What is the recent example of a knitted structure?

One recent example used shape memory alloy wires to form an active knit, where the force output was increased by additive contributions from individual wires. [9]

What temperature range did the strains of the CNT/SPX4 textile increase?

Electrothermal heating over the same temperature range generated maximum contractile strains of 16%, 25% and 24% for CNT/SPX with n = 1, 4 and 12, respectively.

Why did the CNT/SPX knitted textiles show such high tensile?

Because of large tensile actuation, low driving voltage, high repeatability, scalability, and stretchability the CNT/SPX knitted textiles could be used for adjustable smart clothing, robotics and medical devices.

How was the voltage applied to the knitted fabric?

The voltage applied was tuned to achieve approximately equivalent heating rates for all samples, as determined by a small thermocouple positioned in close contact with one end of the actuating fabric.

Why were higher voltage inputs needed for the higher SPX contents?

Higher voltage inputs were needed for samples with the higher SPX contents because of their larger thermal mass of actuating material.

How many cycles did the CNT/SPX knitted fabrics undergo?

The strain sensing capabilities of the CNT/SPX knitted fabrics were assessed byrepeated loading and unloading from 0% to 100% strain for a minimum of 1000 cycles.

What is the effect of the non-linear elasticity of rubbers?

The non-linear elasticity of rubbers means that more complicated behavior is likely than that described by the above relation and can even account for the declining actuation strain at higher stresses.

What is the description of the CNT/SPXn fabrics?

The CNT/SPXn fabrics performed well as thermally driven artificial muscles usingdirect current (DC) for electro-thermal stimulation (see movie S2).

What is the weight loss of the knitted textiles at 450 °C?

TGA shows a weight loss at ∼300– 450 °C of ∼100%, 90.9%, 93.2%, 96.9% and ∼97.9% for spandex and CNT/SPXn (n = 1, 4, 8and 12) knitted textiles, respectively.

What voltage switching rate was used to generate strains?

Strain amplitudes for all samples decreased with increasing voltage switching rates when the same supply voltage was used (Figures S4 and S5).

What is the gauge factor for the CNT/SPXn fabrics?

The gauge factorincreases with increasing number of SPX fibers in the feed supply from 0.12, 0.16, 0.25 to 0.4, for n = 1, 4, 8, 12, respectively.

what is the strain of a knitted CNT/SPX4 textile?

Figure S4 Actuation cycles at different frequencies for a knitted CNT/SPX4 textile that is under an applied stress of 25 MPa, which provides a tensile strain of 100% for the non-actuated state.

What is the effect of the CNT coating on the fiber?

The tension and rotation of the yarn during the knitting process securely consolidated the CNT coating on the outer surface of the SPX fiber or yarn (Figure 1).

What is the tensile strength of the knitted fabric?

All knitted textiles were highly stretchable (FigureS3a) with breaking strains of between 600% to 900% and tensile strengths in the range 75 MPa to 86 MPa.

What is the maximum work densities of the CNT/SPX1 textile?

The maximum work densities were as high as 640 J/kg and the maximum power-weight ratio was 1278 W/kg, which were both achieved with the CNT/SPX1 textile pre-stretched to 100% and activated at 20 V/cm at 2 Hz.

Open AccessJournal Article10.1021/ACSNANO.6B04125

Knitted Carbon-Nanotube-Sheath/Spandex-Core Elastomeric Yarns for Artificial Muscles and Strain Sensing

Javad Foroughi, +7 more

- 15 Sep 2016

- ACS Nano

- Vol. 10, Iss: 10, pp 9129-9135

215

TL;DR: The knitted textile provides the combination of strain sensing and the ability to control dimensions required for smart clothing that simultaneously monitors the wearer's movements and adjusts the garment fit or exerts forces or pressures on the wearer, according to needs.

Abstract: Highly stretchable, actuatable, electrically conductive knitted textiles based on Spandex (SPX)/CNT (carbon nanotube) composite yarns were prepared by an integrated knitting procedure. SPX filaments were continuously wrapped with CNT aerogel sheets and supplied directly to an interlocking circular knitting machine to form three-dimensional electrically conductive and stretchable textiles. By adjusting the SPX/CNT feed ratio, the fabric electrical conductivities could be tailored in the range of 870 to 7092 S/m. The electrical conductivity depended on tensile strain, with a linear and largely hysteresis-free resistance change occurring on loading and unloading between 0% and 80% strain. Electrothermal heating of the stretched fabric caused large tensile contractions of up to 33% and generated a gravimetric mechanical work capacity during contraction of up to 0.64 kJ/kg and a maximum specific power output of 1.28 kW/kg, which far exceeds that of mammalian skeletal muscle. The knitted textile provides the co...

