EXHIBIT 1008
`
`U.S. PATENT NO. 6,040,195 TO CARROLL ET AL.
`
`Infopia Ex. 1008 pg. 1
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`

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`HIIIIllllllllllllllll|||||Illll|||!||||||||||||l|||lllllllllllllllllllllll
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`US006040195A
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`United States Patent
`Carroll et al.
`,
`
`[19]
`
`[11] Patent Number:
`[45] Date of Patent:
`
`6,040,195
`Mar. 21, 2000
`
`i
`
`[75]
`
`Inventors: Patrick Carroll, Ft. Lauderdale; Jon
`Schneider, Weston, both of F1a.;
`Dwglas E‘ Bell’ Woodstock’ Ga’
`.
`.
`.
`.
`[731 AS51399“ H9“: (?‘1ag‘;?ls"°s’ 1”" Ft‘
`L3“ 6‘ ‘W:
`a-
`
`[21] Appl.N0.: 08/872,088
`
`[22]
`
`Filed;
`
`Jun_ 10, 1997
`
`7
`
`Int. Cl.
`[51]
`[52] U.s. Cl.
`
`................................................... G01N 33/558
`.............................. 436/514; 422/55; 422/56;
`422/58; 422/61; 435/11; 435/14; 435/174;
`435/180; 435/287.1; 435/287.2; 435/257.7;
`435/287.8; 435/287.9; 435/805; 435/810;
`435/970; 436/66; 436/71; 436/164; 436/169;
`436/170; 436/518; 436/531; 436/805; 436/810;
`436/815; 436/827
`[58] Field of Search ................................ .. 422/55-58, 61;
`435/11, 14, 174, 180, 287.1, 287.2, 287.7,
`
`287-8: 287-9: 805: 810a 9703 436/66» 71:
`194: 169: 170» 5140 518: 531: 805» 810’
`815: 327
`
`[56]
`
`References Cited
`US‘ PATENT DOCUMENTS
`
`.................. .. 23/253
`
`128/770
`128/770
`436/530
`.. 128/770
`N .. 422/56
`422/58
`
`
`
`3,992,158 11/1976 Przyblowicz eta].
`4,059,405
`11/1977 Sodickson et al.
`4,199,261
`4/1980 Tidd et al.
`4,627,445 12/1986 Garcia et al.
`4,637,403
`1/1987 Garcia et al.
`4,774,192
`9/1988 Termirliello et al.
`4,787,398 11/1988 Garcia et al.
`4,790,979 12/1988 Terminiello et al.
`4,877,580 10/1989 Aronowitz et al.
`
`4,935,346
`4,987,085
`
`6/1990 Phillips et al.
`1/1991 Allen et al.
`
`.............................. 435/4
`. 436/169
`
`5,049,437
`
`-
`9/1991 vP11f11§P5 6‘ 31-
`£1]:$}P5 e: 3% -
`2/1994 KrauE:eet
`I
`5:284:622
`41994 Phill'
`.
`1.
`5,304,468
`6/1995 Phillig: :1. .
`5,426,032
`5,563,042 10/1996 Phillips eta]. .
`5,780,304
`7/1998 Phillips et al.
`.
`5,843,692 12/1998 Phillips etal.
`
`
`
`- 435/4
`42423/S81-£1‘
`ii.’ 422/60
`435 14
`435/14
`435/14
`. 436/169
`............... 435/14
`
`PrimaryExaminer—Christopher L. Chin
`Attorney, Agent, or Firm—Malin, Haley & DiMaggio, P.A.
