US 6,058,934 A · Planar hematocrit sensor incorporating a seven-electrode conductivity measurement cell

Abstract

A conductivity sensor for measuring hematocrit and a sensor housing for a blood analysis instrument using the conductivity sensor are described. The conductivity sensor includes a seven-electrode conductivity measurement cell in which three symmetric pairs of electrodes are arranged on opposite sides of a central electrode. The central electrode is connected to an AC source and the outermost pair of electrodes, which provide a return path for the current, are maintained at a ground or reference potential. The two inner pairs of electrodes measure the voltage drop along the current flow path. This arrangement confines the measurement current and potential within the sensor chamber, thereby preventing the sensor from interfering with other electrochemical sensors that may be provided in the blood analysis instrument. The sensor housing provides a linear arrangement of flow cells defining a fluid flow path through the housing. The conductivity and other sensors are each located within an associated cell to form a wall portion of the flow path. The housing arrangement is simple to assemble and provides a flow path which resists fouling and is readily flushed out.

Claims16

Dependent claims

A fluid conductivity measuring sensor comprising:

a substrate comprising an insulating material adapted to define a flow path across the substrate surface when the substrate is installed in a cell of a fluid flow system;
seven electrodes disposed in parallel alignment on the substrate, the electrodes comprising:
a central electrode adapted to be in electrical communication with a source of current when the substrate is installed in the cell of the fluid flow system,
an outermost pair of electrodes symmetrically spaced on either side of the central electrode and adapted to be electrically connected as a return current path to the current source at a reference potential when the substrate is installed in the cell of the fluid flow system;
a first pair and a second pair of voltage measuring electrodes disposed symmetrically on opposite sides of the central electrode, the first pair and the second pair adapted to be electrically connected in parallel to instrumentation to measure the potential difference across each of the pairs of voltage measuring electrodes when the substrate is installed in the cell of the fluid flow system.

2 more elements

A blood analysis system comprising:

an elongated housing having a longitudinally extending axis, a flow path formed through the housing and extending generally along the longitudinally extending axis, a plurality of flow cells linearly arranged along the flow path, each flow cell having a sensor receiving receptacle formed in a wall thereof;
and
a hematocrit sensor formed as a chip disposed in an associated sensor receiving receptacle within the housing, the hematocrit sensor comprising:
a planar substrate comprising an insulating material adapted to define a flow path across the substrate surface;
seven electrodes disposed in parallel alignment on the substrate, the electrodes comprising:
a central electrode adapted to be in electrical communication with a source of current,
an outermost pair of electrodes symmetrically spaced on either side of the central electrode and adapted to be electrically connected as a return current path to the current source at a reference potential;
a first pair and a second pair of voltage measuring electrodes disposed symmetrically on opposite sides of the central electrode, the first pair and the second pair adapted to be electrically connected in parallel to instrumentation to measure the potential difference across each of the pairs of voltage measuring electrodes;
the chip disposed in the sensor receiving receptacle with the seven electrodes arranged perpendicularly to the flow path.

6 more elements

Dependencies are inferred from the claim text.

Planar hematocrit sensor incorporating a seven-electrode conductivity measurement cell

Life of this patent

Planar hematocrit sensor incorporating a seven-electrode conductivity measurement cell

Life of this patent

Abstract

Claims16