System and method for separating particles in suspension utilizing bubbles

Patent metadata

Field	Value
Publication number	US-11161124-B2
Application number	US-201916381136-A
Country	US
Kind code	B2
Filing date	Apr 11, 2019
Priority date	Apr 11, 2018
Publication date	Nov 2, 2021
Grant date	Nov 2, 2021

Abstract

Disclosed is a process for separating suspended particles based on size. When confined in a tube, a bubble moves relative to the liquid as a small fraction of the liquid leaks backwards through a very thin gap between the bubble and the internal wall of the tube. The lubricating film formed around the bubble can be fine-tuned by simply changing the average flow speed. With this thin film of liquid, the confined air bubble can be used to separate particles in, for example, poly-disperse microspheres suspensions. As the bubble passes through the suspension, only particles smaller than the liquid gap thickness can leak through the gap towards the back of the bubble, resulting a filtered particle suspension containing only small particles at the back of the bubble. Compared to the traditional methods, this particle separation process is easy to perform, and is flexible in filtering different suspensions with one set-up. Due to the flexibility of the bubble interface and the special film thickness profile of a translating confined bubble, this process also avoids clogging, and can be easily adapted to, e.g., separate different poly-disperse suspensions based on size.

First claim

What is claimed is:

1. A system for separating suspended particles, comprising:
at least one channel having an inner surface with a first fixed diameter, the inner surface defining a first opening at a first end of the channel and a second opening at a second end of the channel;
a plurality of particles within a first fluid in the at least one channel, the plurality of particles comprising a first and second particle, the first particle having different dimensions from the second particle; and
a non-spherical bubble within the first fluid, the bubble comprising a second fluid and having a bubble length and diameter, the bubble configured to have a gap between an outer surface of the bubble and an inner surface of the at least one channel such that the bubble is not in contact with the channel,
wherein the device is configured such that a thickness of the gap is capable of being controlled by a flow rate within the channel.

2. The system according to claim 1 , wherein the outer surface of the bubble and the inner surface of the at least one channel defines an annular gap having a uniform thickness, the uniform thickness being smaller than at least one second diameter of at least one of the plurality of particles.

3. The system according to claim 1 , wherein the flow rate of the first fluid is controlled such that the capillary number (Ca) is 1×10 −4 <Ca<2.

4. The system according to claim 1 , wherein each particle has a density substantially equal to a density of the fluid.

5. The system according to claim 1 , wherein there exists attractive intermolecular interactions between the particles and the interface between the first and second fluids.

6. The system according to claim 1 , wherein the second fluid comprises a gas.

7. The system according to claim 1 , wherein the second fluid comprises a liquid.

8. The system according to claim 1 , wherein an axis of the at least one channel is oriented in a substantially vertical or substantially horizontal direction.

9. The system according to claim 1 , further comprising a pump or syringe operably connected to the first opening.

10. The system according to claim 1 , wherein the thickness of the gap is capable of being adjusted to be between about 0.1 μm and about 1 mm.

11. The system according to claim 1 , further comprising a camera configured to receive light passing through the at least one channel.

12. The system according to claim 1 , wherein the device comprises a plurality of channels.

13. A method for separating particles in a fluid, comprising the steps of:
flowing at least a first and second particle suspended in a first fluid into a first end of a channel, the first and second particles having different dimensions;
creating a first bubble at the first end of the channel, the first bubble having a bubble length and diameter, the first bubble not being in contact with the channel, and an outer surface of the first bubble and an inner surface of the channel defining a gap; and
controlling a flow rate within the channel such that the gap has a uniform thickness insufficiently large to allow the first suspended particle to enter a volume of space upstream of the first bubble, but sufficiently large to allow the second suspended particle to enter a volume of space upstream of the first bubble.

14. The method according to claim 13 , further comprising flowing additional first fluid without suspended particles into the channel after the first bubble.

15. The method according to claim 13 , further comprising
generating a second bubble in the at least one channel, the second bubble being upstream of the first bubble.

16. The method according to claim 15 , further comprising flowing additional first fluid without suspended particles into the channel after generating the second bubble.

17. The method according to claim 13 , further comprising absorbing the first particle on an interface of the bubble.

18. The method according to claim 13 , wherein the first and second particles have a minimum characteristic dimension of between 0.1 μm and 1 mm.

19. A method for separating particles in a fluid, comprising the steps of:
flowing at least a first and second particle suspended in a first fluid into a first end of a channel;
creating a first bubble at the first end of the channel, the first bubble having a bubble length and diameter, the first bubble not being in contact with the channel, and an outer surface of the first bubble and an inner surface of the channel defining a gap; and
controlling a flow rate within the channel such that the gap has a uniform thickness insufficiently large to allow the first suspended particle to enter a volume of space upstream of the first bubble; and
collecting a sample of the first fluid ahead of the bubble and quantifying particle size distribution.

20. A method for separating particles in a fluid, comprising the steps of:
flowing at least a first and second particle suspended in a first fluid into a first end of a channel;
creating a first bubble at the first end of the channel, the first bubble having a bubble length and diameter, the first bubble not being in contact with the channel, and an outer surface of the first bubble and an inner surface of the channel defining a gap; and
controlling a flow rate within the channel such that the gap has a uniform thickness insufficiently large to allow the first suspended particle to enter a volume of space upstream of the first bubble; and
collecting a sample of the first fluid after the bubble and quantifying particle size distribution.

Assignees

• Univ Princeton

Inventors

• Stone Howard A
• Khodaparast Sepideh
• Yu Yingxian

Classifications

• B03B5/62 Primary

  by hydraulic classifiers, e.g. of launder, tank, spiral or helical chute concentrator type · CPC title