Electrothermal Characterization of Series- and Parallel-Based Heating Textiles with Insulation Layers

Textile-based electric heaters, known for their flexibility and comfort, are gaining popularity as an innovative approach in thermotherapy applications. Our study focuses on the electrothermal performance of knitted heaters in series and parallel arrangements using various insulators like air, fleece, terry, and lining. A simple rib knitting structure was used to fabricate the heating pad using stainless steel yarn and cotton yarn on the V-bed knitting machine. The parallel (P-CNKF-parallel with copper and nickel-coated electrode as the bus bar) and series-based heating pad could be heated up to 47 and 26 °C, respectively, at 9 V DC power source in the standard environment (20 °C and 65% RH) condition. Various insulating layers were placed over the parallel-based heating pad (P-CNKF), producing samples such as S1 (air-heating textile-air), S2 (lining-heating textile-lining), S3 (lining-fleece-heating textile-fleece), and S4 (lining-terry-heating textile-terry). The findings showed that samples S2, S3, and S4 demonstrated surface temperatures that were 17, 33, and 27% higher, respectively, compared to a heating pad without insulation. The findings suggest that using fleece-knitted insulation layers can boost the performance of heating pads, enabling their use in thermotherapy for joint and muscle pain, with reduced power consumption. Using the S3 sample, a lab-based heating pad was developed to alleviate pain in the knees and elbows.