Motion Artifact Rejection Microelectrode

• US 20110230745A1
• Filed: 03/17/2010
• Published: 09/22/2011
• Est. Priority Date: 03/17/2010
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Goravar, Shivappa, Chandrasekaran, Shankar, Virtanen, Juha
• Granted Patent: US 8,229,537 B2
• Time in Patent Office: Days
• US Class Current: 600/372
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/685 Microneedles
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

An electrode system for the measurement of biopotential signals includes a substrate. A microelectrode is coupled to the substrate. An accelerometer is coupled to the substrate. A biopotential amplifier is electrically coupled to the microelectrode and acceleration measurement circuit is electrically coupled to the accelerometer. A method of measuring a biopotential from a patient includes sensing a biopotential with a microelectrode. The biopotential is amplified with an amplifier in electrical communication with the microelectrode. A movement of the electrode is sensed with an accelerometer integrated with the electrode substrate. The sensed biopotential and the sensed movement are provided to an electronic controller. Portions of the sensed biopotential that correspond to sensed movement are identified as artifact contaminated portions.

Claims

1. An electrode system for the measurement of biopotential signals, the system comprising:

a substrate;

a microelectrode coupled to the substrate, the microelectrode comprising a plurality of conductive spikes;

an accelerometer coupled to the substrate;

a biopotential amplifier coupled to the microelectrode; and

an acceleration measurement circuit coupled to the accelerometer.

2. The system of claim 1, further comprising an electronics that processes a biopotential signal obtained by the microelectrode and an acceleration signal obtained by the accelerometer to improve the quality of the biopotential signals.

3. The system of claim 2 wherein the electronics use the acceleration signal to identify a motion artifact contaminated portion of the biopotential signal.

4. The system of claim 1, wherein the plurality of conductive spikes comprise silver or a silver/silver chloride coating.

5. The system of claim 1, wherein the accelerometer is a first accelerometer and further comprising a second accelerometer, both the first and second accelerometers being mechanically integrated with the substrate, the first accelerometer and the second accelerometer being oriented in the substrate to measure acceleration in at least two orthogonal directions.

6. The system of claim 1, wherein the electrode system measures electroencephalographic (EEG) biopotentials.

7. The system of claim 1, wherein the biopotential amplifier and the acceleration measurement circuit are mechanically separate from the substrate.

8. The system of claim 7, wherein the biopotential amplifier and the acceleration measurement circuit share at least one lead wire between the microelectrode and the biopotential amplifier and the acceleration measurement circuit.

9. The system of claim 1, wherein the biopotential amplifier and the acceleration measurement circuit are integrated with the substrate.

10. The system of claim 9, further comprising an insulative layer disposed between the microelectrode and the substrate.

11. The system of claim 8, wherein the accelerometer measurement circuitry comprises an acceleration detector front end and a back-end circuitry.

12. The system of claim 11, wherein the acceleration detector is integrated with the substrate and the power supply is mechanically separated therefrom.

13. The system of claim 12, wherein the communication between the acceleration detector front-end and back-end circuitry shares at least one lead wire used for the biopotential measurement.

14. A method of measuring a biopotential from a patient using an electrode with a plurality of microelectrodes extending from an electrode substrate, the method comprising:

sensing a biopotential with the plurality of microelectrodes;

amplifying the biopotential with an amplifier in electrical communication with the plurality of microelectrodes;

sensing a movement of the electrode with an accelerometer integrated with the electrode substrate;

providing the sensed biopotential and the sensed movement to an electronic controller; and

identifying portions of the sensed biopotential that correspond to sensed movement as artifact contaminated portions.

15. The method of claim 14, comprising providing power to the accelerometer at a frequency greater than a frequency of the biopotential, such that an acceleration signal from the accelerometer is at a frequency greater than the frequency of the biopotential.

16. The method of claim 15, wherein the amplifier is limited to amplify the frequency of the biopotential and not amplify the frequency of the acceleration signal.

17. A biopotential electrode, comprising:

a silicon substrate;

a microelectrode deposited on the silicon substrate; and

an accelerometer integrated with the silicon substrate, the accelerometer including a proof mass etched from the silicon substrate and suspended from the substrate by at least one support.

18. The biopotential electrode of claim 17, further comprising a biopotential amplifier coupled to the substrate and coupled to the microelectrode.

19. The biopotential electrode of claim 18, further comprising a capacitor coupled to the silicon substrate, the accelerometer being a capacitive accelerometer.

20. The biopotential electrode of claim 18, further comprising a piezoresistor coupled to the silicon substrate, the accelerometer being a piezoresistive accelerometer.