FORCE MEASUREMENTS OF OPTICAL TWEEZERS IN ELECTROOPTICAL CAGES

We introduce a new device for measuring optically induced forces on mi croparticles and cells. It uses high-frequency electric field cages (o ctopoles); dielectrophoretic force calculations allow calibration of o ptical tweezers. A microsystem in the form of a microscope slide was f abricated by photolithography and electrically connected to a 4-phase high-frequency generator. The possibilities and advantages of a combin ed electro-optical trap are exemplified by the manipulation of latex b eads and human erythrocytes. The system clearly detects misalignments of optical tweezers. In spite of instabilities it is possible to obtai n a force-versus-power calibration. Further possibilities of the techn ique are discussed.