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

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.

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2531
Author(s):  
Yelin Ko ◽  
Ji-seon Kim ◽  
Chi Cuong Vu ◽  
Jooyong Kim

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.


2021 ◽  
Author(s):  
Lu Liu ◽  
Libo Wang ◽  
Xuqing Liu ◽  
Wenfeng Yuan ◽  
Mengmeng Yuan ◽  
...  

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.


Author(s):  
Mohammed Al-Rubaiai ◽  
Ryohei Tsuruta ◽  
Umesh Gandhi ◽  
Chuan Wang ◽  
Xiaobo Tan

Stretchable strain sensors with large strain range, high sensitivity, and excellent reliability are of great interest for applications in soft robotics, wearable devices, and structure-monitoring systems. Unlike conventional template lithography-based approaches, 3D-printing can be used to fabricate complex devices in a simple and cost-effective manner. In this paper, we report 3D-printed stretchable strain sensors that embeds a flexible conductive composite material in a hyper-plastic substrate. Three commercially available conductive filaments are explored, among which the conductive thermoplastic polyurethane (ETPU) shows the highest sensitivity (gauge factor of 5), with a working strain range of 0%–20%. The ETPU strain sensor exhibits an interesting behavior where the conductivity increases with the strain. In addition, an experiment for measuring the wind speed is conducted inside a wind tunnel, where the ETPU sensor shows sensitivity to the wind speed beyond 5.6 m/s.


Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 156 ◽  
Author(s):  
Jae Hyuk Choi ◽  
Myung Gyu Shin ◽  
Young Jung ◽  
Dong Hwan Kim ◽  
Jong Soo Ko

In this study, we fabricated strain sensors by aligning silver nanowires and transferring them with polydimethylsiloxane (PDMS) and compared the performances of the fabricated strain sensors along the alignment direction. Two types of flexible strain sensors embedded with the aligned silver nanowires were fabricated: one in the longitudinal direction, which is the same as the alignment direction, and the other in the lateral direction, which is perpendicular to the alignment direction. We then evaluated their properties. The proposed longitudinally aligned strain sensor showed the maximum sensitivity (gauge factor (GF) = 89.99) under 25% tensile conditions, which is 7.08 times higher than the sensitivity (GF = 12.71) shown by the laterally aligned strain sensor under 25% tensile conditions. This finding confirmed that the alignment direction of silver nanowires influences the sensitivity of flexible strain sensors. Furthermore, this study demonstrates that the laterally aligned strain sensor (ε > 60%) can be used in wearable devices because it satisfies the required strain range (ε > 50%). Since the strain sensors were fabricated using the temperature-controlled dip coating process, they can be produced at low cost in large quantities, and thus they have advantages for commercialization. These characteristics will be applicable to various flexible devices as well as to flexible strain sensors.


2019 ◽  
Vol 6 (11) ◽  
pp. 3119-3124 ◽  
Author(s):  
Runfei Wang ◽  
Wei Xu ◽  
Wenfeng Shen ◽  
Xiaoqing Shi ◽  
Jian Huang ◽  
...  

Transparent film strain sensors based on silver nanowires and thermoplastic polyurethane are promising candidates for detecting various human motions and monitoring the mass of some kinetic objects.


2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Morteza Vatani ◽  
Yanfeng Lu ◽  
Kye-Shin Lee ◽  
Ho-Chan Kim ◽  
Jae-Won Choi

There have been increasing demands and interests in stretchable sensors with the development of flexible or stretchable conductive materials. These sensors can be used for detecting large strain, 3D deformation, and a free-form shape. In this work, a stretchable conductive sensor has been developed using single-walled carbon nanotubes (SWCNTs) and monofunctional acrylate monomers (cyclic trimethylolpropane formal acrylate and acrylate ester). The suggested sensors have been fabricated using a screw-driven microdispensing direct-write (DW) technology. To demonstrate the capabilities of the DW system, effects of dispensing parameters such as the feed rate and material flow rate on created line widths were investigated. Finally, a stretchable conductive sensor was fabricated using proper dispensing parameters, and an experiment for stretchability and resistance change was accomplished. The result showed that the sensor had a large strain range up to 90% with a linear resistance change and gauge factor ∼2.7. Based on the results, it is expected that the suggested DW stretchable sensor can be used in many application areas such as wearable electronics, tactile sensors, 3D structural electronics, etc.


