2026 Volume 21 Issue 1 Pages 25-00184
This study investigates the frost growth behaviors on a silver iodide (AgI) dot-patterned surface under desublimation conditions. The surface was fabricated using a two-step process combining UV lithography and UV nanoimprinting, resulting in a flat substrate with AgI dots embedded in a UV-curable resin (X433). The main objectives were to capture 3D frost morphologies through replica method and to evaluate whether such localized nucleation sites can induce laterally confined frost growth as observed in previous studies using AgI stripe patterns. Experiments were conducted at ambient temperatures of 2 ℃ and 10 ℃ with 40% relative humidity. Surface temperatures of −15.5 ℃ and −20.5 ℃ were selected to realize desublimation conditions, where the dew point is below freezing point. Frost formations on the AgI-patterned and bare resin surfaces were compared. On the AgI dot-patterned surface, frost nucleated selectively at certain AgI dots and grew horizontally, forming isolated columnar and planar crystals. These structures remained spatially separated for over 3 hours. In contrast, the bare surface exhibited typical frost behavior, i.e. dropwise condensation, droplet freezing, ice bridging, and eventually full coverage. Frost growth rate increased at lower surface temperature on both surfaces. On the AgI-patterned surface, the combination of higher ambient temperature and lower surface temperature further promoted nucleation and growth from the AgI dots, enhancing horizontal crystal development. To reconstruct the 3D frost structures, the replica method was applied. The AgI-patterned surface exhibited clear, laterally extended frost morphologies, while the bare PET surface showed random, interconnected frost growth. These results demonstrate that AgI dot patterns can effectively localize nucleation and preserve isolated and directional frost growth, offering a valuable approach for investigating frost growth mechanisms and developing frost controlling strategy.
