scholarly journals Inkjet Printing of Highly Sensitive, Transparent, Flexible Linear Piezoresistive Strain Sensors

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Ting-Kuo Kang
Keyword(s):  
Thin Film ◽  
Inkjet Printing ◽  
Mechanical Strain ◽  
Strain Range ◽  
Phase Segregation ◽  
Strain Sensors ◽  
Tunneling Effect ◽  
Gauge Factor ◽  
Highly Sensitive ◽  
Thin Film Resistors

Flexible strain sensors are fabricated by using a simple and low-cost inkjet printing technology of graphene-PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) conductive ink. The inkjet-printed thin-film resistors on a polyethylene terephthalate (PET) substrate exhibit an excellent optical transmittance of about 90% over a visible wavelength range from 400 to 800 nm. While an external mechanical strain is applied to thin-film resistors as strain sensors, a gauge factor (GF) of the piezoresistive (PR) strain sensors can be evaluated. To improve the GF value of the PR strain sensors, a high resistive (HR) path caused by the phase segregation of the PEDOT:PSS polymer material is, for the first time, proposed to be perpendicular to the PR strain sensing direction. The increase in the GF with the increase in the HR number of the PR strain sensors without a marked hysteresis is found. The result can be explained by the tunneling effect with varied initial tunneling distances and tunneling barriers due to the increase in the number of HR. Finally, a high GF value of approximately 165 of three HR paths is obtained with a linear output signal at the strain range from 0% to 0.33%, further achieving for the inkjet printing of highly sensitive, transparent, and flexible linear PR strain sensors.

scholarly journals Graphene as a Piezoresistive Material in Strain Sensing Applications

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Farid Sayar Irani ◽  
Ali Hosseinpour Shafaghi ◽  
Melih Can Tasdelen ◽  
Tugce Delipinar ◽  
Ceyda Elcin Kaya ◽  
...  
Keyword(s):  
Mechanical Strain ◽  
Evolutionary Process ◽  
Strain Range ◽  
Device Fabrication ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Characterization Methods ◽  
Accuracy Measurement ◽  
Sensing Applications

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 types of graphene-based strain sensors with side-by-side tabular comparison in terms of figures-of-merit, including strain range and sensitivity, otherwise referred to as the gauge factor. We demonstrate the material synthesis, device fabrication and integration challenges for researchers to achieve both wide strain range and high sensitivity in graphene-based strain sensors. Last of all, several applications of graphene-based strain sensors for different purposes are described. All in all, the evolutionary process of graphene-based strain sensors in recent years, as well as the upcoming challenges and future directions for emerging studies are highlighted.

scholarly journals Development of Highly Sensitive Strain Sensor Using Area-Arrayed Graphene Nanoribbons

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura
Keyword(s):  
Graphene Nanoribbons ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Bending Test ◽  
Gauge Factor ◽  
Four Point Bending ◽  
Current Voltage ◽  
Highly Sensitive ◽  
Current Voltage Relationship

In this study, a basic design of area-arrayed graphene nanoribbon (GNR) strain sensors was proposed to realize the next generation of strain sensors. To fabricate the area-arrayed GNRs, a top-down approach was employed, in which GNRs were cut out from a large graphene sheet using an electron beam lithography technique. GNRs with widths of 400 nm, 300 nm, 200 nm, and 50 nm were fabricated, and their current-voltage characteristics were evaluated. The current values of GNRs with widths of 200 nm and above increased linearly with increasing applied voltage, indicating that these GNRs were metallic conductors and a good ohmic junction was formed between graphene and the electrode. There were two types of GNRs with a width of 50 nm, one with a linear current–voltage relationship and the other with a nonlinear one. We evaluated the strain sensitivity of the 50 nm GNR exhibiting metallic conduction by applying a four-point bending test, and found that the gauge factor of this GNR was about 50. Thus, GNRs with a width of about 50 nm can be used to realize a highly sensitive strain sensor.

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.

scholarly journals Printed Strain Sensors Based on an Intermittent Conductive Pattern Filled with Resistive Ink Droplets

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4181 ◽  
Author(s):  
Daniel Zymelka ◽  
Takahiro Yamashita ◽  
Xiuru Sun ◽  
Takeshi Kobayashi
Keyword(s):  
Strain Range ◽  
Functional Materials ◽  
Cost Effective ◽  
Hybrid Structure ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Strain Sensitivity ◽  
Sensor Design ◽  
Good Strain ◽  
Single Droplets

In this study, we demonstrate a strain sensor fabricated as a hybrid structure of a conductive intermittent pattern with embedded single droplets of a functional resistive ink. The main feature of our proposed sensor design is that although the intermittent pattern comprises the majority of the entire sensor area, the strain sensitivity depends almost selectively on the resistive droplets. This opens up the possibility for fast and inexpensive evaluation of sensors manufactured from various functional materials. As the use of resistive ink was limited to single droplets deposition, the required ink amount needed to build a sensor can be considerably reduced. This makes the sensors cost-effective and simple for fabrication. In this study, our proposed sensor design was evaluated when a carbon-based ink was used as the resistive material incorporated into an intermittent structure made of silver. The developed strain sensors were tested during bending deformations demonstrating good strain sensitivity (gauge factor: 7.71) and no hysteresis within the investigated strain range.

