Carbon Nanotube Coated Fibrous Tubes for Highly Stretchable Strain Sensors Having High Linearity

Abstract

Strain sensors are currently limited by an inability to operate over large deformations or to exhibit linear responses to strain. Producing strain sensors meeting these criteria remains a particularly difficult challenge. In this work, the fabrication of a highly flexible strain sensor based on electrospun thermoplastic polyurethane (TPU) fibrous tubes comprising wavy and oriented fibers coated with carboxylated multiwall carbon nanotubes (CNTs) is described. By combining spraying and ultrasonic-assisted deposition, the number of CNTs deposited on the electrospun TPU fibrous tube could reach 12 wt%, which can potentially lead to the formation of an excellent conductive network with high conductivity of 0.01 S/cm. The as-prepared strain sensors exhibited a wide strain sensing range of 0–760% and importantly high linearity over the whole sensing range while maintaining high sensitivity with a GF of 57. Moreover, the strain sensors were capable of detecting a low strain (2%) and achieved a fast response time whilst retaining a high level of durability. The TPU/CNTs fibrous tube-based strain sensors were found capable of accurately monitoring both large and small human body motions. Additionally, the strain sensors exhibited rapid response time, (e.g., 45 ms) combined with reliable long-term stability and durability when subjected to 60 min of water washing. The strain sensors developed in this research had the ability to detect large and subtle human motions, (e.g., bending of the finger, wrist, and knee, and swallowing). Consequently, this work provides an effective method for designing and manufacturing high-performance fiber-based wearable strain sensors, which offer wide strain sensing ranges and high linearity over broad working strain ranges.

A Highly Sensitive and Flexible Strain Sensor Based on Dopamine-Modified Electrospun Styrene-Ethylene-Butylene-Styrene Block Copolymer Yarns and Multi Walled Carbon Nanotubes

“…In the initial cycles, the relative resistance increased before stabilizing. This can be attributed to the continuous destruction and reconstruction of MWCNTs pathways, and then the conductive pathways stabilized at the commencement of strain cycles [ 38 , 39 , 40 , 41 , 42 , 43 ]. The change of relative resistance exhibited a good response in 15,000 tensile cycles, indicating PDA@SEBS/MWCNTs yarn had good resilience.…”

Miniaturized retractable thin-film sensor for wearable multifunctional respiratory monitoring

“…As shown in Fig. 1(e), the characteristics of the RSPS were compared with resistive, capacitive, triboelectricity, optical, and thermal effect-based stretchable (or strain) sensors in terms of tensile cycles and measured resolution [26,27,[30][31][32][33][34][35][36][37][38][39][40]. The RSPS proposed in this research exhibits higher durability (1 million continuous stretching cycles) and resolution (arc length: ~ 0.13 mm), demonstrating the advantages of the device as a wearable sensor for sensing slight stretch such as breathing.…”

Strain Sensors for Human Movement Detection Based on Fibrous Membranes Comprising Thermoplastic Polyurethane, Ag Nanoparticles, and Carbon Nanotubes

“…46−49 Li et al 50 fabricated a strain sensor by ultrasonically securing CNTs to electrospun TPU fibrous membranes, which demonstrated a large strain response range (600%) but limited sensitivity. Zhou et al 51 prepared an electrospun TPU fibrous membrane decorated with CNTs via spraying and ultrasound-assisted deposition. It exhibits high linearity and a wide response range (up to 760%) but low sensitivity (gauge factor of 57).…”