Multi-stage target cell enrichment using a microfluidic device

1. A microfluidic device, comprising:

at least one inlet for receiving a sample comprising target cells and non-target cells;

a first spiral channel portion having an upstream end in a central region and a downstream end in a peripheral region, the upstream end being coupled to the inlet, the first spiral channel portion being configured such that the target cells and the non-target cells occupy different streams at the downstream end;

a first waste outlet arranged to couple with streams of non-target cells at the downstream end of the first spiral channel portion;

a link channel portion arranged to couple with streams of target cells at the downstream end of the first spiral channel portion;

a second spiral channel portion having an upstream end in a peripheral region and a downstream end in a central region, the upstream end of the second spiral channel portion being coupled to the link channel portion, the second spiral channel portion being configured such that the target cells and the non-target cells occupy different streams at the downstream end;

a second waste outlet arranged to couple with streams of non-target cells at the downstream end of the second spiral channel portion;

a sample outlet arranged to couple with streams of target cells at the downstream end of the second spiral channel portion;

a first waste outlet portion and a pressure compensator path forming part of the first waste outlet portion and coupling the downstream end of the first spiral channel portion to the first waste outlet;

a sample outlet coupling path coupling the second spiral channel portion to the sample outlet;

a second waste outlet coupling path coupling the second spiral channel portion to the second waste outlet;

a first buffer inlet coupled to the upstream end of the first spiral channel portion, the first buffer inlet configured to receive a sheath buffer; and

a second buffer inlet coupled to the upstream end of the second spiral channel portion, the second buffer inlet configured to receive a sheath buffer,

wherein the pressure compensator path is configured to have a fluid resistance proportionate to a sum of the fluid resistance of the link channel portion and the fluid resistance of the second spiral channel portion and the parallel combination of the sample outlet coupling path and the second waste outlet coupling path;

wherein a channel width of the link channel portion is less than a channel width of the pressure compensator path;

wherein the link channel portion, the first spiral channel portion, and the second spiral channel portion are of equal height; and

wherein a channel width of an entire length of the link channel portion is less than a channel width of the pressure compensator path.

2. The microfluidic device of claim 1 , wherein the first buffer inlet is arranged to introduce the sheath buffer to the first spiral channel portion adjacent to an inner wall of the first spiral channel portion and the at least one inlet is arranged to introduce the sample to the first spiral channel portion adjacent to an outer wall of the first spiral channel portion.

3. The microfluidic device of claim 1 , wherein the sample is a blood sample or blood constituents.

4. The microfluidic device of claim 1 , wherein the target cells are circulating tumor cells or circulating rare cells.

5. The microfluidic device of claim 1 , wherein the first and the second spiral channel portions are configured such that the target cells undergo inertial focusing and the non-target cells migrate in lateral position under the influence of Dean forces.

6. The microfluidic device of claim 1 , wherein the target cells have a cell diameter greater than a cell diameter threshold and the non-target cells have a diameter less than the cell diameter threshold.

7. The microfluidic device of claim 1 , wherein flow resistances associated with the first waste outlet and the link channel portion are configured according to a flow rate ratio.

8. The microfluidic device of claim 7 , wherein channel widths associated with the first waste outlet and the link channel portion are configured according to a flow rate ratio.

9. The microfluidic device of claim 7 , wherein flow resistances associated with the second waste outlet and the sample outlet are configured according to the flow rate ratio.

10. The microfluidic device of claim 9 , wherein channel widths associated with the second waste outlet and the sample outlet are configured according to the flow rate ratio.

11. The microfluidic device of claim 7 , wherein the flow rate ratio is in the range of 0.1 to 1.