NEBULIZER PARTICULARLY ADAPTED FOR ANALYTICAL PURPOSES

摘要

A nebulizer for analytical purposes includes a needle through which flows a liquid to be nebulized. The liquid flows from the needle onto a diaphragm planar surface that is vibrated in successive pulses. A continuous bridge of the liquid subsists between the liquid and the planar surface when the diaphragm is in the non-vibrating state. The liquid is nebulized to an aerosol when the diaphragm is pulsed. The needle and diaphragm are always spaced from each other. A wick on the planar surface in contact with the film removes excess amounts of the liquid not involved in forming the aerosol. The diaphragm vibration is pulsed by a piezoelectric crystal that responds to an FM wave whose frequency is swept over a band spanning the resonant frequency of the crystal. The crystal is configured as a spherical segment to direct a focused pressure wave on the diaphragm via a liquid medium. The diaphragm has a thickness that is about one-half wave length of the pressure wave supplied to the liquid medium by the crystal, to provide destructive interference of waves reflected from opposite faces of the diaphragm. A carrier gas for the nebulized aerosol is supplied to the diaphragm planar face to form a curtain about the liquid flowing from the needle to the diaphragm. The liquid circulates between the diaphragm and crystal to cool them and enable gases in the liquid to be removed.