| An homogeneous thin film of fluid is usually stable. It may become unstable by the local change on the surface tension due to gradients of temperature, chemical reactions or electric fields, giving rise to pattern formation. Surfactants are amphiphilic molecules, which remain in the surface and reduce the surface tension. We consider the destabilization of the fluid by the action of a surfactant with the ability to push perpendicularly the interface. However, typical surfactants are usually passive objects and they are not able to perform any mechanical force. Some proteins can swim in a fluid and generate mechanical forces in the presence of chemical energy. A molecule can swim in a fluid with a low Reynolds number depending on its ability to change from one conformational state to another by a particular way and to go back to the initial conformation by a different way. We consider model where such molecular machines attached to the interface for the generation of normal forces in the surface of the fluid and induce pattern formation. |
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