Collective states of T. Aceti near flexible boundaries

We are experimentally studying the behavior of the nematode T. Aceti inside flexible boundaries. While there exist theoretical and numerical works that study the interaction between active matter and elastic walls, experimental realizations remain scare due notably to the difficulty of finding an active agent strong enough to deform a surface. Under favorable conditions of confinement, T. Aceti is capable of synchronizing the oscillations of their bodies and in this state produce a strong collective pushing force. We leverage this collective state to study the behavior of the nematode at the interface of two immiscible fluids, which act as a stretchable and deformable barrier due to the surface tension of the liquids. By adjusting the fluid properties, we are able to change the surface tension and the formed collective states, which strongly differ from the ones produced near rigid walls, opening another way of controlling active matter.