Effects of stitch classes on the electrical properties of conductive threads

Abstract

Bio-physical signal measurement tools embedded in clothing are becoming a viable alternative in mobile health monitoring systems, particularly Wearable Electronic Textile-based Systems (WETS). To assure clinical viability, utilizing flexible and inconspicuous conductive media that can acquire and transmit reliable signals while assuring signal durability and biocompatibility are particularly important when developing WETS for medical applications. To accomplish this task, conductive threads are emerging as an appropriate electrical medium for health monitoring garments. However, little has been studied on the behavior of these conductive threads under various conditions. We report here the electrical conductive properties of specific conductive threads under two conditions: (i) as sewn configurations onto a textile substrate with different stitch types and (ii) as independent strands under controlled extension independent from a sewing machine. Statistical results showed that the stitch class and thread location significantly influenced the electrical resistance of the conductive thread, revealing the chain stitch to provide resistance even lower than the un-stitched conductive thread. In addition, under controlled extension all three of the conductive threads exhibited both a hysteresis and a stress-relaxation effect. These are important phenomena to examine when conductive threads are incorporated into WETS because the choice of stitch type will influence the strength of the signals received and transmitted, while the wearers’ body movements will cause the threads to encounter multi-axial stretch. Knowing the influence of stitch type, stretch, and relaxation on conductive thread resistance will inform objective design and manufacturing decisions for developing clinical-grade textile-based electrical circuits for medical applications.

Performance Evaluation of Knitted and Stitched Textile Strain Sensors

“…They selected a silver plated 22/1 dtex nylon yarn, since preliminary experiments showed that it had the highest strain sensitivity. They further considered Ruppert-Stroescu and coworkers [73] investigated the sensor properties of three conductive yarn types Shieldex 117/7 (a silver coated two-ply nylon, 985 Ω/m), Shieldex 234/34 (a four-ply silver coated yarn, 80 Ω/m) and Lame Lifesaver yarn (a three-ply silver coated yarn with 65 Ω/m resistance) on plain woven cotton fabric (muslin). Furthermore, they considered five stitch types (310, 304, 315, and 401, and adapted 304) with fixed stitch densities.…”

Effecting factors on electrical resistance of conductive paths

“…When using conductive yarns sewing is the most preferred technique for both electronic component and conductive path production. 8,9 When previous studies were examined, it is seen that lock stitch and zigzag stitch are the commonly used stitch types for the smart applications. [10][11][12][13][14][15][16][17] Parkova et al studied electrical behavior of different conductive yarns in sewn and un-sewn form to define their suitability for specific applications and used lock stitch for sample production.…”

Electrical Characterization of Conductive Threads for Textile Electronics

“…So far, researchers have primarily focused on investigating the effects of adverse conditions on the fabrics, such as the effects of different types and classes of stitching [20], consecutive abrasion [21] or repeated washing cycles [15,21], as well as the effects of chemicals used as detergents or ironing agents [22]. However, very little light has been shed on how the conductive thread itself can handle power fed through it, and how that can affect it [23,24].…”