| 摘要 |
A disposable first tube (68) extends axially through, and is detachably connected to, an annular main body (10'). An input piezo electric element (38) is attached to a first end of the tubular main body (10'). A second, sensor piezo electric element (40) is attached to the opposite end of the main body (10'). A nozzle (20') having a nozzle passageway (110) and a discharge opening (112) is detachably secured to an outlet end of the first tube (68). A second tube (102) within the first tube (68) delivers a core liquid to the nozzle passageway (110). A sheath liquid is delivered through a space in the first tube (68) surrounding the second tube (102). The nozzle passageway (110) forms the core and sheath liquids into a small diameter jet stream. Electrical energy is delivered to the input piezo electric element (38), to vibrate the nozzle (20') and break the jet stream into droplets. The sensor element (40) determines the amplitude of vibration at the nozzle (20') and delivers this information to a control circuit that adjusts the electrical energy input to the input piezo electric element (38) for maintaining a desired amplitude of vibration at the nozzle (20'). The frequency of vibration is determined by the length of the main body (10') between the two piezo electric elements (38, 40). The first and second tubes (68, 102) are disposable and are replaced after a use rather than being cleaned and sterilized.
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