Highly Sensitive and Stretchable Carbon Nanotube/Fluoroelastomer Nanocomposite with a Double‐Percolated Network for Wearable Electronics

Abstract

A smart stretchable material is developed from a composite of carbon nanotube (CNT) and fluoroelastomer (FKM), which is fabricated via an internal melt‐mixer method. A unique, double‐percolated, electrically conductive network is observed with ultralow percolation thresholds of 0.45 phr and 1.40 phr CNT. This provides the CNT/FKM nanocomposites with a wide range of strain sensitivity. Thin‐film nanocomposites at the first plateau of conductivity show an ultrahigh sensitivity with a gauge factor (GF) of 1010 at 23% strain for 0.6 phr and of 6750 at 34% strain for 1 phr. At the second plateau of conductivity, 1.5 phr nanocomposite corresponds to higher levels of strain of 78% strain with ultrahigh GF of more than 4 × 104 and 2 phr nanocomposite to almost 100% strain with GF of 1.3 × 105. The CNT/FKM nanocomposites possess a high elongation at break of 430% and up to 232% strain sensitivity. The unique distribution of CNTs in the polar fluoroelastomer FKM facilitates simultaneous high sensitivity and high stretchability, and improved mechanical strength over reported polymer‐based nanocomposite stretchable sensors. The novel, stretchable CNT‐based FKM conductors have great potential for wearable electronics such as stretchable sensors, stretchable light‐emitting diodes (LEDs), and human motion monitoring.

A High‐Performance, Sensitive, Wearable Multifunctional Sensor Based on Rubber/CNT for Human Motion and Skin Temperature Detection

“…[ 17 ] Effective and uniform distribution of CNTs in the polymer matrix plays a major role in the formation of percolation networks at low filler loadings. [ 18 ] Unfortunately, massive van der Waals forces and strong π–π interactions of CNTs make it difficult to disperse homogeneously in rubber, [ 19 ] especially in a latex film‐forming preparation method without intensive mechanical mixing. Chemical modifications, such as oxidation, [ 20 ] plasma treatment, [ 21 ] and polymer grafting [ 22 ] have been employed to alter the surface characteristics of CNTs to improve the dispersity of CNTs in the solvent and polymer matrix.…”

Smart Coatings with Carbon Nanoparticles

“…The addition of these nanoparticles to polymers with high strain capabilities such as fluoroelastomers [37], thermoplastic polyurethane [38], or vulcanized silicone [39] has demonstrated excellent sensing capabilities. More specifically, they present enormous potential for human motion sensing or wearable electronics [37] as the GF at high strain levels (>20%) can be in the range of 400-4000 depending on the content and morphology of the carbon nanofiller. Here, a highly accused exponential behavior is observed at higher strain levels due to the prevalence of tunneling mechanisms in the carbon nanoparticle network.…”

A Screen-Printed Metal Hybrid Composite for Wireless Wind Sensing

“…When applying printed flexible strain sensors for wind sensing, the conductive material is an important component, since it mainly determines the sensing properties. Carbon nanotubes (CNTs) have been broadly used in strain sensors as conductive materials due to their excellent mechanical properties, chemical inertness, and low cost [ 25 , 26 , 27 ]. To make up for certain defects that carbon base materials often suffer from, such as low conductivity (sheet resistance of ≈4 KΩ sq −15 ) and relatively low sensitivity, researchers have mixed CNTs with other metal materials.…”