Social insect aggregations as inspiration for mesoscopic active matter*

Social insects such as ants and bees exhibit extraordinary co-operative behavior to form aggregations and are often called super-organisms due to their ability to achieve complex structures and functionalities. Individual interactions include attachment and detachment of legs, bodies and mandibles that result in active re-organization of the network that can drastically transform the aggregation from a solid-like to fluid-like material and vice-versa. As the interactions in these aggregations operate in the mesoscale, they are easily observable and are attractive candidates to emulate in synthetic systems. Drawing inspiration from insects, we have designed a synthetic mesoscopic aggregation in our lab made of particles resembling mini gears and interact through magnetic and shear forces to self-organize into a network. The aggregation is infused with leader particles containing battery powered motors that induce motion and activity in the entire network. The aggregation behavior can be tuned by varying the magnetic strength, motor activity of leaders and their positions and diversity in particle size. Using statistical mechanics, we show that the aggregation can be programmed to achieve specific shapes and even transport solid metal objects through them.