Inductive damping brain sensor
Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.
1. An inductive sensor apparatus for brain diagnostics comprising:
a sensor coil connected with a resistive, inductive, and capacitive (RLC) circuit and frequency counter to form a sensor unit;
a memory storing control values derived from prior sensor coil measurements of one or more normal brains in vivo, each control value associated with a corresponding cranial location;
a computer processor operatively connected with a machine-readable non-transitory medium embodying information indicative of instructions for causing the computer processor to perform operations comprising:
generating measured values based on output from the frequency counter when the sensor unit is at a cranial location;
determining the cranial location at which the measured values are associated;
retrieving, from the memory, control values associated with the cranial location;
comparing the measured values to the control values to generate deltas;
comparing the deltas to a positive threshold and a negative threshold associated with each cranial location to ascertain an exceedance, the exceedance having a sign and a magnitude; and
outputting an indication based on the sign of the exceedance, and
an indicator or display connected with the computer processor for the indication.
2. The apparatus of claim 1 wherein the indication includes the magnitude of the exceedance.
3. The apparatus of claim 1 further comprising:
a position gauge attached to the sensor unit,
wherein the determining of the cranial location at which the measured values are associated includes reading from the position gauge.
4. The apparatus of claim 3 further comprising:
a head-mounting frame including fiducial markers indicating cranial locations,
wherein the position gauge is configured to identify cranial locations based on the fiducial markers.
5. The apparatus of claim 4 further comprising:
an attachment point on the head-mounting frame configured to releasably connect with the sensor unit.
6. The apparatus of claim 5 wherein the attachment point is configured to guide the coil of the sensor unit in a direction normal from a surface at the cranial location.
7. The apparatus of claim 1 further comprising:
an accelerometer or gyroscope connected with the sensor unit and configured to determine the cranial location at which each measured value is taken.
8. The apparatus of claim 1 wherein the operations further comprise:
generating a matrix of exceedances based on measured values from multiple cranial locations.
9. The apparatus of claim 8 wherein the operations further comprise:
rendering an image based on the matrix of exceedances.
10. The apparatus of claim 1 further comprising:
a temperature sensor connected with the computer processor,
wherein the operations further comprise compensating the measured values for temperature.
11. The apparatus of claim 1 wherein an exceedance based upon a frequency higher than a control value indicates a hemorrhagic stroke, and an exceedance based upon a frequency lower than a control value indicates an ischemic stroke.
12. The apparatus of claim 1 further comprising:
a second RLC circuit as part of the sensor unit.
13. The apparatus of claim 12 wherein the sensor coil is connected with a separate unit of analog components.
14. A method of diagnosing an issue in a subject's brain, the method comprising:
reading measured values from a frequency counter on a resistive, inductive, and capacitive (RLC) circuit connected with a sensor coil of sensor unit, the sensor unit held to a subject's head;
determining a cranial location at which the measured values are read;
retrieving, from a memory, control values associated with the cranial location;
comparing the measured values with the control values to generate deltas;
comparing each delta to a positive threshold and a negative threshold in order to ascertain an exceedance, the exceedance having a sign and a magnitude; and
indicating, to a user, a type of issue based on the sign of the exceedance.
15. The method of claim 14 further comprising:
indicating, to the user, the magnitude of the exceedance.
16. The method of claim 14 wherein the determining of the cranial location includes reading from a position gauge.
17. The method of claim 16 wherein the determining of the cranial location includes reading from an accelerometer or gyroscope connected with the sensor unit.
18. The method of claim 14 further comprising:
moving the sensor unit in a direction normal from a surface at the cranial location.
19. The method of claim 14 further comprising:
generating a matrix of exceedances corresponding to multiple cranial locations; and
rendering an image based on the matrix of the exceedances.
20. The method of claim 14 further comprising:
distinguishing between an ischemic and a hemorrhagic stroke based on the sign of the exceedance.