Snap-Through Thermomechanical Metamaterials for High-Performance Thermal Rectification

TL;DR

This paper introduces a thermomechanical metamaterial-based thermal diode that uses shape memory alloys and structural bistability to achieve high thermal rectification, surpassing existing designs in efficiency and scalability.

Contribution

The work presents a novel passive thermal diode design combining shape memory alloys and bistable structures, enabling high rectification ratios and scalable modular configurations.

Findings

Thermal rectification ratio exceeds 900.

Device demonstrates robust cycling stability.

Modular stacking enhances scalability.

Abstract

Thermal diodes that enable directional heat transport are essential for advanced thermal management in microelectronics, energy systems, and thermal logic devices. However, existing designs based on phase-change materials, nanostructures, or interfacial engineering suffer from limited rectification performance, configurational inflexibility, and poor scalability. Here, we present a thermomechanical metamaterial-based thermal diode that combines temperature-responsive actuation with structural bistability to achieve high-efficiency, nonreciprocal thermal transport. The device integrates shape memory alloy (SMA) springs with pre-buckled copper strips that undergo snap-through transitions in response to thermal gradients. This reconfiguration enables contact-based conduction in the forward mode and suppresses reverse heat flow via radiative isolation. We develop a coupled analytical model combining Euler-Bernoulli beam theory and a thermal resistance network, and validate the system through finite element (FE) simulations and experiments. The device achieves a thermal rectification ratio exceeding 900, with robust cycling stability and structural integrity. A modular stacking strategy further enhances scalability without compromising performance. This work establishes a new design framework for high-performance, passive thermal rectifiers that bridge mechanical metamaterials and advanced thermal engineering.