Processing of micro-particles by UV laser irradiation in a field cage

An electric cage-laser micro-turning lathe was realised and applied to contact-free handling and mechanical processing of micro particles. Since particles with diameters of several micrometers cannot be fixed in mechanical chucks, an octode field cage was used to trap and rotate a single particle in a fluid without any mechanical surface contact. A pulsed nitrogen laser of high beam quality focused to about 1 mu m in diameter could be adjusted independently of the cage position, The trapping forces (negative dielectrophoresis) acting on a bead of 5 to 15 mu m are up to several hundred pN. This and the surrounding fluid damp down the effect of the laser pulses during bead processing. Examples demonstrating the possibilities of this technique are shown. Microsystems with high optical quality were fabricated photolithographically or by laser direct-write chemical vapor deposition (LCVD). Technical and biotechnological applications are discussed.