`
`ABSTRACT
`[573
`An improved multi-layered diagnostic sanitary test strip for
`receiving a heterogenous fluid, such as whole blood, to test
`for ‘presence and/or amount of a suspected analyte in the
`fluid by facilitating a color change in the strip corresponding
`to the amount of the analyte in the fluid, wherein the test
`strip includes fluid volume control dams to prevent spillage
`of the fluid from the strip and a chemical reagent solution
`that facilitates end-point testing. The improved test strip
`comprises (a) an upper support strip having a fluid receiving
`port and (b) a lower support strip having a color change
`viewing port and securely sandwiched therebetween (c) a
`spreading mesh screen for uniformly distributing the fluid,
`(d) a chemically treated separating layer for removing an
`undesirable element, e.g. red blood cells, from the fluid
`received from the mesh screen, (e) an isotropic membrane
`1 chemically treated with a reagent indicator Solution for
`removing any remaining portions of the undesirable
`element, producing a color change proportionate‘ to the
`amount of the suspected arlalyte 1n the fluid and facilitating
`an end—point ramp test, and (1) Volume control dam parti-
`tions for retaining fluid 011 and in the Strip-
`
`23 Claims, 3 Drawing Sheets
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`/2
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`1
`§
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`1
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`Infopia Ex. 1008 pg. 2
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`

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`U.S. Patent
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`Mar. 21, 2000
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`Sheet 1 of 3
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`.21 23
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`lnfopia Ex. 1008 pg. 3
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`TU.S. Patent
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`Mar. 21, 2000
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`Sheet2 0f3
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`6,040,195
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`/3
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`7/1
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`,4
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`4:”
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`/egg. 36
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`Infopia Ex. 1008 pg. 4
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`

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`U.S. Patent
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`Mar. 21, 2000
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`Sheet 3 of 3
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`6,040,195
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`Infopia Ex. 1008-pg. 5
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`

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`6,040,195
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`1
`DIAGNOSTIC SANITARY TEST STRIP
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates generally to analytical test strip
`devices, and more particularly to, an improved diagnostic
`sanitary test strip device for determining the presence,
`absence, and/or amount of a predetermined analyte, and
`having a fluid sample volume control, structure to facilitate
`proper orientation of the strip in a Corresponding meter, and
`an improved agent treatment solution for facilitating end-
`point testing.
`‘
`2. Description of the Background Art
`Analytical test strips for testing analytes in heterogeneous
`fluid samples are well known in the art and comprise Various
`structures and materials. These test strips typically include
`single or multi-layered fibrous membrane devices which
`receive a heterogeneous fluid, such as whole blood, and
`undergo a color change in response to interaction with
`agents/reactants imbibed into the membrane. Prior to reach-
`ing the reactants,
`the fluid sample is filtered to facilitate
`accurate testing of the analyte. For instance, a blood sample
`being treated for glucose levels requires the removal of red
`blood cells before testing the plasma. Some test strips
`include additional layers that provide the requisite filtering.
`Other test strips attempt to filter and test a sample for a
`suspected analyte in a single membrane. Terminiello et al.,
`U.S. Pat. No. 4,774,192,
`teaches such a dry chemistry
`reagent system which comprises a porous anisotropic
`(asymmetrical) membrane having a porosity gradient from
`one planar surface to the other for filtering a fluid sample and
`includes an indicator, flow control agent, and reagent cock-
`tail imbibed therein for initiating the chemical reaction with
`the fluid sample. Anisotropic membranes, however, provide
`inadequate filtering and can have a tendency to produce
`unreliable results.
`
`Test strip devices operate by allowing the applied hetero-
`geneous sample to migrate to a reaction site in the
`membrane, where the analyte of interest in the sample reacts
`with the imbibed agents. The results of the reaction are
`usually visible through a color change in the membrane. The
`color change may be viewed with the naked eye and
`measured by a visual comparison with a color chart or
`reading it with a reflectance meter.
`Certain problems have been noted in existing analytical
`test strips. Some of these problems include spillage of the
`sample over the edges of the strip, excessive absorption, and
`incomplete filtering, all of which can adversely afiect test
`integrity. Other strips, such as those disclosed in U.S. Pat.
`No. 3,298,789 issued to Mast and U.S. Pat. No. 3,630,957
`issued to Rey et al., require the‘ sample to remain in contact
`with the reagant pad for specified time and that the blood
`sample be either washed or wiped oif the pad. In addition,
`conventional strips have been known to be diflicult to use in
`terms of the proper amount of heterogeneous fluid to place
`on the strip. It is also difficult to properly place and/or orient
`strips in a corresponding meter.