scholarly journals Ultrasensitive Strain Sensor Based on Pre-Generated Crack Networks Using Ag Nanoparticles/Single-Walled Carbon Nanotube (SWCNT) Hybrid Fillers and a Polyester Woven Elastic Band

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2531
Author(s):  
Yelin Ko ◽  
Ji-seon Kim ◽  
Chi Cuong Vu ◽  
Jooyong Kim
Keyword(s):  
High Performance ◽  
Strain Sensor ◽  
Strain Range ◽  
Human Motion ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Elastic Band ◽  
Practical Applications ◽  
Single Walled Carbon ◽  
Novel Strategy

Flexible strain sensors are receiving a great deal of interest owing to their prospective applications in monitoring various human activities. Among various efforts to enhance the sensitivity of strain sensors, pre-crack generation has been well explored for elastic polymers but rarely on textile substrates. Herein, a highly sensitive textile-based strain sensor was fabricated via a dip-coat-stretch approach: a polyester woven elastic band was dipped into ink containing single-walled carbon nanotubes coated with silver paste and pre-stretched to generate prebuilt cracks on the surface. Our sensor demonstrated outstanding sensitivity (a gauge factor of up to 3550 within a strain range of 1.5–5%), high stability and durability, and low hysteresis. The high performance of this sensor is attributable to the excellent elasticity and woven structure of the fabric substrate, effectively generating and propagating the prebuilt cracks. The strain sensor integrated into firefighting gloves detected detailed finger angles and cyclic finger motions, demonstrating its capability for subtle human motion monitoring. It is also noteworthy that this novel strategy is a very quick, straightforward, and scalable method of fabricating strain sensors, which is extremely beneficial for practical applications.

scholarly journals Synergistic Effect of Graphene/Silver Nanowire Hybrid Fillers on Highly Stretchable Strain Sensors Based on Spandex Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2063
Author(s):  
Tan Thong Vo ◽  
Hyeon-Jong Lee ◽  
Sang-Yun Kim ◽  
Ji Won Suk
Keyword(s):  
Synergistic Effect ◽  
High Performance ◽  
Silver Nanowires ◽  
Large Strain ◽  
Strain Range ◽  
Strain Sensors ◽  
Silver Nanowire ◽  
Gauge Factor ◽  
Hybrid Fillers ◽  
Conductive Nanomaterials

Embedding conductive nanomaterials into elastomeric polymer matrices is one of the most promising approaches for fabricating stretchable strain sensors capable of monitoring large mechanical movements or deformation through the detection of resistance changes. Here, hybrid fillers comprising graphene and silver nanowires (AgNWs) are incorporated into extremely stretchable spandex to fabricate strain sensors. Composites containing only graphene and those containing the graphene/AgNW hybrid fillers are systematically investigated by evaluating their electrical and mechanical properties. The synergistic effect between graphene and AgNWs enable the strain sensors based on the composites to experience a large strain range of up to 120%, and low hysteresis with a high gauge factor of 150.3 at a strain of 120%. These reliable strain sensors are utilized for monitoring human motions such as heartbeats and body movements. The findings of this study indicate the significant applicability of graphene/AgNW/spandex composites in future applications that demand high-performance stretchable strain sensors.

Ultra-stretchable and highly sensitive strain sensor based on gradient structure carbon nanotubes

Nanoscale ◽  
2018 ◽  
Vol 10 (28) ◽  
pp. 13599-13606 ◽  
Author(s):  
Binghao Liang ◽  
Zhiqiang Lin ◽  
Wenjun Chen ◽  
Zhongfu He ◽  
Jing Zhong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Sensitive Strain ◽  
Gauge Factor ◽  
Gradient Structure ◽  
Highly Sensitive ◽  
Highly Stretchable

A highly stretchable and sensitive strain sensor based on a gradient carbon nanotube was developed. The strain sensors show an unprecedented combination of both high sensitivity (gauge factor = 13.5) and ultra-stretchability (>550%).

