Carbon-Based Nanomaterials Thin Film Deposited on a Flexible Substrate for Strain Sensing Application

Abstract

Hybrid nanomaterial film consisting of multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelet (GNP) were deposited on a highly flexible polyimide (PI) substrate using spray gun. The hybridization between 2-D GNP and 1-D MWCNT reduces stacking among the nanomaterials and produces a thin film with a porous structure. Carbon-based nanomaterials of MWCNT and GNP with high electrical conductivity can be employed to detect the deformation and damage for structural health monitoring. The strain sensing capability of carbon-based hybrid nanomaterial film was evaluated by its piezoresistive behavior, which correlates the change of electrical resistance with the applied strain through a tensile test. The effects of weight ratio between MWCNT and GNP and the total amount of hybrid nanomaterials on the strain sensitivity of the nanomaterial thin film were investigated. Experimental results showed that both the electrical conductivity and strain sensitivity of the hybrid nanomaterial film increased with the increase of the GNP contents. The gauge factor used to characterize the strain sensitivity of the nanomaterial film increased from 7.75 to 24 as the GNP weight ratio increased from 0 wt.% to 100 wt.%. In this work, a simple, low cost, and easy to implement deposition process was proposed to prepare a highly flexible nanomaterial film. A high strain sensitivity with gauge factor of 24 was achieved for the nanomaterial thin film.

Welded Carbon Nanotube–Graphene Hybrids with Tunable Strain Sensing Behavior for Wide-Range Bio-Signal Monitoring

“…Therefore, we used the average GF, which is calculated by dividing the relative resistance change (∆R/R 0 ) by the applied strain (ε), to describe the sensitivity of the strain sensors [43,44]. The average GF of the CNT:GO = 1:3, 1:15 and 1:45 hybrid for 5% strain is 1399, 29.16 and 20.34, respectively (Figure 3c), which is comparable to the state-of-the-art carbon-nanomaterials-based strain sensors [45][46][47]. On the other hand, the strain-sensing performance of the hybrids with CNT:GO = 1:15 before annealing, after 500 • C annealing, and after 1000 • C annealing were also compared (Figure 3d), with the electrical response to strain increasing with annealing temperature.…”