`US. Pat. No. 5,296,192 (the “’192 Patent”), issued to the
`inventors herein, addresses some of these shortcomings
`noted in the background art. The ’192 Patent teaches a
`multi-layered diagnostic test strip for receiving whole blood
`on which a test for a suspected analyte is performed. The
`multi-layered test strip device comprises two outside
`supports, sandwiching therebetween a spreading screen, a
`separating layer, and a membrane. The top support has a port
`for receiving the sample. The spreading screen evenly
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`distributes the sample so that it uniformly passes into the
`separating layer. The separating layer removes a majority of
`the red blood cells from the blood sample, and the mem-
`brane removes the remaining cells. The membrane is also
`pretreated with reagents and conditioning agents needed for
`the reaction and insuring a readable, reliable color genera-
`tion. The ’192 Patent provides a strip that may be visually
`read with a color comparator or a reflectance meter. The
`instant invention provides an improved diagnostic test strip
`which is built in part on some of the teachings of the ’192
`Patent, and which has additional features for further enhanc-
`ing the use and reliability of diagnostic testing. These
`improvements are submitted as solving the above-noted
`problems.
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed to an improved, multi-
`layered sanitary test strip for receiving a heterogenous fluid
`that
`is tested for a suspected analyte. In the preferred
`embodiment,
`the heterogeneous fluid comprises a whole
`blood which is analyzed to determine the presence of
`analytes, such as glucose or cholesterol, to determine the
`presence, absence, and/or level of the analyte in the fluid.
`Accordingly, discussion herein is tailored to the receipt and
`testing of glucose analytes in a whole blood sample. As such,
`the suggested chemical reagents herein are specific to testing
`glucose in blood. It is important to note, however, that the
`instant invention may be used to determine the presence,
`absence, and/or amount of a substance in other heteroge-
`neous fluids by modifying the chemical reagent solutions
`and/or concentrations employed. The diagnostic sanitary test
`strip may be used for other enzymes and immunoassays,
`such as cholesterol (HDL or LDL), ketones, theophylline,
`osteoporosis, H1AC, fructosamine and others. The present
`invention confirms the presence, absence, and/or amount of
`these analytes.
`The multi-layered diagnostic sanitary test strip generally
`comprises two outside layers, between which are,
`in
`descending order, a spreading screen, a separating layer, a
`membrane, and a pretreatment reagent solution imbibed into
`the membrane. The multi-layered test strip taught herein
`improves on the teachings of the test strip disclosed in U.S.
`Pat. No. 5,296,192, the disclosure of which is incorporated
`herein by reference. The instant invention is an improvement
`in that it provides a chemistry reagent solution and concen-
`tration that facilitates end-point
`testing, volume control
`dams to prevent spills or overflow and reduce the amount of
`sample needed to perform a test, and a light absorption
`medium which visually and functionally prevents the test
`strip from being tested upside down. The improved diag-
`nostic test strip also allows for the application of a hetero-
`geneous fluid sample, e.g., blood, to the strip, both inside
`and outside the meter.
`
`It is an object of the present invention to provide an
`improved multi-layered diagnostic sanitary test strip.
`It is another object of the present invention to provide an '
`improved multi-layered diagnostic sanitary test strip that
`prevents a heterogenous fluid sample from overflowing from
`the strip.
`invention to
`It is an additional object of the present
`provide an improved multi-layered diagnostic sanitary test
`strip that is easier to use, requires a smaller amount of the
`heterogenous fluid sample and facilitates application of the
`sample on the strip when the strip is either outside or
`inserted in a meter.
`
`It is a further object of the present invention to provide an
`improved multi-layered diagnostic sanitary test strip that
`
`Infopia Ex. 1008 pg. 6
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`

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`6,040,195
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`3
`facilitates proper placement and orientation of the strip in a
`corresponding meter.
`It is yet another object of the present invention to provide
`an improved multi-layered diagnostic sanitary test strip that
`may be used in a meter that performs end-point testing.
