Scalp potential measuring method and apparatus

摘要

An apparatus for measuring scalp potential is disclosed, which comprises a plurality of sensors and a pre-amplifier coupled to these sensors. The sensors are adapted to measure a raw scalp potential measurement though a hair and air interface, and may be considered as a difference, reference or common measurement. The interface presents a high and variable source impedance coupling to the scalp. The pre-amplifier is adapted to have an input impedance significantly higher than that presented by the source interface, and receives the raw scalp potential measurement to produce a pre-amplified scalp potential measurement.

主权项

1. A method for processing scalp potential signals comprising receiving an input raw scalp potential signal from a plurality of sensors for defining a respective plurality of channels;
processing the input raw scalp potential signal using a plurality of pre-amplifiers thereby to provide a high input impedance, wherein each pre-amplifier includes: (i) a wideband high impedance input and active biasing network, which presents an impedance of greater than 10 Peta-Ohms from 0.01 Hz to 400 Hz; (ii) a high gain low noise operational amplifier, with an input impedance of 10 Tera Ohms; and (iii) a feedback network for feeding back a first feedback signal interconnected to a conductive shield surrounding the input raw scalp potential signal, and a second feedback signal for actively biasing the input raw scalp potential signal; selecting a measurement mode configuration wherein the measurement mode configuration is selected from the group consisting of: a channel to reference-channel mode; a channel to channel-average mode; and a channel to channel differential mode; biasing said processed input signal while maintaining high input impedance; matching channel gain before differentially deriving a channel signal for each of the plurality of channels; processing each channel signal using the selected measurement mode configuration thereby to provide a corresponding processed channel signal, wherein the processing of each channel signal includes: suppressing radio frequency interference of each channel signal while maintaining gain and phase matching; and suppressing common mode signal interference of each channel signal; band pass filtering each said processed channel signal; and digitizing each said processed channel signal thereby to provide a digital scalp potential measurement signal indicative of said scalp potential signals having been processed.