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.

scholarly journals Flexible and Highly Sensitive Strain Sensor Based on Laser-Induced Graphene Pattern Fabricated by 355 nm Pulsed Laser

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4867 ◽  
Author(s):  
Sung-Yeob Jeong ◽  
Yong-Won MA ◽  
Jun-Uk Lee ◽  
Gyeong-Ju Je ◽  
Bo-sung Shin
Keyword(s):  
Focal Length ◽  
Pulsed Laser ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Gauge Factor ◽  
Functional Evaluation ◽  
Mechanical Fracture ◽  
Highly Sensitive ◽  
Human Finger ◽  
Small Deformations

A laser-induced-graphene (LIG) pattern fabricated using a 355 nm pulsed laser was applied to a strain sensor. Structural analysis and functional evaluation of the LIG strain sensor were performed by Raman spectroscopy, scanning electron microscopy (SEM) imaging, and electrical–mechanical coupled testing. The electrical characteristics of the sensor with respect to laser fluence and focal length were evaluated. The sensor responded sensitively to small deformations, had a high gauge factor of ~160, and underwent mechanical fracture at 30% tensile strain. In addition, we have applied the LIG sensor, which has high sensitivity, a simple manufacturing process, and good durability, to human finger motion monitoring.

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%).

scholarly journals Preparing Polypyrrole-Coated Stretchable Textile via Low-Temperature Interfacial Polymerization for Highly Sensitive Strain Sensor

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 788 ◽  
Author(s):  
Chen ◽  
Li ◽  
Qiao ◽  
Lu
Keyword(s):  
Low Temperature ◽  
Real Time ◽  
Dynamic Range ◽  
Interfacial Polymerization ◽  
Strain Sensor ◽  
Human Motion ◽  
Gauge Factor ◽  
Infrared Spectrometry ◽  
Highly Sensitive ◽  
Human Motions

The stretchable sensor has been considered as the most important component in a wearable device. However, it is still a great challenge to develop a highly sensitive textile-based strain sensor with good flexibility, excellent skin affinity, and large dynamic range. Herein, polypyrrole (PPy) was immobilized on a stretchable textile knitted by polyester and spandex via low-temperature interfacial polymerization to prepare a conductive strain sensor for human motion and respiration measurements. Scanning electron microscopy, Fourier transform infrared spectrometry, and thermal gravimetric data verify that a thin layer of PPy has been successfully coated on the textile with a high density and very uniform distribution. The resistance of the as-prepared textile is 21.25 Ω/cm2 and the PPy-coated textile could be used as an electric conductor to light up a LED lamp. Moreover, the textile could tolerate folding at an angle of 180° and 500 times of bending-twisting cycles without significant changes on its resistance. A negative correlation between the resistance change and the applied strain is observed for the textile-based sensor in the strain ranging from 0 to 71% with the gauge factor of −0.46. After more than 200 cycles of stretching-releasing under the strain of 26%, there is no obvious alteration on the sensing responses. The sensors were attached on volunteers’ body or clothes for the real-time measurement of human motions and respiration, demonstrating that the textile-based sensor could sensitively detect finger, elbow, and knee bending and differentiate deep, normal, and fast breath. This work may provide an approach to uniform and dense coating conductive polymers on textiles for highly sensitive and stretchable sensors, which possess great potentials in practical applications for real-time monitoring human motions and physiological signs.

scholarly journals Flexible Metal/Polymer Composite Films Embedded with Silver Nanowires as a Stretchable and Conductive Strain Sensor for Human Motion Monitoring

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 372 ◽  
Author(s):  
Jinjin Luan ◽  
Qing Wang ◽  
Xu Zheng ◽  
Yao Li ◽  
Ning Wang
Keyword(s):  
Polymer Composite ◽  
Silver Nanowires ◽  
Composite Films ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Human Motion ◽  
Applied Strain ◽  
Potential Candidate ◽  
Flexible Metal ◽  
Metal Polymer

To avoid conductive failure due to the cracks of the metal thin film under external loads for the wearable strain sensor, a stretchable metal/polymer composite film embedded with silver nanowires (AgNWs) was examined as a potential candidate. The combination of Ag film and AgNWs enabled the fabrication of a conductive film that was applied as a high sensitivity strain sensor, with gauge factors of 7.1 under the applied strain of 0–10% and 21.1 under the applied strain of 10–30%. Furthermore, the strain sensor was demonstrated to be highly reversible and remained stable after 1000 bending cycles. These results indicated that the AgNWs could act as elastic conductive bridges across cracks in the metal film to maintain high conductivity under tensile and bending loads. As such, the strain sensor engineered herein was successfully applied in the real-time detection and monitoring of large motions of joints and subtle motions of the mouth.

