Bioinspired Moisture-Responsive Smart Knitted Fabric with Artificial Leaf Stomata Based on Polyacrylamide Hydrogel

Dynamic moisture-responsive textiles are highly desirable for smart clothing that adapts to physiological and environmental changes to enhance the wearer's comfort. Unfortunately, many moisture-responsive fabrics suffer from slow response times, poor reversibility, and insufficient durability. Moreover, these fabrics frequently fail to satisfy requirements such as tactile softness, appearance retention, and integration compatibility with existing clothing systems. This research reports a commercial strategy to engineer artificial leaf stomata into knitted fabrics by using screen-printed polyacrylamide (PAAm) hydrogel coatings followed by laser cutting. Inspired by natural stomatal function, our design enables the fabric to autonomously open and close moisture-responsive slits without altering its surface appearance or tactile properties. By investigating the hydrogel formulation, coating and cutting direction, and aspect ratio of the pattern, we optimized the actuation performance. Fabrics coated with 0.12 wt % cross-linked PAAm showed rapid and reversible opening behavior: slits cut along the weft direction at an 8:9 aspect ratio reached a maximum width of 1.07 ± 0.01 mm, while those at the warp direction at 7:9 reached 0.80 ± 0.04 mm. Upon absorbing moisture equivalent to 95% of their dry weight, slits opened within 10 s, increasing air permeability by 63.3% compared to control fabrics. The pores remained stable after repeated laundering. Under wet conditions, the slits enhanced heat and moisture dissipation, keeping the skin drier. This bioinspired integration of moisture actuation into textiles offers a promising route toward high-performance, moisture-responsive garments with durability.