Device and method for sensing electrical activity in tissue
An exemplary embodiment providing one or more improvements includes apparatus and methods for sensing electrical activity in tissue of a person in a manner which is substantially limits or eliminates interference from noise in a surrounding environment.
1. A headset to gather electroencephalographic signals from a person, the headset comprising:
a headband to be worn around a head of the person;
a sensor electrode;
a reference electrode; and
an electronics module including a housing and electronics circuitry in the housing, the sensor electrode and the electronics module carried by the headband such that when the headband is worn on the head of the person, the sensor electrode is disposed on a forehead of the person over a pre-frontal lobe of the person and the housing with the electronics circuitry is disposed over a temple of the person,
the sensor electrode, when disposed on the forehead of the person, configured to obtain a signal of interest, an undesired signal, and noise,
the sensor electrode electrically coupled with the electronics circuitry via a first connector,
the reference electrode electrically coupled with the electronics circuitry via a second connector,
the electronics circuitry including:
a front end amplifier circuit, the first connector electrically coupled with a first input of the front end amplifier circuit and the second connector electrically coupled with a second input of the front end amplifier circuit, the front end amplifier circuit configured to (1) amplify the signal of interest and the undesired signal occurring in a first frequency range and (2) attenuate the noise occurring in a second frequency range, an output of the front end amplifier circuit electrically coupled to the second input via a parallel resistor and capacitor;
a filter electrically coupled with the output of the front end amplifier circuit, the filter configured to receive an output signal from the front end amplifier circuit containing the signal of interest and the undesired signal, the filter configured to isolate the signal of interest by attenuating the undesired signal; and
a processor configured to operate on the signal of interest from the filter.
2. The headset of claim 1 , wherein the electronics module is in a pocket of the headband.
3. The headset of claim 1 , further including a clip to be attached to an ear of the person, the reference electrode coupled to the clip.
4. The headset of claim 1 , wherein the electronics circuitry includes a power source having a power source reference terminal electrically coupled with the reference electrode.
5. The headset of claim 1 , wherein the output signal of the front end amplifier circuit is an analog output signal, the headset further including a converter to convert the analog output signal to a digital output signal.
6. The headset of claim 5 , wherein the processor is configured to transform the digital output signal using a Fourier transform to determine an energy spectrum of the digital output signal, the energy spectrum including a plurality of bins representing energy in corresponding frequencies of the digital output signal.
7. The headset of claim 6 , wherein the processor is configured to sum the energy in the bins corresponding to frequencies of from 4 hertz (Hz) to 8 Hz to create a Theta band energy signal.
8. The headset of claim 7 , wherein the processor is configured to sum the energy in the bins corresponding to frequencies of from 8 Hz to 12 Hz to create an Alpha band energy signal.
9. The headset of claim 8 , wherein the processor is configured to determine a ratio of the Alpha band energy signal and the Theta band energy signal.
10. The headset of claim 8 , wherein the electronics circuitry includes a wireless transmitter to transmit an output of a calculation based on the Alpha band energy signal and the Theta band energy signal to a wireless receiver of an electronic device.
11. A headset to gather electroencephalographic signals from a person, the headset comprising:
a sensor electrode;
a reference electrode;
an electronics module including a housing and electronics circuitry in the housing; and
means for supporting the sensor electrode on a forehead of the person over a pre-frontal lobe of the person and the housing with the electronics circuitry over a temple of the person,
the sensor electrode, when disposed on the forehead of the person, to obtain a signal of interest, an undesired signal, and noise,
the sensor electrode electrically coupled with the electronics circuitry via a first connector,
the reference electrode electrically coupled with the electronics circuitry via a second connector,
the electronics circuitry including:
a front end amplifier, the first connector electrically coupled with a first input of the front end amplifier and the second connector electrically coupled with a second input of the front end amplifier, the front end amplifier configured to (1) amplify the signal of interest and the undesired signal occurring in a first frequency range and (2) attenuate the noise occurring in a second frequency range, an output of the front end amplifier electrically coupled to the second input via a parallel resistor and capacitor;
a filter electronically coupled with the output of the front end amplifier, the filter configured to receive an output signal from the front end amplifier containing the signal of interest and the undesired signal, the filter configured to isolate the signal of interest by attenuating the undesired signal; and
means for analyzing the signal of interest from the filter.
12. The headset of claim 11 , further including means for supporting the reference electrode on an ear of the person.
13. The headset of claim 11 , wherein the electronics circuitry includes a power source having a power source reference terminal electronically coupled with the reference electrode.
14. The headset of claim 11 , wherein the output of the front end amplifier is an analog output signal, the headset further including means for converting the analog output signal to a digital output signal.
15. The headset of claim 14 , further including means for determining an energy spectrum of the digital output signal, the energy spectrum including a plurality of bins representing energy in corresponding frequencies of the digital output signal.
16. The headset of claim 15 , wherein the means for determining is configured to sum the energy in the bins corresponding to frequencies of from 4 hertz (Hz) to 8 Hz to create a Theta band energy signal.
17. The headset of claim 16 , wherein the means for determining is configured to sum the energy in the bins corresponding to frequencies of from 8 Hz to 12 Hz to create an Alpha band energy signal.
18. The headset of claim 17 , further including means for generating an output signal of a ratio of the Alpha band energy signal and the Theta band energy signal.
19. The headset of claim 18 , wherein the electronics circuitry includes means for transmitting the output signal to a wireless receiver of an electronic device.