Crack-Controlled Adhesive Interface for Payload-Bearing Robotic Manipulation with Directional Release

This study developed a crack-controlled adhesive manipulation interface designed to support payload-bearing robotic manipulation while enabling predictable directional release without external actuation, vacuum, or complex release hardware. The interface, termed CAMI, integrates hexagonal mushroom-tipped PDMS micropillars with a directional nonlinear open-cut architecture. The micropillar array provides strong normal adhesion by increasing real contact area, redistributing interfacial stress, and repeatedly arresting microscale cracks during detachment, while the nonlinear cut pattern programs macroscale crack propagation to create strong peel resistance in load-bearing directions and facile release in a selected direction. The CAMI achieved a pull-off strength of 249.7 kPa, retained stable pull-off performance over more than 100 attachment-detachment cycles, and supported a 1 kg payload over a 1 cm² contact area. Peel testing showed a maximum peel capacity of 209.5 N/m in the maximum-force direction and a directionality ratio of 10.7, demonstrating strong adhesion asymmetry. Spatial peel mapping confirmed that the cut layout created mirrored high-adhesion lateral domains, an intermediate stabilization direction, and a low-resistance release direction. When mounted on a robotic end-effector, CAMI supported a 1 kg payload up to 30.2° in the load-bearing direction and released at only 6.3° in the programmed release direction. Overall, the work demonstrates a passive structurally programmed adhesive system for repeatable robotic pick-and-place manipulation, where attachment, stabilization, and release are governed by engineered crack pathways.