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 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 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 Flexible and wearable strain sensor based on electrospun carbon sponge/polydimethylsiloxane composite for human motion detection

RSC Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4186-4193
Author(s):  
He Gong ◽  
Chuan Cai ◽  
Hongjun Gu ◽  
Qiushi Jiang ◽  
Daming Zhang ◽  
...  
Keyword(s):  
Motion Detection ◽  
Strain Sensor ◽  
Human Motion ◽  
Gauge Factor ◽  
Human Motion Detection ◽  
Tensile Strains

Electrospun carbon sponge was used to measure tensile strains with a high gauge factor.

Polydiacetylene hydrogel self-healing capacitive strain sensor

2020 ◽  
Vol 8 (18) ◽  
pp. 6034-6041 ◽  
Author(s):  
V. Kesava Rao ◽  
Nitzan Shauloff ◽  
XiaoMeng Sui ◽  
H. Daniel Wagner ◽  
Raz Jelinek
Keyword(s):  
Strain Sensor ◽  
Mechanical Deformation ◽  
Human Motion ◽  
Self Healing ◽  
Highly Sensitive ◽  
Capacitive Strain

Highly sensitive and stretchable PDA–PAA–Cr3+ hydrogel capacitive strain sensor is fabricated and used to monitor mechanical deformation and human motion.

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 Quantitative Detection of Listeria monocytogenes and Listeria innocua by Real-Time PCR: Assessment of hly, iap, and lin02483 Targets and AmpliFluor Technology

2004 ◽  
Vol 70 (3) ◽  
pp. 1366-1377 ◽  
Author(s):  
David Rodr�guez-L�zaro ◽  
Marta Hern�ndez ◽  
Mariela Scortti ◽  
Teresa Esteve ◽  
Jos� A. V�zquez-Boland ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Real Time ◽  
Real Time Pcr ◽  
Target Genes ◽  
Dynamic Range ◽  
Significant Proportion ◽  
Quantitative Detection ◽  
Target Sequence ◽  
Food Borne ◽  
Highly Sensitive

ABSTRACT We developed and assessed real-time PCR (RTi-PCR) assays for the detection and quantification of the food-borne pathogen Listeria monocytogenes and the closely related nonpathogenic species L. innocua. The target genes were hly and iap for L. monocytogenes and lin02483 for L. innocua. The assays were 100% specific, as determined with 100 Listeria strains and 45 non-Listeria strains, and highly sensitive, with detection limits of one target molecule in 11 to 56% of the reactions with purified DNA and 3 CFU in 56 to 89% of the reactions with bacterial suspensions. Quantification was possible over a 5-log dynamic range, with a limit of 15 target molecules and R 2 values of >0.996. There was an excellent correspondence between the predicted and the actual numbers of CFU in the samples (deviations of <23%). The hly-based assay accurately quantified L. monocytogenes in all of the samples tested. The iap-based assay, in contrast, was unsuitable for quantification purposes, underestimating the bacterial counts by 3 to 4 log units in a significant proportion of the samples due to serovar-related target sequence variability. The combination of the two assays enabled us to classify L. monocytogenes isolates into one of the two major phylogenetic divisions of the species, I and II. We also assessed the new AmpliFluor technology for the quantitative detection of L. monocytogenes by RTi-PCR. The performance of this system was similar to that of the TaqMan system, although the former system was slightly less sensitive (detection limit of 15 molecules in 45% of the reactions) and had a higher quantification limit (60 molecules).

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 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.

Highly Sensitive and Large-Range Strain Sensor with a Self-Compensated Two-Order Structure for Human Motion Detection

2019 ◽  
Vol 11 (8) ◽  
pp. 8527-8536 ◽  
Author(s):  
Jianhua Ma ◽  
Peng Wang ◽  
Hongyu Chen ◽  
Shenjie Bao ◽  
Wei Chen ◽  
...  
Keyword(s):  
Motion Detection ◽  
Large Range ◽  
Strain Sensor ◽  
Human Motion ◽  
Order Structure ◽  
Human Motion Detection ◽  
Highly Sensitive
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