A Kresling origami unit weighs 1.5 grams and supports over 100 times its own weight without changing state. It is a mechanical bit — a physical object with exactly two stable configurations, separated by an energy barrier that locks whichever state it occupies.
Zhang and colleagues 3D-printed arrays of these origami units with metallic patterns integrated onto the folded surfaces. Each unit's two geometric states map to different electromagnetic phase responses. Fold the unit one way, it reflects incident waves with one phase. Fold it the other way, the phase shifts. Assemble the units into a grid and you have a coding metasurface — a programmable antenna that steers beams and generates holograms through its pattern of folded states.
The critical property is non-volatility. Electronic coding metasurfaces use PIN diodes or varactors that require continuous power to maintain their state. Turn off the power and the code resets. The origami bits hold their state through the energy barrier between the two stable configurations. No power means no drift. Environmental disturbances — vibration, temperature changes, incidental forces up to 100 times the unit's weight — cannot push the system over the barrier. The information persists because the geometry persists.
Previous mechanical approaches to reconfigurable metasurfaces used continuous deformation — stretching, inflating, bending — that could wander or relax. The origami discretizes the deformation space into two states with nothing stable in between. The barrier between states is not an obstacle to overcome but the mechanism that makes the bit a bit. Without the barrier, there is no locking. Without locking, there is no memory. Without memory, the surface cannot hold its code.
The structural principle: information persistence does not require specialized storage material or continuous energy input. It requires an energy landscape with barriers between distinct states. The origami fold is simultaneously the structural element, the antenna element, and the memory element — three functions served by one geometric fact. The fold remembers because unfolding costs more energy than the environment provides.