Strain sensing using a multiwalled carbon nanotube film

Abstract

The effectiveness of multiwalled carbon nanotubes (MWCNTs) as strain sensors is investigated. The key contribution of this paper is the study of real-time strain response at the macroscale of MWCNT film under tensile load. In addition, real-time voltage change as a function of temperature is examined. MWCNT films attached to a brass specimen by epoxy using vacuum bonding have been studied. The brass specimen is subjected to tensile loading, and voltage output from the MWCNT film is obtained using a four-point probe and a sensitive voltage measurement device. Experimental results show that there is a linear change in voltage across the film when subjected to tension, and the MWCNT film both fully recovers its unstressed state upon unloading and exhibits stable electromechanical properties. The effect of temperature on the voltage output of the nanotube film under no load condition is investigated. From the results obtained it is evident that MWCNT films exhibit a stable and predictable voltage response as a function of temperature. An increase in temperature leads to an increase in conductivity of the nanotube film. The study of MWCNT film for real-time strain sensing at the macroscale is very promising, and the effect of temperature on MWCNT film (with no load) can be reliably predicted.

In situ strain monitoring of fiber-reinforced polymers using embedded piezoresistive nanocomposites

“…The increase in capacitance is justified by the fact that the value for capacitance is typically inversely related to the distance between conductive geometries. However, the increasingly negative gage factors for (MWNT-PSS/PVA) 29 and (MWNT-PSS/PVA) 50 do not extend to films of 100 and 150 bilayers. After the lowstrain region, these nanocomposites respond to strain with a positive strain sensitivity for R p and a near-zero strain sensitivity for C p , potentially due to the morphology of the thin film-fiber system of these thicker films.…”

“…In the low-strain region (0 to 10000 le), the gage factors tend to stay constant across this range and decrease in value as the number of bilayers increases (i.e., with increasing film thicknesses). It should be noted that the (MWNT-PSS/PVA) 50 films have a higher average strain sensitivity than the films with 29 bilayers. It Table 4 The average low-strain (i.e., 0 to 10000 le) bulk resistance strain sensitivity determined using the multi-linear fitting method for nanocomposite sample sets of 29, 50, 100, and 150 bilayers is presumed that films of smaller thicknesses are less homogeneous than those with higher thicknesses to cause this discrepancy.…”

“…In the case of numerous piezoresistive materials presently investigated for strain sensing and structural monitoring applications, most of them often demonstrate linear strain sensitivities with a few demonstrating a bilinear sensitivity in dynamic or monotonic load tests [33,34,42,[47][48][49][50][51][52][53][54]. In these studies, the researchers typically report the gage factor in these linear regions using a least-squares linear fit to identify the slope (thus the gage factor).…”

A Flexible Multifunctional Sensor Based on Carbon Nanotube/Polyurethane Composite

“…The copper has a GF of about 2.5, the metal sheet strain gauges have values of GF 2-5, GF of the pure MWCNT network (buckypaper) was experimentally determined as 0.34 [1], or 7 [2] at small strain about 0.1 % due to the weak van der Waals attraction between nanotubes. GF of stretchable composite consisting of multi-walled carbon nanotubes network/polyurethane (MWCNT/PU) stretched up to 400 % and GF was found to be nearly 69 at this strain [3].…”

Advances in Health Monitoring and Management

“…Figure 11 illustrates the linear response of a buckypaper film attached to a brass tensile sample. Vemuru et al [33] have improved the buckypaper strain sensor range (500 µε) by using Multi-Walled CNT (MWCNT). They have observed a sensitivity of 0.4 and a linear sensor response up to a strain of 1000 µε.…”