Abstract: An improved device and method for measuring the amount of liquid to be discharged that is present in an apparatus, such as a nebulizer. A first member has holes through which the liquid passes to be nebulized. A second member is spaced from the first member so that a volume is defined in the nebulizer by the area of mutual overlap of the first and second members and the amount of spacing between them. The first and second members are formed to establish a mutual capacitance that reflects the amount of liquid in the volume. A measuring circuit measures the capacitance existing between the first and second members and hence the amount of liquid in the nebulizer. The capacitance measurement can be used to control the supply of liquid into the volume in the nebulizer.

Abstract: A nebulizer determines the pressure and flow direction of the receiving gas for atomized liquid. A member of the apparatus is subjected to pressure exerted by the gas. The member is coupled to a bi-directional mechanical-electrical conversion element, such as a piezoelectric element, to form a pressure transducer. The member exerts a mechanical loading on the element responsive to the gas pressure to which it is subjected. In one embodiment, the element mechanically vibrates responsive to alternating electrical energization to discharge the liquid into the gas. The electrical admittance of the element is alterable by the mechanical loading applied to the element by the member. The difference between admittances measured in the loaded condition of the element and in an unloaded condition at the selected energization frequency is an indication of the pressure of the gas.

Abstract: A nebulizer apparatus to atomize liquid solutions or suspensions. The nebulizer is typically used in conjunction with a breathing circuit to deliver atomized medicine to a patient. A housing with an opening covered by a thin mesh plate is supplied with the liquid to be nebulized on an “on-demand” basis. The mesh plate or liquid is vibrated at ultrasonic frequencies to atomize the liquid as it passes through the plate into the breathing gases flowing through the breathing tube. The vibration is produced with a piezoelectric element. The most efficient point to produce vibrations is found by measuring current, voltage or phase angle taken by the piezoelectric element or by measuring the resistance of the strain gauge attached to vibrator.