3D Particle Tracking

Tracking of the three-dimensional position of actively motion-controlled magnetic micro- and nano-particles over flat surfaces

Video image frames recorded for particles residing in the microscope focal plane (right) and 400 nm below the focal plane (left)

Typically, magnetic micro- and nano-particles immersed in a liquid in lab-on-chip systems are moving over a surface in a distance determined by the equilibrium of the acting forces between particle and chip-surface through the liquid. If these forces do change also the equilibrium distance will change. Up to now most of the motion analysis is carried out by determining the particles’ 2D positions as functions of time only, however, a determination also of the height over the substrate would allow a sensitive detection of modified forces by the change of the equilibrium particle-substrate distance, e.g. induced by particle coverage with an analyte. Here we try to develop an AI-based software for such a 3D tracking, exploiting the changing optical contrast of the videos, when particles move in different heights with respect to the focal plane of the microscope used to observe the particles.