Performance of water-based printed hybrid graphene/silver nanoparticle conductive inks for flexible strain sensor applications

Abstract

Flexible electronic devices such as wearable strain sensors have drawn much interest in health monitoring systems. In the present study, hybrid ink-printed flexible strain sensors made of graphene and silver nanoparticles (AgNPs) were formulated. The main aim of the study is to investigate the effect of hybrid graphene and AgNP ratios on the properties of conductive inks and their performance as flexible strain sensors. The new conductive inks were printed on various types of flexible substrates: polyethylene terephthalate (PET), polyimide (PI), and polyvinyl alcohol (PVA). The performance of conductive ink on these substrates was evaluated. The results showed that the ratio of graphene/AgNPs influenced the properties of conductive inks. Graphene/AgNPs with a 0.3/0.2 wt% exhibit higher stability, wettability, and electrical conductivity than 0.4/0.1, 0.2/0.3, and 0.1/0.4 wt%. Hybrid graphene/AgNPs conductive ink printed on PI substrate showed better wettability and electrical performance compared to those on PET and PVA substrates. The gauge factors (GF) of the PI substrate are higher, 6.2% and 32%, compared to PET and PVA, respectively, at the 30% strain range. In short, the hybrid graphene/AgNPs strain sensor on PI that showed good linearity, sensitivity, and stability has a high potential to be used in low-strain health monitoring systems.