Studying the creep behaviour of strechable capacitive sensor with barium titanate silicone elastomer composite

In this paper, the creep behaviour of stretchable interdigital capacitive (IDC) large strain sensors is studied. A generalized Kelvin-Voigt (GKV) model is used to study the creep behaviour of the sensor's substrate material, manufactured from silicone elastomer (Ecoflex 00−30) with barium titanate (BTO) filler. Creep experiments are performed on sensors with 10, 20, 30 and 40 wt% BTO nanoparticles with dimensions of 100 nm and 200 nm dispersed in the elastomer. The BTO was used to increase the overall permittivity of the substrate, hence raising the capacitance of the IDC sensor. The effect of BTO on the GKV model parameters was studied in detail through analysis of the creep response. The pristine Ecoflex silicone elastomer is predominately a hyperelastic material, which shows negligible creep, while the addition of BTO particles led to the composite exhibiting creep such that the composite behaves like a visco-hyperelastic material. Hence, this behaviour results in the creep affecting the electrical sensing performance of the capacitive strain sensors during static loading conditions. This information provides insights on the impact of composite composition on creep-resistance and output signal of the sensor (capacitance).