Shielding techniques for noise reduction in surface electromyography signal measurement and related systems and methods
Techniques for shielding wearable surface electromyography (sEMG) devices are described. According to some aspects, an sEMG device may comprise amplification circuitry comprising at least a first differential amplifier and at least two sEMG electrodes electrically connected to the amplification circuitry. The device may further comprise at least one auxiliary conductor not electrically connected to the amplification circuitry, wherein the at least one auxiliary conductor is configured to be electrically coupled to a wearer of the wearable device, and an electromagnetic shield surrounding the wearable device at least in part and electrically connected to the at least one auxiliary conductor.
1. A wearable device comprising:
amplification circuitry comprising at least a first differential amplifier;
at least two dry sEMG electrodes electrically connected to the amplification circuitry;
at least one auxiliary conductor not electrically connected to the amplification circuitry, wherein the at least one auxiliary conductor is configured to be electrically coupled to a wearer of the wearable device; and
an electromagnetic shield electrically connected to the at least one auxiliary conductor,
wherein the amplification circuitry is positioned between the electromagnetic shield and the at least two dry sEMG electrodes.
2. The wearable device of claim 1 , wherein the electromagnetic shield surrounds at least one input of the first differential amplifier.
3. The wearable device of claim 1 , wherein the electromagnetic shield comprises a metal.
4. The wearable device of claim 1 , wherein the electromagnetic shield comprises a conductive fabric.
5. The wearable device of claim 1 , wherein the electromagnetic shield comprises a conductive paint applied to the at least a portion of the wearable device.
6. The wearable device of claim 1 , wherein the electromagnetic shield comprises a conductive tape.
7. The wearable device of claim 1 , wherein the electromagnetic shield comprises a conductive plastic.
8. The wearable device of claim 1 , wherein the first differential amplifier comprises a field-effect transistor (FET).
9. The wearable device of claim 1 , wherein the first differential amplifier is configured to have an input impedance of at least 1 GΩ.
10. The wearable device of claim 1 , wherein the at least one auxiliary conductor includes one or more sEMG electrodes.
11. The wearable device of claim 1 , wherein the at least one auxiliary conductor includes a conductive cylinder, ring and/or torus.
12. The wearable device of claim 1 , further comprising a housing, and wherein the electromagnetic shield is arranged within the housing.
13. The wearable device of claim 1 , further comprising a housing, and wherein the electromagnetic shield comprises a conductive paint applied to the housing.
14. The wearable device of claim 1 , wherein one or more of the at least two dry sEMG electrodes are configured to pass through at least some portion of the wearer's dermis.