Alpha brain wave sensor

Claim 1

An alpha brain wave sensor including an electrode system and adapted to be operative independently of an electrode cream for developing an audible reproduction of alpha frequency brain waves from a human subject, comprising: electrode means for effecting electrical contact with a human subject independently of an electrode cream including a reference electrode adapted for pOsitioning in direct contact with the forehead of said subject, a signal electrode comprising an electrically conductive, non-apertured electrode base plate means and a plurality of electrically conductive rod members on the order of one-half inch in length disposed in spaced parallel relation and each having one blunt end portion adapted for extending through the hair of said subject to effect electrical non-penetrating contact with the scalp in the region above the occipital lobes and an opposite end portion affixed to said electrode base and a ground electrode adapted to be coupled to said subject, said reference and ground electrodes comprising planar metal discs, said base plate means, comprising a rigid, non-apertured, planar metal disc fixedly secured to said opposite end portion of each of said rod members with said rod members for electrically interconnecting and for physically supporting said rod members in a predetermined spaced relation relative to one another to permit free hair flow intermediate the prongs, signal amplifying means comprising a pair of impedance matched field effect type transistors having individual inputs coupled to said reference and signal electrodes by respective electrical signal conductors, with each of said transistors having an input impedance substantially greater than the surface contact resistance between said reference and signal electrodes and said subject and further having individual outputs, and a differential type transistor amplifier coupled to said individual outputs for developing an amplified difference of said signal outputs of said field effect transistors; band pass filter means included within said amplifying means for attenuating signals outside of the eight to thirteen cycle per second alpha frequency range; sound developing means coupled to said amplifying means for converting the alpha frequency signals developed by said amplifying means and said band pass filter means into audible sounds, said sound developing means comprising an oscillator having a natural oscillation frequency within the lower portion of the audible range, said amplifying means being coupled to said sound developing means through a potentiometer for permitting manual adjustment of the threshold sensitivity level of said sound developing means, said electrode means including a support band for fitting about the head of said subject and carrying said reference and ground electrodes thereon in spaced relation for contact with the forehead of said subject and further carrying said signal electrode, spaced relative to reference and ground electrodes, for contact with the scalp in the region above the occipital lobes, said support band having aperture means therein, said reference electrode, ground electrode and signal electrode having conductor means associated therewith and extending in said aperture means in said support band.