Highly flexible and sensitive graphene-silver nanocomposite strain sensor (original) (raw)
Related papers
Key Engineering Materials, 2014
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.
Graphene as a Piezoresistive Material in Strain Sensing Applications
Micromachines, 2022
High accuracy measurement of mechanical strain is critical and broadly practiced in several application areas including structural health monitoring, industrial process control, manufacturing, avionics and the automotive industry, to name a few. Strain sensors, otherwise known as strain gauges, are fueled by various nanomaterials, among which graphene has attracted great interest in recent years, due to its unique electro-mechanical characteristics. Graphene shows not only exceptional physical properties but also has remarkable mechanical properties, such as piezoresistivity, which makes it a perfect candidate for strain sensing applications. In the present review, we provide an in-depth overview of the latest studies focusing on graphene and its strain sensing mechanism along with various applications. We start by providing a description of the fundamental properties, synthesis techniques and characterization methods of graphene, and then build forward to the discussion of numerous...
Sensors and Actuators A: Physical, 2016
An optically transparent nanographite coating has been developed owing to a poly-methyl methacrylate (PMMA) substrates. The adhesion to the PMMA surface combined with the shear stress allowed an uniform and continuous spreading of the graphite nanocrystals on the substrate surface with formation of a very uniform graphene multilayer coating. This coating is characterized by high piezoresitivity and it is suitable to work as sensible and reliable local strain sensor. Its piezoresistive features have been characterized by bending tests yielding a Gauge Factor (GF) which is of the order of 50. The structural and strain properties of the compound were studied under stress by Infra-Red Thermography (IRT) and micro-Raman spectroscopy. The strain strength has been estimated as a funcition of the bending load. The electrical transport was investigated as a function of the applied stress. Features are consistent with a intergrain electrical transport mechanism among graphene platelets.
A facile approach to fabricate graphene based piezoresistive strain sensor on paper substrate
2018
Sensors, FETs and chemi resistors are few of the devices which show potential in the area of flexible electronics for health monitoring applications. In the present work, piezoresistive strain sensors based on graphite and graphene on cellulose paper substrate has been reported. Graphite sensor has been fabricated by rubbing pencil on paper and graphene sensor by directly coating graphene ink using paint brush. The resistance of the fabricated sensor increases with outwards bending and vice-versa, further the piezoresistive effect has also been evaluated by applying variable longitudinal stress. A comparative study of gauge factor (GF) depending upon different type of strains has been presented and it has been observed that the GF of graphene piezoresistive strain sensor decreases with increase in number of layers, the GF for graphene sensor is higher as compared to graphite sensor. Fabricated piezoresistive strain sensors may find applications as human body motion detection, gait a...
A Flexible Reduced Graphene Oxide Field-Effect Transistor for Ultrasensitive Strain Sensing
Advanced Functional Materials, 2013
Recently, various fl exible pressure, strain, thermal, and optical sensors have been extensively studied for personal health monitoring, electronic skins, robot sensors, and other humanmachine interface requiring mechanical conformality. [ 1-13 ] For high responsivity to external stimuli, many sensors have been fabricated by using a number of nano-scale sensing materials including nanowire, [ 5-9 ] carbon nanotubes, [ 14,15 ] graphene [ 10,16-20 ] and hybrid nanocomposite [ 11-13,21,22 ] on various stretchable or fl exible substrates. Among those, many strain sensors using a resistor structure where changes in conductance or resistance of piezoresistive sensing layer under strain are monitored have been developed. [ 6,7,10,13-15,17-19,21,22 ] While most of them have been still used for detection of a large strain range of about a few to tens of percentages, [ 14,15,19,21,22 ] ultrasensitive strain sensor having the detection limit less than 0.1% has been rarely reported. Furthermore, transport properties in the piezoresistive sensing layer upon strain for understanding of sensing mechanism are not easily extractable. Development of ultrasensitive strain sensors having the capability of detecting extremely low strain levels in electronic skins, robot sensors or other human-machine interfaces is of great interest. Among various strain sensing materials, graphene is a fascinating carbon nanostructure and has received strong interest due to its exceptional electrical, mechanical and optical properties. [ 23-25 ] There have been some recent reports demonstrating that the strain can dramatically modify the electronic and optical properties of graphene. [ 20,26-29 ] Moreover, under strain, the band gap of graphene can be opened because of the breaking of the sublattice symmetry of the two carbon sublattices of graphene. [ 29,30 ] Based on these features, graphene is a promising candidate as a strain sensing material. There have been only a few approaches to assemble a strain sensor from a single sheet of graphene utilizing chemical vapor deposition (CVD), [ 17-19 ] epitaxial growth, [ 10,19 ] or mechanical exfoliation. [ 20 ] However, graphene-based devices used in ultrasensitive strain sensors still have some limitations. For example, modifi cation of the electrical resistance is required under an applied tensile strain but the device cannot detect small levels of strain (the minimum strain that can detected in the graphene-based resistor device was less 2.47% [ 17 ] and the sensing mechanism was not elucidated in detail. In addition, ultrasensitive strain sensing can be possible by observing shifts of the Raman spectrum [ 20 ] but this approach requires costly equipment, making it uneconomical for real-life applications. Another interesting form of strain sensing layer is a networked fi lm of graphene nanosheets. Graphene nanosheets, which are manufactured by the chemical exfoliation of graphite, are often called reduced graphene oxide (rGO) nanosheets. [ 31-33 ] Studies of electronic conduction in the rGO network have shown that the conduction is attributed to two main components: (i) intra-nanosheet resistance (R intra) controlled by
Nano Biomedicine and Engineering, 2021
Strain sensors have spread at present times, and their electrical resistance has been interpreted. In reality, the use of strain sensors has broadened the reach of technology and allowed us to track changes in the environment in various ways. In recent years, due to their distinctive properties, films based on advanced carbon nanomaterials have started applying sophistication sensing. The strength of the tailored material has been obtained in addition to the various functions applied to these nanomaterials due to the particular structure of the nanomaterials. A prime catalyst for developing nanoscale sensors was this excellent feature. Carbon nanomaterials-based films have been increasing widely due to the excellent properties of nanocomposite-based films for sensing applications (piezoelectric application). There is also an instinctive structure of nanomaterials so that the material is high. Carbon nanomaterials such as graphene are now an excellent alternative for the production o...
