Medical Scientific, Inc.

Medical and Scientific Designs Inc.

Arthur H Rogers

Kevin J Sullivan

Charles H Rogers

Gerald R Mansfield

Laughton E Miles

Method and apparatus are provided for carrying out multiple simultaneous transfers of fluid. The method and apparatus are particularly directed toward immunoassays wherein immunologically active compounds, such as antigens and haptens, are detected through their associated antibodies. The device relies on the ability to transfer fluids, such as biological samples and reagents, between a reservoir and an associated receptacle. By providing a receptacle having a port at its lower end and which is otherwise hermetically sealed, such fluid transfer can be effected by immersing the port beneath the surface of the fluid in the reservoir and manipulating the pressure on the remaining surface area outside the port. The transfer of biological fluids at positive pressure provides enhanced fluids flow characteristics, particularly reduction or elimination of the tendency of these fluids to froth or bubble. Moreover, since the fluids can easily be manipulated, they can be agitated to speed up the reaction and reduce the overall reaction time and can be transferred from the reaction zone to allow interim measurements of the extent of reaction to provide for a rate mode assay. The method and apparatus also find use in preparing solid phase reagents for use in assay systems, as well as a highly accurate pipetting system in analytic applications not limited to immunoassays.

Method and apparatus for performing assays

An inner and outer cylindrical cathode are concentrically positioned about a vertical center axis. Vertical anode electrodes extend parallel to the center axis and are symmetrically arranged around the inter-cylinder space between the cathodes. The ends of the anode wires are supported by a pair of insulator rings mounted near the top and bottom of the cathode cylinders. A collection voltage applied to each anode wire for establishing an inward radial E field to the inner cathode cylinder and an outward radial E field to the outer cathode cylinder. The anode-cathode assembly is mounted within a housing containing a conversion gas. A radioactive sample is inserted into the inner cathode which functions as a tubular, deep well radiation window between the sample environment and the conversion gas environment. A portion of the gamma radiations passing through the inter-cylinder region interact with the conversion gas to produce free electrons which are accelerated by the E fields and collected on the anode wires. The extremely small diameter of the anode wires intensifies the electric fields proximate each wire causing avalanche multiplication of the free electrons resulting in a detectable charge pulse.

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Los Altos, CA, United States of America

Arthur H Rogers