MEDICAL FLUID SENSORS AND RELATED SYSTEMS AND METHODS

• US 20140263017A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Inventors: Tuckwell, Mark David, Grover, Simon, Jones, Ross Peter
• Granted Patent: US 9,772,386 B2
• Time in Patent Office: Days
• US Class Current: 210/223
• CPC Class Codes: A61M 1/152 Details related to the interface between cassette and machine
• CPC Class Codes: A61M 1/154 with sensing means or components thereof
• CPC Class Codes: A61M 1/1562 Details of incorporated reservoirs
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1607 before use, i.e. upstream of dialyser
• CPC Class Codes: A61M 1/1609 after use, i.e. downstream of dialyser
• CPC Class Codes: A61M 1/3609 Physical characteristics of the blood, e.g. haematocrit, urea
• CPC Class Codes: A61M 1/36222 Details related to the interface between cassette and machine
• CPC Class Codes: A61M 1/36224 with sensing means or components thereof
• CPC Class Codes: A61M 1/36226 Constructional details of cassettes, e.g. specific details on material or shape
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2230/20 Blood composition characteristics
• CPC Class Codes: G01R 33/307 specially adapted for moving the sample relative to the MR system, e.g. spinning mechanisms, flow cells or means for positioning the sample inside a spectrometer
• CPC Class Codes: G01R 33/34092 RF coils specially adapted for NMR spectrometers
• CPC Class Codes: G01R 33/3635 Multi-frequency operation
• CPC Class Codes: G01R 33/38 Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
• CPC Class Codes: G01R 33/3802 Manufacture or installation of magnet assemblies; Additional hardware for transportation or installation of the magnet assembly or for providing mechanical support to components of the magnet assembly
• CPC Class Codes: G01R 33/3806 Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets
• CPC Class Codes: G01R 33/383 using permanent magnets
• CPC Class Codes: G01R 33/465 : applied to biological material, e.g. in vitro testing

Abstract

This disclosure relates to medical fluid sensors and related systems and methods. In certain aspects, a nuclear magnetic resonance device includes a support frame, a first magnet connected to the support frame, a second magnet connected to the support frame in a manner such that the second magnet is disposed within the magnetic field of the first magnet and a magnetic attraction exists between the first magnet and the second magnet, and a spacer disposed between the first magnet and the second magnet. The spacer is configured to maintain a space between the first magnet and the second magnet.

Claims

1. A nuclear magnetic resonance device comprising:

a support frame,

a first magnet connected to the support frame,

a second magnet connected to the support frame in a manner such that the second magnet is disposed within the magnetic field of the first magnet and a magnetic attraction exists between the first magnet and the second magnet, and

a spacer disposed between the first magnet and the second magnet, the spacer configured to maintain a space between the first magnet and the second magnet, the spacer comprising

a first side that faces the first magnet, and

a second side that is opposed to the first side and faces the second magnet,

wherein the spacer has a shape that orients the first magnet relative to the second magnet in a manner such that a pole face of the first magnet is maintained substantially parallel to a pole face of the second magnet.

2. The device of claim 1, wherein the first side contacts the first magnet, and the second side contacts the second magnet.

3. The device of claim 1, wherein the first side and the second side define therebetween an interior space configured to receive a test sample.

4. The device of claim 1, wherein the first side of the spacer and the second side of the spacer are planar, and a plane defined by the first side of the spacer is substantially parallel to a plane defined by the second side of the spacer.

5. The device of claim 1, wherein the pole face of the first magnet is angled relative to the pole face of the second magnet by no more than 0.2 degrees

6. The device of claim 1, wherein the spacer is formed of a ceramic material.

7. The device of claim 1, wherein the spacer comprises a pair of non-magnetic, electrically-conductive plates, and the spacer is sandwiched between the pair of plates such that a first surface of a first plate of the pair of plates contacts the first magnet, and a surface opposed to the first surface of the first plate contacts a first side of the spacer, and a first surface of a second plate of the pair of plates contacts the second magnet, and a surface opposed to the first surface of the second plate contacts a second side of the spacer.

