scholarly journals Smart Fibrous Structures Produced by Electrospinning Using the Combined Effect of PCL/Graphene Nanoplatelets

2021 ◽  
Vol 11 (3) ◽  
pp. 1124
Author(s):  
Paola Francavilla ◽  
Diana P. Ferreira ◽  
Joana C. Araújo ◽  
Raul Fangueiro
Keyword(s):  
Electrical Conductivity ◽  
High Sensitivity ◽  
Graphene Nanoplatelets ◽  
Electrical Performance ◽  
Gauge Factor ◽  
Homogeneous Distribution ◽  
Piezoresistive Sensor ◽  
Conductive Surface ◽  
External Pressures ◽  
Electrospun Membranes

Over the years, the development of adaptable monitoring systems to be integrated into soldiers’ body gear, making them as comfortable and lightweight as possible (avoiding the use of rigid electronics), has become essential. Electrospun microfibers are a great material for this application due to their excellent properties, especially their flexibility and lightness. Their functionalization with graphene nanoplatelets (GNPs) makes them a fantastic alternative for the development of innovative conductive materials. In this work, electrospun membranes based on polycaprolactone (PCL) were impregnated with different GNPs concentrations in order to create an electrically conductive surface with piezoresistive behavior. All the samples were properly characterized, demonstrating the homogeneous distribution and the GNPs’ adsorption onto the membrane’s surfaces. Additionally, the electrical performance of the developed systems was studied, including the electrical conductivity, piezoresistive behavior, and Gauge Factor (GF). A maximum electrical conductivity value of 0.079 S/m was obtained for the 2%GNPs-PCL sample. The developed piezoresistive sensor showed high sensitivity to external pressures and excellent durability to repetitive pressing. The best value of GF (3.20) was obtained for the membranes with 0.5% of GNPs. Hence, this work presents the development of a flexible piezoresistive sensor, based on electrospun PCL microfibers and GNPs, utilizing simple methods.

scholarly journals Understanding the Impact of Machine Learning Models on the Performance of Different Flexible Strain Sensor Modalities

2021 ◽  
Vol 8 ◽  
Author(s):  
Brett C. Hannigan ◽  
Tyler J. Cuthbert ◽  
Wanhaoyi Geng ◽  
Mohammad Tavassolian ◽  
Carlo Menon
Keyword(s):  
Machine Learning ◽  
Mean Squared Error ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Signal Amplitude ◽  
Electrical Signal ◽  
Gauge Factor ◽  
Piezoresistive Sensor ◽  
Fibre Strain ◽  
The Impact

Fibre strain sensors commonly use three major modalities to transduce strain—piezoresistance, capacitance, and inductance. The electrical signal in response to strain differs between these sensing technologies, having varying sensitivity, maximum measurable loading rate, and susceptibility to deleterious effects like hysteresis and drift. The wide variety of sensor materials and strain tracking applications makes it difficult to choose the best sensor modality for a wearable device when considering signal quality, cost, and difficulty of manufacture. Fibre strain sensor samples employing the three sensing mechanisms are fabricated and subjected to strain using a tensile tester. Their mechanical and electrical properties are measured in response to strain profiles designed to exhibit particular shortcomings of sensor behaviour. Using these data, the sensors are compared to identify materials and sensing technologies well suited for different textile motion tracking applications. Several regression models are trained and validated on random strain pattern data, providing guidance for pairing each sensor with a model architecture that compensates for non-ideal effects. A thermoplastic elastomer-core piezoresistive sensor had the highest sensitivity (average gauge factor: 12.6) and a piezoresistive sensor of similar construction with a polyether urethane-urea core had the largest bandwidth, capable of resolving strain rates above 300% s−1 with 36% signal amplitude attenuation. However, both piezoresistve sensors suffered from larger hysteresis and drift than a coaxial polymer sensor using the capacitive strain sensing mechanism. Machine learning improved the piezoresistive sensors’ root-mean-squared error when tracking a random strain signal by up to 58% while maintaining their high sensitivity, bandwidth, and ease of interfacing electronically.

