Scalable Gecko-Inspired Adhesives via Diffraction-Grated Molds: A Low-Cost, Directional PDMS System

Geckos achieve exceptional adhesion through hierarchical micro/nanoscale setae exploiting van der Waals forces, a mechanism challenging to replicate synthetically due to fabrication complexity. This study presents a cost-effective, lithography-free method for gecko-inspired adhesives by casting PDMS onto commercial diffraction-grated sheets. The resulting microstructure exhibits directional adhesion, passive detachment, and a non-adhesive default state. Shear and peel tests across 8.06–103.23 cm² contact areas demonstrated a maximum shear stress of 19.10 kPa (supporting up to 7.105 kg) and peel forces below 1 N at 90°, confirming controlled release. Durability testing showed performance recovery after contamination and cleaning, ensuring reusability. The fabrication method eliminates cleanroom requirements, using RTV silicone, 3D-printed fixtures for rapid, scalable prototyping, and diffraction-grated molds. Current limitations include single-level microstructures and absent nanoscale features, reducing efficacy on varying surface structures. Future work will integrate resin-printed molds to introduce wedge-shaped/angled structures and microporous filters for nanoscale fidelity, aiming to develop hierarchical adhesives that rival state-of-the-art systems. These advancements target high performance while maintaining affordability and scalability for diverse applications, from robotics to industrial automation. By bridging the gap between biological inspiration and manufacturable design, this approach offers a practical pathway toward reusable, high-capacity adhesives with broad real-world utility.