The invention relates to a system for maintaining an assembly of solid particles, having sizes in the range of micrometers or nanometers, as a suspension, in a limited and well-defined region, without mechanical contact with the walls of an enclosure or with other supporting element. According to the invention, the system comprises a dielectric container (8) of arbitrary shape, fully closed or partially open, containing some particles (10) to be maintained in suspension, which is introduced between some electrodes (1a, 1b, 1c and 1d) of a linear electrodynamic trap, where the particles (10) can be electrized as a consequence of their physical contact, of their interaction with the dielectric wall of the container (8), by including some additional electrodes (2a and 2b) to which high voltage pulses are applied, by the sudden variation of the value of electric voltages applied to the trap electrodes (1a, 1b, 1c and 1d) or as a consequence of the action of a beam of ionizing radiation coming from an external source, the container (8) being made of a dielectric material.