EEG MONITOR WITH CAPACTIVE ELECTRODES AND A METHOD OF MONITORING BRAIN WAVES

• US 20140171775A1
• Filed: 02/24/2014
• Published: 06/19/2014
• Est. Priority Date: 08/24/2011
• Status: Active Grant

• Current Assignee: T&W Engineering A/S (WS Audiology A/S)
• Original Assignee: Widex A/S (WS Audiology A/S)
• Inventors: KILSGAARD, Soren, RANK, Mike Lind, UNGSTRUP, Michael, JENSEN, Morten Holm, KIDMOSE, Preben
• Granted Patent: US 9,918,650 B2
• Time in Patent Office: Days
• US Class Current: 600/379
• CPC Class Codes: A61B 2562/0214 Capacitive electrodes
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/6817 Ear canal
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence

Abstract

A wearable EEG monitor for continuously monitoring the EEG of a user through capacitive coupling to an ear canal of a user comprises an ear insert (1) for positioning within the human ear canal, comprising at least two capacitive electrodes (16) for recording a signal. The electrodes are coated with a dielectricum for electrical insulation. The electrodes are connected to an amplifier (17). The amplifier has an input impedance matched to the impedance of the electrodes. The invention further provides a method of monitoring brain waves.

Claims

1. An EEG monitor for continuously monitoring the EEG of a user through capacitive coupling to an ear canal of a user, said EEG monitor comprising at least two capacitive electrodes adapted for recording a signal, the electrodes being coated with a dielectricum for electrical isolation of the electrode, an amplifier connected to the electrodes for amplification of the electrode signals, wherein the amplifier has an input impedance matched to the impedance of the electrodes, and an ear insert for positioning within the human ear canal, at least one of said electrodes being placed at said ear insert.

2. The EEG monitor according to claim 1, adapted for measuring an EEG response.

3. The EEG monitor according to claim 1, where the connection between the electrodes and the amplifier comprises a signal wire and a shield.

4. The EEG monitor according to claim 1, wherein the amplifier is located within the ear insert.

5. The EEG monitor according to claim 1, wherein the amplifier is an Auto-Zero-Amplifier.

6. The EEG monitor according to claim 1, wherein the amplifier is a chopper-stabilized amplifier.

7. The EEG monitor according to claim 1, wherein the amplifier has an input characteristic of a high pass filter with a corner frequency at 1 Hz.

8. The EEG monitor according to claim 1, wherein the amplifier comprises an Auto-Zero-Amplifier.

9. The EEG monitor according to claim 1, comprising a sample and hold circuit for keeping the shield at a potential close to that of the signal wire.

10. The EEG monitor according to claim 1, comprising a test circuit for testing the capacitive connection, having a signal generator for generating a test signal having a frequency outside the frequency range intended to measure.

11. The EEG monitor according to claim 1, wherein the entire monitor is located at an in ear device.

12. The EEG monitor according to claim 1, comprising a signal processor located at a behind-the-ear device.

13. The EEG monitor according to claim 1, wherein the power supply is located at a behind-the-ear device.

14. The EEG monitor according to claim 1, wherein the ear insert is made of a flexible material that adapts to the shape of the ear canal.

15. The EEG monitor according to claim 1, wherein the electrodes are fixed to an inner non-flexible part, which is covered with an outer flexible part, which conforms to the shape of the ear canal.

16. The EEG monitor according to claim 1, wherein the electrodes are distributed evenly over the circumference of the ear insert.

17. The EEG monitor according to claim 1, wherein the electrode has a double curvature shape.

18. A method of monitoring brain waves comprising arranging a capacitive electrode coated with a dielectricum in an ear insert,

placing the ear insert within an ear canal of a human subject, arranging at least one reference electrode coated with a dielectricum in contact with the head of the subject,

placing a processor adjacent the electrode of the subject, connecting the electrodes to the processor, and

using the processor to record and process the signals from the electrodes thereby monitoring the brain waves.