scholarly journals Stretchable Strain Sensor with Controllable Negative Resistance Sensitivity Coefficient Based on Patterned Carbon Nanotubes/Silicone Rubber Composites

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 716
Author(s):  
Rong Dong ◽  
Jianbing Xie
Keyword(s):  
Carbon Nanotubes ◽  
Silica Gel ◽  
Strain Sensor ◽  
Sensitivity Coefficient ◽  
Negative Resistance ◽  
Human Motion ◽  
Strain Sensors ◽  
Application Range ◽  
Human Motion Monitoring ◽  
Soft Elastomer

In this paper, stretchable strain sensors with a controllable negative resistance sensitivity coefficient are firstly proposed. In order to realize the sensor with a negative resistance sensitivity coefficient, a stretchable stress sensor with sandwich structure is designed in this paper. Carbon nanotubes are added between two layers of silica gel. When the sensor is stretched, carbon nanotubes will be squeezed at the same time, so the sensor will show a resistance sensitivity coefficient that the resistance becomes smaller after stretching. First, nanomaterials are coated on soft elastomer, then a layer of silica gel is wrapped on the outside of the nanomaterials. In this way, similar to sandwich biscuits, a stretchable strain sensor with controllable negative resistance sensitivity coefficient has been obtained. Because the carbon nanotubes are wrapped between two layers of silica gel, when the silica gel is stretched, the carbon nanotubes will be squeezed longitudinally, which increases their density and resistance. Thus, a stretchable strain sensor with negative resistance sensitivity coefficient can be realized, and the resistivity can be controlled and adjusted from 12.7 Ω·m to 403.2 Ω·m. The sensor can be used for various tensile testing such as human motion monitoring, which can effectively expand the application range of conventional tensile strain sensor.

A Stretchable Strain Sensor Based on CNTs/GR for Human Motion Monitoring

NANO ◽  
2022 ◽  
Author(s):  
Delin Chen ◽  
Hongmei Zhao ◽  
Weidong Yang ◽  
Dawei Wang ◽  
Xiaowei Huang ◽  
...  
Keyword(s):  
Strain Sensor ◽  
Human Movement ◽  
Human Motion ◽  
Strain Sensors ◽  
Quick Response ◽  
Practical Applications ◽  
Sensing Range ◽  
Human Monitoring ◽  
Human Motion Monitoring ◽  
Smart Wearable

Flexible/stretchable strain sensors have attracted much attention due to their advantages for human-computer interaction, smart wearable and human monitoring. However, there are still great challenges on gaining super durability, quick response, and wide sensing range. This paper provides a simple process to obtain a sensor which is based on graphene (GR)/carbon nanotubes (CNTs) and Ecoflex hybrid, which demonstrates superb endurance (over 1000 cycles at 100% strain), remarkable sensitivity (strain over 125% sensitivity up to 20) and wide sensing range (175%). All results indicate that it is capable for human movement monitoring, such as finger and knee bending and pulse beat. Most importantly, it can be used as a warning function for the night cyclist’s ride. This research provides the feasibility of using this sensor for practical applications.

Sensitive and wearable carbon nanotubes/carbon black strain sensors with wide linear ranges for human motion monitoring

2018 ◽  
Vol 29 (7) ◽  
pp. 5589-5596 ◽  
Author(s):  
Ruifeng Zhang ◽  
Peng Pan ◽  
Qiuli Dai ◽  
Xiaoping Yang ◽  
Zhengchun Yang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Black ◽  
Human Motion ◽  
Strain Sensors ◽  
Human Motion Monitoring

scholarly journals Multipoint-Detection Strain Sensor with a Single Electrode Using Optical Ultrasound Generated by Carbon Nanotubes

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3877
Author(s):  
Won Young Choi ◽  
Hyeong Geun Jo ◽  
Soo Won Kwon ◽  
Young Hun Kim ◽  
Joo Young Pyun ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Polyvinylidene Fluoride ◽  
Strain Sensor ◽  
Human Motion ◽  
Strain Sensors ◽  
Acoustic Energy ◽  
Multiple Electrodes ◽  
S Curve ◽  
Pulse Echo ◽  
Pulse Echo Method

