Piezoresistive characterization of multi-walled carbon nanotube-epoxy based flexible strain sensitive films by impedance spectroscopy

Sanli, Abdulkadir; Müller, Christian; Kanoun, Olfa; Elibol, Cagatay; Wagner, Martin F.‐X.

doi:10.1016/j.compscitech.2015.11.012

Cited by 120 publications

(98 citation statements)

References 51 publications

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“…As expected these values are higher than the values previously determined on compression molded plates (1.5 .cm) (Dul et al, 2018b), and on the extruded filaments (4.1 .cm) (Dul et al, 2018a). The increase of resistivity of extruded specimens could be attributed to the higher level of anisotropy and alignment in nanocomposite filaments, with respect to the molded plates where conversely CNT are isotropically distributed, as documented in literature (Georgousis et al, 2015;Sanli et al, 2016;Dul et al, 2018b). Moreover, the processing effect is further evidenced in 3D printed specimens and it is directly attributed to the internal structure of FFF samples.…”

Section: Resultssupporting

confidence: 75%

“…Among these three factors, the first two are most likely the most influential on the electrical resistance upon mechanical deformation (Georgousis et al, 2015). The common matrices used for strain sensor materials can be thermosetting (Ku-Herrera and Avilés, 2012;Moriche et al, 2016b;Sanli et al, 2016), thermoplastics (Georgousis et al, 2015;Bautista-Quijano et al, 2016;Dawoud et al, 2018), and elastomers (Bautista-Quijano et al, 2010Oliva-Avilés et al, 2011;Alsharari et al, 2018;Christ et al, 2019;Kim et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Fused Filament Fabrication of Piezoresistive Carbon Nanotubes Nanocomposites for Strain Monitoring

2020

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Conductive carbon nanotubes (CNT)/acrylonitrile butadiene styrene (ABS) nanocomposites parts were easily and successfully manufactured by fused filament fabrication (FFF) starting from composite filaments properly extruded at a laboratory scale. Specific specimens for strain monitoring application were properly evaluated in both short term and long term mechanical testing. In particular, samples of ABS filled with 6 wt.% of CNT were additively manufactured in two different infill patterns: HC (0 • /0 • ) and H45 (−45 • /+45 • ). The piezoresistivity behavior was investigated under various loading conditions such as ramp tensile tests at different rate and extension, and also creep and cyclic loading at room temperature. Experimental work revealed that the resistance changes in the conductive samples were properly detectable during stress or strain modification, as consequence of damage and/or reassembling of the percolation network. The measurement of the gauge factor in various testing conditions evidenced an initial higher sensitivity of the 3D-built parts within H45 pattern in comparison to the correspondent HC counterparts. The CNT conductive network path in the investigated samples seems to be reformed during creep and cycling experiments, showing a progressive reduction of gauge factor that seems to stabilize at about 2.5 for both HC and H45 samples after long term testing. These findings suggest that conductive CNT/ABS nanocomposites at 6 wt.% of loading can be successfully processed by FFF to produce stable strain sensors in the range −25 • and +60 • C, as confirmed by the constancy of resistivity in these temperatures.

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Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Fused Filament Fabrication of Piezoresistive Carbon Nanotubes Nanocomposites for Strain Monitoring

2020

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“…Despite the lack of an experimentally derived thermal conductivity measurement, a ZT value was estimated to be 0.39 and a demonstrator module was made from the composite, producing 2 mV from human body heat. 94 The allotropes of carbon, graphene, and carbon nanotubes have intrinsically favorable electronic properties of interest in the fabrication and optimization of thermoelectric, optoelectronic, 95 piezo electronic 96 and wearable electronic materials. Several studies involving graphene have obtained data with high electrical conductivity and in some cases the potential to reduce the thermal conductivity by phonon scattering.…”

Section: Graphene and Nanocomposite Materialsmentioning

confidence: 99%

Review—Organic Materials for Thermoelectric Energy Generation

Cowen

Atoyo

Carnie

et al. 2017

ECS J. Solid State Sci. Technol.

