Two-Way Shape Memory Micropillar Arrays Enabling Efficient and Continuous Switchable Adhesion for Microparticle Manipulation.

Smart surfaces with efficient, switchable adhesion for micro-objects are desirable for high-precision electronics assembly and targeted micro-delivery. However, they still face challenges like size-dependent detachment and the absence of continuous adhesion control. Here, we propose a two-way shape-memory micropillar array (SMMA) based on liquid crystalline elastomers (LCEs), reversibly and continuously switching between upright and collapsed states under thermal stimulation. By leveraging strong elastic energy released during spontaneous shape change and excellent mechanical strength, the surface enables in situ self-driven detachment of microparticles larger than the pillar spacing. A heat-load-shear-pull (HLSP) protocol is further developed to achieve efficient detachment of microparticles comparable to pillar spacing, with a detachment efficiency of 90.6% for glass microparticles. Optimization of preload depth and shear distance confirms adaptability across multiple particle materials and size ranges. These switchable adhesion capabilities are demonstrated in diverse applications including patterned transport and cyclic handling of microparticles. Overall, shape-memory-assisted shear adhesion provides a programmable route to precise manipulation and flexible transport of micro-objects.