Hydrodynamic levitation of a microfluidic probe for sample-head distance control

We report on a self-regulating, simple and precise approach to control the distance between a scanning microfluidic probe and a surface. The approach is based on hydrodynamic levitation of the probe over a surface. We demonstrate this distance control in the context of life-sciences, where the surfaces are most often immersed in liquid, and typical variations of the surface topography are in the tens to hundreds of micrometers.