Elliptical optical tweezers for trapping a red blood cell aggregate

Red blood cells (RBCs) and their aggregates scatter light strongly. Optical tweezers facilitate the manipulation of cells and light scattering measurements at the single cell level. We show in this letter the successful trapping of an RBC aggregate with elliptical optical tweezers in a free suspension. Two cylindrical lenses are used to form the trap. The distance between the trapped objects and the bottom of the cuvette had a clear effect on image quality. Rotating the cylindrical lenses changes the orientation of the aggregate, which produces a visible change in the light scattering intensity images taken by a CCD camera.