Ultra-sensitive flexible sandwich structural strain sensors based on a silver nanowire supported PDMS/PVDF electrospun membrane substrate

Author(s):  
Zhenhua Yang ◽  
Zijian Wu ◽  
Dawei Jiang ◽  
Renbo Wei ◽  
Xianmin Mai ◽  
...  

Flexible sandwich structural strain sensors based on silver nanowire supported PDMS/PVDF electrospun membrane substrates exhibit a gauge factor of 654.5.

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.


Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1701
Author(s):  
Ken Suzuki ◽  
Ryohei Nakagawa ◽  
Qinqiang Zhang ◽  
Hideo Miura

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.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjie Yan ◽  
Huei-Ru Fuh ◽  
Yanhui Lv ◽  
Ke-Qiu Chen ◽  
Tsung-Yin Tsai ◽  
...  

AbstractThere is an emergent demand for high-flexibility, high-sensitivity and low-power strain gauges capable of sensing small deformations and vibrations in extreme conditions. Enhancing the gauge factor remains one of the greatest challenges for strain sensors. This is typically limited to below 300 and set when the sensor is fabricated. We report a strategy to tune and enhance the gauge factor of strain sensors based on Van der Waals materials by tuning the carrier mobility and concentration through an interplay of piezoelectric and photoelectric effects. For a SnS2 sensor we report a gauge factor up to 3933, and the ability to tune it over a large range, from 23 to 3933. Results from SnS2, GaSe, GeSe, monolayer WSe2, and monolayer MoSe2 sensors suggest that this is a universal phenomenon for Van der Waals semiconductors. We also provide proof of concept demonstrations by detecting vibrations caused by sound and capturing body movements.


2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Heng Zhang ◽  
Dan Liu ◽  
Jeng-Hun Lee ◽  
Haomin Chen ◽  
Eunyoung Kim ◽  
...  

AbstractFlexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications. Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities, existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity. Here, an ultrasensitive, highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers. The bilayer sensor consists of an aligned carbon nanotube (CNT) array assembled on top of a periodically wrinkled and cracked CNT–graphene oxide film. The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched, leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100% strain. The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3, to the benefit of accurate detection of loading directions by the multidirectional sensor. This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity, selectivity, and stretchability, demonstrating promising applications in full-range, multi-axis human motion detection for wearable electronics and smart robotics.


Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1469 ◽  
Author(s):  
Orathai Tangsirinaruenart ◽  
George Stylios

This research presents an investigation of novel textile-based strain sensors and evaluates their performance. The electrical resistance and mechanical properties of seven different textile sensors were measured. The sensors are made up of a conductive thread, composed of silver plated nylon 117/17 2-ply, 33 tex and 234/34 4-ply, 92 tex and formed in different stitch structures (304, 406, 506, 605), and sewn directly onto a knit fabric substrate (4.44 tex/2 ply, with 2.22, 4.44 and 7.78 tex spandex and 7.78 tex/2 ply, with 2.22 and 4.44 tex spandex). Analysis of the effects of elongation with respect to resistance indicated the ideal configuration for electrical properties, especially electrical sensitivity and repeatability. The optimum linear working range of the sensor with minimal hysteresis was found, and the sensor’s gauge factor indicated that the sensitivity of the sensor varied significantly with repeating cycles. The electrical resistance of the various stitch structures changed significantly, while the amount of drift remained negligible. Stitch 304 2-ply was found to be the most suitable for strain movement. This sensor has a wide working range, well past 50%, and linearity (R2 is 0.984), low hysteresis (6.25% ΔR), good gauge factor (1.61), and baseline resistance (125 Ω), as well as good repeatability (drift in R2 is −0.0073). The stitch-based sensor developed in this research is expected to find applications in garments as wearables for physiological wellbeing monitoring such as body movement, heart monitoring, and limb articulation measurement.


2018 ◽  
Vol 4 (2) ◽  
pp. 1 ◽  
Author(s):  
Angelica Campigotto ◽  
Stephane Leahy ◽  
Ayan Choudhury ◽  
Guowei Zhao ◽  
Yongjun Lai

A novel, inexpensive, and easy-to-use strain sensor using polydimethylsiloxane (PDMS)  was developed. The sensor consists of a microchannel that is partially filled with a coloured liquid and embedded in a piece of PDMS. A finite element model was developed to optimize the geometry of the microchannel to achieve higher sensitivity. The highest gauge factor that was measured experimentally was 41. The gauge factor was affected by the microchannel’s square cross-sectional area, the number of basic units in the microchannel, and the inlet and outlet configuration. As a case study, the developed strain sensors were used to measure the rotation angle of the wrist and finger joints.


