Belousov-Zhabotinsky (BZ) reaction computer

The BZ reaction is an oscillating chemical system that produces propagating excitation waves in a thin layer of reagent (typically ferroin or ruthenium catalyst in acidified bromate/malonate). Signals are encoded as wave fronts; the interaction of two colliding wave fragments implements logic at the collision site. Annihilation corresponds to AND; a wave passing through unimpeded corresponds to OR. Adamatzky demonstrated NOT, OR, AND gates in fixed channel geometries. A light-sensitive variant (with ruthenium catalyst) allows gates to be programmed by illumination patterns. A 2024 Nature Communications paper demonstrated a hybrid digital-chemical programmable array. Speed: ~1-10 mm/min wave propagation; seconds to minutes per gate. Capacity: small logic circuits; limited by wave-front geometry and reagent lifetime.