(753f) Local Deformation and Contact Phenomena of Microscopic Objects Near Surfaces: A View From Below

Interference-based techniques have demonstrated great spatial (nanometer-scale) and temporal (microsecond-scale) resolution capabilities in the study of objects near surfaces.  In addition to this, reflection interference contrast microscopy (RICM) offers a unique non-invasive “view from below” perspective that provides valuable information about contact phenomena, if any, and the topography of microscopic objects in close proximity to a transparent substrate. Well-known RICM capabilities, such as contact area and shape determination, have been extensively used in adhesion studies of particles, cells and lipid/polymer vesicles, although a significant drawback has been the complexity of the image analysis required for accurate results.

In this work, we introduce an innovative analysis of RICM interferograms that allows fast reconstruction of an arbitrarily shaped convex object with unprecedented nanometer-scale resolution. In addition, RICM’s “view-from-below” is used to observe, for the first time, femtoliter-scale capillary condensation dynamics underneath micron-sized particles. Therefore, our implementation of RICM provides a high-resolution tool that opens new possibilities to realistically capture statistic/probabilistic behavior of dynamic interactions between ensembles of microscopic objects and surfaces.