8. The device of claim 1, wherein the first side and the second side define therebetween an interior space, and the device further comprises a radio frequency coil supported on the spacer so as enclose a portion of the interior space, the radio frequency coil configured to transmit a radio frequency signal to and receive a radio frequency signal from the interior space.

9. The device of claim 8, wherein the first side of the spacer comprises a first groove and a first support plate disposed in the first groove such that an outward facing surface of the first support plate lies flush with the spacer first side, the second side of the spacer comprises a second groove and a second support plate disposed in the second groove such that an outward facing surface of the second support plate lies flush with the spacer second side, and each of the first support plate and the second support plate includes a through opening that is configured to receive and support the radio frequency coil within the interior space.

10. The device of claim 9, wherein the first support plate and the second support plate are formed of a sodium-free plastic.

11. The device of claim 8, wherein the radio frequency coil comprises a hollow rectangular form and an electrical conductor that is wound about a coil axis, and the radio frequency coil is oriented within the spacer such that the coil axis is generally parallel to the spacer first side and transverse to flux lines associated with the magnetic attraction force of the two magnets.

12. The device of claim 1, wherein the spacer is clamped between the magnets due to the magnetic attractive force.

13. The device of claim 1, wherein the first magnet includes a first pole piece, the second magnet includes a second pole piece, the first side of the spacer contacts the first pole piece, and the second side of the spacer contacts the second pole piece.

14. A dialysis system comprising:

a dialysis fluid circuit, and

a device for measuring a concentration of a substance in a sample of dialysate fluid taken from the dialysis fluid circuit, the device comprising

a support frame,

a first magnet connected to the support frame,

a second magnet connected to the support frame in a manner such that the second magnet is disposed within the magnetic field of the first magnet and a magnetic attraction exists between the first magnet and the second magnet,

a spacer disposed between the first magnet and the second magnet, the spacer comprising

a first side that contacts the first magnet, and

a second side that is opposed to the first side and contacts the second magnet, the first side and the second side defining therebetween an interior space configured to receive the sample, and

a radio frequency coil supported on the spacer so as enclose a portion of the interior space, the radio frequency coil configured to transmit a radio frequency signal to and receive a radio frequency signal from the sample,

wherein the spacer has a peripheral shape that orients the first magnet relative to the second magnet in a manner such that a pole face of the first magnet is maintained substantially parallel to a pole face of the second magnet.

15. The dialysis system of claim 14, further comprising a dialysis machine including a compartment, and a module that can be disposed in the compartment, the module comprising the device.

16. A device for measuring a concentration of a substance in a sample, the device comprising:

a magnet support structure including

a first frame member, and

a second frame member,

a first magnet supported on the first frame member, and

a second magnet supported on the second frame member in such a way that a magnetic attraction exists between the first magnet and the second magnet,

wherein the magnet support structure supports the first magnet in a spaced apart relationship relative to the second magnet such that

the first frame member and the second frame member cooperate to substantially surround both the first magnet and the second magnet

a first air gap exists between the first magnet and the second magnet,

a second air gap exists between the first frame member and the second frame member, and

a third air gap exists between the first frame member and the second frame member at a location spaced apart from the first air gap and the second air gap.

17. The device of claim 16 further comprising a spacer disposed between the first magnet and the second magnet, wherein the spacer is configured to maintain first air gap between the first magnet and the second magnet.

18. The device of claim 16 further comprising a spacer disposed between the first magnet and the second magnet, the spacer configured to maintain a space between the first magnet and the second magnet, the spacer comprising

a first side that faces the first magnet, and

a second side that is opposed to the first side and faces the second magnet,

wherein the spacer has a shape that orients the first magnet relative to the second magnet in a manner such that a pole face of the first magnet is maintained substantially parallel to a pole face of the second magnet.