`It is yet an additional object of the present invention to
`provide an improved multi-layered diagnostic sanitary test
`strip that may be imbibed with a dry chemistry reagent
`solution that facilitates end-point testing.
`In accordance with these and other objects which will
`become apparent hereinafter, the instant invention will now
`be described with particular reference to the accompanying
`drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective View of the preferred embodiment
`of the multi-layered diagnostic sanitary test strip of the
`' instant invention.
`
`FIG. 2 is a perspective view of the multi-layered diag-
`nostic sanitary test strip prior to ultrasonically sealing the
`strip.
`FIG. 3a is an exploded, cross sectional View of the instant
`invention, taken along lines A—A of FIG. 2.
`FIG. 3b is a cross sectional View of the instant invention,
`taken along lines A—A of FIG. 2.
`FIG. 4 is a cross sectional elevation view of the layers of
`the test strip as it appears after construction.
`FIG. 5 is a cross sectional elevation View of another
`embodiment of the invention as it appears after construction.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`With reference to the drawings, FIGS. 1-5 depict the
`preferred embodiment of the improved, multi-layered diag-
`nostic sanitary test strip 10 of the instant invention. The test
`strip 10 represents an improvement over background test
`strips, whereby it contemplates the novel features that make
`the strip more sanitary, easier to use, and more eflicient. In
`a preferred use, a whole blood sample from a finger stick, or
`otherwise, is applied to the strip 10 to test for the presence,
`absence, and/or amount of a suspected analyte, e.g., glucose.
`It is important to note that whole blood may be tested for
`other analytes and that other heterogeneous fluid samples
`may be tested for glucose and other analytes, such as
`LDH/I-IDL cholesterol, H1AC, osteoporosis, fructosamine,
`etc. The test strip 10 generally comprises a spreading layer
`20, a separating layer 30 for filtering, and a preconditioned
`membrane 40. The membrane 40 and separating layer 30 are
`preferably pretreated with reagents and/or conditioning
`solutions, as discussed more fully herein. During use, the
`reagents and conditioning system filters the sample so that
`the analytes of interest can be more easily detected and
`measured without interference. For example, where blood is
`used, the reagent cocktail removes red blood cells from the
`plasma of the sample so that red blood cells do not interfere
`with the color reaction. Thus, liquid plasma remains prior to
`experiencing, viewing, and analyzing the color change in the
`membrane 40.
`As shown in FIG. 1, the test strip 10 generally comprises
`an upper support layer 12 and a lower support layer 13 and
`a spreading layer 20, a separating layer 30, and a semi-
`porous membrane reagent layer 40 sandwiched therebe-
`tween in descending order. At least one of these layers 20,
`30, 40 is pretreated with a dry chemistry reagent and
`conditioning solution. Preferably,
`the membrane 40 and
`
`4
`separating layer 30 are pretreated with the reagent/
`conditioning solution. The spreading screen 20 may also be
`treated. Each layer 20, 30, and 40 is positioned in tight,
`continuous Contact with its adjacent layer as shown in FIGS.
`4 and 5. With reference to FIGS. 2, 3A, and 3B, the support
`layers 12, 13, screen 20, separator 30, and membrane 40 are
`aligned as shown and glued and ultrasonically bonded
`together to provide a sealed composite structure. The sup-
`port strips 12, 13 may contain a layer of adhesive on their
`interior surfaces to physically attach the supporting layers
`12, 13 in a way that tightly compresses the other layers 20,
`30, and 40 therebetween. The support layers 12, 13 and
`operative layers 20, 30, and 40 are further secured by
`ultrasonic welding. Other welding techniques may be
`employed, such as heat-stamping.
`The support strips 12, 13 are preferably constructed from
`mylar. The top and bottom support strips 12, 13 each define
`an aperture or opening therethrough. These apertures or
`openings are oriented in vertical alignment when construct-
`ing‘ the strip. The opening in the upper support strip 12
`defines a sample receiving port 15 and the opening in the
`lower support strip 13 defines a reaction viewing port 18.
