Development of a Color-Changing Face Mask for Fever Detection Applications

This study focused on developing a color-changing fabric face mask for fever detection. Reversible Thermochromic Leuco dye (RTL) was applied as an indicator to alert wearers of elevated body temperatures, with the color change occurring at 37.5 °C. Five fabric types Polyethylene (PE), cotton (CO), a cotton-polyester blend (TC), polyester (PL), and Polyamide (PA) were coated with blue RTL to evaluate their color change responsiveness. The results showed that fabrics with higher thermal conductivity (<b><i>λ</i></b>), thermal absorptivity (<b><i>b</i></b>), and heat flow (<b><i>q</i></b>) exhibited faster color transitions. RTL-coated PE fabric demonstrated the best performance, with a thermal absorptivity of 312.8 Ws^0.5m^-2K^-1 and a heat flow of 2.11 Wm^-2, leading to a rapid color-change time of approximately 4.20 s. Although PE fabric had a lower thermal conductivity (57.6 × 10^-3 Wm^-1K^-1) compared to PA fabric 84.56 (10^-3 Wm^-1K^-1), the highest thickness 0.65 mm of PA fabric slowed its color-change reaction to 11.8 s. When selecting fabrics for optimal heat transfer, relying solely on fiber type or thermal conductivity (<b><i>λ</i></b>) is insufficient. The fabric's structural properties, particularly thickness, significantly impact thermal resistance (<b><i>γ</i></b>). Experimental results suggest that thermal absorptivity and heat flow are more effective criteria for fabric selection, as they directly correlate with color-change performance.