A thermally-electrically double-responsive polycaprolactone – thermoplastic polyurethane/multi-walled carbon nanotube fiber assisted with highly effective shape memory and strain sensing performance

Qu, Meijie; Wang, Hai; Chen, Qiushan; Wu, Lu; Tang, Ping; Fan, Mingshuai; Guo, Yanqiu; Fan, Hongyu; Bin, Yuezhen

doi:10.1016/j.cej.2021.131648

Cited by 50 publications

(24 citation statements)

References 49 publications

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“…[78] Similarly, Wang et al fabricated a bilayer composite sensor based on a network of cracked CNTs and elastomer-infiltrated CNTs to achieve a fast response time of <10 ms. [79] Such sensors with small response and recovery times can be used for abrupt strain measurements, such as healthcare physiological signals. In addition, some sensors suffer from a large gap between response and recovery times, such as a shape memory fiber based on polycaprolactone (PCL), TPU, and CNTs, which has a low response time of 187 ms but a high recovery time of 831 ms. [80]…”

Section: Response and Recovery Timementioning

confidence: 99%

“…Qu et al prepared PCL-TPU fibers by wet spinning and then coated MWCNT onto the fiber surface using an immersion dry coating to prepare conductive PCL-TPU/MWCNT fibers, conductive fibers with better sensitivity, response time, and cycling stability. [80] He et al prepared highly stretchable conductive MWCNT/TPU composite fibers by wet spinning. The MWCNT/TPU mixed DMF suspension was extruded from a syringe through a spinneret into an acetone-based coagulation bath, and continuous wet fibers were collected on an aluminum foil drum.…”

Section: Spinning Processmentioning

confidence: 99%

“…Coating techniques mainly include spraying, [54,67,72,[85][86][87][88] sputtering, [89] vacuum filtration, [65,[90][91][92][93][94] and dip coating. [75,80,[95][96][97] Coating technology is a simple method to fabricate textile-type sensors. Strain sensors with high sensitivity and high stretchability can be fabricated by coating conductive materials on fibers, yarns or textiles using coating technology.…”

Section: Coating Technologymentioning

confidence: 99%

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Carbon Nanotube‐Based Strain Sensors: Structures, Fabrication, and Applications

Wang

Zhu

et al. 2022

Adv Materials Technologies

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flexible devices has received widespread attention. Among them, flexible strain sensors have attracted great interest from the industry and academia due to their promising applications in wearable devices, [1][2][3] electronic skin, [4,5] intelligent robots, [6] healthcare monitoring, [7] and humanmachine interfaces. [8,9] The three primary categories of strain sensors are resistive, [10] capacitive, [11] and piezoelectric. [12] The advantages of capacitive-type strain sensors are high sensitivity, rapid response, and high linearity, but the sensor has poor response performance on various strains due to their structural limitations. The performance of the piezoelectric-type strain sensor mainly focuses on the piezoelectric material, which requires excellent piezoelectricity of the material, but the piezoelectric material is more expensive and the measurable range is narrower. Compared to the above two types of sensors, resistivetype strain sensors have the advantages of a wider strain sensing range, relatively simple reading mechanism and easy fabrication, which have received wide attention in recent years in the fields of wearable devices and electronic skins. Therefore, this paper will focus on the resistive-type strain sensors. The working principle is that the structure of the conductive material changes when the device is stretched, bent, and twisted, causing the resistance of Flexible strain sensors have received widespread attention because of their great potential in many fields. Carbon nanotubes (CNTs) have been used as conductive materials for flexible strain sensors due to their excellent electrical and mechanical properties, and the fabricated flexible strain sensors have excellent sensing performance. This paper systematically summarizes the advances in flexible resistance-type strain sensors based on CNTs. The strain sensing mechanisms are introduced, including crack extension, tunneling effect, and disconnection of overlapping materials. The performance parameters of the sensors, including sensitivity, stretchability, linearity, hysteresis, dynamic durability, and transparency, are discussed comprehensively. The coating methods, 3D printing techniques, chemical vapor deposition, transfer methods, and spinning processes used to fabricate CNT strain sensors are highlighted. The effect of isolated and porous internal conductive structures, folded and microcracked surface structures, films and fabrics macroscopic structures on sensor performance were systematically analyzed. The applications of the sensors in medical health, motion monitoring, gesture recognition, human-computer interaction, and soft robotics are provided in detail. Finally, the future challenges of CNT flexible strain sensors are summarized and the outlook is presented. Although CNT strain sensors have made great progress so far, there are still many problems that need researchers' attention and solutions.

