Passive neutralization of myoelectric interference from neural recording tripoles.
In this paper, we present a simple passive technique for removing myoelectric interference in neural recording systems using tripolar electrodes. Imbalance is simply unavoidable with the conventional quasi-tripole (QT) amplifier and this technakshnique is based on a modified version of the QT, which sees the tripole as a bridge that can be balanced by adding impedance to one of the outer electrodes. We show that parallel resistance and capacitance is better than a series combination for use at all frequencies, and that with a tripole that was intentionally made imbalanced, by an amount that we measure as 3%, the interference can be reduced about 10-fold. It is important to null the interference at low frequencies, in the electromyography (EMG) band, to get the best improvement. Common-mode interference can also be reduced by appropriate trimming if necessary.
Pachnis
Ioannis
I
Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
Demosthenous
Andreas
A
Donaldson
Nick
N
D000200:Action Potentials / Q000502:physiology*; D000669:Amplifiers, Electronic; D016477:Artifacts; D003198:Computer Simulation; D017076:Computer-Aided Design; D004567:Electrodes, Implanted; D004576:Electromyography / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D008959:Models, Neurological; D010525:Peripheral Nerves / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity