Apparatus and method for separating magnetic particles

1. An apparatus for separating a predetermined amount of magnetic particles in a fluid, comprising:

a fluid conveyance portion having at least a first flow channel for supplying a fluid containing the magnetic particles, a second flow channel for discharging the separated magnetic particles, and an intersection at which the first flow channel and the second flow channel intersect each other;

capture means for capturing a predetermined amount of the magnetic particles in the fluid supplied from the first flow channel to the intersection when a magnetic field is applied to the intersection of the fluid conveyance portion; and

discharge means for removing the magnetic field applied to the intersection to discharge the magnetic particles captured by the capture means by way of a medium introduced into the second flow channel.

2. An apparatus for detecting a target substance in a fluid, comprising:

a fluid conveyance portion having at least means for binding a target substance in a fluid to magnetic particles each having a function of specifically binding to the target substance, a first flow channel for supplying a fluid containing the magnetic particles bound with the target substance, a second flow channel for discharging the separated magnetic particles bound with the target substance, and an intersection at which the first flow channel and the second flow channel intersect each other;

capture means for capturing a predetermined amount of the magnetic particles bound with the target substance in the fluid supplied from the first flow channel to the intersection when a magnetic field is applied to the intersection of the flow channels;

discharge means for removing the magnetic field applied to the intersection to discharge the magnetic particles bound with the target substance that have been captured by the capture means by way of a medium introduced into the second flow channel; and

detection means for detecting an amount of the target substance bound with the magnetic particles discharged by the discharge means.

3. An apparatus for detecting a target substance according to claim 2 , wherein the capture means includes magnetic field application means.

4. An apparatus for detecting a target substance according to claim 3 , wherein the magnetic field application means comprises an electromagnet.

5. An apparatus for detecting a target substance according to claim 2 , wherein the capture means has a member with high magnetic permeability and a member with magnetic permeability smaller than that of the member with high magnetic permeability, which are provided adjacent to each other along the first flow channel.

6. An apparatus for detecting a target substance according to claim 2 , wherein the target substance comprises a biomaterial.

7. An apparatus for detecting a target substance according to claim 2 , wherein the predetermined amount is controlled according to a sensitivity range of the detection means.

8. An apparatus for detecting a target substance according to claim 2 , further comprising means for recirculating the fluid from the detection means to the first flow channel.

9. A method of separating a predetermined amount of magnetic particles in a fluid, comprising the steps of:

applying a magnetic field to an intersection of intersecting flow channels composed of a first flow channel for supplying a fluid containing the magnetic particles and a second flow channel for discharging the separated magnetic particles, while supplying a fluid containing the magnetic particles from the first flow channel to the intersection, to capture a predetermined amount of the magnetic particles in the fluid; and

removing the magnetic field applied to the intersection to discharge the captured magnetic particles by way of a medium introduced through the second flow channel.

10. A method of detecting a target substance in a fluid, comprising the steps of:

binding a target substance in a fluid to magnetic particles each having a function of specifically binding to the target substance;

applying a magnetic field to an intersection of intersecting flow channels composed of a first flow channel for supplying a fluid containing the magnetic particles bound with tile target substance and a second flow channel for discharging the separated magnetic particles bound with the target substance, while supplying a fluid containing the magnetic particles bound with the target substance from the first flow channel to the intersection, to capture a predetermined amount of the magnetic particles bound with the target substance in the fluid;

removing the magnetic field applied to the intersection to discharge the captured magnetic particles bound with the target substance by way of a medium introduced through the second flow channel; and

detecting an amount of the target substance bound with the discharged magnetic particles.

11. A method of detecting a target substance according to claim 10 , wherein the fluid containing the magnetic particles has a Reynolds number of 50 or less.

12. A method of detecting a target substance according to claim 10 , wherein the magnetic particles exhibit superparamagnetism.

13. A method of detecting a target substance according to claim 10 , wherein the magnetic particles have an average particle size of 40 nm or less.