Conductive PVDF-HFP/CNT composites for strain sensing

2016 ◽  
Vol 09 (02) ◽  
pp. 1650024 ◽  
Author(s):  
Bin Hu ◽  
Yaolu Liu ◽  
Ning Hu ◽  
Liangke Wu ◽  
Huiming Ning ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Vinylidene Fluoride ◽  
High Sensitivity ◽  
Tunneling Effect ◽  
Gauge Factor ◽  
Metal Foil ◽  
Strain Sensing ◽  
Good Dispersion ◽  
Dispersion State ◽  
Addition Amount

A strain sensor based on the composites of poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) filled by multi-walled carbon nanotube (MWNT) was prepared using a proposed fabrication process. Three kinds of MWNT loadings, i.e., 1.0[Formula: see text]wt.%, 2.0[Formula: see text]wt.% and 3.0[Formula: see text]wt.% were employed. Due to good dispersion state of MWNT in PVDF-HFP matrix, which was characterized by scanning electron microscope (SEM), this sensor was found to be of high sensitivity and stable performance. The sensor’s piezoresistivity varied in a weak nonlinear pattern, which was probably caused by the tunneling effect among neighboring MWNTs. The gauge factor of the sensor of 1.0[Formula: see text]wt.% MWNT loading was identified to be the highest, i.e., 33. This sensor gauge factor decreased gradually with the increase of addition amount of MWNT, which was 5 for the sensor of 3.0[Formula: see text]wt.% MWNT loading. This gauge factor was still higher than that of conventional metal-foil strain sensors. The electrical conductivity of PVDF-HFP/MWNT composites was also studied. It was found that with the increase of the addition amount of MWNT, the electrical conductivity of the PVDF-HFP/MWNT composites varied in a perfect percolation pattern with a very low percolation threshold, i.e., 0.77 vol.%, further indicating the very good dispersion of MWNT in the PVDF-HFP matrix.

scholarly journals The Potential of Graphene Nanoplatelets in the Development of Smart and Multifunctional Ecocomposites

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2189
Author(s):  
Pedro Pereira ◽  
Diana P. Ferreira ◽  
Joana C. Araújo ◽  
Armando Ferreira ◽  
Raul Fangueiro
Keyword(s):  
Electrical Conductivity ◽  
Polyethylene Glycol ◽  
Electrical Properties ◽  
Smart Materials ◽  
Textile Composites ◽  
Graphene Nanoplatelets ◽  
Gauge Factor ◽  
Sensing Applications ◽  
Ultraviolet Protection ◽  
Natural Fabrics

Graphene and its derivatives have shown outstanding potential in many fields and textile/composites industry are not an exception. Giving their extraordinary properties, Graphene Nanoplatelets (GNPs) are excellent candidates for providing new functionalities to fibers and composites. In this work, natural fabrics (flax) were functionalized with chitosan (CS) based polymeric formulations of GNPs to develop fibrous systems with electrical properties as well as other functionalities. One of the greatest disadvantages of using carbon-based materials for fabrics’ impregnation is their difficult dispersion. Therefore, several polymers were used as matrices, binding and dispersive agents including chitosan, polyethylene glycol (PEG), and glycerol. All the systems were characterized using several techniques that demonstrated the presence and incorporation of the GNPs onto the composites. Besides their characterization, considering their use as smart materials for monitoring and sensing applications, electrical properties were also evaluated. The highest value obtained for electrical conductivity was 0.04 S m−1 using 2% of GNPs. Furthermore, piezoresistive behavior was observed with Gauge Factor (GF) of 1.89 using 0.5% GNPs. Additionally, UV (ultraviolet) protection ability and hydrophobicity were analyzed, confirming the multifunctional behavior of the developed systems extending their potential of application in several areas.

scholarly journals Effect of GNPs on the Piezoresistive, Electrical and Mechanical Properties of PHA and PLA Films

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 86
Author(s):  
Gonzalo Mármol ◽  
Usha Kiran Sanivada ◽  
Raul Fangueiro
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Polyethylene Glycol ◽  
Polylactic Acid ◽  
Cellulose Nanocrystals ◽  
Graphene Nanoplatelets ◽  
Gauge Factor ◽  
Solvent Casting ◽  
Nanoparticle Distribution ◽  
Primary Focus

