Emergence of multimodal odd matter enabled by robo-embryos

Nonreciprocity in living and synthetic active matter gives rise to striking properties such as odd elasticity and viscosity, reflecting distinct ways materials store, dissipate and transduce energy and information. Yet these responses have rarely coexisted within a single system. Here, we ask: can we design robotic odd matter with multimodal, tunable behavior? We develop a Magnetically-Augmented Spinning Robotic Swarm (MASbotS) that operates at the air–water interface through magnetic and hydrodynamic interactions, producing tunable nonreciprocal dynamics. This control drives transitions from a hexagonally ordered odd-elastic crystal to a fluidized odd-viscous state and ultimately a chiral active gas, realizing a macroscopic nonequilibrium phase transition. Unlike conventional active matter with homogeneous driving, MASbotS provides precise particle-level control of nonequilibrium forcing, enabling patterned activity and heterogeneous symmetry breaking. This control yields emergent phenomena such as phase separation and collective translation. Altogether, MASbotS offers a versatile platform to probe nonequilibrium statistical physics and harness nonreciprocity as a design principle for robotic swarms with programmable collective behavior.