Sample pad assay initiation device

• US 5,260,221 A
• Filed: 07/02/1991
• Issued: 11/09/1993
• Est. Priority Date: 03/16/1989
• Status: Expired due to Term

• Current Assignee: Michael P. Allen, Prithipal Singh, Urs A. Ramel
• Original Assignee: Michael P. Allen, Prithipal Singh, Urs A. Ramel
• Inventors: Ramel, Urs A., Allen, Michael P., Singh, Prithipal
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): JASTRZAB, KRISANNE MARIE
• Application Number:
  US07/724,919
• Time in Patent Office: 861 Days
• Field of Search: 422/56-58, 422/61, 422/63, 422/82, 422/100-102, 422/104, 436/169-170, 436/177, 436/805, 435/11, 435/810, 210/651
• US Class Current: 436/169
• CPC Class Codes: B01L 2200/0621 Control of the sequence of chambers filled or emptied
• CPC Class Codes: B01L 2200/16 Reagents, handling or storing thereof
• CPC Class Codes: B01L 2300/0672 Integrated piercing tool
• CPC Class Codes: B01L 2400/0683 mechanically breaking a wall or membrane within a channel or chamber
• CPC Class Codes: B01L 3/5023 with a sample being transported to, and subsequently stored in an absorbent for analysis
• CPC Class Codes: C12Q 1/00 Measuring or testing processes involving enzymes, nucleic acids or microorganisms measuring or testing apparatus with condition measuring or sensing means, e.g. colony counters, C12M1/34; Compositions therefor; Processes of preparing such compositions
• CPC Class Codes: C12Q 1/26 involving oxidoreductase
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: C12Q 1/60 involving cholesterol
• CPC Class Codes: G01N 33/525 Multi-layer analytical elements
• CPC Class Codes: Y10S 435/81 Packaged device or kit
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]

Abstract

A self-contained assay device is provided, where an analyte may be detected or be quantitated by measuring the distance of a detectable signal from a predetermined site. The device employs two strips separated by a gap, where a flow path is completed by movement of a sample receiving pad into the gap. The movement of the sample receiving pad also results in release of a reagent solution which is then transported through the pad into the quantitation area where the amount of analyte may be determined. Various chemistries may be employed for providing a detectable signal.

Claims

1. An analyte measuring device which cooperates with a signal producing system for producing a detectable signal in a detection zone, said device comprising:

a housing comprising a well adjacent to one end of said housing, a pouch enclosing a liquid for release into said well, a flow path for holding in position two bibulous strips spaced apart in tandem relationship to define a space, and proximal to said well an interspace for receiving a slide mechanism;

an orifice for receiving a sample displaced from and substantially aligned with the space between said two bibulous strips;

in said orifice for preparing plasma free of red blood cells from blood with minimal lysis of said red blood cells, a membrane system comprising first and second membranes, said first membrane being a coarse separation membrane, having a pore size greater than said second membrane;

said second membrane in fluid-receiving relationship with said first membrane and having an average porosity in the range of about 0.65μ

to 7μ

, or an asymmetric membrane having a maximum porosity of greater than about 40μ and

a minimum porosity of not less than about 0.4μ

;

a slide element in said interspace comprising;

(1) a sample receiving element positioned (i.) under said orifice when said slide element is in a first position, and (ii.) positioned in said space, when said slide is in a second position; and

means for releasing a liquid into said well when said slide is moved from said first position to said second position; and

first and second bibulous strips in said flow path, said first strip extending from said well to said space to transport liquid from said well to said sample receiving element and said second strip comprising said detection zone and extending from said space toward the end opposite from said well, wherein said second strip has non-diffusibly bound at least one member of said signal-producing system.

2. A device according to claim 1, wherein said first membrane is a glass fiber membrane wherein the diameter of said glass fiber is in the range of about 0.5-9μ

and the density of said membrane is in the range of about 50-150 g/m².

3. A device according to claim 1, wherein said second membrane has a porosity in the range of about 1-5μ

.

4. An analyte measuring device which cooperates with a signal producing system for producing a detectable signal in a detection border, said device comprising:

a housing comprising a well adjacent to one end of said housing, a pouch enclosing a liquid for release into said well, a flow path for holding in position two bibulous strips spaced apart in tandem relationship to define a space, and proximal to said well an interspace for receiving a slide mechanism;

an orifice for receiving a sample displaced from and substantially aligned with the space between said two bibulous strips;

in said orifice for preparing plasma free of red blood cells from blood with minimal lysis of said red blood cells, a membrane system comprising first and second membranes, said first membrane being a coarse separation membrane, having a pore size greater than said second membrane;

said second membrane in fluid-receiving relationship with said first membrane having an average porosity in the range of about 0.65μ

to 7μ

, or an asymmetric membrane having a maximum porosity of greater than about 40μ and

a minimum porosity of not less than about 0.4μ

;

a slide element in said interspace comprising;

(1) a sample receiving element positioned (i.) under said orifice when said slide element is in a first position, and (ii.) positioned in said space, when said slide is in a second position, said sample receiving element comprising a member of said signal producing system non-diffusively bound; and

means for opening a pouch when said slide is moved from said first position to said second position;

means for removing excess sample from said sample receiving element as said sample receiving element moves from said first position to said second position; and

first and second bibulous strips in said flow path, said first strip extending from said well to said space to transport liquid from said well to said sample receiving element and said second strip extending from said space toward the end opposite from said well comprising a measuring region in which a member of said signal producing system is non-diffusibly bound, wheren said member is at least one of a component of a dye or an enzyme.

5. A device according to claim 4, wherein said enzyme member is a peroxidase.

6. A method for detecting the presence of an analyte in a blood sample employing a signal producing system having a plurality of reagents being distributed between being bound non-diffusibly to a surface or free in solution, said signal producing system with said analyte producing a detectable signal in a detection zone on a measuring strip employed as a said surface, said method comprising:

placing said blood sample, wherein said filtering element is a membrane system comprising first and second membranes, said first membrane being a coarse separation membrane, having a pore size greater than said second membrane;

said second membrane in fluid-receiving relationship with said first membrane and having an average porosity in the range of about 0.65μ

to 7μ

or an asymmetric membrane having a maximum porosity of not greater than about 40μ and

a minimum porosity of not less than about 0.4μ

over a filtering element which removes red blood cells from said blood sample to provide a plasma sample;

applying said plasma sample to a sample receiving element capable of moving from a first position to a second position, said second position in liquid transferring relationship with said measuring strip;

moving said sample receiving element to said second position;

transporting fluid to said sample receiving element for transporting at least one member of said signal producing system from said sample receiving element to said measuring strip; and

allowing said fluid to wick through said measuring strip with formation of a detectable boundary at a distance from said sample receiving element in relation to the amount of analyte in said blood sample.

7. A method according to claim 6, wherein said analyte is cholesterol.