Design and Fabrication of Embroidered Textile Strain Sensors: An Alternative to Stitch-Based Strain Sensors

Abstract

Smart textile sensors have been gaining popularity as alternative methods for the continuous monitoring of human motion. Multiple methods of fabrication for these textile sensors have been proposed, but the simpler ones include stitching or embroidering the conductive thread onto an elastic fabric to create a strain sensor. Although multiple studies have demonstrated the efficacy of textile sensors using the stitching technique, there is almost little to no information regarding the fabrication of textile strain sensors using the embroidery method. In this paper, a design guide for the fabrication of an embroidered resistive textile strain sensor is presented. All of the required design steps are explained, as well as the different embroidery design parameters and their optimal values. Finally, three embroidered textile strain sensors were created using these design steps. These sensors are based on the principle of superposition and were fabricated using a stainless-steel conductive thread embroidered onto a polyester–rubber elastic knit structure. The three sensors demonstrated an average gauge factor of 1.88±0.51 over a 26% working range, low hysteresis (8.54±2.66%), and good repeatability after being pre-stretched over a certain number of stretching cycles.

Strain/pressure sensors utilizing advanced nanomaterials

“…11 A strain/pressure sensor is capable of converting impact of strain/pressure into electrical signal, usually capacitance or resistance change. 12 Such a change of resistance when the material is strained is inversely proportional to the © 2024 Vietnam Academy of Science and Technology and Wiley-VCH GmbH. cross-sectional area being impacted, and proportional to the length of the affected areas on the materials.…”

“…cross-sectional area being impacted, and proportional to the length of the affected areas on the materials. 12 To date, many different kinds of materials have been applied to strain/pressure sensors such as silicone, semiconductors, 13 nanoparticles, 14 nanowires, 15 which have made huge progress in fabrication of strain/pressure sensor with dramatic decrease in the component size that results in convenient components and devices. A variety of principles including piezoresistivity, capacitance, piezoelectricity and triboelectricity can be introduced in this section, which is based on the transduction mechanism accordingly.…”

“…20,29 Strain can be understood as the relative change in length of a component or structure under stress. 11,12 In general, there is a wide range of direct causes that induce mechanical strain such as forces, moments, and even thermal expansion, etc. The relative change in length ε is described as follows: 5 𝜀 = ΔL∕L 0 where L 0 is the original length (m), and ΔL is the absolute change in length (m).…”

Influence of stitch type division and geometry on the electrical properties of conductive embroidered structures

“…Furthermore, the ease on the manufacturability of stitched and embroidered structures allows for a mass production of textile sensors without compromising their cost and reproducibility. 13 Electrical properties of embroidered structures with conductive threads depend on numerous parameters, as it was shown by Zheng et al, 14 who conducted an overlay plot analysis to predict the change in the electrical resistance by changing embroidering speed, stitch length, needle thread pre-tension, and embroidering direction. It was observed that the combined output of stitch length and embroidery speed can affect largely the electrical parameters for the fabrication of e-textiles, such as high-performance circuits.…”

“…Furthermore, the ease on the manufacturability of stitched and embroidered structures allows for a mass production of textile sensors without compromising their cost and reproducibility. 13…”