Porous GNP/PDMS composites with significantly reduced percolation threshold of conductive filler for stretchable strain sensors

2021 ◽  
pp. 101033
Author(s):  
Hailong Hu ◽  
Yalun Ma ◽  
Jianling Yue ◽  
Fan Zhang
Keyword(s):  
Percolation Threshold ◽  
Conductive Filler ◽  
Strain Sensors

scholarly journals Non-Monotonic Sensor Behavior of Carbon Particle-Filled Textile Strain Sensors

2021 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Johannes Mersch ◽  
Henriette Probst ◽  
Andreas Nocke ◽  
Chokri Cherif ◽  
Gerald Gerlach
Keyword(s):  
Thermoplastic Polyurethane ◽  
Carbon Particle ◽  
Equivalent Circuit Model ◽  
Conductive Filler ◽  
Underlying Mechanism ◽  
Human Motion ◽  
Strain Sensors ◽  
Material Behavior ◽  
Strain History ◽  
Filled Elastomers

Carbon particle-filled elastomers are a widely researched option to be used as piezoresistive strain sensors for soft robotics or human motion monitoring. Therefore, various polymers can be compounded with carbon black (CB), carbon nanotubes (CNT) or graphene. However, in many studies, the electrical resistance strain response of the carbon particle-filled elastomers is non-monotonic in dynamic evaluation scenarios. The non-monotonic material behavior is also called shoulder phenomenon or secondary peak. Until today, the underlying cause is not sufficiently well understood. In this study, several influencing test parameters on the shoulder phenomena are explored, such as strain level, strain rate and strain history. Moreover, material parameters such as CNT content and anisotropy are varied in melt-spun CNT filled thermoplastic polyurethane (TPU) filament yarns, and their non-monotonic sensor response is evaluated. Additionally, a theoretical concept for the underlying mechanism and thereupon-based model is presented. An equivalent circuit model is used, which incorporates the visco-elastic properties and the characteristic of the percolation network formed by the conductive filler material. The simulation results are in good agreement when compared to the experimental results.

Percolation and Electrical Conductivity Modeling of Novel Microstructured Insulator-Conductor Nanocomposites Fabricated from PMMA and ATO

2014 ◽  
Vol 1692 ◽  
Author(s):  
Youngho Jin ◽  
Rosario A. Gerhardt
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Percolation Threshold ◽  
Polymer Matrix ◽  
Polymer Matrix Composites ◽  
Conductive Filler ◽  
Molding Pressure ◽  
Shape Transformation ◽  
Element Analysis ◽  
3D Network

ABSTRACTThe electrical conductivity of insulating polymer matrix composites undergoes radical increase at a certain concentration of conductive filler, which is known as the percolation threshold. Polymer matrix conductive nanocomposites were fabricated by compression molding the mechanically mixed poly (methyl methacrylate) (PMMA) and antimony tin oxide (ATO) nanoparticles, as has been done with other polymer composites before. The electrical conductivity of PMMA/ATO nanocomposites increased by several orders of magnitude at a small concentration of ATO (∼ 0.27 vol %). The continuous 3D network like distribution of ATO nanoparticles contributed to this percolation at subcritical filler concentrations. The effects of processing parameters on these unique microstructures and electrical properties were investigated. The tetrakaidecahedron-like microstructure was observed by scanning electron microscopy (SEM) and was found to be affected by the molding pressure, temperature and amount of nanoparticles. The viscoelastic flow of matrix under the optimum processing conditions allowed the shape transformation of PMMA into space filling polyhedra and an ordered distribution of ATO nanoparticles along the sharp edges of the PMMA. Parametric finite element analysis was performed to model this unique microstructure-driven percolation. The 2D simplified model was generated in AC/DC frequency domain mode in COMSOL Multiphysics® to solve the effects of ordered distribution of conductive nanoparticles on the electrical properties of the composite. There was excellent agreement between experimental and simulated values of electrical conductivity and percolation concentration. This model can be used to predict percolation threshold and electrical properties for any types of composite systems containing insulating matrix and conductive fillers that can form this unique microstructure.

