A multifunctional Janus metamaterial with a tunable anisotropic layer for universal Laplacian field control.

Multifunctional metamaterials have enabled the tailored manipulation of multiphysical fields, driving advancements in frontiers such as flexible electronics, advanced thermal management, and energy conversion. However, their practical deployment in complex environments requires not only structural compactness but also the ability to switch dynamically among multiple operations. Here, we propose and experimentally demonstrate a compact and tunable bilayer Janus metamaterial that achieves on-demand switching among concentration, rotation, and transparency functions in both thermal and electric fields, a methodology that can be readily extended to arbitrary Laplacian fields. This multifunctionality originates from engineered anisotropic thermal and electrical conductivity tensors, realized by alternately stacking high- and low-conductivity layers, which allow directional control of heat flux and electric current density. Specifically, by dynamically reorienting the anisotropic principal axis, the system exhibits controllable concentration, transparency, and rotation effects when the Laplacian flux passes parallel, perpendicular, or at an oblique angle relative to the layered stripes, respectively. Based on the mathematical isomorphism underlying the Laplace equation, this approach provides a readily implementable strategy for advanced multiphysical field regulation.