Topology-optimized freeform thermal metamaterials for omnidirectionally cloaking sensors

Abstract

The cloaked sensor, which is capable of cloaking itself and still receiving an incoming signal simultaneously, has attracted widespread concern. In the thermal diffusion community, the possibility of designing thermal metamaterials for cloaking sensors has been successfully proved with the help of transformation thermotics and scattering cancelling technology. However, a long-held issue is that designing thermal metamaterials with freeform shape and omnidirectional functionality for cloaking sensors. Here, a synthetic strategy is reported to design freeform thermal metamaterials for omnidirectionally cloaking sensors and making sensors normally receive and measure external heat signals without distortion simultaneously. An irregularly shaped thermal metamaterial is designed by multiscale topology optimization and fabricated by 3D printing, and its thermal functionality is verified numerically and experimentally. This work addresses an intriguingly important challenge in cloaking sensors in terms of freeform thermal metamaterials with omnidirectional functionality that is not possibly achieved via the current design technologies for thermal metamaterials, thus laying a foundation for the application of thermal metamaterials in sensing systems, and it may be extended to thermal energy harvesting, thermoelectric converting, thermal camouflage and illusion metadevices.