Noncontact frictional force between surfaces by peristaltic permittivity modulation

In this study, we reveal noncontact frictional forces between surfaces in the presence of peristaltic permittivity modulation. Our setup comprises a conducting medium, an air gap, and a dielectric substrate on which we have a space-time-modulated grating that emits electromagnetic radiation. The radiation receives energy and momentum from the grating, which is eventually absorbed by the conducting medium or propagates away from the grating on the dielectric side, resulting in electromagnetic power loss and lateral forces at the surfaces.