3D microrheology using multiplane imaging

Microrheology is the study of the viscoelastic properties of materials on a microscopic scale. This is normally done by using a ~ 1µm bead as a tracer particle, and tracking its motion with time as it undergoes constrained Brownian motion. The constraint is either provided by the stiffness of the material the bead has been embedded in, or in the case of liquids, an optical trap. Generally, microrheology is carried out only in a single plane, giving the viscoelastic properties in x and. However, in many biologically relevant systems, these properties may be anisotropic in x,y and z.
Multiplane imaging is a technique which has been developed at Heriot Watt over a number of years, and which seems well suited to 3D localisation, due to the fact it gives multiple planes in z simultaneously. In this seminar, I will outline how we may use multiplane imaging to track a particle in 3D, and use these results to extract the rheological properties of a medium.