Selection of conductive yarns for knitting an electrical heating element

Abstract

By the integration of electro-conductive properties in the fabric structure a flexible textile can be obtained that does not reduce the quality of comfort, maintenance and wearability of clothing. Each type of yarn has its advantages and disadvantages, for example, metal coated polymer multifilament yarn has a lower resistance to heat than metal multifilament yarn, but it is more flexible. During this research conductive knitted patterns were made and tested. For the experiments more suitable yarns for knitting were selected, which had a lower resistance and were visually less changing of the knitted pattern in appearance: silver coated multifilament polyamide, products of two different companies; stainless steel multifilament yarn and polyester/stainless steel spun yarn. The single-faced patterns of non-conductive yarn and straight and figural conductive traces of conductive yarns were knitted. A test was made with the purpose of finding out the electrical resistance of knitted textile affected by force. Knit warm-up potency was researched during temperature measurement tests. Knitting test pieces were also evaluated by aspect of technical structure and visual appearance. Generally, it was concluded that steel yarns could not be used for knitting while silver coated polyamide yarns are suitable for the manufacture of knitted heating elements. As a result of this research, knitwear with a textile heating element was made.

Textile elements for car seat to improve user’s driving comfort

“…Three trajectory patterns were prepared. Due to limitations in performance of spacer fabric knitting machines, and after further extended practical and theoretical knowledge, the final designs were characterised with the following features [31,32]:placement of a heating element was unidirectional,the straight trajectory of the heating element line was avoided not to limit the stretchability of the base material,the trajectory of a heating element within one design was kept in even distance in order to provide the most uniform heating,the smallest distance between heating yarns was 1 cm to avoid hotspots. Step 2. Calculating the resistance needed to obtain the estimated power of the whole mat…”

“…Preparation of the trajectories of heating cables Three trajectory patterns were prepared. Due to limitations in performance of spacer fabric knitting machines, and after further extended practical and theoretical knowledge, the final designs were characterised with the following features [31,32]:…”

Advanced Functional Materials for Intelligent Thermoregulation in Personal Protective Equipment

“…While finding that the maximum equilibrium temperature of the heating elements was influenced by the method of integration of conductive yarns, the authors concluded that an optimal heating element should contain conductive yarns with low electrical resistance and minor variations in electrical resistance to elongation, providing good temperature uniformity during the heating process, while being mechanically suitable for knit structure. In this work, silver-coated polyamide yarns in a three-ply configuration were able to provide the most uniform heating zones while being technically suitable for a knit structure [168]. Analysis of the method of manufacturing flexible heating fabrics by integrating a copper coil filament between two pieces of flexible interlining fabric using the thermal adhesion process, has demonstrated that reducing the copper wire spacing and the applied tension, while improving the thermal conductivity of the textile structure of the fabric, not only increases the temperature and heating rate, but also helps to maintain the fabric at a uniform temperature [169].…”

“…The study of the behavior of steel wire-based heating panels using single and multilayer steel wire integrated in clothes showed that the thermal effect obtained, and the time required to reach an equilibrium temperature at a fixed voltage, depended on the number of wire folds in the cloths [167]. In addition, the criteria for selecting conductive yarns for knitting an electric heater was explored using two types of steel yarn, two types of silver-coated polyamide yarn and one polyester/steel blend yarn, each of which was knit in two patterns: 1) wool/polyamide knit with a 1 m long conductive yarn in three rows of loops; 2) a conductive area in a multiply knit fabric [168]. While finding that the maximum equilibrium temperature of the heating elements was influenced by the method of integration of conductive yarns, the authors concluded that an optimal heating element should contain conductive yarns with low electrical resistance and minor variations in electrical resistance to elongation, providing good temperature uniformity during the heating process, while being mechanically suitable for knit structure.…”

Inductive Power Transmission for Wearable Textile Heater using Series-None Topology

“…We designed a textile coil by sewing the conductive thread onto the clothing. This textile coil simultaneously performs the roles of the Rx coil and thermal material [15]. The proposed wearable heater with an IPT system using a textile coil is shown in Figure 1.…”