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Section: Response and Recovery Timementioning

confidence: 99%

Section: Spinning Processmentioning

confidence: 99%

Section: Coating Technologymentioning

confidence: 99%

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Carbon Nanotube‐Based Strain Sensors: Structures, Fabrication, and Applications

Wang

Zhu

et al. 2022

Adv Materials Technologies

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“…As a promising class of nanomaterials with excellent mechanical, thermal, and electrical properties, carbon nanotubes (CNTs) are uniquely superior in the context of electroactive SMPU preparation (Mahapatra et al, 2014;Ren et al, 2019;Qu et al, 2022). However, to obtain ideal CNTpolymer composites, one must achieve a uniform CNT dispersion in the polymer matrix and sufficient interfacial adhesion.…”

Section: Introductionmentioning

confidence: 99%

Electroactive shape memory polyurethane composites reinforced with octadecyl isocyanate-functionalized multi-walled carbon nanotubes

Sun

Teng

Kuang

et al. 2022

Front. Bioeng. Biotechnol.

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Shape memory polymers (SMPs) have a wide range of potential applications in many fields. In particular, electrically driven SMPs have attracted increasing attention due to their unique electrical deformation behaviors. Carbon nanotubes (CNTs) are often used as SMP conductive fillers because of their excellent electrical conductivities. However, raw CNTs do not disperse into the polymer matrix well. This strictly limits their use. In this study, to improve their dispersion performance characteristics in the polymer matrix, hydroxylated multi-walled carbon nanotubes (MWCNT-OHs) were functionalized with octadecyl isocyanate (i-MWCNTs). Polyurethane with shape memory properties (SMPU) was synthesized using polycaprolactone diol (PCL-diol), hexamethylene diisocyanate (HDI), and 1,4-butanediol (BDO) at a 1:5:4 ratio. Then, electroactive shape memory composites were developed by blending SMPU with i-MWCNTs to produce SMPU/i-MWCNTs. The functionalized i-MWCNTs exhibited better dispersibility characteristics in organic solvents and SMPU composites than the MWCNT-OHs. The addition of i-MWCNTs reduced the crystallinity of SMPU without affecting the original chemical structure. In addition, the hydrogen bond index and melting temperature of the SMPU soft segment decreased significantly, and the thermal decomposition temperatures of the composites increased. The SMPU/i-MWCNT composites exhibited conductivity when the i-MWCNT content was 0.5 wt%. This conductivity increased with the i-MWCNT content. In addition, when the i-MWCNT content exceeded 1 wt%, the composite temperature could increase beyond 60°C within 140 s and the temporary structure could be restored to its initial state within 120 s using a voltage of 30 eV. Therefore, the functionalized CNTs exhibit excellent potential for use in the development of electroactive shape memory composites, which may be used in flexible electronics and other fields.

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“…At present, flexible electronics have great potential in flexible displays, − smart robots, , and wearable electronic devices − and are the fundamental materials for “Internet of Things” applications. With the advantages of tunable performance and easy industrialization, elastomer-based conductive composites (ECCs) are valuable components of flexible strain sensors and thus are widely researched.…”

Section: Introductionmentioning

confidence: 99%

Improved Sensitivity of Flexible Conductive Composites Throughout the Working Strain Range Based on Bioinspired Strain Redistribution

Zhang

Sun

et al. 2022

ACS Appl. Polym. Mater.

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Elastomer conductive composites (ECCs) are wonderful candidates for stretchable strain sensors. However, the sensitivity of ECC-based flexible strain sensors is limited in low-strain range, the main working range for human movements, due to the insignificant geometric change of the sample shape and weak tunneling effect of the conductive network. Herein, bioinspired heterogeneous thermoplastic polyurethane (TPU)/carbon black (CB) composites (TCs) are assembled by hot pressing two TCs with different Young’s moduli in series. The modulus of the TCs is controlled by the CB content, Young’s modulus of TPU, and plasticizer content. Experimental results and finite element analysis (FEA) confirm that the low Young’s modulus component undergoes higher strain compared with the high Young’s modulus component, resulting in a more serious change of the conductive network and higher gauge factor (GF) values. Compared with homogeneous TCs, the GF of heterogeneous TCs was improved by a factor of 20.7 and 9.6 in the low-strain (0–6%) and high-strain range, respectively. The relationship between modulus variety and GF is quantitatively described, and the GF values depend on the Young’s modulus of the individual components. Constructing a heterogeneous structure with different Young’s moduli is a valuable and facile way to increase the sensitivity of ECC-based flexible strain sensors.

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A thermally-electrically double-responsive polycaprolactone – thermoplastic polyurethane/multi-walled carbon nanotube fiber assisted with highly effective shape memory and strain sensing performance

Cited by 50 publications

References 49 publications

Carbon Nanotube‐Based Strain Sensors: Structures, Fabrication, and Applications

Carbon Nanotube‐Based Strain Sensors: Structures, Fabrication, and Applications

Electroactive shape memory polyurethane composites reinforced with octadecyl isocyanate-functionalized multi-walled carbon nanotubes

Improved Sensitivity of Flexible Conductive Composites Throughout the Working Strain Range Based on Bioinspired Strain Redistribution

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