Active Liquid Matter Driven by Nonequilibrium Interfacial Tension

Many experimental studies have shown that changes in the interfacial tension trigger the self-propulsion of active liquid matter. It is widely believed that for the self-propulsion of a liquid droplet, the interfacial spontaneous convection generated by the Marangoni effect is required. However, several experimental and theoretical studies have demonstrated that the Marangoni effect has a retarding effect on the moving velocity. This contradiction has led to the investigation of alternative propulsion mechanisms. A new understanding of self-propulsion obtained by resolving the interpretation of this discrepancy is discussed in this review. Furthermore, this review summarizes the current state of experimental and theoretical research on the bifurcation of movement modes.