Particle separating apparatus and method

• US 6,003,678 A
• Filed: 10/13/1998
• Issued: 12/21/1999
• Est. Priority Date: 08/21/1997
• Status: Expired due to Term

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Van den Engh, Gerrit J.
• Primary Examiner(s): Terrell, William E.
• Assistant Examiner(s): DILLON JR, JOSEPH A
• Application Number:
  US09/170,017
• Time in Patent Office: 434 Days
• Field of Search: 73/865.5, 324/71.4, 356/441, 356/442
• US Class Current: 209/158
• CPC Class Codes: B01L 3/0268 using pulse dispensing or spraying, eg. inkjet type, piezo actuated ejection of droplets from capillaries
• CPC Class Codes: G01N 15/10 Investigating individual particles
• CPC Class Codes: Y10S 209/92 Vibratory feed conveyor
• CPC Class Codes: Y10S 209/921 Reciprocating or oscillating feed conveyor

Abstract

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.

Claims

1. A particle separator, comprising:

an axially elongated, tubular main body having a central axial opening and first and second ends;

a separate tube extending axially through the central axial opening in said main body, said tube being connected to the main body and defining a sheath liquid passageway, said separate tube including a sheath liquid inlet and an outlet;

a nozzle at the outlet of the separate tube, said nozzle having a central nozzle passageway and a discharge opening, said sheath liquid passageway discharging into said nozzle passageway;

a core liquid passageway in said sheath liquid passageway, said core liquid passageway having a discharge opening discharging into the nozzle passageway;

an input piezo electric element connected to the first end of said tubular main body and adapted to vibrate said main body when excited by electrical energy, whereby said main body will function as an oscillator; and

a second piezo electric element connected to the second end of the tubular main body, said second piezo electric element functioning to generate a voltage signal related to the strength of the vibration in the assembly body,

wherein the length of the tubular main body between the two piezo electric elements establishes the frequency of vibration.

2. A particle separator according to claim 1, wherein said outlet of said separate tube includes an outlet portion extending axially outwardly from the second end of the tubular main body, and said nozzle is a separate structure that is detachably connected to the outlet portion of said separate tube.

3. A particle separator according to claim 1, further comprising a screw connection between the separate tube and the tubular main body, at the second end of the main body, said tube extending from such connection through the central axial opening, in a radially spaced relationship to said opening.

4. A particle separator according to claim 3, wherein said separate tube includes an inlet portion that projects axially outwardly from the first end of the tubular main body, said particle separator including an end cap connected to said inlet portion, said end cap including a sheath liquid inlet.

5. A particle separator according to claim 4, said separate tube further comprising a small diameter tube structure that defines the core liquid passageway, said tube structure extending axially through said separate tube, and wherein the inlet cap includes an opening to which said tube structure extends.

6. A method of forming droplets, comprising:

providing an axially elongated, tubular main body having a central axial opening and first and second ends;

providing a sheath liquid passageway within the tubular main body extending from the first end to the second end;

providing a core liquid passageway in said sheath liquid passageway;

providing a nozzle having a central nozzle passageway and a discharge opening;

providing the core liquid passageway with a discharge opening and positioning it to discharge core liquid into the nozzle passageway;

providing the sheath liquid passageway with a discharge opening and positioning it to discharge a sheath liquid into the inlet of the nozzle passageway, in a surrounding relationship to the discharging core liquid;

introducing a core liquid into the core liquid passageway and a sheath liquid into the sheath liquid passageway;

configuring the nozzle passageway so that the core liquid and the sheath liquid are formed by said nozzle into a small diameter jet stream that discharges from the discharge opening of the nozzle;

providing an input piezo electric element and connecting to the first end of said tubular main body;

applying electrical energy to the input piezo electric element so as to vibrate the tubular main body, and cause it to function as a mechanical oscillator, for vibrating the nozzle so as to cause vibrations that will break the jet stream into droplets; and

establishing a frequency of vibration by a selection of the length of the tubular main body.

7. A method of claim 6, further comprising connecting a sensor piezo electric element to the second end of said tubular main body, and using said sensor piezo electric element to determine the amplitude of vibration of the nozzle, and using the amplitude of vibration as a feedback control signal, for adjusting the electrical energy input to the input piezo electric element for the purpose of maintaining a desired vibration energy at the nozzle.

8. The method of claim 6, comprising providing an elongated first tube, extending said first tube through the central axial opening in the tubular main body, and detachably connecting said first tube to the tubular main body;

providing a second smaller tube within the first tube;

using the smaller second tube to provide the core liquid passageway;

using an annular space that is defined by and between the first and second tubes to provide the sheath liquid passageway;

detachably connecting the nozzle to the first tube; and

following the formation of droplets, disconnecting the first tube from the tubular main body and the nozzle from the first tube, disposing the first tube, and replacing the disposed first tube with a new first tube.