Electro-rotation in octopole micro cages

We have developed a new design for a three-dimensional (3D) micro electrode octopole, driven by rotating electric fields in the MHz range. It allows s imultaneous caging and rotation of single cells or particles with a size be tween 5 and 30 mu m. The conflict between particle caging and the induction of particle rotation has been solved by breaking the symmetry of the elect rode arrangement. The octopole consists of two layers of planar electrodes processed on glass and separated by a 40 mu m thick polymer spacer, which f orms a flow channel. Unlike planar four-electrode devices, the 3D octopole electrode cage can trap micro objects in free suspension. In addition, we h ave developed a new method for the automatic detection of single particle d ynamics (MOSPAD). We also give calculations for dielectric forces and torqu e moments and a comparison of differences to four electrodes structures.