Buckling of circular rings and its applications in thin-film electronics

Buckling-guided transformations of thin-film materials into three-dimensional (3D) architectures are extensively utilized in electronic microsystems. However, the mechanically-guided assembly technique exploits a pre -stretched substrate, such that low-stiffness precursors would fail to realize global buckling due to the difficulty in overcoming interfacial adhesion (i.e., Van der Waals forces). Here, based on finite element analysis (FEA), a novel buckling-guided 3D assembly method by electromagnetic actuation is introduced through investigating the buckling behavior of a laminated thin circular ring. In this method, interfacial adhesion could be notably reduced by replacing soft substrates with rough platforms, thereby allowing formation of 3D structures with ultralow stiffnesses. Scaling laws for the critical current of buckling and the effect of joule heating are developed to guide controlled deformations and ensure rational designs. Numerical demonstration of a morphable, reconfigurable four-petal rose suggests the applicability and advantages of the proposed Lorentz force-guided 3D assembly method. In addition, we show that simultaneous measurement of the elastic moduli and thickness of planar materials could be possible based on the established scaling law for critical buckling current. The results pre-sented here serve as design guidelines for applying electromagnetically-actuated buckling behavior of thin-film materials in future applications such as soft grippers and biomedicine.

Automated summary

This study investigates the buckling-guided assembly of thin-film materials using electromagnetic actuation, proposing a novel approach by replacing soft substrates with rough platforms to reduce interfacial adhesion. The scaling laws for critical buckling current and the effect of joule heating are developed to guide controlled deformations and rational designs. The experimental demonstration of a morphable, reconfigurable four-petal rose showcases the applicability and advantages of this Lorentz force-guided 3D assembly method. Additionally, the study suggests the potential for simultaneous measurement of elastic moduli and thickness of planar materials based on the established scaling law for critical buckling current.