Chemically Induced Ferroic-like Phase and Collective Chemotaxis in an Active Swarm

Amplification of weak chemical signals through intracellular cascade networks is crucial for long-range cohesive migration in biological processes, such as embryogenesis and cancer metastasis. While this capability has transformative potential for synthetic systems in precision medicine and adaptive materials, the lack of cascade communication in artificial matter has been a significant barrier. This study demonstrates that a binary active colloid mixture, mediated by a chemical reaction, forms a simple chemical reaction network capable of self-organizing into polarized dynamic swarms, dramatically enhancing chemical amplification. By applying the classical Ising model, we rationalize the self-polarization with increasing chemical activity, drawing an analogy to ferroic materials in the chemically polarized active phase. Under optimal conditions, these "ferrochemical" swarms can amplify weak chemical gradients by over 10⁴ times, resulting in exceptional chemical sensitivity and remarkable long-range collective chemotaxis. As a proof of concept, we demonstrate the application of silver-doped active swarms to enhance antibacterial efficacy, showcasing a chemotactic swarm that effectively combats dental biofilm growth on human teeth.