WIRELESS MONITORING OF LABORATORY ANIMALS

• US 20110087136A1
• Filed: 10/12/2009
• Published: 04/14/2011
• Est. Priority Date: 10/12/2009
• Status: Active Grant

• Current Assignee: Vertex Pharmaceuticals Incorporated
• Original Assignee: Vertex Pharmaceuticals Incorporated
• Inventors: Nguyen, Trang, Salzmann, Philip, Sinclair, James
• Granted Patent: US 8,468,975 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• CPC Class Codes: A01K 1/031 Cages for laboratory animals; Cages for measuring metabolism of animals
• CPC Class Codes: A01K 11/006 Automatic identification systems for animals, e.g. electronic devices, transponders for animals identification systems for access to feeding pens A01K1/0209; ear tags with electronic identification means A01K11/004
• CPC Class Codes: A01K 29/005 Monitoring or measuring activity, e.g. detecting heat or mating
• CPC Class Codes: G01N 27/028 Circuits therefor measuring impedance per se G01R27/02

Abstract

Systems and methods for monitoring laboratory animals includes a tag comprising an inductive element and a capacitive element attached to a portion of a laboratory animal. The position of the portion is detected by monitoring the effect of the tag on a time-varying magnetic field having different frequencies, one near tag resonance, and one away from tag resonance.

Claims

1. A system for detecting the position of a portion of a laboratory animal, comprising:

at least one coil;

a resonant circuit attached to said portion of said laboratory animal, said resonant circuit defining a resonant frequency;

a signal generator electrically coupled to said coil and configured to drive said at least one coil with at least a first drive signal comprising a first frequency and a second drive signal comprising a second frequency, wherein the second frequency is more distant from said resonant frequency than the first frequency; and

a detection circuit coupled to said at least one coil and configured to detect an impedance change in said at least one coil between application of said first frequency to said at least one coil and application of said second frequency to said at least one coil, and to generate an output signal representative of resonant circuit position with respect to said at least one coil based at least in part on said impedance change.

2. The system of claim 1, wherein said detection circuit generates at least a first measurement signal when the drive signal comprises said first frequency and a second measurement signal when the drive signal comprises said second frequency, and wherein the difference between the first and second measurement signals is representative of resonant circuit position with respect to said at least one coil.

3. The system of claim 1, wherein said system comprises a first coil and a second coil.

4. The system of claim 3, wherein said two coils are connected as two legs of a bridge circuit.

5. The system of claim 4, wherein the signal generator is coupled to opposite nodes of said bridge.

6. The system of claim 5, wherein the detection circuit is coupled to opposite nodes of said bridge.

7. The system of claim 1, wherein said resonant circuit comprises an inductor and a capacitor electrically coupled in parallel.

8. The system of claim 1, wherein within the signal generator is configured to sweep the frequency of the drive signal through a frequency range including the resonant frequency of the resonant circuit.

9. The system of claim 3, wherein the first coil and the second coil are aligned along a longitudinal axis, and the laboratory animal is placed on a floor located at approximately the mid point between the first and second coil.

10. The system of claim 9, wherein the output signal is representative of the vertical position of said resonant circuit with respect to said floor.

11. The system of claim 10, wherein the output signal is substantially independent of the horizontal position of said tag with respect to said floor.

12. The system of claim 3, wherein the first and second coils are wired in series, the system comprises a bridge of four legs, wherein the first and second coils form two legs of a bridge.

13. The system of claim 12, wherein the other two legs of the bridge comprise two resistors.

14. The system of claim 13, wherein the signal generator is coupled to a first and second node of said bridge, the first and second nodes being opposite nodes.

15. The system of claim 14, wherein the detection circuit is coupled to a third and fourth node of said bridge, the third and fourth nodes being opposite nodes.

16. The system of claim 14, wherein the detection circuit comprises a differential amplifier electrically coupled to said bridge.

17. The system of claim 16, wherein the detection circuit comprises an envelope detector electrically coupled to said differential amplifier.

18. The system of claim 17, wherein the detection circuit comprises a sampling circuit coupled to the envelope detector.

19. The system of claim 1, wherein the difference between the first and second measurement signals is indicative of an impedance imbalance between first and second coils.

20. The system of claim 1, wherein said resonant circuit is mounted to a printed circuit board.

21. The system of claim 1, wherein said portion of said laboratory animal comprises a paw of a rodent.

22. The system of claim 1, wherein said portion of said laboratory animal comprises a head of a rodent.

23. A system for detecting a laboratory animal behavior of interest, comprising:

a resonant circuit attached to a portion of said laboratory animal, said resonant circuit defining a resonant frequency;

means for driving at least one coil with a signal comprising at least two different frequencies; and

means for detecting an impedance change in said at least one coil between said at least two different frequencies; and

means for sensing a position of said resonant circuit with respect to said at least one coil based at least in part on said detected impedance change.

24. The system of claim 23, wherein said behavior of interest comprises paw guarding.

25. A method of detecting the position of a portion of a laboratory animal, comprising:

attaching a resonant circuit to said portion of said laboratory animal;

placing said laboratory animal proximate to at least one coil;

driving said at least one coil with a signal of at least a first frequency and a second frequency; and

detecting an impedance change in said at least one coil between said first and second frequencies.

26. The method of claim 25, comprising generating a first measurement signal at said first frequency and a second measurement signal at said second frequency, and determining a difference between said first measurement signal and said second measurement signal.

27. The method of claim 26, wherein the difference between the first and second measurement signals is related to the vertical distance between said resonant circuit and said floor.

28. The method of claim 25, wherein the second frequency is more distant from the resonant frequency of the resonant circuit than the first frequency.

29. The method of claim 25, wherein the at least one coil comprises a first coil and a second coil.

30. The method of claim 29, comprising aligning the first coil and the second coil along a longitudinal axis, and placing the animal on a floor located at approximately the mid point between the first and second coil.

31. A method of assaying for an anti-nociceptive drug, comprising:

attaching a resonant circuit to a paw of a rodent;

administering a potential anti-nociceptive drug to a rodent;

exposing said paw to a nociceptive stimulus;

placing said rodent proximate to at least one coil;

detecting paw guarding using, at least in part, said resonant circuit and said at least one coil.

32. The method of claim 31 comprising:

driving said at least one coil with a signal of at least a first frequency and a second frequency; and

detecting an impedance change in said at least one coil between said first and second frequencies.

33. The method of claim 32, comprising generating a first measurement signal at said first frequency and a second measurement signal at said second frequency, and determining a difference between said first measurement signal and said second measurement signal.

34. The method of claim 33, wherein the difference between the first and second measurement signals is related to the vertical distance between said resonant circuit and said floor.

35. The method of claim 32, wherein the second frequency is more distant from the resonant frequency of the resonant circuit than the first frequency.

36. The method of claim 32, wherein the at least one coil comprises a first coil and a second coil.

37. The method of claim 36, comprising aligning the first coil and the second coil along a longitudinal axis, and placing the rodent on a floor located at approximately the mid point between the first and second coil.

38. A cage for holding and monitoring a rodent comprising:

a first coil positioned below a floor of the cage; and

a second coil positioned above the floor of the cage.

39. The cage of claim 38, wherein said first coil, said second coil, and said floor are substantially aligned along a common longitudinal axis.

40. The cage of claim 38, wherein said floor is positioned at approximately midway between said first coil and said second coil.