Enhanced Strain Sensing Performance of Polymer/Carbon Nanotube‐Coated Spandex Fibers via Noncovalent Interactions

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mame.201900525. Over the past decade, flexible strain sensors have been of tremendous interest due to their wide application in robotics, medical diagnostics, human motion detection, and healthcare. Herein, a fiber strain sensor is fabricated by continuously coating a layer of ultrathin multi-walled carbon nanotube (MWCNT)/thermoplastic polyurethane (TPU) nanocomposites onto the surface of commercial spandex fiber. The effect of noncovalent functionalization of MWCNTs using 1-pyrenecarboxylic acid (PCA) on the electrical conductivity as well as the sensing performance of the fiber sensor is investigated. The low-cost strain sensor possesses a large workable strain (up to 200% strain), high sensitivity (gauge factor is 14 191.5 under 170-200% strain), and excellent stability (up to 1000 cycles), and regular signal responses within a wide measuring frequency range of 0.01-1 Hz are achieved with the introduction of PCA via enhanced nanotube dispersion and polymer-nanofiller interactions.Additionally, the resistance response to strain is fitted with a model based on tunneling theory to understand the sensing mechanism, and to prove that the fitted results are in agreement with the experimental results. Furthermore, the developed sensor is successfully applied in human motion detection, such as joint movement, facial microexpressions, and speech recognition. Conflict of InterestThe authors declare no conflict of interest.

Flexible and high-performance piezoresistive strain sensors based on carbon nanoparticles@polyurethane sponges

“…From Fig. 6c, the strain detection range and sensitivity of CNT/GNP/CNT@PU under compression are also much higher compared with a series of piezoresistive sensors recently reported in the literature [5,8,16,[24][25][26][27]1719] [5,8,16,[24][25][26][27]17,19]. Additionally, the CNT/GNP/CNT@PU strain sensor exhibited ultra-high sensitivity at very low strain (GF = − 12 at 0.05% strain), which is far superior to those reported in current literature [23][24][25][26].…”

“…Carbon nanotubes (CNTs) have large aspect ratios and high electrical conductivity making them very suitable for use as the conductive nanofillers in flexible strain sensors [ 18]. However, CNTs are difficult to uniformly disperse in a polymer matrix due to surface inertness, which limits the sensitivity of the sensor [19]. By contrast, GNPs are apt to slip during deformation due to their special twodimensional structure, which improves the sensitivity of the sensor and reduces the strain response range [13].…”

“…Furthermore, the use of 1-pyridinecarboxylic acid (PCA) improved the dispersability of the carbon nanotubes and the interfacial adhesion between the polymer and nanofillers via non-covalent interactions, which enhanced the sensitivity of strain sensor (GF = 14191.5) and resulted in a larger strain monitoring range (>200% strain) [19 ]. Gong et al [20] prepared a high-performance strain sensor by doping polystyrene (PS) nanoparticles into reduced graphene oxide (rGO) film.…”

Omnidirectional Tactile Profiling Using a Deformable Pressure Sensor Array Based on Localized Piezoresistivity

“…The interface between MWCNTs and PU was reported to be stable. [41] Figure S7 of the Supporting Information compares SEM images of the MWCNTs deposited on the PU sponge before and after 10 000 pressing cycles, and also an SEM image after ultrasonication in water. We could not find any morphological difference by the mechanical and sonic stimulation.…”

3D‐Printed Flexible Piezoresistive Sensors for Stretching and Out‐of‐Plane Forces

“…For instance, Deng and co-workers [13] selectively dispersed carbon nanotubes (CNTs) in poly(styrene-butadiene-styrene) (SBS) block polymer and thermoplastic polyurethane (TPU) to form the double percolation structure, noticeably enhancing sensing performance of the related device. Chen et al [14] performed noncovalent modification of 1-pyrenecarboxylic acid (PCA) to increase the interface bonding force between CNTs and TPU, thereby achieving better dispersion of CNTs in a TPU matrix. Constructing a multiple structure has also become a common strategy to improve sensing performance for CPCbased sensors.…”