A Comparative Study between Knocked-Down Aligned Carbon Nanotubes and Buckypaper-Based Strain Sensors (original) (raw)

Aligned carbon nanotube based sensors for strain sensing applications

Sensors and Actuators A: Physical, 2019

This paper presents an aligned carbon nanotube (CNT)-based strain sensor. Vertical aligned carbon nanotubes (VA-CNT), synthesized by chemical vapour deposition (CVD), were knocked down onto polymeric films, in order to obtain a thin 10 × 10 × 0.05 mm CNT patch. Different polymeric substrates, ADEXepoxy, polyethylene terephthalate (PET) and polyimide (PI) were used. The samples' morphology before and after the knock down process, specifically their alignment, was observed by scanning electron microscopy (SEM). The good quality of the synthesized VA-CNT was assessed by Raman spectroscopy. Furthermore, transmission electron microscopy (TEM) analysis was carried out to determine the average wall number and diameters (inner and outer) of the VA-CNT. A MATLAB software with an adapted Van der Pauw method for anisotropic conductors was developed to determine the electric properties of the obtained samples, which were strained in the transverse (X) and parallel (Y) directions with respect to the CNT alignment. The electric anisotropy, defined as electric resistance ratio between obtained measurements along the X (R xx) and Y (R yy)-axes, decreases with deformation increment when the sample was strained in the Y-direction, while it increases when strained in the X-direction. Moreover, the obtained Gauge factor values showed a much sensitive response to deformation, i.e., approximately 47% increase in GF values, when the samples are strained transversely to CNT alignment. These results showed that the piezoresistive CNT/polymeric based sensor produced is suitable for strain sensing applications.

An investigative study on application of carbon nanotubes for strain sensing

Nanosystems: Physics, Chemistry, Mathematics, 2016

Traditional strain sensors, such as metal foil gauges, can measure the strains only on the structural surface in designated directions and locations. Hence, there is a need to develop new types of strain sensors which can function on both the micro-and macro-scale, either on the surface or embedded in the structure, and able to behave as multifunctional materials. Owing to its outstanding electrical and mechanical properties carbon nanotubes (CNTs) can be used as strain sensing material. A film (Bucky paper/CNT network) made from multiwalled carbon nanotubes by use of solvent/surfactant and vacuum filtration method is used as strain sensor. The paper discusses the experimental work involving preparation of CNT film sensor specimen, its application on aluminum and brass strips along with conventional foil gauge and subjecting the metal strips to axial loading to measure gauge factor. It was found that CNT film strain sensor shows linear relationship between change in resistance and strain. Furthermore, the gauge factor increases as the film aspect ratio increases, and for the same aspect ratio, a higher gauge factor was observed for brass than aluminum.

Flexible Carbon Nanotube Films for High Performance Strain Sensors

Sensors, 2014

Compared with traditional conductive fillers, carbon nanotubes (CNTs) have unique advantages, i.e., excellent mechanical properties, high electrical conductivity and thermal stability. Nanocomposites as piezoresistive films provide an interesting approach for the realization of large area strain sensors with high sensitivity and low manufacturing costs. A polymer-based nanocomposite with carbon nanomaterials as conductive filler can be deposited on a flexible substrate of choice and this leads to mechanically flexible layers. Such sensors allow the strain measurement for both integral measurement on a certain surface and local measurement at a certain position depending on the sensor geometry. Strain sensors based on carbon nanostructures can overcome several limitations of conventional strain sensors, e.g., sensitivity, adjustable measurement range and integral measurement on big surfaces. The novel technology allows realizing strain sensors which can be easily integrated even as buried layers in material systems. In this review paper, we discuss the dependence of strain sensitivity on different experimental parameters such as composition of the carbon nanomaterial/polymer layer, type of polymer, fabrication process and processing parameters. The insights about the relationship between film

Nanotube film based on single-wall carbon nanotubes for strain sensing

2004

Abstract Carbon nanotubes change their electronic properties when subjected to strains. In this study, the strain sensing characteristic of carbon nanotubes is used to develop a carbon nanotube film sensor that can be used for strain sensing on the macro scale. The carbon nanotube film is isotropic due to randomly oriented bundles of single-wall carbon nanotubes (SWCNTs). Using experimental results it is shown that there is a nearly linear change in voltage across the film when it is subjected to tensile and compressive stresses.

Directional Response of Randomly Dispersed Carbon Nanotube Strain Sensors

Sensors, 2020

Tests on a double lap bonded joint, with transverse strips of randomly oriented carbon nanotubes (CNT) sprayed onto an epoxy adhesive film, showed a positive increment in electrical resistance under tensile load, even though the transverse strains were negative. Other experiments included in this work involved placing longitudinal and transversal CNT sensors in a tensile loaded aluminum plate, and, as reported by other authors, the results confirm that the resistance change is not only dependent on the strains oriented with the electrode line, while the other strain components also influence the response. This behavior is quite different to that of conventional strain gages which have a near zero sensitivity to strains not aligned to the sensor direction. The dependence of the electrical response on all the strain components makes it quite difficult, possibly unfeasible, to experimentally determine the individual strain components with this kind of sensors; however, the manufacturin...

Multiwalled carbon nanotube film for strain sensing

Nanotechnology, 2008

We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications.

Strain sensing using a multiwalled carbon nanotube film

2009

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.

Flexural strain sensing using carbon nanotube film

2004

Abstract: Strain sensing characteristic of carbon nanotubes has been established in the past at nanoscale. In this study, it is shown that the carbon nanotube film sensors, made up of randomly oriented carbon nanotubes, can be used as strain sensors at macro level. A nearly linear trend between the change in voltage, measured using a movable four point probe, and strains, measured using conventional electrical strain gage, indicates the potential of such carbon nanotube films for measuring flexural strains at macro level.

Piezoresistive Strain Sensors Based on Carbon Nanotube Networks

june 2015 | IEEE nanotEchnology magazInE | 11 S zhEng h. zhu Piezoresistive Strain Sensors Based on Carbon Nanotube Networks Treated CNT/SPU [84] Pristine CNT/PP [85] Pristine CNT/PA12 [86] Pristine CNT/TPU [87] Pristine CNT/IPPAM [88] Pristine CNT/PP12 [89] Pristine CNT/PBT [89] Pristine CNT/PC [89] Pristine CNT/PEEk [89] Pristine CNT/LDPE [89]