A Review: Carbon Nanotube-Based Piezoresistive Strain (original) (raw)
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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]
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
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.
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.
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.
Tailoring Piezoresistive Sensitivity of Multilayer Carbon Nanotube Composite Strain Sensors
Journal of Intelligent Material Systems and Structures, 2007
In recent years, carbon nanotubes have been utilized for a variety of applications, including nanoelectronics and various types of sensors. In particular, researchers have sought to take advantage of the superior electrical properties of carbon nanotubes for fabricating novel strain sensors. This article presents a single-walled carbon nanotube (SWNT)-polyelectrolyte (PE) composite thin film strain sensor fabricated with a layerby-layer (LbL) process. Optimization of bulk SWNT-PE strain sensor properties is achieved by varying various LbL fabrication parameters, followed by characterization of strain-sensing electromechanical responses. A resistor and capacitor (RC)-circuit model is proposed and validated with electrical impedance spectroscopy to fit experimental results and to identify equivalent circuit element parameters sensitive to strain. Experimental results suggest consistent trends between SWNT and PE concentrations to strain sensor sensitivities. Simply by adjusting the weight fraction of SWNT solutions and film thickness, strain sensitivities between 0.1 and 1.8 have been achieved. While SWNT-PE strain sensitivity is lower than some metal-foil strain gauges ($2), the LbL method allows for precise tailoring of the properties (i.e., strain sensitivity, resistivity, among others) of a high-capacity (AE10,000 mm m À1 ) homogeneous multilayer strain sensor. Figure 17. (a) Series resistor R s decreases resistance as carbon nanotube concentration is increased (a similar effect is observed for R t ) while PSS concentration is fixed. (b) Plot of R s showing increasing resistance with greater PSS concentration while SWNT concentration is fixed.
Journal of Materials Science, 2018
In recent years, the increasing demand for flexible and wearable devices requires the synthesis of novel stretchable and piezoresistive materials. Piezoresistive polymer composites are popular due to their excellent piezoresistivity and high stretchability, which can readily be attached to clothes or human body. In this study, a stretchable and sensitive strain sensor based on multi-wall carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composite with an excellent overall performance was fabricated in a facile and effective way. The composite with 7% MWCNTs is ideal for strain sensor compared to those with 5% and 9% MWCNTs. Not only can the gauge factor reach 5-9 under 10-40% strain, but also the curve of relative change in resistance versus strain is almost linear. The strain sensor can respond immediately with low hysteresis. The strain sensor also exhibits great stability under 1000 cycles of stretching/releasing, demonstrating the desirable long-term endurance to mechanical stimuli as well. The strain sensor was then implemented to monitor human motions (finger and wrist bending), precisely sensing the motion deformation and states. In conclusion, the reported sensor based on MWCNT/ PDMS composite possesses numerous favorable characteristics including high sensitivity, good stretchability, ease of fabrication, and promising practical application in the field of biomedical system and wearable electronic devices.
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.
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.