Abstract:

Objective The production of skin moisture perception does not necessarily require water; however, contact with dry and cold fabrics can also induce a wet perception due to skin cooling. Nevertheless, no comparative analysis of the subjective feeling when using the same fabric with consistent skin cooling has been proposed. This research aims to explore the influence of dry and wet fabrics on subjective perception by controlling for an equal amount of skin temperature drop.

Method The pre-test determined the amount of water added to the wet fabric when the skin cooling was equivalent to that of the dry fabric. Three groups of controlled skin cooling experiments were designed, with skin cooling set at 0.9 ℃ (produced by contacting 18 ℃ dry fabric or wet fabric with 2 mL water added), 1.2 ℃ (produced by contacting 13 ℃ dry fabric or wet fabric with 12 mL water added) and 1.4 ℃ (produced by contacting 8 ℃ dry fabric or wet fabric with 16 mL water added), respectively. Sixteen subjects were invited to touch fabrics from each of the three different groups and report their subjective sensation scores for cold/warmth, dryness/wet ness and smooth ness/roughness.

Results The Wilcoxon non-parametric test results were conducted on the two associated samples. It was found that the cold sensation of dry fabric at 18 ℃ was significantly stronger than that of the wet fabric with 12 mL water (Z=-2.961, P=0.003). Additionally, the dry fabric at 13 ℃ had a significantly stronger cold sensation compared to the wet fabric with 12 mL (Z=-2.456, P=0.014), but no significant difference existed between the dry fabric at 8 ℃ and the wet fabric with 16 mL water (Z=-1.611, P=0.107). No significant difference existed in roughness sensation between the dry fabric at 18 ℃ and the wet fabric with 2 mL water (Z=-1.459, P=0.145), while roughness of the dry fabric at 13 ℃ was significantly lower than that of the wet fabric with 12 mL (Z=-2.645, P=0.008), and roughness of the dry fabric at 8 ℃ was significantly lower than that of the wet fabric with 16 mL water (Z=-2.646, P=0.008). The wet sensation scores showed no significant difference between the dry fabric at 18 ℃ and the wet fabric with 2 mL water (Z=-0.656, P=0.512), while the wet feeling of the wet fabric with 12 mL water was significantly stronger than that of the dry fabric at 13 ℃ (Z=-2.616, P=0.009), and the same was found between wet sensation of the wet fabric with 16 mL water and the dry fabric at 8 ℃(Z=-3.339, P=0.001). Specifically, when the skin temperature drop increased to approximately 1.2 ℃ and 1.4 ℃, the wetness of the wet fabric was significantly stronger. The Friedman test was adopted to further analyze changes in the wetness of both dry and wet fabrics with temperature and water addition. The perception of wetness in dry fabrics among the three groups showed significant differences (χ²=10.906, P=0.004), with a significantly stronger sensation of wetness in the dry fabric at 13 ℃ compared to that in the dry fabric at 18 ℃ (Sig.=1). Significant differences existed in perceived wetness among different groups for wet fabrics (χ²=24.875, P<0.001), where a lower sensation of wetness was observed for the wet fabric with 2 mL water compared to that for both the 12 mL and 16 mL soaked fabrics (Sig.=1).

Conclusion When the skin cooling is (0.965±0.015) ℃ and (1.165±0.015) ℃, the cold sensation of dry fabric is significantly stronger than that of wet fabric in the same group (P<0.05), indicating that a larger initial temperature difference makes it easier to experience a strong feeling of coldness. When the skin temperature consistently drops to(0.965±0.015) ℃, neither the dry nor wet state of the fabric significantly affects the perception of smoothness/roughness or dryness/wetness. In groups 2 and 3, wet fabrics feel rougher and wetter compared to dry fabrics, indicating that higher moisture content (12 mL, 16 mL) increases adhesion to the skin and enhances sensations of roughness and wetness. The comparative research of dry and water-containing fabrics enriches the theoretical basis of contact sensing characteristics. In the wetness reproduction device, the immersion feeling of wetness in the virtual world can be increased by reducing the contact temperature.

Key words: wetness sensation, contact perception, dry fabric, wet fabric, subjective evaluation, skin temperature