`The spreading screen 20 abuts the interior glue surface 1211
`of the upper support 12. The separating layer 30 abuts the
`lower surface of spreading screen 20 and the upper surface
`of membrane 40. The upper surface of membrane 40 abuts
`the lower surface of separating screen 30 and the membrane
`lower surface abuts the interior glue surface of the lower
`support strip 13. The interior layers are oriented in vertical
`alignment with the sample receiving port 15 and the reaction
`viewing port 18. This allows the sample received by the strip
`10 to pass directly from the receiving port 15 to the viewing
`port 18. This movement, however, is facilitated and assisted
`by the operative layers 20, 30, and 40 of the strip and volume
`control structure 14 built therein. By the time the sample
`reaches the viewing port 18 it has undergone a color change
`indicative of the analyte of interest and is viewable from the
`viewing port 18.
`Volume control dam partitions 14 are formed in the upper
`support strip 12 around the sample receiving port 15 and
`depend downward into the strip to control the flow of the
`sample volume therein. The dam partitions 14 help direct the
`fluid sample downward toward the viewing port 18. In
`addition, the dam partitions 14 resist overflow by retaining
`the sample and guiding the sample to provide a more
`sanitary diagnostic test strip 12 and decreasing the amount
`of sample needed to conduct a test. The strip 10 is shown
`With four dam partitions 14 positioned approximately 90°
`apart around a substantially circular sample receiving port
`15. This orientation enhances volume flow control. It should
`be noted, however, that the number and configuration of dam
`partitions 14 may vary without departing from the scope and
`spirit of the invention so long as fluid sample is properly
`retained and vertically directed. The dam partitions 14 are
`formed by either die-stamping or embossing the upper strip
`12 when the strip layers 12, 13, 20, 30, and 40 are bound
`together through ultrasonic welding or stamping. The vol-
`ume controldam partitions 14 provide a unique feature of
`the instant invention which makes the strip easier and more
`comfortable to use. Moreover,
`the likelihood of sample
`overflow or spilling is greatly reduced by the novel structure
`of the instant invention.
`In reference to FIGS. 1, 4, and 5, two Branson detents 16
`are provided for strengthening the strip and accommodating
`Branson securing post which may be found on a correspond-
`ing meter. The Branson post and detents 16 are designed to
`interlock when a strip 10 is inserted into a corresponding
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`6,040,195
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`meter. The dam partitions 14 also serve to enhance the bond ,
`between the support strips 12, 13 and operative layers 20,
`30, and 40. The bonds formed by the dam partitions 14 and
`Branson detent 16 result from the application of energy,
`preferably ultrasonic energy, applied to the upper surface of
`support strip 12 during assembly. The penetration of the
`dams 14 and detents 16 are shown by perforated lines and
`generally comprise deep indentations in the assembled strip
`10. The location of the Branson detents 16 correspond to
`location of the Branson post found in the corresponding
`meter. The dam partitions 14 are positioned to retain and
`direct fluid sample in a manner that prevents overflow and
`facilitates efficient sample flow through the strip 10. The
`preferred orientation of the dams 14 are shown in FIG. 1.
`The above noted operative layers 20, 30 and 40 are
`preferably assembled as shown in FIGS. 1 and 4 using
`accepted techniques in the art and mylar strips 12, 13 as the
`support medium for the interior three layers 20, 30 and 40.
`The inside surfaces of the mylar strips have been previously
`treated with glue to hold the screen and the reaction mem-
`brane in place. In some applications it is desirable to select
`a separating layer 30 which is slightly larger in width than
`the reaction membrane 40 so that the edges of the separating
`layer 30 may overlap the reaction membrane 40 and meet the
`lower mylar strip 13 at the glued surface to aid further in
`securing the separating layer 30 to the rest of the device.