Sustainability has become the primary focus for researchers lately. Biopolymers such as polyhydroxyalkanoate (PHA) and polylactic acid (PLA) are biocompatible and biodegradable. Introducing piezoresistive response in the films produced by PLA and PHA by adding nanoparticles can be interesting. Hence, a study was performed to evaluate the mechanical, electrical and piezoresistive response of films made from PHA and PLA. The films were produced by solvent casting, and they were reinforced with graphene nanoplatelets (GNPs) at different nanoparticle concentrations (from 0.15 to 15 wt.%). Moreover, cellulose nanocrystals (CNC) as reinforcing elements and polyethylene glycol (PEG) as plasticizers were added. After the assessment of the nanoparticle distribution, the films were subjected to tests such as tensile, electrical conductivity and piezoresistive response. The dispersion was found to be good in PLA films and there exist some agglomerations in PHA films. The results suggested that the incorporation of GNPs enhanced the mechanical properties until 0.75 wt.% and they reduced thereon. The addition of 1% CNCs and 20% PEG in 15 wt.% GNPs’ tensile values deteriorated further. The PHA films showed better electrical conductivity compared to the PLA films for the same GNPs wt.%. Gauge factor (GF) values of 6.30 and 4.31 were obtained for PHA and PLA, respectively.

A capacitive sensor using resin thermoplastic elastomer and carbon fibers for monitoring pressure distribution

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guanzheng Wu ◽  
Siming Li ◽  
Jiayu Hu ◽  
Manchen Dong ◽  
Ke Dong ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fibers ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Thermoplastic Elastomer ◽  
Gauge Factor ◽  
Capacitive Pressure Sensor ◽  
Wearable Electronics ◽  
Content Type

Purpose This paper aims to study the working principle of the capacitive pressure sensor and explore the distribution of pressure acting on the surface of the capacitor. Herein, a kind of high sensitivity capacitive pressure sensor was prepared by overlaying carbon fibers (CFs) on the surfaces of the thermoplastic elastomer (TPE), the TPE with high elasticity is a dielectric elastomer for the sensor and the CFs with excellent electrical conductivity were designed as the conductor. Design/methodology/approach Due to the excellent mechanical properties and electrical conductivity of CFs, it was designed as the conductor layer for the TPE/CFs capacitive pressure sensor via laminating CFs on the surfaces of the columnar TPE. Then, a ‘#' type structure of the capacitive pressure sensor was designed and fabricated. Findings The ‘#' type of capacitive pressure sensor of TPE/CFs composite was obtained in high sensitivity with a gauge factor of 2.77. Furthermore, the change of gauge factor values of the sensor under 10 per cent of applied strains was repeated for 1,000 cycles, indicating its outstanding sensing stability. Moreover, the ‘#' type capacitive pressure sensor of TPE/CFs was consisted of several capacitor arrays via laminating CFs, which could detect the distribution of pressure. Research limitations/implications The TPE/CFs capacitive pressure sensor was easily fabricated with high sensitivity and quick responsiveness, which is desirably applied in wearable electronics, robots, medical devices, etc. Originality/value The outcome of this study will help to fabricate capacitive pressure sensors with high sensitivity and outstanding sensing stability.

scholarly journals A Study of Highly Sensitive Wearable Strain Sensor Based on Graphical Sensitive Units

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jie Wang ◽  
Yi Du ◽  
Qiang Zhang ◽  
Zhu Jing ◽  
Kai Zhuo ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Real Time ◽  
Silver Nanowires ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Sine Wave ◽  
Gauge Factor ◽  
Soft Substrate ◽  
Highly Sensitive ◽  
Sensitivity Improvement

The sensitivity improvement is the choke point of the soft strain sensor’s development. This paper focuses on heightening the soft strain sensor’s sensitivity through changing the sensitive unit’s shape. The sensitive units in shape of square or sine wave with different periods were studied in this work. Silver nanowires (Ag NWs) in excellent electrical conductivity and flexible polydimethylsiloxane (PDMS) were used as sensitive nanomaterials and soft substrate. The soft strain sensor whose sensitive unit is double cycled square wave performs the highest sensitivity whose gauge factor (GF) reaches to 14763.8. Based on the high sensitivity, the sensor was applied on real-time detection of the human expression.

