Effect of aligning conductive particles on the piezoresistivity of composites

Purpose - The purpose of this paper is to study the effect of alignment of conductive particles on the piezoresistivity of composite based on a theoretical model. The piezoresistivity of composite is associated with the characteristics of conductive network formed by the conductive particles distributed in the composite, which can be changed through aligning the conductive particles. Design/methodology/approach - The orientations of the tunnel resistors formed by each two adjacent conductive particles are dependent on the aligned level of the conductive particles, and different orientations induce different deformations for a tunnel resistor under external strain, which determines the piezoresistivity of the composites. To investigate the resistance behavior of composites with various characteristics of conductive networks, a piezoresistivity model is developed in this paper by considering the aligned level of conductive particles. Findings - The results obtained from the proposed piezoresistivity model indicate that the sensitivity and stability of composites can be enhanced through aligning the conductive particles. Also, the piezoresistivity of composites filled with randomly distributed conductive particles is isotropic, and it turns to be anisotropic when the conductive particles are aligned. Originality/value - The change and its mechanism of the piezoresistivity upon the aligned level of conductive particles have been pointed out in this paper based on the proposed model. The achievement of this paper will help the people understand, predict and optimize the piezoresistivity of composites, and provide a new approach to design a strain sensor based on the piezoresistivity.