`Referring to FIGS. 2-5, it can be seen that the spreading
`screen 20 extends beyond the side edges of the separating
`layer 30 and that the separating layer 30 extends beyond the
`side edges of the membrane 40. The spreading layer 20
`adheres to the upper support strip 20 and the membrane 40
`adheres to the lower support strip 13. The support strips 12,
`13 are adhered and/or welded together. The spreading screen
`20 overextends beyond the separating layer 30 to allow the
`screen 20 to adhere to the glued surfaces of the support strips
`12, 13 and insures a tight, secure connection between layers
`20, 30, and 40. Once these layers have been assembled, the
`test strip is inserted into an ultrasonic point welding device
`and strip welded at the points shown at 14 and 16 in FIG. 1.
`This results in the volume control dams 14 and Branson
`holes 16. Asuitable strip is two (2) inches long by 0.5 inches
`wide by 0.035 inches thick with a sample receiving port 15
`and reaction viewing port 18 of about 0.2 inches in diameter,
`preferably sized to snugly fit in the shroud of a correspond-
`ing commercially available reflective type meter. When
`placed in a meter the Branson holes 16 are intended to align
`and mate with corresponding posts in the meter. The strip
`may also be read by comparing the color change in the
`viewing port 18 to a color chart depicting the amount of
`analyte found, e.g., glucose.
`Proper orientation of the strip 10 in a meter is not always
`easily ascertainable. To insure that the strip 10 of the instant
`invention is oriented with the proper surface facing up, the
`upper surface of the upper support strip 12 includes a light
`absorption region 19 at one selected end. The light absorp-
`tion region 19 also serves to indicate the leading end of the
`strip 10 to be placed in the meter first. Additional indicia in
`the form of an arrow 21 and blood fluid/fluid drop 23 may
`also be provided to indicate the direction of insertion and the
`top surface, respectively. The light absorption region 19
`comprises an optically dark, such as black, region adjacent
`the test area, preferably proximal to the end of the strip.
`Once inserted, the meter performs a test, such as a light
`reflection test,
`to determine whether the strip is properly
`oriented.
`
`In addition to the foregoing, the strip 10 of the instant
`invention is designed to allow a blood/heterogeneous fluid
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`sample to be applied to the strip 10 regardless of Whether the
`strip is inserted in or is outside a meter. This is possible
`because of the volume control provided by the dam parti-
`tions 14 and because of the location of the Branson post 16
`as shown in FIG. 1.
`
`A spreading screen 20 having a plurality of mesh open-
`ings is in contiguous contact with the sample receiving port
`15 for receiving and uniformly distributing, or spreading, the
`heterogeneous fluid over the screen 20. When blood is being
`analyzed, the sample is typically applied from a finger stick
`and comprises approximately 15-50 microliters. However,
`less sample is now required because of the dam partitions 14
`provide volume control to limit overflow and direct sample
`into the strip. This has the added benefit of improved
`sanitation. The screen 20 is defined by mesh openings that
`momentarily hold the sample, via surface tension, as the
`sample uniformly spreads out over the screen 20 to fill the
`receiving port. Eventually, the sample passes through the
`screen mesh 20 to the separating layers 30 to deposit an even
`distribution of the sample onto the separating layer 30. A
`uniform distribution is required to produce uniform color
`development. This is important because an uneven distribu-
`tion of the blood, or other heterogeneous fluid, will cause an
`uneven distribution to the membrane, which will afiect the
`color change therein and produce an unreliable reading. A
`preferred screen 20 which may be used with the instant
`invention is a polyester medical screen, designated PeCap/-
`7-16/8, provided by Tetko, Inc., Elmsford, N.Y., and having
`a mesh opening of about 16 microns, a thickness of about 75
`microns, and an open area of voids of 8% is. The screen is
`preferably dipped into a 10% solution of sodium chloride
`and allowed to dry.
`Separating layer 30 comprises a pretreated fabric woven
`screen material placed in contiguous Contact with the lower
`surface of the spreading screen 20. The treated separating
`layer 30 removes approximately 80% of the red blood cells
`from the blood sample. The remaining blood cells are then
`removed by the membrane 40. A preferred separating layer
`30 includes a woven fabric of 50% polyester/50% cotton
`having mesh openings of about 25 microns, open voids area
`of 16-20%, and a thickness of about 0.010 inches. The
`separating layer 30 is treated before assembly with one or
`more ‘agents that bond or adhere to the red blood cells
`without lysing them so as to avoid releasing red colorization
`to the reaction membrane. These bonding agents capture the
`red blood cells and hold them on the separating layer.