ACS Omega
In recent times, flexible piezoresistive polymer nanocomposite-based strain sensors are in high demand in wearable devices and various new age applications. In the polymer nanocomposite-based strain sensor, the dispersion of conductive nanofiller remains challenging due to the competing requirements of homogenized dispersion of nanofillers in the polymer matrix and retaining of the inherent characteristics of nanofillers. In the present work, waterproof and flexible poly(vinylidene difluoride) (PVDF) with a polymer-functionalized hydrogenexfoliated graphene (HEG)-based piezoresistive strain sensor is developed and demonstrated. The novelty of the work is the incorporation of polystyrene sulfonate sodium salt (PSS) polymer-functionalized HEG in a PVDF-based flexible piezoresistive strain sensor. The PSS-HEG provides stable dispersion in the hydrophobic PVDF polymer matrix without sacrificing its inherent characteristics. The electrical conductivity of the PVDF/PSS-HEG-based strain sensor is 0.3 S cm −1 , which is two orders of magnitude higher than the PVDF/HEG-based strain sensor. Besides, near the percolation region, the PVDF/PSS-HEG shows a maximum gauge factor of 10, which is about two times higher than the PVDF/HEG-based flexible strain sensor and 5-fold higher than the commercially available metallic strain gauge. The enhancement in the gauge factor is due to the stable dispersion of PSS-HEG in the PVDF matrix and electron conjugation caused by the adherence of negatively charged sulfonate functional groups on the HEG. The developed waterproof flexible strain sensor is demonstrated using portable wireless interfacing device for various applications. This work shows that the waterproof flexible PVDF/ PSS-HEG-based strain sensor can be a potential alternative to the commercially available metallic strain gauge.
Graphene–polymer coating for the realization of strain sensors
Beilstein Journal of Nanotechnology, 2017
In this work we present a novel route to produce a graphene-based film on a polymer substrate. A transparent graphite colloidal suspension was applied to a slat of poly(methyl methacrylate) (PMMA). The good adhesion to the PMMA surface, combined with the shear stress, allows a uniform and continuous spreading of the graphite nanocrystals, resulting in a very uniform graphene multilayer coating on the substrate surface. The fabrication process is simple and yields thin coatings characterized by high optical transparency and large electrical piezoresitivity. Such properties envisage potential applications of this polymer-supported coating for use in strain sensing. The electrical and mechanical properties of these PMMA/graphene coatings were characterized by bending tests. The electrical transport was investigated as a function of the applied stress. The structural and strain properties of the polymer composite material were studied under stress by infrared thermography and micro-Rama...
Quantifying the Piezoresistive Mechanism in High-Performance Printed Graphene Strain Sensors
ACS Applied Materials & Interfaces
Printed strain sensors will be important in applications such as wearable devices, which monitor breathing and heart function. Such sensors need to combine high sensitivity and low resistance with other factors such as cyclability, low hysteresis, and minimal frequency/strain-rate dependence. Although nanocomposite sensors can display a high gauge factor (G), they often perform poorly in the other areas. Recently, evidence has been growing that printed, polymer-free networks of nanoparticles, such as graphene nanosheets, display very good all-round sensing performance, although the details of the sensing mechanism are poorly understood. Here, we perform a detailed characterization of the thickness dependence of piezoresistive sensors based on printed networks of graphene nanosheets. We find both conductivity and gauge factor to display percolative behavior at low network thickness but bulk-like behavior for networks above ∼100 nm thick. We use percolation theory to derive an equation for gauge factor as a function of network thickness, which well-describes the observed thickness dependence, including the divergence in gauge factor as the percolation threshold is approached. Our analysis shows that the dominant contributor to the sensor performance is not the effect of strain on internanosheet junctions but the strain-induced modification of the network structure. Finally, we find these networks display excellent cyclability, hysteresis, and frequency/strain-rate dependence as well as gauge factors as high as 350.
Scientia Iranica
A cost-effective piezoresistive sensor based on PVC/Reduced graphene oxide (rGO) was fabricated and its performance was investigated. The weight percent range from 0.1 to 30% of rGO in PVC matrix was studied. Composite parts were prepared by using the solution casting method from tetrahydrofurane (THF) solvent followed by solvent evaporation. The plot of electrical conduction versus rGO percentage was constructed to obtain the percolation threshold concentration. It was found that the percolation threshold of rGO leading to a continuous stable electrical conductivity in PVC matrix is about 25% beyond which electrical resistance was reduced from about 800 GΩ to lower than 100 KΩ range. The relative changes in electrical resistance of prepared polymer parts as a result of impact (stress), stretch and bending deformation were studied. The results showed that the fabricated composite can be used for sensing and/or monitoring and measurement of any mechanical displacement with high sensitivity, promising reproducibility and satisfactory durability. It must be mentioned that, during impact tests of polymer composites, a small piezoelectric effect was also observed for which further complimentary studies are being planned to be performed in near future in order to better understand this effect and its underlining molecular basis.