Programmable Information Processing With Reconfigurable Self-Contact Variable Stiffness Mechanical Metamaterial.

Confronting the limitations of conventional electronics, such as electromagnetic interference and poor extreme environment reliability, mechanical metamaterials offer a promising pathway for robust physical information processing. A core challenge remains achieving dynamic, reversible stiffness programming. Here, we propose a reconfigurable self-contact variable stiffness (SVS) metamaterial based on shape memory polymers (SMPs). The design features two unit cells with complementary asymmetry: one soft in tension/stiff in compression, and the other stiff in tension/soft in compression. By leveraging the shape memory effect, we precisely program the gap between internal contact blocks of the unit cell, actively controlling stiffness jumps and switching asymmetry modes. We demonstrate the platform's potential in two dimensions. First, an in-plane array achieves information storage (465.9 KB/m2) and encryption. Crucially, it retains data integrity under strong electromagnetic fields, outperforming traditional electronics. Second, combining units into a four-cell structure allows switchable asymmetric stiffness to convert symmetric vibrations into directional responses, realizing programmable matter transport (∼30 mm/s). This work provides a viable, robust mechanical solution for information processing in extreme environments where electronic systems are prone to failure.