Static and dynamic strain sensing using a polymer : carbon nanotube film strain sensor (original) (raw)
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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.
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
2016
released the strain to create wavy buckled structures. These wavy buckled structures provided strain relief for brittle materials rendering them stretchable. [13,14] Typical wearable strain sensors consist of patterned thin films on flexible elastomeric substrates. Recent developments in creating highly stretchable wearable strain sensors used nanoscale metal thin films, [15] nanoparticles, [16] nanowires (NWs), [17-19] nanotubes, [20-26] and graphene. [27-31] For example, Kang et al. utilized brittle platinum thin films to achieve high sensitivity (GF > 2000), but the strain sensor was only able to withstand strains of up to 2%. [32] Li et al. investigated graphene woven fabric for strain sensing (GF ≈ 1000), but was still limited to a maximum strain of 6%. [33] Conversely, Yan et al. reported highly stretchable graphene-nanocellulose nanopaper that can stretch out to 100% strain, but the strain sensor only had a GF of 7.1. [34] Zaretski et al. reported a highly sensitive strain sensor using metallic nanoislands on graphene with GF 1335 at 1% strain. However, the dynamic range of this sensor was limited, with strain of less than 10% strain. Additionally, the GF dropped to 743 after 19 cycles at 1% strain. [35] Another popular functional material that is used for strain sensing is carbon nanotubes (CNTs). Percolating networks of CNTs on flexible elastomeric substrates have been reported to have electromechanical stability under high strain due to the robust contact between individual CNTs. [36] CNT thin films have also shown the ability to bend repeatedly without fracturing. [37-41] Therefore, percolating networks of CNTs have the potential to be used as highly stretchable strain sensing devices. For instance, Yamada et al. aligned CNT thin film on PDMS and showed 280% strain but low sensitivity (GF < 0.82), [25] and Lipomi et al. investigated spring like structures in the nanotube that reach 150% strain with good conductivity. [22] Ryu et al. showed that aligned CNT fibers grown on flexible substrates were able to stretch out to 900% having GF of up to 47. [42] However, this process required highly ordered alignment of CNT fibers using intricate dry spinning methods. Another aspect to consider for improving wearable strain sensor is the careful selection of the stretchable elastomeric substrate. Many strain sensors have been fabricated using polydimethylsiloxane (PDMS) as the stretchable and flexible substrate due to its flexibility, nontoxicity, ease of fabrication, and biocompatibility. [43,44] Amjadi et al. reported highly flexible, stretchable sensitive strain sensors based on silver nanowires with PDMS that had a GF of 14 at 70% strain. [44] However, many PDMS substrate based strain sensors showed low stretchability with high hysteresis due to poor adhesion between the functional material and substrate polymer, as well as increased friction during the strain. [45,46] Furthermore, PDMS becomes stiffer, delaminates, and slips after absorbing human sweat www.MaterialsViews.com www.advmattechnol.de
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.
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.
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.
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.
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.
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]
Elastomeric carbon nanotube circuits for local strain sensing
Applied Physics Letters, 2006
We use elastomeric polydimethylsiloxane substrates to strain single-walled carbon nanotubes and modulate their electronic properties, with the aim of developing flexible materials that can sense local strain. We demonstrate micron-scale nanotube devices that can be cycled repeatedly through strains as high as 20% while providing reproducible local strain transduction by via the device resistance. We also compress individual nanotubes, and find they undergo an undulatory distortion with a characteristic spatial period of 100-200 nm. The observed period can be understood by the mechanical properties of nanotubes and the substrate in conjunction with continuum elasticity theory. These could potentially be used to create superlattices within individual nanotubes, enabling novel devices and applications.