2020 ◽  
Author(s):  
Joana P. Neto ◽  
Adriana Costa ◽  
Joana Vaz Pinto ◽  
André Marques–Smith ◽  
Júlio Costa ◽  
...  

AbstractThis work explored hybrid films of silver nanowires (AgNWs) with indium-doped zinc oxide (IZO) for developing high-performance and low-cost electrocorticography (ECoG) electrodes.The hybrid films achieved a sheet resistance of 6 Ω/sq while maintaining a transparency of ≈60% at 550 nm. Electrodes with 500 μm diameter were fabricated with these films and reached an impedance of 20 kΩ at 1 kHz and a charge storage capacity of 3.2 mC/cm2, a 2× and 320× improvement over IZO electrodes, respectively. Characterization of light-induced artifacts was performed showing that small light intensities (<14 mW/mm2) elicit electrical potential variation in the magnitude order of baseline noise. The validation of electrodes in vivo was achieved by recording electrical neural activity from the surface of rat cortex under anaesthesia. Moreover, the presence of the films did not cause obstruction of light during fluorescence microscopy.The presented film and electrode characterization studies highlighted the capabilities of this hybrid structure to fabricate transparent and flexible electrodes that are able to combine the superior temporal resolution of extracellular electrophysiology with the spatial resolution offered by optical imaging.


Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4181 ◽  
Author(s):  
Daniel Zymelka ◽  
Takahiro Yamashita ◽  
Xiuru Sun ◽  
Takeshi Kobayashi

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.


2021 ◽  
Vol 35 (06) ◽  
pp. 2150086
Author(s):  
Y. H. Wang ◽  
X. L. Wu ◽  
X. Yang ◽  
H. Xie

Flexible silver nanowires (AgNWs) transparent conductive films (TCFs) were fabricated on poly(ethylene terephthalate) (PET) substrate by using spray coating process. Effects of concentration and amount of AgNWs suspension on the performances of optoelectronics and microstructures of AgNWs TCFs were investigated. The experimental results demonstrate that as the increase of both of concentration and amount of AgNWs suspension, the sheet resistance and nonuniformity factor of the sheet resistance (NUF) and transmittance of AgNWs TCFs decrease and the root mean square (RMS) roughness and figure of merit (FoM) and haze of the AgNWs TCFs increase, respectively, due to the increase of the deposition density of AgNWs on the substrate. The flexible AgNWs TCFs with excellent comprehensive performance, which is a NUF of 0.48, haze of 1.94%, FoM of 148.5, transmittance of 84.5%, and sheet resistance of [Formula: see text], can be obtained under the proper experimental conditions. The pressure treatment can improve the electrical conductivity of AgNWs TCFs due to the increase of contact area and the decrease of contact resistance. AgNWs TCF with pressure treatment also exhibits excellent reliability against mechanical bending over 1000 cycles. Our works demonstrate that flexible AgNWs TCFs with high performance can be obtained by using spray coating method, which is one of the common techniques for preparing coatings or films.


Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 889
Author(s):  
Lu Liu ◽  
Libo Wang ◽  
Xuqing Liu ◽  
Wenfeng Yuan ◽  
Mengmeng Yuan ◽  
...  

Flexible and comfortable wearable electronics are as a second skin for humans as they can collect the physiology of humans and show great application in health and fitness monitoring. MXene Ti3C2Tx have been used in flexible electronic devices for their unique properties such as high conductivity, excellent mechanical performance, flexibility, and good hydrophilicity, but less research has focused on MXene-based cotton fabric strain sensors. In this work, a high-performance wearable strain sensor composed of two-dimensional (2D) MXene d-Ti3C2Tx nanomaterials and cotton fabric is reported. Cotton fabrics were selected as substrate as they are comfortable textiles. 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. 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.


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