Modeling Electrical Resistance Behavior of Soft and Flexible Piezoresistive Sensors Based on Carbon-Black/Silicone Elastomer Composites

Abstract

Soft and flexible strain piezoresistive sensors are gaining interest in wearable and robotic applications, but resistance relaxation limits the widespread use of the sensors. As soft, flexible, and stretchable sensors, they can easily be retrofitted into any existing robotic hand. To understand the resistance relaxation of stretchable sensors, three different elastomers were used to fabricate soft piezoresistive sensors. The experimental results showed that the sensor has good linearity and scalability while their resistance is strongly influenced by the stretching speed and modulus of the elastomer. Thus, the Kevin Voigt model was adopted to describe the sensor’s change of resistance during the stretching process. The model is sufficient to describe the change of resistance of the carbon black/elastomer filler when the sensors are stretched before the fracturing of the conductive filler. However, when the filler fractures, the model is invalid. The behavior indicates that the elongation of the sensor must not exceed the strain that causes the filler to fracture.