Strain-sensing fiber with a core–sheath structure based on carbon black/polyurethane composites for smart textiles

Abstract

Fiber-shaped sensors have great potential for real-time monitoring of human physiological signals thanks to the merging of electronic and textile technologies. This work reports on the fabrication of a core–sheath structured strain-sensing fiber based on the wet-spinning method. The sensing fiber is composed of a core of non-conducting polyurethane and a conducting sheath of carbon black in a polyurethane matrix. Microscopic observation reveals the irregular shape or scattered appearance of the core as well as the porous structure of the fiber, the diameter of which is in the range 200–500 μm. The electro-mechanical properties and their dependence on carbon black concentration in the sheath and draw ratio between the spinneret and first drafting roller are experimentally investigated. It has been found that the percolation threshold of the fiber is in the range 15–16 wt%. The resistance of the fiber rises stably as the fiber is stretched up to a strain of 120% and increases with the increase of draw ratio between the spinneret and first drafting roller. In the cyclic tensile tests, the resistance of the fiber exhibits good repeatability in subsequent loading–unloading cycles after pre-stretching, despite partial recovery of the resistance in the first few cycles. The integration of the strain-sensing fiber into textiles is demonstrated by the core-spun yarn fabricated based on a modified vortex spinning method. The results of this study indicate the fiber could be a promising candidate for a sensor for smart textiles.

A Review of Flexible Strain Sensors Based on Natural Fiber Materials

“…The sensor had no cytotoxicity and good cytocompatibility. In addition to directly using RCF as the flexible matrix of the sensing element, Li et al [136] prepared a core-spun yarn with a strain sensing function using eddy spinning viscose staple fiber and CB/PU composite conductive fiber. By adjusting the structure and properties of core-spun yarns using outer viscose fibers, the core-spun yarn had the potential to be blended with traditional textile fibers to produce intelligent textiles.…”

Contacting of Bicomponent TPU-Fibres with a Conductive Core: A Method for Data Acquisition and Analysis of the Electrical Properties

“…Despite the detailed previous work, the filaments are always produced in a fashion so that the filament surface is the electrically conductive component [7][8][9]. This may be beneficial if the sensor is meant to detect moisture or electrical signals, but detrimental when strain is to be sensed in a possible environment of moisture, such as rain or sweat, or other conductive components, such as carbon fiber.…”

Carbon Black Nanoparticle/Polydopamine-Coated Core-Spun Yarns for Flexible Strain Sensors

“…Li and Pei 40 reported a strain sensing fiber composed of a nonconductive core of polyurethane and a conductive sheath of carbon black, produced with wet spinning. However, compared with the experiment of directly changing the carbon black fraction to test the mechanical and electrical properties of fibers, this study is committed to changing the reaction time of carbon black coating solution to test and obtain more suitable fibers.…”