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Most frequently asked questions

1. What are the contributions in "Knitted carbon-nanotube-sheath/spandex-core elastomeric yarns for artificial muscles and strain sensing" ?

Foroughi et al. this paper developed an up-scalable knitting technique capable of continuously producing electrically conducting 3D fabrics made from hybrid spandex ( SPX ) yarns.

2. What is the effect of stretching rubber?

The stretched rubber has lower entropy than does the non-stretched rubber, so heating the stretched rubber increases the modulus of the stretched rubber, thereby causing the isotonically loaded rubber fibers to contract.

3. How many strain cycles did the fractional change in resistance change?

The fractional change in resistance was highly repeatable, with the amplitude for each strain cycle changing by less than 2.3% over the 1000 strain/relaxation cycles.

4. What is the effect of the absence of substantial hysteresis on the sensor?

The absence of substantial hysteresis greatly improves the accuracy of the sensor and the linear response allows a single gauge factor to be obtained as = dR*/d for each material[14].

Figure 3 a) Change in resistance, normalized to the non-loaded fabric resistance (R0), measured during 1000 stretch/relaxation cycles of 0 to 100% strain at 0.2 Hz for a knitted CNT/SPX8 textile. (b) Change in normalized electrical resistivity versus applied strain during loading and unloading for CNT/SPXn textiles.

Figure 2 a) Effect of n for CNT/SPXn textiles on isobaric actuator strain during electrothermal heating to 70oC at 0.2 Hz, where all samples were stretched by 100 % strain by an applied load before actuation (which is the non-actuated strain for all of the below isobaric measurements). b) Muscle contraction recorded over 10,000 on-off cycles for knitted CNT/SPX4 at 0.2 Hz, 30 V/cm. c) Muscle contraction of CNT/SPXn knitted textiles as a function of load at 0.1 Hz and 10 V/cm: (CNT/SPX1), 20V/cm (CNT/SPX4), 30 V/cm (CNT/SPX8) and 60 V/cm (CNT/ SPX12). d) Effect of voltage on tensile actuation and sample temperature for CNT/SPX4 muscles at 0.1 Hz. The contractile strains are normalized with respect to the non-loaded muscle length. Here and elsewhere, applied stresses are engineering stresses, which are normalized by the non-stretched fiber cross-sectional area.

Figure 1 a) Schematic of the process for producing a knitted CNT/SPX textile. The illustrated items are: (1) a “Spool of SPX fibers”, (2) a “n-fiber SPX yarn”, (3) a “CNT forest”, (4) a “Circular knitting machine”, and (5) a “Knitted CNT/SPX textile”. A CNT ribbon drawn for a CNT forest was wrapped around n SPX fibers and knitted in the knitting machine to produce the circular knitted textile shown in b) and c). Unlike for the case for twist-based CNT yarn spinning, the above schematically-illustrated wedge is a time average of the actual draw process, since a much narrower CNT ribbon migrates over the broader illustrated width in response to stresses applied during wrapping the SPX yarn with CNT. b) Photograph of knitted CNT/SPX structures, from left-to-right containing 1, 4, 8 and 12 SPX fibers, respectively. From left-to-right, the weight percent of CNT in the textile is increasing, as shown in Table S1. c) A knitted CNT/SPX12 textile, showing the transition between CNT non-wrapped SPX12 yarns and CNT wrapped SPX12 yarns.

Citations

Journal Article•10.1016/J.CEJ.2020.125152

Gene reconstruction spandex with intrinsic antimicrobial activity

Yachao Jiang, +5 more

- 15 Jan 2021

- Chemical Engineering Journal

TL;DR: In this article, polyhexamethylene guanidine hydrochloride (PHMG) was used as a functional "gene" to replace the diamine in ordinary spandex.

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Journal Article•10.1021/ACSNANO.1C04972

Carbon Nanotube Research in Its 30th Year.

Yan Li

- 22 Jun 2021

- ACS Nano

Journal Article•10.1002/admt.202200082

A Scalable Durable and Seamlessly Integrated Knitted Fabric Strain Sensor for Human Motion Tracking

Lulu Zhou, +3 more

- 01 May 2022

- Advanced materials & technologies

TL;DR: In this article , a fabric strain sensor that can be seamlessly integrated into various apparel under precise tension through industrial-scale production is presented, which has a high sensitivity of 2% strain detection limit and excellent durability and repeatability for 10 000 cycles.

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•Journal Article•10.1002/adma.202212046

Plant-like tropisms in artificial muscles.

Shazed Md. Aziz, +5 more

- 25 Mar 2023

- Advanced Materials

TL;DR: In this article , a hierarchical patterned helically wound yarns are used to simulate the hydrotropism and thermotropism of helical plants to their microfibril level using plant-like microstructural memories.