2011 ◽  
Vol 22 (18) ◽  
pp. 2155-2159 ◽  
Author(s):  
Y. Miao ◽  
L. Chen ◽  
Y. Lin ◽  
R. Sammynaiken ◽  
W. J. Zhang

The use of carbon nanotubes (CNTs) for construction of sensors is promising. This is due to some unique characteristics of CNTs. In recent years, strain sensors built from CNT composite films have been developed; however, their low piezoresistive sensitivity (gauge factor (GF)) in in-plane strain detection is a concern compared with other strain sensors. This article reports an experimental discovery of the superior piezoresistive response of a CNT film that is free of surfactants, known as the pure CNT film. The mechanism for the high GF with the pure CNT film strain sensors is also discussed.


Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 792 ◽  
Author(s):  
Hsuan-Ling Kao ◽  
Cheng-Lin Cho ◽  
Li-Chun Chang ◽  
Chun-Bing Chen ◽  
Wen-Hung Chung ◽  
...  

A fully inkjet-printed strain sensor based on carbon nanotubes (CNTs) was fabricated in this study for microstrain and microcrack detection. Carbon nanotubes and silver films were used as the sensing layer and conductive layer, respectively. Inkjet-printed CNTs easily undergo agglomeration due to van der Waals forces between CNTs, resulting in uneven films. The uniformity of CNT film affects the electrical and mechanical properties. Multi-pass printing and pattern rotation provided precise quantities of sensing materials, enabling the realization of uniform CNT films and stable resistance. Three strain sensors printed eight-layer CNT film by unidirectional printing, rotated by 180° and 90° were compared. The low density on one side of eight-layer CNT film by unidirectional printing results in more disconnection and poor connectivity with the silver film, thereby, significantly increasing the resistance. For 180° rotation eight-layer strain sensors, lower sensitivity and smaller measured range were found because strain was applied to the uneven CNT film resulting in non-uniform strain distribution. Lower resistance and better strain sensitivity was obtained for eight-layer strain sensor with 90° rotation because of uniform film. Given the uniform surface morphology and saturated sheet resistance of the 20-layer CNT film, the strain performance of the 20-layer CNT strain sensor was also examined. Excluding the permanent destruction of the first strain, 0.76% and 1.05% responses were obtained for the 8- and 20-layer strain sensors under strain between 0% and 3128 µε, respectively, which demonstrates the high reproducibility and recoverability of the sensor. The gauge factor (GF) of 20-layer strain sensor was found to be 2.77 under strain from 71 to 3128 µε, which is higher than eight-layer strain sensor (GF = 1.93) due to the uniform surface morphology and stable resistance. The strain sensors exhibited a highly linear and reversible behavior under strain of 71 to 3128 µε, so that the microstrain level could be clearly distinguished. The technology of the fully inkjet-printed CNT-based microstrain sensor provides high reproducibility, stability, and rapid hardness detection.


Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4838
Author(s):  
Zhengyang Du ◽  
Ji’an Chen ◽  
Chang Liu ◽  
Chen Jin ◽  
Min Han

We use gas phase deposition of well-defined nanoparticles (NPs) to fabricate closely-spaced Pd NP arrays on flexible membranes prepatterned with interdigital electrodes (IDEs). The evolution of the morphology and electron conductance of the NP arrays during deposition is analyzed. The growth of two-dimensional percolation clusters of interconnected NPs, which correlate with the percolation pathway for electron conduction in the NP deposits, is demonstrated. The percolative nature of the NP arrays permits us to finely control the percolation geometries and conductance of the NP film by controlling the NP deposition time so as to realize a precise and reproducible fabrication of sensing materials. Electron transport measurements reveal that the electrical conductance of the NP films is dominated by electron tunneling or hopping across the NP percolating networks. Based on the percolative and quantum tunneling nature, the closely-spaced Pd NP films on PET membranes are used as flexible strain sensors. The sensor demonstrates an excellent response ability to distinguish tiny deformations down to 5×10−4 strain and a high sensitivity with a large gauge factor of 200 up to 4% applied strain.


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