Pump for low flow rates

• US 20020087110A1
• Filed: 06/19/2001
• Published: 07/04/2002
• Est. Priority Date: 06/21/2000
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Kraemer, Peter, Harttig, Herbert, Effenhauser, Carlo
• Granted Patent: US 6,860,993 B2
• Time in Patent Office: Days
• US Class Current: 604/6.11
• CPC Class Codes: F04B 17/00 Pumps characterised by combination with, or adaptation to, specific driving engines or motors
• CPC Class Codes: F04B 43/06 Pumps having fluid drive
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

The present invention concerns a pump for flow rates from about 1 to 1000 nl/min in which liquid transport takes place by evaporation of a transport liquid through a wettable membrane. The pumps according to the invention are particularly suitable for applications in the field of medical diagnostics such as microdialysis or ultrafiltration.

Claims

1. Pump for low flow rates comprising

a channel which is at least partially filled with a transport liquid (3)

a membrane (4, 12) at one opening of the channel that can be wetted by the transport liquid,

a space having an essentially constant vapour pressure of the transport liquid located at the side of the membrane opposite to the transport liquid.

2. Pump as claimed in claim 1, in which the space contains a sorbent (6, 15) which sorbs evaporated transport fluid.

3. Pump as claimed in claim 1, in which the space and the transport liquid are separated from one another by the membrane.

4. Pump as claimed in claim 2 or 3, in which the sorbent is located in a housing (7) having an opening, wherein the opening is closed by the membrane.

5. Pump as claimed in claim 3 or 4, in which the sorbent has no direct contact with the membrane.

6. Pump as claimed in claim 1, in which the space is formed by a housing (7′

) which exchanges evaporated transport liquid with the outer space.

7. Pump as claimed in claim 1, in which the membrane is hydrophilic.

8. Pump as claimed in claim 1, in which the membrane has a hydrophilic region facing the transport liquid and a hydrophobic region which faces the sorbent.

9. Pump as claimed in claim 8, in which the sorbent is in contact with the hydrophobic region of the membrane.

10. Pump as claimed in claim 1, which has at least one non-wettable membrane (5) which is located on a side of the wettable membrane facing away from the transport liquid.

11. Pump as claimed in claim 1, in which the channel contains a working liquid that is segmented from the transport liquid.

12. Pump as claimed in claim 1, in which the membrane is formed by an array of capillary channels.

13. Pump as claimed in claim 12, in which the capillary channels are located in a body in which the channel conveying the transport liquid is also located.

14. Pump as claimed in claim 12 or 13, in which the capillary channels are manufactured by microtechnology using etching processes, laser machining, or by stamping, injection moulding or moulding processes.

15. Pump as claimed in claim 12, in which the array comprises 3 to 100, preferably 5 to 25 capillary channels.

16. Pump as claimed in claim 12, in which the capillary channels of the array have a diameter of the individual channels in the range of 10 nm to 100 μ

m.

17. Microdialysis system comprising a pump as claimed in claim 1 and a microdialysis membrane past which the transport liquid or a working liquid is transported by the pump.

18. Microdialysis system as claimed in claim 17 containing a sensor located downstream of the microdialysis membrane for the detection of one or several analytes in the transport or working liquid.

19. Ultrafiltration device comprising a pump as claimed in claim 1 and an ultrafiltration membrane through which the body fluid is drawn into the channel.

20. Ultrafiltration device as claimed in claim 19 containing a sensor located downstream of the ultrafiltration membrane for the detection of one or several analytes in the body fluid.

21. System for pumping a working liquid at a low flow rate, wherein at least one dilution reservoir (22) containing a liquid which is essentially free of substances that cannot evaporate at the membrane is located between the fluid system in which the working liquid is located and a pump as claimed in claim 1.

22. System as claimed in claim 21, in which two or more reservoirs that are connected to one another (22¹, 22², 22³, 22⁴, 22⁵, 22⁶, 22⁷, 22⁸) which form a dilution cascade are arranged between the fluid system containing the working liquid and the pump.