Investigation of carbon black/silicone elastomer/dimethylsilicone oil composites for flexible strain sensors

Conductive carbon black (CB) nano-particle filled silicone elastomer (SE) composites with dimethyl silicone oil (SO) as a diluting agent and plasticizer were fabricated for potential strain sensing applications. Heat treatment was used to stabilize the composites, and thermal gravimetric analysis confirmed the good stability of the composites after heat treatment. Effect of CB loading on electrical properties of the composites was studied and a percolation transition range of 0.5-2.5 wt% was observed. I-V characteristics and impedance analysis were used to reveal the conductive mechanisms of the composites. The presence of SO reduced the Young's modulus of the composites without lowering the elongation at break. Characterization of coupled electromechanical properties of the composites demonstrates that, in the post-percolation range, the 9.0CB composite possesses suitable strain sensitivity, good repeatability and linearity as well as slight strain rate dependence, so that it can be used in flexible strain sensors for measuring repeated large deformations.