Inkjet Printing of Carbon Nanotube-Polyimide Nanocomposite Strain Sensor

2016 ◽  
Author(s):  
Qiuyan Li ◽  
Qing-Ming Wang
Keyword(s):  
Thin Film ◽  
Carbon Nanotube ◽  
Inkjet Printing ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Humidity Effect ◽  
Resistance Change ◽  
Drop On Demand ◽  
Potential Factors ◽  
Mechanical Devices

Inkjet printing has become a promising way to fabricate electrical mechanical devices and it has become a tool for rapid manufacturing technology. In this paper, the fabrication procedure and the characterization of the piezoresistive properties of Carbon nanotube (CNT) - Polyimide (PI) nanocomposites are presented. The suspensions of CNT-PI nanocomposites of five different CNT weight concentration based on the percolation threshold were fabricated, and the suspensions were then deposited on the polyimide substrate by a drop-on-demand piezoelectric inkjet printer. This makes it possible for the uniformity and geometry of the thin film to be highly controlled. Once the nanocomposites were fully cured, the strain sensors were ready for calibration. Under uniaxial tension, the strain and resistance change of the strain sensors were measured, and the gauge factors could be calculated. The temperature and humidity are two potential factors to effect the performance of the strain sensors. The temperature coefficients of the CNT-PI nanocomposites were measured and the temperature compensation methods were proposed. The humidity effect on the nanocomposites was also monitored, and a thin layer of Parylene-C was coated on the surface of the nanocomposites thin film and the effect of the coating was tested. In general, the inkjet printing technique was proved to be a convenient way to fabricate flexible nanocomposites thin film with uniform thickness and precise geometry control. The CNT-PI nanocomposite has good performance as piezoresistive strain sensor.

scholarly journals High-Performance Wearable Strain Sensor Based on MXene@Cotton Fabric with Network Structure

2021 ◽  
Author(s):  
Lu Liu ◽  
Libo Wang ◽  
Xuqing Liu ◽  
Wenfeng Yuan ◽  
Mengmeng Yuan ◽  
...  
Keyword(s):  
Cotton Fabric ◽  
High Performance ◽  
Mechanical Performance ◽  
Active Material ◽  
Large Body ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Gauge Factor

Abstract Although 2D nanomaterials such as MXene Ti3C2Tx have been used in flexible electronic devices for their unique properties such as high conductivity, excellent mechanical performance, flexibility, and good hydrophilicity, less research has focused on of MXene-based cotton fabric strain sensors. Moreover, fabrication of wearable strain sensors with a low cost, high sensitivity, good biocompatibility, and broad sensing range is still a challenge. In this work, a high-performance wearable strain sensor composed of 2D MXene d-Ti3C2Tx nanomaterials and cotton fabric is reported. As the active material in the sensor, MXene d-Ti3C2Tx exhibited an excellent conductivity and hydrophilicity and adhered well to the fabric fibers by electrostatic adsorption. Due to the unique structure of the fabric substrate and the properties of MXene sheets, the fabricated pressure sensor achieved a high sensitivity. The gauge factor of the MXene@cotton fabric strain sensor reached up to 4.11 within the strain range of 15 %. Meanwhile, the sensor possessed high durability (>500 cycles) and a low strain detection limit of 0.3%. Finally, the encapsulated strain sensor was used to detect subtle or large body movements and exhibited a rapid response. This study shows that the MXene@cotton fabric strain sensor reported here have great potential for use in flexible, comfortable, and wearable devices for health monitoring and motion detection.

An Approach on the Use of Co-Sputtered W-DLC Thin Films as Piezoresistive Sensing Materials

2021 ◽  
Vol 14 ◽  
Author(s):  
Gabriela Leal ◽  
Humber Furlan ◽  
Marcos Massi ◽  
Mariana Amorim Fraga
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Synthesis Method ◽  
Pressure Sensors ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Diamond Like Carbon ◽  
Piezoresistive Sensors ◽  
Thin Film Resistors ◽  
Lift Off

Background: Miniaturized piezoresistive sensors, particularly strain gauges, pressure sensors, and accelerometers, have been used for measurements and control applications in various fields, such as automotive, aerospace, industrial, biomedical, sports, and many more. A variety of different materials have been investigated for the development of these sensors. Among them, diamond-like carbon (DLC) thin films have emerged as one of the most promising piezoresistive sensing materials due to their excellent mechanical properties, such as high hardness and high Young’s modulus. At the same time, metal doping has been studied to enhance its electrical properties. Objective: This article explores the use of co-sputtered tungsten-doped diamond-like carbon (W-DLC) thin films as microfabricated strain gauges or piezoresistors. Methods: Different serpentine thin-film resistors were microfabricated on co-sputtered W-DLC thin films using photolithography, metallization, lift-off, and RIE (reactive ion etching) processes. In order to evaluate their piezoresistive sensing performance, gauge factor (GF) measurements were carried out at room temperature using the cantilever beam method. Results: GF values obtained in this study for co-sputtered W-DLC thin films are comparable to those reported for W-DLC films produced and characterized by other techniques, which indicates the feasibility of our approach to use them as sensing materials in piezoresistive sensors. Conclusion: W-DLC thin films produced by the co-magnetron sputtering technique can be considered as sensing materials for miniaturized piezoresistive sensors due to the following key advantages: (i) easy and well-controlled synthesis method, (ii) good piezoresistive properties exhibiting a GF higher than metals, and (iii) thin-film resistors formed by a simple microfabrication process.

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