Selective preamplifier of cell potentials

Claim 1

Apparatus for the selective detection and amplification of intranuclear and/or intracellular biopotentials comprising: a first metallic microelectrode for collecting the intracellular and/or intranuclear action biopotentials adapted to be inserted into a biological cell; a double screened central wire lead having two screening sheaths connected to said first metallic microelectrode; an amplifier with unity gain control having a sufficient sensitivity to action biopotentials released by cells with a very high internal resistance, the amplifier having an input terminal and an output terminal and a plurality of stages, the input terminal of said amplifier being the input terminal of the first stage of the amplifier, said input terminal being directly coupled with the said first metallic microelectrode through the central wire of the said double screened lead, the first stage of the amplifier having a floating reference point; a power supply circuit providing the feeding terminals of all active and passive electronic circuits and components of the said apparatus with two equal and of contrary sign stabilized voltages in comparison with a grounded null point; first circuit means electrically connected to and separating the said floating reference point of the first stage of the amplifier from the said power supply grounded null point; second circuit means for neutralizing the offset voltages in the stages of the said amplifier, whereby to obtain a good equality between the potential of the said floating reference point of the first stage of the amplifier and the biopotential applied, by means of said metallic mircoelectrode and said double screened lead wire to the input terminal of the said first stage, and an extremely low input capacity as well as high input resistance to the input terminal of said first stage of the amplifier; a second metallic microelectrode functioning as a first reference electrode means for the power supply circuit allowing the first microelectrode to collect the intranuclear biopotentials only and adapted to be inserted in said biological cell; and a third metallic electrode functioning as a second reference electrode means for the power supply circuit, adapted to be placed closely upon the outer surface of the cell, for allowing the first microelectrode to collect the intracellular biopotentials or both intranuclear and intracellular ones, in relation to the tip position of said first metallic microelectrode in the interior plasma of the cell under study.