A carbon nanotube strain sensor for structural health monitoring

TLDR

Carbon nanotube polymer sensors improve interfacial bonding and avoid distortion from van der Waals slipping seen in earlier buckypaper sensors. The authors aim to use the derived electrical model to design nanotube sensor systems. They fabricated a piezoresistive sensor from multi‑walled CNTs embedded in polymer and modeled its response with electrochemical impedance spectroscopy and strain tests to enhance strain transfer, repeatability, and linearity. Extending the sensor length produced a low‑cost, lightweight, continuous strain sensor—an artificial neuron—that offers adequate sensitivity, low bandwidth, and can detect large strains and cracking while reducing data‑acquisition channels.

Abstract

A carbon nanotube polymer material was used to form a piezoresistive strain sensor for structural health monitoring applications. The polymer improves the interfacial bonding between the nanotubes. Previous single walled carbon nanotube buckypaper sensors produced distorted strain measurements because the van der Waals attraction force allowed axial slipping of the smooth surfaces of the nanotubes. The polymer sensor uses larger multi-walled carbon nanotubes which improve the strain transfer, repeatability and linearity of the sensor. An electrical model of the nanotube strain sensor was derived based on electrochemical impedance spectroscopy and strain testing. The model is useful for designing nanotube sensor systems. A biomimetic artificial neuron was developed by extending the length of the sensor. The neuron is a long continuous strain sensor that has a low cost, is simple to install and is lightweight. The neuron has a low bandwidth and adequate strain sensitivity. The neuron sensor is particularly useful for detecting large strains and cracking, and can reduce the number of channels of data acquisition needed for the health monitoring of large structures.