129

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Organic semiconductor materials have been promising alternatives to their inorganic counterparts in several electronic applications such as solar cells, light emitting diodes, field effect transistors as well as thermoelectric generators. Their low cost, light weight and flexibility make them appealing in future applications such as foldable electronics and wearable circuits using printing techniques. In this report, we present a mini-review on the organic materials that have been used for thermoelectric energy generation. The reduction in the effects of climate change, caused by the burning of fossil fuels, has recently been given increased emphasis by major world governments and it is therefore necessary to consider the efficiency of the methods we currently use to generate energy. It has previously been estimated that 63% of global energy consumption is wasted with the major form of this waste being heat.1,2 It is therefore important to develop methods of reconverting this wasted heat back in to useful forms of energy, such as electricity.Thermoelectric generators (TEG) are a promising technology which make use of a process known as the Seebeck effect for heat recovery. The Seebeck effect can be described as two dissimilar conductors or semiconductors connected thermally in parallel and electrically in series and exposed to a temperature gradient causing a difference in voltage between the two materials.3,4 In a TEG one p-type and one ntype semiconductor make use of the Seebeck effect by connecting one to the other electrically in series and thermally in parallel; a general device setup is shown in Figure 1. By connecting the two components, by a junction which is heated, the n-type component of the device transports electrons from the hot junction to a heat sink while the p-type material transports positively charged holes along the same direction of the temperature gradient. The reverse is also possible if the holes and electrons flow away from a cold connecting junction to a heated point at the end of each semiconductor, this induces a constant cooling at the junction through the Peltier effect. 4,5The quantification of the Seebeck effect, in a specific material, is given by the Seebeck coefficient, α, and is the open circuit voltage of a material subjected to a temperature gradient, commonly with units on the scale of μVK −1 to mVK −1 . 6 A materials overall efficiency in the conversion of heat to electricity is given by the dimensionless figure of merit, ZT, defined as,where σ is the electrical conductivity and κ is the thermal conductivity. [6][7][8] It is therefore necessary for thermoelectric materials to have a high electrical conductivity and a low thermal conductivity making electrically conducting metals inappropriate for thermoelectric applications due to their high thermal conductivities and low z E-mail: m.j.carnie@swansea.ac.uk; derya.baran@kaust.edu.sa; b.c.schroeder@qmul .ac.uk Seebeck coefficients. The ideal thermoelectric materials should be an electrical crystal to maximize σ and at the s...

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“…This viewpoint includes primarily the network effects imposed by the tunnel contacts alongside the percolation system of the CNT solid (bundle or network) . The concept of CNT thin films extends this picture to interactions of the CNT network with its surrounding matrix (indicated by a color change in the surrounding from green for CNT networks to gray for CNT films in Figure ).…”

Section: Cnt Strain Sensor Technologymentioning

confidence: 99%

“…Macroscopic approaches are not capable of testing structures of single CNTs; instead, they focus on the creation of macroscopic structures as films, dog bones, or yarns which are tested using macroscopic tensile testing devices Besides this, substrate bending (as shown in Figure ) and three‐ or four‐point bending setups are discussed as alternatives. Besides such classical approaches, studies are presented in which CNT compounds are directly attached to the human body to sense the action of knees, fingers, and facial muscles—which also strains or bends the substrate.…”

Section: Cnt Strain Sensor Technologymentioning

confidence: 99%

Carbon Nanotubes for Mechanical Sensor Applications

Wagner

Blaudeck

Meszmer

et al. 2019

Physica Status Solidi (a)

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Herein, the evolution of carbon nanotubes (CNTs) as functional material in nano‐ and microelectromechanical systems (N/MEMS) is featured. Introducing material morphologies for the CNTs in a homologue series (single CNTs—bundles, fibers, yarns—networks and thin films), different concepts for mechanical sensors based on the intrinsic and extrinsic properties of the CNT materials are introduced (piezoresistive effect, strain‐induced band bending, charge tunneling). In a rigorous theoretical treatment, the limits of the achievable sensor performance (i.e., gauge factor) are derived and discussed in the context of applications. A careful literature survey shows that highest sensitivity is reached for devices exploiting the intrinsic transport properties of single CNTs. For reliability tests of such sensor systems made from nanomaterials and classical MEMS, the specimen‐centered approach (SCA) is introduced to give viable insights into the structure property relationships and failure modes of CNT mechanical sensors. CNT actuation occurs on the macro‐, micro‐, and nanoscales via atomic force microscopy, electrostatic gating, integration in N/MEMS systems, or through substrate bending.

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Piezoresistive characterization of multi-walled carbon nanotube-epoxy based flexible strain sensitive films by impedance spectroscopy

Cited by 120 publications

References 51 publications

Fused Filament Fabrication of Piezoresistive Carbon Nanotubes Nanocomposites for Strain Monitoring

Fused Filament Fabrication of Piezoresistive Carbon Nanotubes Nanocomposites for Strain Monitoring

Review—Organic Materials for Thermoelectric Energy Generation

Carbon Nanotubes for Mechanical Sensor Applications

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