Combined dielectrophoretic field cages and laser tweezers for electrorotation

Symmetric rotating octode field cages do not allow simultaneous particle tr apping and electrorotation. Laser-trapped particles can stably be held in i nhomogeneous rotating electric fields. Therefore, in a combination of laser tweezers and field-cage (electro-optical cage) dielectric single-particle spectroscopy (DSPS) of particles and cells can be carried out at low electr ic field strength. The electro-optical cage overcomes the limitation of low enough effective particle conductivity ensuring repelling dielectrophoreti c forces in conventional field cages. At low power, forces in field cages a nd laser tweezers hardly interfere and can be used to calibrate each other.