Superconducting biomagnetometer with inductively coupled pickup coil

• US 5,158,932 A
• Filed: 07/17/1990
• Issued: 10/27/1992
• Est. Priority Date: 07/31/1989
• Status: Expired due to Term

• Current Assignee: Biomagnetic Technologies, Inc.
• Original Assignee: Biomagnetic Technologies, Inc.
• Inventors: Hinshaw, Waldo S., Buchanan, David S., Paulson, Douglas N., Black, William C. Jr., DiIorio, Mark S., Hirschkoff, Eugene C.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US07/551,841
• Time in Patent Office: 833 Days
• Field of Search: 324/117 R, 324/201, 324/204, 324/248, 505/846, 505/1, 128/653 R, 128/731, 336/200, 336/220, 336/DIG. 1
• US Class Current: 505/162
• CPC Class Codes: A61B 5/245 specially adapted for magnetoencephalographic [MEG] signals
• CPC Class Codes: G01R 33/0358 coupling the flux to the SQUID gradiometer coils G01R33/022; coils with superconductive winding H01F6/06
• CPC Class Codes: Y10S 505/846 using superconductive quantum interference device, i.e. squid

Abstract

A biomagnetometer has a magnetic pickup coil positioned remotely from a detector and inductively coupled to the detector. The detector is preferably made from a low-temperature superconductor, while the pickup coil can be made of a high-temperature superconductor. The detector and pickup coil can therefore be placed into separate containers, with an inductive coupler between the containers. In one approach, the detector is maintained at liquid helium temperature, and the pickup coil and electrical connector are cooled by liquid nitrogen. The resulting biomagnetometer permits the container with the pickup coil to be moved and positioned easily, and to be changed readily between various configurations particularly suited for performing various functions.

Claims

1. A biomagnetometer, comprising:

a magnetic pickup coil formed of a material that is superconducting at a temperature less than its superconducting transistion temperature;

a first container that contains the pickup coil, the first container maintaining the pickup coil at a temperature at which it is superconducting;

a detector of small electrical currents formed of a material that is superconducting at a temperature less than its superconducting transition temperature;

a second container that contains the detector, the second container maintaining the detector at a temperature at which it is superconducting, the second container being disposed such that it is not within the first container; and

an inductive coupler having a pair of induction coils positioned adjacent each other such that an electrical current flowing in a first coil is coupled to a second coil,

the first induction coil being within the first container, electrically connected to the magnetic pickup coil, and made of a material that is superconducting at the temperature at which the magnetic pickup coil is superconducting, and

the second induction coil being within the second container, electrically connected to the detector, and made of a material that is superconducting at the temperature at which the detector is superconducting.

2. The biomagnetometer of claim 1, wherein the detector is a superconducting quantum interference device.

3. The biomagnetometer of claim 1, wherein the detector is formed of a material having a superconducting transition temperature of less than 77K.

4. The biomagnetometer of claim 1, wherein the pickup coil is formed of a material having a superconducting transition temperature of less than 77K.

5. The biomagnetometer of claim 1, further including a first liquefied gas in the first container, the first liquefied gas having a boiling point of no less than 77K.

6. The biomagnetometer of claim 1, further including a second liquefied gas in the second container, the second liquefied gas having a boiling point of no greater than about 10K.

7. The biomagnetometer of claim 1, further including a second liquefied gas in the second container, the second liquefied gas being liquid helium.

8. A biomagnetometer, comprising:

a magnetic pickup coil formed of a material that is superconducting at a temperature less than its superconducting transition temperature;

a detector of small electrical currents formed of a material that is superconducting at a temperature less than its superconducting transition temperature;

a first container that contains the pickup coil, the first container maintaining the pickup coil at a temperature at which it is superconducting and having a first interfacing surface;

a second container that contains the detector, the second container maintaining the detector at a temperature at which it is superconducting and having a second interfacing surface, the first and second containers being conformed to the same shape to fit together when the first and second interfacing surfaces are brought into contact; and

an inductive coupler having a pair of induction coils positioned adjacent each other across the first and second interfacing surfaces between the two containers such that an electrical current flowing in a first coil is coupled to a second coil,

the first induction coil being within the first container, electrically connected to the magnetic pickup coil, and made of a material that is superconducting at the temperature at which the magnetic pickup coil is superconducting, and

the second induction coil being within the second container, electrically connected to the detector, and made of a material that is superconducting at the temperature at which the detector is superconducting.

9. The biomagnetometer of claim 8, wherein the biomagnetometer includes a plurality of pickup coils in the first container and a plurality of detectors in the second container, each pickup coil being inductively coupled to its respective detector.

10. The biomagnetometer of claim 8, wherein the detector has a superconducting transition temperature of no more than about 10K.

11. The biomagnetometer of claim 8, wherein the pickup coil has a superconducting transition temperature of greater than 77K.

12. The biomagnetometer of claim 8, wherein the first induction coil and the second induction coil are flat coils.

13. The biomagnetometer of claim 8, wherein the first induction coil and the second induction coil are spiral coils.

14. A biomagnetometer, comprising:

a first container which has a first container interfacing wall;

a magnetic pickup coil located within the first container;

a second container which has a second container interfacing wall, the first container interfacing wall and the second container interfacing wall being shaped so that they may be placed adjacent each other;

a detector of small electrical currents located within the second container; and

an electrical conductive lead system that electrically connects the pickup coil to the detector, the lead system including at least the following portions

a first lead having two ends located in the first container, a first end of the first lead being connected to the magnetic pickup coil,

a second lead having two ends located in the second container, a first end of the second lead being connected to the detector, and

an inductive coupler having a first portion located within the first container adjacent the first container interfacing wall and connected to a second end of the first lead, and a second portion located within the second container adjacent the second container interfacing wall and connected to a second end of the second lead, the first portion and the second portion being located adjacent each other across the interface between the first and second containers to permit an electrical signal to be communicated from the pickup coil to the detector,

wherein each of the pickup coil, the detector, the lead system, and the inductive coupler are made of materials that become superconducting at a temperature below their respective superconducting transition temperatures.

15. The biomagnetometer of claim 14, wherein the first lead and second lead are made of different materials that have different superconducting transition temperatures.

16. The biomagnetometer of claim 14, wherein the inductive coupler includes a pair of facing but spaced apart flat coils, one coil connected to the first lead and the other coil connected to the second lead.

17. The biomagnetometer of claim 14, wherein the inductive coupler includes a first spiral coil connected to the first lead and a second spiral coil connected to the second lead, one of the spiral coils being disposed within the other spiral coils.