Analysis of biological signals using data from arrays of sensors

• US 4,977,896 A
• Filed: 05/26/1989
• Issued: 12/18/1990
• Est. Priority Date: 05/26/1989
• Status: Expired due to Term

• Current Assignee: Biomagnetic Technologies, Inc.
• Original Assignee: Biomagnetic Technologies, Inc.
• Inventors: Black, William C. Jr., Robinson, Stephen E.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Pfaffle, Krista M.
• Application Number:
  US07/359,640
• Time in Patent Office: 571 Days
• Field of Search: 128/653, 128/731, 324/245, 324/248
• US Class Current: 600/409
• CPC Class Codes: A61B 5/242 Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents

Abstract

Signals produced by brain activity are measured by each sensor of an array of magnetic and/or electrical sensors external to but proximate to the head (or other portion of the body) of a subject. The measurements obtained simultaneously from all of the sensors are combined in a manner to permit selective measurement of the electrical activity from a specified location within the body, or alternatively, to permit the location in the body producing a particular type of response to be identified. The instantaneous measurement of each sensor is scaled by a weighting coefficient for that sensor, and the products added over all of the sensors. The weighting coefficients are calculated from a mathematical model of the brain that includes information on the shape of the potential source, the extent or type of source activity, the electrical and magnetic properties of the media, and the locations and orientations of the sources and the sensors.

Claims

1. A process for sensing and evaluating signals emanating from the brain of a subject, comprising the steps of:

providing an array of magnetic field sensors disposed external to a head of said subject at known locations;

measuring a signal strength detected by each of said sensors;

multiplying the signal strength measured by each of said sensors times a weighting coefficient for that sensor selected to focus the sensitivity of the array of said field sensors on a selected location in the brain, to determine a virtual sensor contribution for each of said sensors; and

adding together the virtual sensor contribution of each of said sensors, to define a virtual sensor signal.

2. The process of claim 1, wherein each of said sensors includes a superconducting quantum interference device.

3. The process of claim 1, including, after the step of adding, the additional step of:

correlating the virtual sensor signal with a physiological activity.

4. A process for sensing and evaluating signals emanating from a body of a subject, comprising the steps of:

measuring a signal strength detected by each sensor of an array of electromagnetic sensors placed proximately to said body of a subject; and

calculating a virtual sensor signal for the array, as a sum, over all of said sensors, of a product of a weighting coefficient for each said sensor times the signal measured for that sensor, the weighting coefficients being selected to focus the array of sensors on a selected location in the body.

5. The process of claim 4, wherein the weighting coefficient for each of said sensors is selected to optimize a contribution to a virtual signal of a selected target source relative to signals not produced by that target source.

6. The process of claim 4, wherein the sensors are placed proximately to a head of the subject.

7. The process of claim 4, wherein the sensors are placed proximately to a chest of the subject.

8. A process for sensing and evaluating electromagnetic signals emanating from a body of a subject, comprising the steps of:

providing an array of electromagnetic field sensors disposed external to a body of a subject at known locations;

determining a weighting coefficient applicable to each of said sensors, the step of determining including the steps of

characterizing a geometry of the body,

characterizing a nature of the magnetic fields emanating from possible sources in the body,

characterizing a medium through which the magnetic fields propagate,

formulating a mathematical model of the response of said sensors to a source within the body, and

calculating each of said weighting coefficients from the model;

measuring the signal strength detected by each of said sensors;

multiplying the signal strength measured by each of said sensors times the calculated weighting coefficient for that sensor to determine a virtual sensor contribution for each of said sensors; and

adding together said virtual sensor contributions of each of said sensors, to define a virtual sensor signal.

9. The process of claim 8, wherein the calculated weighting coefficient for each of said sensors is selected using the mathematical model to optimize a contribution to the virtual signal of a selected target source, relative to signals not produced by the target source.

10. The process of claim 8, including, after the step of adding, the additional step of:

correlating the virtual sensor signal with physiological information.

11. The process of claim 8, wherein each of said sensors includes a superconducting quantum interference device.

12. The process of claim 8, wherein the mathematical model is a finite mesh model.

13. The process of claim 8 wherein each of said sensors is placed proximately to a head of the subject.

14. The process of claim 8, wherein each of said sensors is placed proximately to a chest of the subject.