Micropillar-Engineered Hybrid Adhesive Patch for Surface-Conformable and Directional Adhesion

This study introduces a hybrid bioinspired adhesive patch that integrates height-optimized hexagonal PDMS micropillars with nonlinear open-rectangular cuts to achieve strong, surface-conformable, and directionally switchable adhesion on rough substrates. Through systematic tuning of pillar height (10–25 µm), the authors identify 20 µm pillars (H.20) as the optimal geometry to balance compliance, asperity penetration, and structural stability. The optimized patch achieves a pull-off strength of 79.5 kPa on rough PDMS surfaces (RMS = 20.1 µm) and enhanced peel capacity reaching 106.3 N m⁻¹, driven by synergistic microscale crack arrest and macroscale crack reversion. The hybrid architecture enables up to 20× directional adhesion contrast and >100-cycle durability. Integration into a robotic gripper demonstrates stable grasp–release operation on objects of varied shapes and roughness, validating real-world applicability for soft robotics, wearables, and biomedical interfaces.