Non-invasive sensing of a physical parameter

• US 6,292,680 B1
• Filed: 02/16/2000
• Issued: 09/18/2001
• Est. Priority Date: 05/21/1997
• Status: Expired due to Term

• Current Assignee: Lucent Medical Systems, Inc.
• Original Assignee: Lucent Medical Systems, Inc.
• Inventors: Golden, Robert N., Somogyi, Christopher P.
• Primary Examiner(s): Lacyk, John P.
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US09/424,160
• Time in Patent Office: 580 Days
• Field of Search: 600/9-15, 600/481, 600/485-486, 600/504, 600/505, 600/508-509, 600/513, 600/529, 600/538, 600/561, 600/407, 600/409, 600/549, 600/587
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0265 using electromagnetic means, e.g. electromagnetic flowmeter
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/1121 Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/224 Measuring muscular strength

Abstract

There is disclosed a method and device for non-invasively sensing a physical parameter within the body of a patient by employing a magnetically-based sensing device and monitoring device. The magnetically-based sensing device has a first magnet and a second magnet which generate a combined magnet field. The first and second magnets are positioned such that a change in a physical parameter causes a change in the combined magnet field, which change is monitored by the monitoring device.

Claims

1. A method for sensing a physical parameter within the body of a patient, comprising:

associating a first magnet with a tissue substrate within the body of the patient, wherein the first magnet generates a first magnetic field;

positioning a second magnet at an initial orientation with, and in close proximity to, the first magnet such that a change in the physical parameter alters the initial orientation between the first magnet and second magnet, wherein the second magnet generates a second magnetic field and the initial orientation is such that the first and second magnets are selectively oriented in alignment such that the first and second magnetic fields combine additively or in inverse alignment such that the first and second magnetic fields are substantially canceled by each other, the sum of the first and second magnetic fields yields an initial combined magnetic field;

measuring the initial combined magnetic field; and

monitoring the combined magnetic field over a period of time to sense a change in the physical parameter.

2. The method of claim 1 wherein the tissue substrate is bone and the second magnet is associated with an orthotic device.

3. The method of claim 2 wherein the physical parameter is movement between the bone and orthotic device.

4. The method of claim 1 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is increased in strength over time.

5. The method of claim 1 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is decreased in strength over time.

6. The method of claim 1 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is changed with regard to orientation of the same over time.

7. A method for sensing a physical parameter within the body of a patient, comprising:

associating a first magnet with a device implanted within the body of the patient, wherein the first magnet generates a first magnetic field;

positioning a second magnet at an initial orientation with, and in close proximity to, the first magnet such that a change in the physical parameter alters the initial orientation between the first magnet and second magnet, wherein the second magnet generates a second magnetic field and the initial orientation is such that the first and second magnets are selectively oriented in alignment such that the first and second magnetic fields combine additively or in inverse alignment such that the first and second magnetic fields are substantially canceled by each other, the sum of the first and second magnetic fields yields an initial combined magnetic field;

measuring the initial combined magnetic field; and

monitoring the combined magnetic field over a period of time to sense a change in the physical parameter.

8. The method of claim 7 wherein the device implanted into the body of the patient is selected from catheters, tubes, surgical staples, tissue joining devices, shunts, stents, artificial valves, artificial vessels, esophagus, trachea, tags and markers.

9. The method of claim 7 wherein the physical parameter is selected from strain, pressure, force, impact, volume, temperature, rotation, displacement, flow rate, oscillation frequency and damping coefficient.

10. The method of claim 7 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is increased in strength over time.

11. The method of claim 7 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is decreased in strength over time.

12. Thee method of claim 7 wherein a change in the physical parameter alters the initial orientation between the first magnet and second magnet such that the initial combined magnetic field is chanted with regard to orientation of the same over time.

13. A magnetically-based sensor system for sensing a physical parameter within the body of a patient, the system comprising a sensing device having a first magnet which generates a first magnetic field and a second magnet which generates a second magnetic field in initial orientation with, and in close proximity to, the first magnet, with the first and second magnets being initially oriented in alignment with each other or in inverse alignment with each other such that a change in the physical parameter alters the initial orientation between the first magnet and second magnet, wherein the sum of the first and second magnetic fields yields an initial combined magnetic field detectable by a magnetic detector, and a monitoring device capable of measuring the combined magnetic field.

14. The system of claim 13 wherein the magnetically-based sensing device is implantable.

15. The system of claim 14 wherein the device is selected from catheters, tubes, surgical staples, tissue joining devices, shunts, stents, artificial valves, artificial vessels, esophagus, trachea, tags and markers.

16. The system of claim 13 wherein the physical parameter is selected from strain, pressure, force, impact, volume, temperature, rotation, displacement, flow rate, oscillation frequency and damping coefficient.