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Journal Article•10.1021/ACSBIOMATERIALS.1C00591

Cation-Induced Assembly of Conductive MXene Fibers for Wearable Heater, Wireless Communication, and Stem Cell Differentiation.

Xuemei Fu, +11 more

- 23 Jul 2021

- ACS Biomaterials Science & Engineering

TL;DR: In this article, a cation-induced assembly process is developed for the scalable fabrication of conductive fibers with MXene sheaths and alginate cores (abbreviated as MXene@A), which can be repeatedly contracted and generate large contraction stress that is >40 times higher than the ones of mammalian skeletal muscle.

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References

Journal Article•10.1126/SCIENCE.1060928

Carbon Nanotubes--the Route Toward Applications

Ray H. Baughman, +2 more

- 02 Aug 2002

- Science

TL;DR: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects.

...read moreread less

10.5K

Journal Article•10.1038/NNANO.2011.36

A stretchable carbon nanotube strain sensor for human-motion detection

Takeo Yamada, +6 more

- 01 May 2011

- Nature Nanotechnology

TL;DR: A class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes capable of measuring strains up to 280% with high durability, fast response and low creep is reported.

...read moreread less

3.1K

Journal Article•10.1126/SCIENCE.1104276

Multifunctional Carbon Nanotube Yarns by Downsizing an Ancient Technology

Mei Zhang, +2 more

- 19 Nov 2004

- Science

TL;DR: By introducing twist during spinning of multiwalled carbon nanotubes from nanotube forests to make multi-ply, torque-stabilized yarns, this work achieves yarn strengths greater than 460 megapascals, nearly as tough as fibers used for bulletproof vests.

...read moreread less

1.8K

Journal Article•10.1126/SCIENCE.1115311

Strong, Transparent, Multifunctional, Carbon Nanotube Sheets

Mei Zhang, +15 more

- 19 Aug 2005

- Science

TL;DR: Self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers and the measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel.

...read moreread less

1.7K

Journal Article•10.1038/NMAT3380

A flexible and highly sensitive strain-gauge sensor using reversible interlocking of nanofibres

Changhyun Pang, +6 more

- 01 Sep 2012

- Nature Materials

TL;DR: A simple architecture for a flexible and highly sensitive strain sensor that enables the detection of pressure, shear and torsion and can be used to monitor signals ranging from human heartbeats to the impact of a bouncing water droplet on a superhydrophobic surface is presented.

...read moreread less

1.6K

...

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Knitted Carbon-Nanotube-Sheath/Spandex-Core Elastomeric Yarns for Artificial Muscles and Strain Sensing

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AI Agents for this Paper

Most frequently asked questions

1. What are the contributions in "Knitted carbon-nanotube-sheath/spandex-core elastomeric yarns for artificial muscles and strain sensing" ?

2. What is the effect of stretching rubber?

3. How many strain cycles did the fractional change in resistance change?

4. What is the effect of the absence of substantial hysteresis on the sensor?

5. What is the recent example of a knitted structure?

6. What temperature range did the strains of the CNT/SPX4 textile increase?

7. Why did the CNT/SPX knitted textiles show such high tensile?

8. How was the voltage applied to the knitted fabric?

9. Why were higher voltage inputs needed for the higher SPX contents?

10. How many cycles did the CNT/SPX knitted fabrics undergo?

11. What is the effect of the non-linear elasticity of rubbers?

12. What is the description of the CNT/SPXn fabrics?

13. What is the weight loss of the knitted textiles at 450 °C?

14. What voltage switching rate was used to generate strains?

15. What is the gauge factor for the CNT/SPXn fabrics?

16. what is the strain of a knitted CNT/SPX4 textile?

17. What is the effect of the CNT coating on the fiber?

18. What is the tensile strength of the knitted fabric?

19. What is the maximum work densities of the CNT/SPX1 textile?

Figures

Citations

Gene reconstruction spandex with intrinsic antimicrobial activity

Carbon Nanotube Research in Its 30th Year.

A Scalable Durable and Seamlessly Integrated Knitted Fabric Strain Sensor for Human Motion Tracking

Plant-like tropisms in artificial muscles.

Cation-Induced Assembly of Conductive MXene Fibers for Wearable Heater, Wireless Communication, and Stem Cell Differentiation.

References

Carbon Nanotubes--the Route Toward Applications

A stretchable carbon nanotube strain sensor for human-motion detection

Multifunctional Carbon Nanotube Yarns by Downsizing an Ancient Technology

Strong, Transparent, Multifunctional, Carbon Nanotube Sheets

A flexible and highly sensitive strain-gauge sensor using reversible interlocking of nanofibres

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