19. The device of claim 16 further comprising a radio frequency coil disposed in the first air gap between the first magnet and the second magnet, the radio frequency coil configured to transmit a radio frequency signal to, and receive a radio frequency signal from, the sample when the sample is disposed within the radio frequency coil.

20. The device of claim 16 wherein the main air gap has a dimension corresponding to the distance between the first magnet and the second magnet, and the dimension is in a range of 20 mm to 30 mm.

21. The device of claim 16 wherein the second air gap and the third air gap have a dimension corresponding to the distance between the first frame member and the second frame member, and the dimension is in a range of 0.5 mm to 2.0 mm.

22. A nuclear magnetic resonance device comprising

a first magnet,

a second magnet disposed adjacent to the first magnet in such a way that a first space exists between the first magnet and the second magnet and an attractive magnetic field exists in the space,

a radio frequency coil assembly disposed in the space, the radio frequency coil assembly configured to transmit a radio frequency signal to, and receive a radio frequency signal from, a sample disposed in the space, and

a first non-magnetic, electrically-conductive member disposed between the radio frequency coil assembly and the first magnet, and a second non-magnetic, electrically-conductive member disposed between the radio frequency coil assembly and the second magnet.

23. The device of claim 22 wherein the first member and the second member are formed of metal.

24. The device of claim 22 wherein the first member and the second member are formed of copper.

25. The device of claim 22 wherein the first member and the second member have a skin depth corresponding to an operating frequency of the radio frequency coil, and the first member and the second member have a thickness that is at least equal to the skin depth, where the thickness corresponds to the dimension of the first member and the second member in a direction parallel to the magnetic field.

26. The device of claim 22 wherein the first member and the second member have a shape that corresponds to the shape of a pole face of the first magnet and the second magnet.

27. The device of claim 22 comprising a spacer disposed in the space and configured to maintain the space between the first magnet and the second magnet, the spacer including

a spacer first side that contacts the first magnet, and

a spacer second side that is opposed to the spacer first side and contacts the second magnet, the spacer first side and the spacer second side defining therebetween a recess that is configured to receive the sample.

28. The device of claim 22, wherein the first side of the spacer and the second side of the spacer are planar, and a plane defined by the first side of the spacer is substantially parallel to a plane defined by the second side of the spacer.

29. The device of claim 22, comprising a spacer disposed in the space and configured to maintain the space between the first magnet and the second magnet, the spacer including

a first side including a first groove and a first support plate disposed in the first groove such that an outward facing surface of the first support plate lies flush with the spacer first side,

a second side including a second groove and a second support plate disposed in the second groove such that an outward facing surface of the second support plate lies flush with the spacer second side,

each of the first support plate and the second support plate including a through opening that is configured to receive and support the radio frequency coil within the space.

30. The device of claim 29, wherein the first support plate and the second support plate are formed of a sodium-free plastic.

31. The device of claim 22 wherein the radio frequency coil comprises a hollow rectangular form and an electrical conductor that is wound about a coil axis, and the radio frequency coil is oriented within the spacer such that the coil axis is generally parallel to the spacer first side and transverse to flux lines associated with the magnetic attraction force of the two magnets.

32. A dialysis system comprising

a dialysis fluid circuit, and

a device for measuring a concentration of a substance in a sample, the device comprising

a first magnet,

a second magnet disposed within the magnetic field of the first magnet in such a way that a magnetic attraction exists between the first magnet and the second magnet,

a spacer disposed between the first magnet and the second magnet, the spacer configured to maintain a space between the first magnet and the second magnet, the spacer defining a recess configured to receive the sample,

a radio frequency coil supported by the spacer within the magnetic field and configured to transmit a radio frequency signal to, and receive a radio frequency signal from, the sample, and

a first non-magnetic, electrically-conductive member disposed between the radio frequency coil and the first magnet, and a second non-magnetic, electrically-conductive member disposed between the radio frequency coil and the second magnet.

33. The dialysis system of claim 32 further comprising a dialysis machine including a compartment, and a module that can be disposed in the compartment, the module comprising the device.