Percolation network study of highly sensitive buckled elastomeric piezoresistive sensors

Abstract

Flexible pressure sensors are needed for future artificial electronic skin applications. Carbon black (CB)-enhanced elastomers are known for their unique conductivity, allowing for special uses in sensor technology. This research analyzes the sensitivity of elastomeric sensors reinforced with CB, under a pre-strained buckle, using a modified percolation network model to enhance performance in sensing applications. The finite element method is employed to analyze the piezoresistive characteristics of the sensors across various thicknesses. The research involves analyzing the strain patterns of buckled piezoresistive sensors when an indenter applies a load, and how this influences the sensors' resistivity. The mechanical parameter is directly correlated to the sensor sensitivity through the maximum principal strain. The model shows a good agreement with the experimental data. The pressure sensitivity resulting from indenter compressive contact is 0.03 and 0.006 1/kPa in the pressure range of 0-1 and 0-5 kPa for wavy and straight 1000 μm buckled sensors, respectively. The results show that the film with 50% taller waves has a 40-60 % narrower pressure sensing ranges. Moreover, results indicate that adding waves to the geometry of the sensor improves the piezoresistive behavior by increasing the relative displacements of edges. Results also reveal more stable performance from fewer waves and a higher working range by thicker sensors.