E.i. Dupont De Nemours and Company

Other

Leeds & Northrup Company

Herman W Levin

Robert K Kobos

Scot D Abbott

Dale R Peterson

Henn Kilkson

David T Bach

Peter J Clack

George C Mergner

Roger A Gruenke

It is proposed to increase the utility of intracellular fluorescence and absorbance measurements for control of fermentation and cell culture by correcting on-line for background fluorescence of the media, also to be able to measure the fluorescence or absorbance of the fluid media in the presence of suspended cells or particles. The measurements could be extended to measure the optical properties of other fluids which contain suspended particles. This invention uses the characteristics of the evanescent wave at the surface of an optic waveguide. The wave penetrates into the less dense medium only to about the depth of about 1/2 wavelength. The thickness of media swept by the evanescent wave is much less than the size of a cell, thereby essentially separating the fluorescence or absorbance of the media from that of the cells. Apparatus is disclosed for carrying out the methods taught herein, including the use of an optical fiber to generate the evanescent wave and the use of a flat plate waveguide to generate it. Apparatus that can read both bulk fluorescence and evanescent wave fluorescence employs a flat plate waveguide to generate the evanescent wave and fiber optics to create an alternating dual-beam approach to generating both sets of data.

Evanescent wave background fluorescence/absorbance detection

A method for measuring hematocrit is provided. An electrochemically detectable marker is measured before and after the ratio of red cell volume to plasma volume is decreased. The measured concentrations are used in a mathematical formula to determine hematocrit value.

Electrochemical determination of hematocrit

An optical cell provides a measuring chamber which is L-shaped with an absorbance optical path lying along the horizontal leg of the L. A second optical path is provided transverse to the absorbance path and sized to permit the passage of radiation into the entire L-shaped chamber. The exit slit for the cell receives radiation from the entire vertical leg of the L and may serve as the entrance slit to a photometer.

Optical detector cell

A flow-through thermal detector for determining the temperature change resulting from a reaction in a fluid stream includes a pair of parallel fluid paths one of which carries the fluid stream in which the reaction occurs while the other carries a similar fluid without the occurrence of a reaction. The detector includes a temperature sensor for each path. The first of the sensors is mounted to sense the temperature of the reacting stream after said reaction has occurred while the second of the sensors is mounted to sense the temperature of the non-reacting stream at a point in its flow path comparable to that at which the first sensor is mounted. A heat shield is provided surrounding the parallel paths and the heat shield is controllable to a predetermined temperature. Preheating of the streams is carried out by a preheating means positioned within the heat shield to receive the fluid stream entering the shield. The preheating means is controlled to bring the fluid streams of the parallel paths to the same predetermined temperature to which the heat shield is controlled. The streams then enter an equalizing means surrounding that part of the paths between the preheating means and the region in which the reaction occurs for equalizing the temperatures of the streams in the parallel paths prior to the streams reaching the reaction region.

Flow-through thermal detector

Growing community of inventors

Philadelphia, PA, United States of America

Herman W Levin