Simulation and Analysis of Strain Sensitivity of CNT-Based Strain Sensors

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660005
Author(s):  
Gaurav Sapra ◽  
Renu Vig ◽  
Manu Sharma
Keyword(s):  
Percolation Threshold ◽  
Dynamic Range ◽  
Strain Sensor ◽  
Applied Strain ◽  
Strain Sensors ◽  
Tunneling Effect ◽  
Gauge Factor ◽  
Strain Sensitivity ◽  
Total Resistance ◽  
Intrinsic Resistance

Carbon nanotubes (CNT) is turning out to be a replacement to all the existing traditional sensors due to their high gauge factor, multidirectional sensing capability, high flexibility, low mass density, high dynamic range and high sensitivity to strains at nano and macro- scales. The strain sensitivity of CNT-based strain sensors depends on number of parameters; quality and quantity of CNT used, type of polymer used, deposition and dispersion technique adopted and also on environmental conditions. Due to all these parameters, the piezoresistive behavior of CNT is diversified and it needs to be explored. This paper theoretically analyses the strain sensitivity of CNT-based strain sensors. The strain sensitivity response of CNT strain sensor is a result of change in total resistance of CNT network with respect to applied strain. The total resistance of CNT network consists of intrinsic resistance and inter-tube resistance. It has been found that the change in intrinsic resistance under strain is due to the variation of bandgap of individual, which depends on the chirality of the tube and it varies exponentially with strain. The inter-tube resistance of CNT network changes nonlinearly due to change in distance between neighboring CNTs with respect to applied strain. As the distance [Formula: see text] between CNTs increases due to applied strain, tunneling resistance [Formula: see text] increases nonlinearly in exponential manner. When the concentration of CNTs in composite is close to percolation threshold, then the change of inter-tube resistances is more dominant than intrinsic resistance. At percolation threshold, the total resistance of CNT networks changes nonlinearly and this effect of nonlinearity is due to tunneling effect. The strain sensitivity of CNT-based strain sensors also varies nonlinearly with the change in temperature. For the change of temperature from [Formula: see text]C to 50[Formula: see text]C, there is more than 100% change in strain sensitivity of CNT/polymer composite strain sensor. This change is mainly due to the infiltration of polymer into CNTs.

Tunable Piezoresistivity of Low Percolation Threshold Micro-Nickel Wires/PDMS Conductive Composite Regulated by Magnetic Field

2021 ◽  
Author(s):  
Shaoyu Niu ◽  
Shan Wang ◽  
qilong yan ◽  
zheyi han ◽  
xiang lou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Percolation Threshold ◽  
High Performance ◽  
Pressure Sensors ◽  
Conductive Filler ◽  
Conductive Composite ◽  
Flexible Pressure Sensors

High performance flexible pressure sensors with tunable piezoresistivity are proposed with percolative composites as single sensing layer using micro-nickel (μNi) wires as conductive filler and polydimethylsiloxane (PDMS) as matrix. The...

scholarly journals Review of Graphene-Based Textile Strain Sensors, with Emphasis on Structure Activity Relationship

Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 151
Author(s):  
Rufang Yu ◽  
Chengyan Zhu ◽  
Junmin Wan ◽  
Yongqiang Li ◽  
Xinghua Hong
Keyword(s):  
Structural Changes ◽  
Conductive Filler ◽  
Strain Sensors ◽  
Woven Fabric ◽  
Gauge Factor ◽  
Future Research ◽  
Wearable Electronics ◽  
Deformation Stage ◽  
Main Challenge ◽  
The Impact