With the development of wearable devices, strain sensors have attracted large interest for the detection of human motion, movement, and breathing. Various strain sensors consisting of stretchable conductive materials have been investigated based on resistance and capacitance differences according to the strain. However, this method requires multiple electrodes for multipoint detection. We propose a strain sensor capable of multipoint detection with a single electrode, based on the ultrasound pulse–echo method. It consists of several transmitters of carbon nanotubes (CNTs) and a single polyvinylidene fluoride receiver. The strain sensor was fabricated using CNTs embedded in stretchable polydimethylsiloxane. The received data are characterized by the different times of transmission from the CNTs of each point depending on the strain, i.e., the sensor can detect the positions of the CNTs. This study demonstrates the application of the multipoint strain sensor with a single electrode for measurements up to a strain of 30% (interval of 1%). We considered the optical and acoustic energy losses in the sensor design. In addition, to evaluate the utility of the sensor, finger bending with three-point CNTs and flexible phantom bending with six-point CNTs for the identification of an S-curve having mixed expansion and compression components were carried out.

scholarly journals Highly Skin-Conformal Laser-Induced Graphene-Based Human Motion Monitoring Sensor

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 951
Author(s):  
Sung-Yeob Jeong ◽  
Jun-Uk Lee ◽  
Sung-Moo Hong ◽  
Chan-Woo Lee ◽  
Sung-Hwan Hwang ◽  
...  
Keyword(s):  
Porous Structure ◽  
Conductive Polymer ◽  
Strain Sensor ◽  
Human Motion ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Direct Writing ◽  
Flexible Strain Sensor ◽  
Human Motion Monitoring ◽  
Monitoring Devices

Bio-compatible strain sensors based on elastomeric conductive polymer composites play pivotal roles in human monitoring devices. However, fabricating highly sensitive and skin-like (flexible and stretchable) strain sensors with broad working range is still an enormous challenge. Herein, we report on a novel fabrication technology for building elastomeric conductive skin-like composite by mixing polymer solutions. Our e-skin substrates were fabricated according to the weight of polydimethylsiloxane (PDMS) and photosensitive polyimide (PSPI) solutions, which could control substrate color. An e-skin and 3-D flexible strain sensor was developed with the formation of laser induced graphene (LIG) on the skin-like substrates. For a one-step process, Laser direct writing (LDW) was employed to construct superior durable LIG/PDMS/PSPI composites with a closed-pore porous structure. Graphene sheets of LIG coated on the closed-porous structure constitute a deformable conductive path. The LIG integrated with the closed-porous structure intensifies the deformation of the conductive network when tensile strain is applied, which enhances the sensitivity. Our sensor can efficiently monitor not only energetic human motions but also subtle oscillation and physiological signals for intelligent sound sensing. The skin-like strain sensor showed a perfect combination of ultrawide sensing range (120% strain), large sensitivity (gauge factor of ~380), short response time (90 ms) and recovery time (140 ms), as well as superior stability. Our sensor has great potential for innovative applications in wearable health-monitoring devices, robot tactile systems, and human–machine interface systems.

A highly stretchable strain sensor based on electrospun carbon nanofibers for human motion monitoring

RSC Advances ◽  
2016 ◽  
Vol 6 (82) ◽  
pp. 79114-79120 ◽  
Author(s):  
Yichun Ding ◽  
Jack Yang ◽  
Charles R. Tolle ◽  
Zhengtao Zhu
Keyword(s):  
Carbon Nanofibers ◽  
Strain Sensor ◽  
Human Motion ◽  
Sensitive Strain ◽  
Free Standing ◽  
Highly Stretchable ◽  
Human Motion Monitoring

A highly stretchable and sensitive strain sensor assembled by embedding a free-standing electrospun carbon nanofibers (CNFs) mat in a polyurethane (PU) matrix shows a fast, stable, and reproducible response to strain up to 300%.

Highly Stretchable, Hysteresis-Free Ionic Liquid-Based Strain Sensor for Precise Human Motion Monitoring

2017 ◽  
Vol 9 (2) ◽  
pp. 1770-1780 ◽  
Author(s):  
Dong Yun Choi ◽  
Min Hyeong Kim ◽  
Yong Suk Oh ◽  
Soo-Ho Jung ◽  
Jae Hee Jung ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Strain Sensor ◽  
Human Motion ◽  
Highly Stretchable ◽  
Human Motion Monitoring

scholarly journals A Fully Inkjet-Printed Strain Sensor Based on Carbon Nanotubes

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 792 ◽  
Author(s):  
Hsuan-Ling Kao ◽  
Cheng-Lin Cho ◽  
Li-Chun Chang ◽  
Chun-Bing Chen ◽  
Wen-Hung Chung ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Surface Morphology ◽  
Silver Film ◽  
Strain Sensor ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Lower Sensitivity ◽  
High Reproducibility ◽  
Silver Films ◽  
Microcrack Detection

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.

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