Microstructural Design of Graphene Nanocomposites for Improved Electrical Conductivity

2021 ◽  
pp. 1-23
Author(s):  
Audrey Gbaguidi ◽  
Sirish Namilae ◽  
Daewon Kim
Keyword(s):  
Electrical Conductivity ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
Graphene Nanoplatelets ◽  
Hybrid Nanocomposites ◽  
Electrical Performance ◽  
Partial Replacement ◽  
Minimal Amount ◽  
Graphene Nanocomposites ◽  
Aspect Ratios

Abstract The electrical conductivity and percolation onset of graphene-based nanocomposites are studied by varying both planar and transversal aspect ratios of graphene nanoplatelets (GNP) fillers using a three-dimensional stochastic percolation-based model. The graphene nanoplatelets are modeled as elliptical fillers to enable aspect ratio variations. We find that decreasing the graphite's thickness results in an exponential performance improvement of the nanocomposites, in contrast to a linear improvement obtained when the planar aspect ratio is increased, for same filler volume. Furthermore, we show that hybrid nanocomposites fabricated with partial replacement of GNP by carbon nanotube (CNT) may improve the electrical performance of the GNP monofiller composites. Improvement or deterioration of the electrical properties is mainly based on the morphology and content of the fillers mixed in the hybrids. Nonetheless, using a minimal amount of CNT for substitution always leads to the highest improvement in conductivity, while additional CNTs only leads to smaller improvement at best or even deterioration. The results are validated by comparing with experimental works and offer useful insights for the fabrication of highly conductive nanocomposites.

Investigation of a New High Sensitive Micro-Electromechanical Strain Gauge Sensor Based on Graphene Piezoresistivity

2014 ◽  
Vol 605 ◽  
pp. 207-210 ◽  
Author(s):  
Mohammed Gamil ◽  
Osamu Tabata ◽  
Koichi Nakamura ◽  
Ahmed M.R. Fath El-Bab ◽  
Ahmed A. El-Moneim
Keyword(s):  
Strain Gauge ◽  
Low Cost ◽  
Graphene Film ◽  
Chemical Vapor ◽  
High Sensitivity ◽  
Monolayer Graphene ◽  
Gauge Factor ◽  
Homogeneous Distribution ◽  
Graphene Monolayer ◽  
Strain Gauge Sensor

A new strain gauge based on graphene piezoresistivity was fabricated by a novel low cost technique which suits mass production of micro piezoresistor sensors. The strain gauge consists of a monolayer graphene film made by chemical vapor deposition on a copper foil surface, and transferred to Si/SiO2 surface by using a polymethyl-methacrylate (PMMA) assisted transfer method. The film is shaped by laser machine to work as a conductive-piezoresistive material between two deposited electrical silver electrodes. This method of fabrication provides a high productivity due to the homogeneous distribution of the graphene monolayer all over the Si/SiO2 surface. The experimentally measured gauge factor of graphene based device is 255, which promises a new strain gauge sensor of high sensitivity.

scholarly journals Scalable fabrication of carbon materials based silicon rubber for highly stretchable e-textile sensor

2020 ◽  
Vol 9 (1) ◽  
pp. 1183-1191
Author(s):  
Xinlin Li ◽  
Rixuan Wang ◽  
Leilei Wang ◽  
Aizhen Li ◽  
Xiaowu Tang ◽  
...  
Keyword(s):  
Carbon Nanomaterials ◽  
Electrical Performance ◽  
Gauge Factor ◽  
Multiwalled Carbon ◽  
Silicon Rubber ◽  
Smart Clothing ◽  
Mechanical And Electrical Properties ◽  
Highly Stretchable ◽  
Textile Sensor ◽  
High Level

AbstractDevelopment of stretchable wearable devices requires essential materials with high level of mechanical and electrical properties as well as scalability. Recently, silicone rubber-based elastic polymers with incorporated conductive fillers (metal particles, carbon nanomaterials, etc.) have been shown to the most promising materials for enabling both high electrical performance and stretchability, but the technology to make materials in scalable fabrication is still lacking. Here, we propose a facile method for fabricating a wearable device by directly coating essential electrical material on fabrics. The optimized material is implemented by the noncovalent association of multiwalled carbon nanotube (MWCNT), carbon black (CB), and silicon rubber (SR). The e-textile sensor has the highest gauge factor (GF) up to 34.38 when subjected to 40% strain for 5,000 cycles, without any degradation. In particular, the fabric sensor is fully operational even after being immersed in water for 10 days or stirred at room temperature for 8 hours. Our study provides a general platform for incorporating other stretchable elastic materials, enabling the future development of the smart clothing manufacturing.

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