Graphene-based textile strain sensors were reviewed in terms of their preparation methods, performance, and applications with particular attention on its forming method, the key properties (sensitivity, stability, sensing range and response time), and comparisons. Staple fiber strain sensors, staple and filament strain sensors, nonwoven fabric strain sensors, woven fabric strain sensors and knitted fabric strain sensors were summarized, respectively. (i) In general, graphene-based textile strain sensors can be obtained in two ways. One method is to prepare conductive textiles through spinning and weaving techniques, and the graphene worked as conductive filler. The other method is to deposit graphene-based materials on the surface of textiles, the graphene served as conductive coatings and colorants. (ii) The gauge factor (GF) value of sensor refers to its mechanical and electromechanical properties, which are the key evaluation indicators. We found the absolute value of GF of graphene-based textile strain sensor could be roughly divided into two trends according to its structural changes. Firstly, in the recoverable deformation stage, GF usually decreased with the increase of strain. Secondly, in the unrecoverable deformation stage, GF usually increased with the increase of strain. (iii) The main challenge of graphene-based textile strain sensors was that their application capacity received limited studies. Most of current studies only discussed washability, seldomly involving the impact of other environmental factors, including friction, PH, etc. Based on these developments, this work was done to provide some merit to references and guidelines for the progress of future research on flexible and wearable electronics.

Electrical properties of stretchable and skin–mountable PDMS/MWCNT hybrid composite films for flexible strain sensors

2019 ◽  
Vol 53 (21) ◽  
pp. 3047-3060 ◽  
Author(s):  
M Nankali ◽  
NM Nouri ◽  
N Geran Malek ◽  
MA Sanjari Shahrezaei
Keyword(s):  
Electrical Properties ◽  
Percolation Threshold ◽  
Wearable Sensors ◽  
Composite Films ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Threshold Region ◽  
Sem Images ◽  
Filtration Method ◽  
Conductive Films

Flexible strain sensors based on carbon nanofillers have great potential in the application of skin-adhesive sensors, wearable sensors, and tactile sensors, due to their superior electrical properties. Herein, the electrical properties of highly sensitive PDMS/MWCNT strain sensors made by vacuum filtration method were investigated. In order to obtain the electrical percolation curve of the flexible conductive films, first different samples were made with the same surface area but with different wt. % of CNTs. Then, depending on CNT content, the obtained conductive films exhibited initial electrical resistance in the range of 12.5 KΩ to 22.8 MΩ. The piezoresistive films with the CNT concentration of 1.4 to 2.9 [Formula: see text] had shown superior resistance drop, so this interval was determined as the percolation threshold region. According to the SEM images, the nanocomposite layer thickness of the flexible strain sensors in this region was 790 nm to 1210 nm. Afterward, the percolation curve was obtained using curve fitting to the experimental data and the exact value of the percolation threshold was defined as [Formula: see text]. Finally, in order to determine the minimum gauge factor ([Formula: see text]) of the sensors in percolation region, a flexible strain sensor in the upper limit of this region was selected and the piezoresistive properties of the selected sample were investigated.

Modeling of Contact Patch in Dual-Chamber Pneumatic Tires

2018 ◽  
Vol 46 (2) ◽  
pp. 78-92 ◽  
Author(s):  
A. I. Kubba ◽  
G. J. Hall ◽  
S. Varghese ◽  
O. A. Olatunbosun ◽  
C. J. Anthony
Keyword(s):  
Strain Sensors ◽  
Surface Strain ◽  
Wireless Data ◽  
Data Logger ◽  
Dual Chamber ◽  
Piezoelectric Polymer ◽  
Pure Rolling ◽  
Piezoelectric Elements ◽  
Strain Data ◽  
Deformation Patterns

ABSTRACT This study presents an investigation of the inner tire surface strain measurement by using piezoelectric polymer transducers adhered on the inner liner of the tire, acting as strain sensors in both conventional and dual-chamber tires. The piezoelectric elements generate electrical charges when strain is applied. The inner liner tire strain can be found from the generated charge. A wireless data logger was employed to measure and transmit the measured signals from the piezoelectric elements to a PC to store and display the readout signals in real time. The strain data can be used as a monitoring system to recognize tire-loading conditions (e.g., traction, braking, and cornering) in smart tire technology. Finite element simulations, using ABAQUS, were employed to estimate tire deformation patterns in both conventional and dual-chamber tires for pure rolling and steady-state cornering conditions for different inflation pressures to simulate on-road and off-road riding tire performances and to compare with the experimental results obtained from both the piezoelectric transducers and tire test rig.

Sign in / Sign up

Export Citation Format

Share Document