Medical diagnostic device with enough-sample indicator

Details Medical diagnostic device with enough-sample indicator Medical diagnostic device with enough-sample indicator

1999-07-16

2001-07-17

Alexander, Lyle A. (Department: 1743)

Chemical apparatus and process disinfecting, deodorizing, preser

Analyzer, structured indicator, or manipulative laboratory...

Calorimeter

C422S067000, C436S164000, C436S169000, C436S177000, C436S178000, C436S069000

Reexamination Certificate

active

06261519

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fluidic medical diagnostic device for measuring the concentration of an analyte in or a property of a biological fluid.
2. Description of the Related Art
A variety of medical diagnostic procedures involve tests on biological fluids, such as blood, urine, or saliva, and are based on a change in a physical characteristic of such a fluid or an element of the fluid, such as blood serum. The characteristic can be an electrical, magnetic, fluidic, or optical property. When an optical property is monitored, these procedures may make use of a transparent or translucent device to contain the biological fluid and a reagent. A change in light absorption of the fluid can be related to an analyte concentration in, or property of, the fluid. Typically, a light source is located adjacent to one surface of the device and a detector is adjacent to the opposite surface. The detector measures light transmitted through a fluid sample. Alternatively, the light source and detector can be on the same side of the device, in which case the detector measures light scattered and/or reflected by the sample. Finally, a reflector may be located adjacent to the opposite surface. A device of this latter type, in which light is first transmitted through the sample area, then reflected through a second time, is called a “transflectance” device. References to “light” throughout this specification and the appended claims should be understood to include the infrared and ultraviolet spectra, as well as the visible. References to “absorption” are meant to refer to the reduction in intensity as a light beam passes through a medium; thus, it encompasses both “true” absorption and scattering.
An example of a transparent test device is described in Wells et al. WO94/02850, published on Feb. 3, 1994. Their device comprises a sealed housing, which is transparent or translucent, impervious, and rigid or semi-rigid. An assay material is contained within the housing, together with one or more assay reagents at predetermined sites. The housing is opened and the sample introduced just before conducting the assay. The combination of assay reagents and analyte in the sample results in a change in optical properties, such as color, of selected reagents at the end of the assay. The results can be read visually or with an optical instrument.
U.S. Pat. No. 3,620,676, issued on Nov. 16, 1971 to Davis, discloses a calorimetric indicator for liquids. The indicator includes a “half-bulb cavity”, which is compressible. The bulb is compressed and released to form a suction that draws fluid from a source, through a half-tubular cavity that has an indicator imprinted on its wall. The only controls on fluid flow into the indicator are how much the bulb is compressed and how long the indicator inlet is immersed in the source, while the bulb is released.
U.S. Pat. No. 3,640,267, issued on Feb. 8, 1972 to Hurtig et al., discloses a container for collecting samples of body fluid that includes a chamber that has resilient, collapsible walls. The walls are squeezed before the container inlet is placed into the fluid being collected. When released, the walls are restored to their uncollapsed condition, drawing fluid into and through the inlet. As with the Davis device, discussed above, control of fluid flow into the indicator is very limited.
U.S. Pat. No. 4,088,448, issued on May 9, 1978 to Lilja et al., discloses a cuvette, which permits optical analysis of a sample mixed with a reagent. The reagent is coated on the walls of a cavity, which is then filled with a liquid sample. The sample mixes with the reagent to cause an optically-detectable change
U.S. Pat. Nos. 4,426,451; 4,868,129; 5,104,813; and 5,230,866 disclose various devices for diluting and/or analyzing biological fluid samples. The devices include a “stop flow junction” to control the flow of the sample. The junction consists of an abrupt change in the cross-sectional area of a flow channel. Typically, the junction is formed when a small-diameter capillary channel enters a larger channel. The stop junction creates a back pressure that stops the normal blood flow until some additional pressure, such as hydrostatic pressure, acts to cause the sample to break through the junction into the larger channel.
U.S. Pat. No. 5,627,041, issued on May 6, 1997 to Shartle et al., discloses a diagnostic device that includes a stop junction, and the force that causes sample to break through the junction is a centrifugal force provided by rotating the device.
European Patent Application EP 0 803 288, of Naka et al., published on Oct. 29, 1997, discloses a device and method for analyzing a sample that includes drawing the sample into the device by suction, then reacting the sample with a reagent in an analytical section. Analysis is done by optical or electrochemical means. In alternate embodiments, there are multiple analytical sections and/or a bypass channel. The flow among these sections is balanced without using stop junctions.
FIG. 9
of Naka et al. depicts a “liquid pooling portion” at the sample inlet and an air vent passage branching from the drawing channel. These two elements, in combination, permit a two-stage process for introducing the sample to the analytical section.
U.S. Pat. No. 5,700,695, issued on Dec. 23, 1997 to Yassinzadeh et al., discloses an apparatus for collecting and manipulating a biological fluid that uses a “thermal pressure chamber” to provide the driving force for moving the sample through the apparatus.
U.S. Pat. No. 5,736,404, issued on Apr. 7, 1998, to Yassinzadeh et al., discloses a method for determining the coagulation time of a blood sample that involves causing an end of the sample to oscillate within a passageway. The oscillating motion is caused by alternately increasing and decreasing the pressure of the sample.
U.S. Pat. No. 5,208,163, issued on May 6, 1993 to Charlton et al., discloses a sample analysis device that includes a metering chamber and capillary that allows an operator to determine that sample has been applied in excess of the amount needed for the measurement.
SUMMARY OF THE INVENTION
The present invention provides a fluidic diagnostic device for measuring an analyte concentration or property of a biological fluid. The device comprises
a first layer and second layer at least one of which has a resilient region over at least part of its area, separated by an intermediate layer, in which cutouts in the intermediate layer form, with the first and second layers,
a) a sample port for introducing a sample of the biological fluid into the device;
b) a measurement area, in which a physical parameter of the sample is measured and related to the analyte concentration or property of the fluid;
c) a first channel, having a first end and a second end, to provide a fluidic path from the sample port at the first end through the measurement area;
d) a bladder at the second end of the first channel, comprising at least a part of the resilient region in at least the first or second layer and having a volume that is at least about equal to the combined volume of the measurement area and first channel;
e) a stop junction in the first channel between the measurement area and bladder that comprises a co-aligned through-hole in at least the first or second layer, the through-hole being overlaid with a third layer; and
f) a second channel having a first end in fluid communication with the first channel at a first point between the sample port and measurement area and a second end vented, in which
(i) at least the first or second layer has a transparent section at a predetermined second point adjoining the second channel and
(ii) the volume of the part of the second channel lying between the first and second points is at least about equal to the volume of the measurement area.
The device is particularly well adapted for measuring prothrombin time (PT time), with the biological fluid being whole blood and the measurement area having a composition that facilitates the blood clotting casca

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