Piezoresistive anisotropy in conductive silicon rubber/multi-walled carbon nanotube/nickel particle composites via alignment of nickel particles

Conventional piezoresistive sensors of flexible conductive polymer composites (FCPC) are mostly isotropic because of the weak controllable fabrication strategies. In this study, a facile strategy was introduced to fabricate the polydimethylsiloxane (PDMS)/multi-walled carbon nanotubes (CNT)/aligned nickel particles (Ni) composites under a low magnetic field. The PDMS pre-polymer firstly mixed with CNT and Ni particles with ultrasonic and solvent assistant, and then cured under a magnetic field with a magnetic flux density of 75 mT to form the composites. Because of the alignment of Ni particles, the PDMS/CNT/align-Ni composites exhibited obviously electrical, mechanical and piezoresistive anisotropy. Specifically, the compression modulus of the composites with 0.23 vol% CNTs and 3.93 vol% Ni particles was ~4.93 and ~3.66 MPa at the direction parallel to (X direction) and vertical to the alignment direction of Ni particles (Y direction), respectively. The anisotropic index of the electrical conductivity could reach 2.6 x 10(5) in the PDMS/CNT/aligned-Ni composites containing 0.23 vol % CNT and 3.37 vol% Ni particles. Furthermore, the PDMS/CNT/aligned-Ni composites showed a negative piezoresistive effect at X direction and a positive piezoresistive effect at Y direction.

Automated summary

A facile strategy was introduced to fabricate PDMS/CNT/aligned-Ni composites under a low magnetic field, resulting in significant electrical, mechanical, and piezoresistive anisotropy.