Electrothermal performance in electrically heating textiles

Abstract Electrically Heating Textiles (EHTs) generate heat through Joule heating and are widely applied in fields such as healthcare, defense and wearable technologies. Despite the growing interest there is a lack of standardized reporting for evaluating the electrothermal performance of these heaters. This work identifies the geometrical dimensions of sheet-like heaters, specifically the current flow path length and active heating area as a critical yet often overlooked determinant of performance. A simplified 1D analytical model was developed to predict steady-state surface temperature as a function of sheet resistance, applied voltage, and convective heat loss. The model was validated using carbon ink coated textile heaters with varying dimensions. Electrical and thermal measurements, including current, voltage, surface temperature, sheet resistance, power density and heat transfer coefficients, were used to evaluate performance. Experimental results showed strong agreement with the theoretical model. A figure of merit (FoM), defined as the ratio of effective heat transfer coefficient to sheet resistance ( h/R _sheet ) is proposed to benchmark heater performance across different dimensions and materials. This ratio captures the interplay between electrical resistance governed Joule heating and ease of heat transfer to the surroundings, offering a robust and scalable metric for sheet-like heaters. This FoM was applied to different existing studies, and it helped explain performance discrepancies among heaters with different dimensions and highlighted the importance of reporting dimensional parameters alongside electrical data. This framework provides a practical tool for researchers to evaluate, compare, and design EHTs more effectively, and encourages more rigorous and geometry-aware reporting practices for future studies.