Microfluidic device and method for detecting rare cells

1. A microfluidic device for detecting rare cells in a fluid sample comprising the rare cells and other cells, the microfluidic device comprising:

an inlet for receiving the fluid sample;

a labyrinth channel structure in fluid communication with the inlet and comprising at least one channel through which the fluid sample flows with the at least one channel having a rectangular cross-section, a width of from 500 to 1000 μm, and a height of from 1 to 150 μm, the at least one channel having a plurality of segments and a plurality of corners with each corner defined between adjacent segments to induce separation of the rare cells from the other cells in the fluid sample as the rare cells move to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 2 to 10; and

an outlet in fluid communication with the at least one channel for collecting the rare cells separated from the other cells in the fluid sample.

2. The microfluidic device as set forth in claim 1 wherein the labyrinth channel structure comprises at least 2 corners.

3. The microfluidic device as set forth in claim 1 wherein the labyrinth channel structure comprises from 40 to 50 corners.

4. The microfluidic device as set forth in claim 1 wherein the other cells include white blood cells, and the at least one channel has the plurality of segments and the plurality of corners to induce separation of the white blood cells as the white blood cells move to a second equilibrium position within the at least one channel wherein a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 1 to 5.

5. The microfluidic device as set forth in claim 4 wherein the first equilibrium position defines a first stream comprising rare cells and the second equilibrium position defines a second stream comprising white blood cells, and wherein a spacing between the first and second stream is from 50 to 100 μm.

6. The microfluidic device as set forth in claim 1 wherein the at least one channel has a length of from 1 μm to 1000 μm.

7. The microfluidic device as set forth in claim 1 wherein the labyrinth channel structure is configured to separate at least rare cells and white blood cells, and the outlet comprises a first flow path for the rare cells and a second flow path for the white blood cells.

8. The microfluidic device as set forth in claim 1 wherein each of the plurality of corners induces at least a 90° change in direction of the flow of the fluid sample.

9. A method of detecting rare cells in a fluid sample comprising the rare cells and other cells, the method comprising the steps of:

providing a microfluidic device comprising:

an inlet;

a labyrinth channel structure in fluid communication with the inlet and comprising at least one channel having a plurality of segments and a plurality of corners with each corner defined between adjacent segments with the at least one channel having a rectangular cross-section, a width of from 500 to 1000 μm, and a height of from 1 to 150 μm; and

an outlet in fluid communication with the at least one channel;

introducing the fluid sample into the inlet of the microfluidic device;

flowing the fluid sample through the labyrinth channel structure of the microfluidic device; and

separating the rare cells from the other cells as the fluid sample flows past the plurality of corners in the at least one channel of the labyrinth channel structure, the rare cells moving to a first equilibrium position within the at least one channel when a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 2 to 10.

10. The method as set forth in claim 9 wherein the step of separating of the rare cells is further defined as separating the rare cells from the other cells as the fluid sample flows through 40 to 50 corners.

11. The method as set forth in claim 9 wherein the step of introducing of the fluid sample into the inlet is further defined as introducing the fluid sample at a volumetric flow rate of from 0.1 to 30 mL/hr.

12. The method as set forth in claim 9 wherein the other cells comprise white blood cells and the method further comprises the step of separating the white blood cells as the fluid sample flows past the plurality of corners in the at least one channel of the labyrinth channel structure, the white blood cells moving to a second equilibrium position within the at least one channel when a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 1 to 5.

13. The microfluidic device as set forth in claim 12 wherein the separating of the rare cells is further defined as separating the rare cells into a first stream and the separating of the white blood cells is further defined as separating the white blood cells into a second stream, and wherein separation between the first and second stream is from 50 to 100 μm.

14. The method as set forth in claim 9 wherein the other cells comprise white blood cells and the outlet comprises a first flow path for the rare cells and a second flow path for the white blood cells, and wherein the method further comprises the step of collecting the rare cells in the first flow path and collecting the white blood cells in the second flow path.

15. The method as set forth in claim 9 further comprising the step of recovering at least 95% of the rare cells after the method step of separating the rare cells from the other cells.

16. A microfluidic device for detecting rare cells in a fluid sample comprising the rare cells and other cells, the microfluidic device comprising:

an inlet for receiving the fluid sample;

at least one channel having a plurality of segments and a plurality of corners to separate the rare cells from the other cells in the fluid sample by causing the rare cells to move to an equilibrium position within a flow of the fluid sample when a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 2 to 10, wherein each of the plurality of channels having a rectangular cross-section, a width of from 500 to 1000 μm, and a height of from 1 to 150 μm; and

an outlet for collecting the rare cells.

17. The microfluidic device as set forth in claim 16 wherein the other cells include white blood cells, and presence of the plurality of corners in the at least one channel induces separation of the white blood cells as the white blood cells move to a second equilibrium position within the at least one channel wherein a ratio of inertial lift forces (F z ) and Dean flow (F D ) of the fluid sample is from 1 to 5.

18. The microfluidic device as set forth in claim 17 wherein the equilibrium position defines a first stream comprising rare cells and the second equilibrium position defines a second stream comprising white blood cells, and wherein a spacing between the first and second stream is from 50 to 100 μm.

19. The microfluidic device as set forth in claim 16 wherein the at least one channel has a length of from 1 μm to 1000 μm.

20. The microfluidic device as set forth in claim 16 wherein the at least one channel is configured to separate at least rare cells and white blood cells, and the outlet comprises a first flow path for the rare cells and a second flow path for the white blood cells.