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.

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.

scholarly journals Robust and conductive hydrogel based on mussel adhesive chemistry for remote monitoring of body signals

Friction ◽  
2020 ◽  
Author(s):  
Weijun Li ◽  
Hao Liu ◽  
Yuanyuan Mi ◽  
Miaoran Zhang ◽  
Jinmiao Shi ◽  
...  
Keyword(s):  
Antibacterial Properties ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Smart Device ◽  
Gauge Factor ◽  
Self Healing ◽  
3D Network ◽  
Mussel Adhesive ◽  
Physical And Chemical

AbstractThere is a high demand for hydrogels with multifunctional performance (a combination of adhesive, mechanical, and electrical properties) in biological, tissue engineering, robotics, and smart device applications. However, a majority of existing hydrogels are relatively rigid and brittle, with limited stretchability; this hinders their application in the emerging field of flexible devices. In this study, cheap and abundant potato residues were used with polyacrylamide (PAM) to fabricate a multifunctional hydrogel, and chitosan was used for the design of a three-dimentional (3D) network-structured hydrogel. The as-prepared hydrogels exhibited excellent stretchability, with an extension exceeding 900% and a recovery degree of over 99%. Due to the combination of physical and chemical cross-linking properties and the introduction of dopamine, the designed hydrogel exhibits a remarkable self-healing ability (80% mechanical recovery in 2 h), high tensile strength (0.75 MPa), and ultra-stretchability (900%). The resultant products offer superior properties compared to those of previously reported tough and self-healing hydrogels for wound adhesion. Chitosan and potato residues were used as scaffold materials for the hydrogels with excellent mechanical properties. In addition, in vitro experiments show that these hydrogels feature excellent antibacterial properties, effectively hindering the reproduction of bacteria. Moreover, the ternary hydrogel can act as a strain sensor with high sensitivity and a gauge factor of 1.6. The proposed strategy is expected to serve as a reference for the development of green and recyclable conductive polymers to fabricate hydrogels. The proposed hydrogel can also act as a suitable strain sensor for bio-friendly devices such as smart wearable electronic devices and/or for health monitoring.

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 Enhanced Stretchable and Sensitive Strain Sensor via Controlled Strain Distribution

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 218 ◽  
Author(s):  
Huamin Chen ◽  
Longfeng Lv ◽  
Jiushuang Zhang ◽  
Shaochun Zhang ◽  
Pengjun Xu ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Tensile Strain ◽  
Strain Sensor ◽  
Gauge Factor ◽  
Simple Method ◽  
Practical Applications ◽  
Simple Strategy ◽  
Highly Sensitive ◽  
Highly Stretchable ◽  
Maximum Tensile Strain

Stretchable and wearable opto-electronics have attracted worldwide attention due to their broad prospects in health monitoring and epidermal applications. Resistive strain sensors, as one of the most typical and important device, have been the subject of great improvements in sensitivity and stretchability. Nevertheless, it is hard to take both sensitivity and stretchability into consideration for practical applications. Herein, we demonstrated a simple strategy to construct a highly sensitive and stretchable graphene-based strain sensor. According to the strain distribution in the simulation result, highly sensitive planar graphene and highly stretchable crumpled graphene (CG) were rationally connected to effectively modulate the sensitivity and stretchability of the device. For the stretching mode, the device showed a gauge factor (GF) of 20.1 with 105% tensile strain. The sensitivity of the device was relatively high in this large working range, and the device could endure a maximum tensile strain of 135% with a GF of 337.8. In addition, in the bending mode, the device could work in outward and inward modes. This work introduced a novel and simple method with which to effectively monitor sensitivity and stretchability at the same time. More importantly, the method could be applied to other material categories to further improve the performance.

scholarly journals Polymer-Based Self-Standing Flexible Strain Sensor

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Fernando Martinez ◽  
Gregorio Obieta ◽  
Ion Uribe ◽  
Tomasz Sikora ◽  
Estibalitz Ochoteco
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistance ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Wearable Electronics ◽  
Rehabilitation Devices ◽  
Flexible Strain Sensor

The design and characterization of polymer-based self-standing flexible strain sensors are presented in this work. Properties as lightness and flexibility make them suitable for the measurement of strain in applications related with wearable electronics such as robotics or rehabilitation devices. Several sensors have been fabricated to analyze the influence of size and electrical conductivity on their behavior. Elongation and applied charge were precisely controlled in order to measure different parameters as electrical resistance, gauge factor (GF), hysteresis, and repeatability. The results clearly show the influence of size and electrical conductivity on the gauge factor, but it is also important to point out the necessity of controlling the hysteresis and repeatability of the response for precision-demanding applications.

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