High frequency uniform droplet maker and method

• US 9,321,071 B2
• Filed: 09/28/2012
• Issued: 04/26/2016
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: 6K Incorporated, University of Connecticut (State of Connecticut)
• Original Assignee: Amastan Technologies LLC, University of Connecticut (State of Connecticut)
• Inventors: Jordan, Eric, Redjdal, Makhlouf, Hadidi, Kamal
• Primary Examiner(s): JONAITIS, JUSTIN M
• Application Number:
  US13/630,318
• Publication Number:
  US 20140091155A1
• Time in Patent Office: 1,306 Days
• Field of Search: 239/102.1, 239/102.2, 239/690, 239/699, 239/225.1, 239/226, 239/230, 239/4, 239/260, 347/5, 347/9, 347/10, 347/11, 347/12, 347/20, 347/44, 347/47, 347/48, 347/57, 347/58, 347/59, 347/73, 347/74, 347/75
• US Class Current: 1/1
• CPC Class Codes: B05B 17/0607 generated by electrical means, e.g. piezoelectric transducers
• CPC Class Codes: B05B 17/0669 Excitation frequencies

Abstract

There is disclosed a piezoelectric droplet maker that is driven at high frequency and energized with high power and high frequency Operational Amplifier (OP-AMP) electronics. The droplet maker implements a method of producing jets of uniform droplets of solution precursors (or any other homogeneous liquids). The formation of droplets results from stream break up due to the disturbance of liquid jets by the piezo actuator as they leave an orifice. This disturbance can be electronically tuned to produce uniform droplets with high repeatability. In another aspect, the droplet maker can be used to inject axially uniform diameter solution precursor droplets into process gas flow of a microwave plasma apparatus.

Claims

1. A system for producing droplet streams having droplets with uniform diameter, the system comprising:

a solution dispenser in fluid communication with a fluid reservoir in a fluid reservoir vessel and disposed to maintain the fluid reservoir filled with fluid and under pressure via a channel running substantially parallel to a main axis of the fluid reservoir in the direction of one or more capillary nozzles;

a separation membrane defining a first end of the fluid reservoir and in contact with the fluid on one side of the separation membrane;

a piezo actuator in contact with the separation membrane on a side opposite that in contact with the fluid; and

the one or more capillary nozzles disposed at a second end of the fluid reservoir away from the separation membrane, the fluid within the fluid reservoir contacting both the separation membrane and the one or more capillary nozzles, wherein the one or more capillary nozzles receive fluid from the fluid reservoir and eject a droplet stream from the capillary nozzle.

2. The system for producing droplet streams according to claim 1, wherein the fluid reservoir vessel is generally or substantially cylindrical in shape.

3. The system for producing droplet streams according to claim 1, wherein the solution dispenser is in communication with the fluid reservoir vessel via a fluid transfer line between the solution dispenser and the fluid reservoir vessel.

4. The system for producing droplet streams according to claim 1, wherein one or more perturbations are provided to the fluid reservoir by action of the piezo actuator on the separation membrane and the one or more perturbations are evenly distributed to the one or more nozzles.

5. The system for producing droplet streams according to claim 4, wherein the capillary nozzle is made of stainless steel or dielectric material.

6. The system for producing droplet streams according to claim 3, wherein the solution dispenser transfers fluid therefrom to the fluid reservoir vessel by a peristaltic pump or pressurized tank.

7. The system for producing droplet streams according to claim 3, wherein the fluid reservoir vessel has an outlet disposed generally at or near an upstream surface of the fluid reservoir vessel.

8. The system for producing droplet streams according to claim 1, further comprising:

an electronics driver circuit for driving a piezo capacitor, the electronics driver circuit comprised of a signal generator, an operational amplifier, a transformer stage, a loading stage having a choke inductor, and a piezo capacitor, and wherein the choke inductor is in series with the piezo capacitor.

9. The system for producing droplet streams according to claim 8, wherein the signal generator delivers sinusoidal, triangular, or square waves with frequencies from 0 to 1 MHz or higher, and an output voltage between 0 to 10 volt to the operational amplifier.

10. A method for producing droplet streams having the droplets with a uniform diameter, the method comprising:

providing a solution to a fluid reservoir vessel;

filling a fluid reservoir within the fluid reservoir vessel with the solution via a channel running substantially parallel to a main axis of the fluid reservoir in the direction of a capillary nozzle, such that the solution contacts a separation membrane and the capillary nozzle;

contacting a piezo actuator with the separation membrane on a side opposite that in contact with the solution;

causing the piezo actuator to send at least one perturbation pulse to the separation membrane and the fluid reservoir to create at least one perturbation wave through the fluid reservoir;

receiving fluid from the fluid reservoir by the capillary nozzle disposed away from the separation membrane; and

ejecting a droplet stream from the capillary nozzle.

11. A system for producing droplets, the system comprising:

a fluid reservoir vessel defining a fluid reservoir, the fluid reservoir vessel including a rigid separation membrane having a thickness of about 0.723 mm disposed at a first end;

one or more capillary nozzles disposed at a second end of the fluid reservoir vessel opposite the separation membrane;

a solution dispenser in fluid communication with the fluid reservoir and disposed to maintain the fluid reservoir filled with fluid such that the fluid contacts the separation membrane and the one or more capillary nozzles, the solution dispenser further disposed to maintain the fluid reservoir under pressure to create a fluid stream exiting the one or more capillary nozzles; and

a piezo actuator in contact with the separation membrane on a side opposite that in contact with the fluid, the piezo actuator disposed to transfer a pressure wave through the fluid in the fluid reservoir to break up the fluid stream into droplets.

12. The system of claim 11, wherein the solution dispenser is disposed to maintain the fluid reservoir filled with fluid and under pressure using a peristaltic pump or pressurized tank.

13. The system of claim 11, further comprising:

an electronics driver circuit for driving a piezo capacitor, the electronics driver circuit comprising a signal generator, an operational amplifier, a transformer stage, a loading stage having a choke inductor, and wherein the choke inductor is in series with the piezo capacitor.

14. The system of claim 13, wherein the signal generator is disposed to deliver sinusoidal, triangular, or square waves with frequencies from 0 to 1 MHz or higher, and an output voltage between 0 to 10 volts to the operational amplifier.

15. The system of claim 11, wherein the fluid reservoir is substantially cylindrical in shape.

16. The system of claim 11, wherein the one or more capillary nozzles are made of stainless steel or a dielectric material.

17. A method for producing droplets, the method comprising:

providing a solution to a fluid reservoir vessel;

filling the fluid reservoir vessel with the solution such that the solution contacts a rigid separation membrane having a thickness of about 0.723 mm and creates a fluid stream exiting a capillary nozzle;

activating a piezo actuator to create a pressure wave traveling through the filled reservoir toward the capillary nozzle, the piezo actuator in contact with the separation membrane on a side opposite that in contact with the solution; and

breaking up the fluid stream into droplets using the pressure wave traveling through the filled reservoir.