Active control of bioinspired dry adhesion via magneto-responsive microstructures and PDMS composite backing

Bioinspired dry adhesives require a balance between flexibility for conformal surface contact and stiffness for stable load-bearing adhesion. Here, we present a magnetically tunable dry adhesive that addresses this challenge by integrating 10 µm cylindrical polydimethylsiloxane (PDMS) microstructures with a composite backing containing ∼20 wt% Fe₃O₄ particles. The adhesion behavior of the fabricated samples is investigated both experimentally and using finite element analysis. The results reveal that application of an external magnetic field induces localized stiffening within the backing layer, actively reinforcing the adhesive interface. This magnetic activation suppresses premature microstructure bending, reduces interfacial stress concentrations, and enhances load transfer during adhesion. The optimized magnetically activated configuration reached its maximum shear strength at a displacement approximately 22% lower than that of the control and exhibited a 94% increase in peak adhesive stress during peel-off testing, reaching 0.062 N/cm². Numerical simulations corroborated the experimentally observed stress redistribution and adhesion enhancement mechanisms. These findings demonstrate a practical strategy for achieving magnetically tunable, high-performance dry adhesion through real-time magnetic control, with potential applications in soft robotics, advanced manufacturing, and intelligent gripping systems.