Motion analysis of floating micro-granules: Microscale beads, inactivated Escherichia coli and platelets

Motions of floating micro-granules were observed by using the system of an inverted microscope with a complementary metal-oxide semiconductor camera. The granules of microscale size, namely, beads, inactivated Escherichia coli and platelets, were contained on the sample stage, the temperature of which was controlled precisely. Under conditions of various temperatures, the positions of the granules were recorded and analyzed to obtain the velocity distributions in one-dimensional and two-dimensional projected space. Under the assumption of isotropy, an exponential-type function for the velocity distributions was proposed for the phenomenological descriptions of the motions. Thermodynamic aspects of the micro-granule motions were also discussed for possible application in the study of biological systems.