Contact?Driven Snapping in Thermally Actuated Metamaterials for Fully Reversible Functionality

Mechanical instability is often harnessed in mechanical metamaterials to generate a diverse range of functionalities, and can be triggered by either or field stimulus, such as temperature. Existing field-responsive with snap-through instability, however, need rely on input realize functional reversibility, limitation depriving them the capacity operate solely via applied field. This work demonstrates reversible bi-material framework that exclusively driven environmental The for intervention bypassed leveraging thermally induced contact mismatched thermal expansion constituent materials. A combination experiments, theory simulations, unveils physics underpinning snapping undergoing four successive regimes deformation: noncontact, full contact, partial release. advantages concept are showcased two applications. first development switches ternary operation (OFF-ON-OFF) logic functions, going beyond capabilities current binary switches. second temporal morphing deployable structures programmed snap sequentially multiple locked configurations at predefined values temperature, opening door applications across sectors, antennas, soft robots, self-reconfigurable medical devices.