A biophotonic study of live, flowing red blood cells in an optical trap

Abstract

We investigate the physics of an optically trapped red blood cell under physiological conditions. When a single, live red blood cell, is placed in an optical trap, the normal biconcave disk shaped cell is observed to undergo a folding action and thereby take up a rod like shape. If such an RBC has any shape anisotropies due to perturbation through malarial infection or hyperosmotic stress, it is observed to rotate in the linearly polarised laser field. Finally when such an optically trapped RBC is exposed to a shear flow, a tank treading like behaviour of the red blood cell membrane is visualised (wherein the RBC membrane revolves around the central body of the cell). The tank treading motion of a red blood cell held stationary in the optical trap allows for the dynamics to be viewed in a prolonged manner without the usage of earlier constraints such fast imaging system.