Highly Stable and Flexible Pressure Sensors with Modified Multi-Walled Carbon Nanotube/Polymer Composites for Human Monitoring

Abstract

A facile method for preparing an easy processing, repeatable and flexible pressure sensor was presented via the synthesis of modified multi-walled carbon nanotubes (m-MWNTs) and polyurethane (PU) films. The surface modification of multi-walled carbon nanotubes (MWNTs) simultaneously used a silane coupling agent (KH550) and sodium dodecyl benzene sulfonate (SDBS) to improve the dispersibility and compatibility of the MWNTs in a polymer matrix. The electrical property and piezoresistive behavior of the m-MWNT/PU composites were compared with raw multi-walled carbon nanotube (raw MWNT)/PU composites. Under linear uniaxial pressure, the m-MWNT/PU composite exhibited 4.282%kPa−1 sensitivity within the pressure of 1 kPa. The nonlinear error, hysteresis error and repeatability error of the piezoresistivity of m-MWNT/PU decreased 9%, 16.72% and 54.95% relative to raw MWNT/PU respectively. Therefore, the piezoresistive response of m-MWNT/PU had better stability than that of raw MWNT/PU composites. The m-MWNT/PU sensors could be utilized in wearable devices for body movement detection, monitoring of respiration and pressure detection in garments.

Challenges in Design and Fabrication of Flexible/Stretchable Carbon- and Textile-Based Wearable Sensors for Health Monitoring: A Critical Review

“…The ACNT/Gr hybrid composite film not only helped the pressure sensor to detect bending, torsion, and acoustic signals but also helped to have a high sensitivity of 19.8 kPa −1 (<0.3 kPa) and high stability (>35,000 cycles) [ 83 ]. In addition, as shown in Figure 4 c,d, by adjusting the dispersion/neighboring interaction between the CNTs and the polymer matrix, the functionality of the CNTs-polymer composite was improved to demonstrate a highly stable and flexible/stretchable pressure sensor [ 35 , 84 ]. In this regard, a micro dome-shaped CNT-PDMS composite film was used for the detection of human respiratory flows and voice vibration.…”

“…The fabricated pressure sensor showed a minimum detection limit of 0.2 Pa and a sensitivity of 15.2 kPa −1 with a fast response/recovery time (~0.04 s) [ 84 ]. He et al also used a modified multi-walled carbon nanotube (m-MWCNT)/PU composite and a PDMS’s encapsulation layer, and the fabricated pressure sensor exhibited a sensitivity of 4.282 kPa −1 within 1 kPa and successfully detected finger gestures, respiratory, and pulse of the subject [ 35 ].…”

“…In this article, we focus on recent trends in developing flexible/stretchable electronics for wearable sensors in health monitoring. In particular, two strategies, including carbon-based sensors and e-textiles, are discussed by summarizing advanced functional materials and fabrication technologies and describing their application in wearable applications, as shown in Figure 1 [ 34 , 35 , 36 , 37 ]. In addition to the challenges to wearable sensors based on carbon and e-textiles, we review various effective research that created flexible and stretchable electronics made by carbon materials or textile configurations.…”

Experimental and Analytical Investigation of Epoxy/MWCNT Nanocomposites: Electrical, Thermal Properties, and Electric Heating Behavior

“…Over the past years, carbon-based conductive fillers including zero-dimensional carbon blacks [3],one-dimensional carbon nanotubes (CNTs) [4,5], and carbon nanofiber [6], and twodimensional graphene or its oxide [7,8] have been employed to improve the electrical, thermal properties, and other physical properties of polymer-matrix composite due to their unique nanostructure and understanding physical attributes. As a result, conductive nanocomposites have been extensively applied in many advanced fields, such as shape-memory actuator [9], supercapacitors [10], pressure sensors [11,12], and electromagnetic interference (EMI) shielding [13]. Most recently, the polymermatrix composites filled with the carbon allotropes and their derivatives to achieve the heating functionality have attracted a lot of attention [14][15][16][17].…”

Pressure-induced electro-switching of polymer/nano-graphene composites

“…Flexible polymer composites with dispersed metal, inorganic or carbon allotropes nanoparticles have been used to develop pressure sensors and electro-mechanical switches. Depending on the polymer used, these structures are employed for different in different applications, such as micro-electronic and biocompatible human monitoring devices [1,2,3]. .…”