conductivity, and electromechanical properties over time. The results demonstrate that GNP-based nanocomposites exhibit superior hydrostability due to their enhanced barrier properties and uniform nanoparticle dispersion, while CNT-based sensors show consistent electromechanical performance with moderate sensitivity variations. Applicability was confirmed for real-time healthcare applications, even after prolonged aging, through wrist tendon and respiratory real-time monitoring tests. The findings emphasize the potential of doped PVDF-HFP composites in advancing wearable technology for healthcare.