`The separating layer 30 should comprise a material that
`minimizes the absorption of plasma to maximize the plasma
`which reaches the membrane 40. This is desirable as it
`results in requiring less blood from the user. The separating
`layer 30 is more dense than the spreading screen 20. Thus,
`mesh size openings found in the separating layer 30 are
`smaller than that for the spreading screen 20, preferably
`from 20 to 200 microns. The amount of fabric occupied by
`voids is preferably 15 to 60%. A preferred fabric for the
`separating layer is polyester, cotton, or a 50/50 polyester-
`cotton blend.
`
`The‘ separating layer 30 is preferably pretreated with a
`blood cell separating agent prior to assembly to enhance
`filtration. The blood cell separating agents imbibed in the
`separating layer 30 may be any agent known by a practiced
`artisan to bind to red blood cells without lysing them. These
`agents include lectins, antibodies to red blood cells, water
`soluble, salts with potassium citrate, ammonium sulfate, zinc
`sulfate, and the like. Lectins are preferred and include
`proteins or glycoproteins that recognize specific sequences
`ofpolysaccharide residues. The lectin or other binding agent
`
`lnfopia Ex. 1008 pg. 8
`
`

`
`6,040,195‘
`
`7
`is applied by dipping the separating layer fabric into a
`solution of the lectin or other agent and allowing the wetted
`fabric to air dry. The solution can be prepared in concen-
`trations that are easily handled in standard test strip manu-
`facturing equipment. Typically, 2—7% solutions are accept-
`able. The separating layer 30 is preferably dipped into a 2%
`solution of a lectin derived from kidney beans and allowed
`to air dry.
`Numerous other lectins are commercially available. Some
`commercially available lectins and the specific sugar resi-
`dues they recognize are ConcanavalinA(Alpha-glucose and
`alpha-D-mannose), soybean lectin (D-galactose and
`N-acetyl-D-galactosamine), wheat germ lectin (N-acetyl
`glucosamine),
`lotus seed lectin (fucose), potato lectin
`(N-acetyl glucosamine), dilichos biflorus agglutinin
`(N-acetyl galactose-aminyl), and legume derived lectins
`such as lentil
`lectin (Alpha-D-mannose and alpha-D-
`glucose).
`-
`The membrane 40 is preferably isotropic (symmetrical),
`that
`is, uniformly porous. The membrane 40 should be
`optically White. The membrane 40 provides a medium for
`holding a reagent and conditioning solution which together
`produces a color change in the membrane 40 in response to
`the analyte of interest. In addition, the treated membrane 40
`filters the blood sample to remove any remaining red blood
`. cells from the whole blood sample. For other samples, the
`treated membrane 40 provides necessary filtration as well. A
`preferred membrane for the detection of glucose analytes
`comprises a hydrophilic polysulfone membrane having a
`pore size of 0.2 to 3.0 microns. Such a membrane is
`manufactured by Gelman Sciences ofAnn Arbor, Mich., and
`has been referred to as Thermopor®. The Supor® 450
`membrane is another acceptable membrane which has a pore
`size of approximately 0.45 microns. Although these mem-
`brane are preferred, other isotropic membranes may be used.
`In fact, membranes produced by other manufacturers may be
`required for testing analytes other than glucose. Some of
`these membranes include nylon membranes made by Pall
`and supported polysulfone membranes made by MSI.
`Prior to assembly of the strip 10, the membrane 40 is
`treated with reagents and conditioning agents in a single dip
`process. Thereafter,
`the membrane is allowed to dry. It
`should be noted that the conditioning process may be other
`than single dip. Preferably, a six-inch wide membrane of
`Thermopor®, having a pore size between 0.2 and 3.0
`microns is dipped into a solution at seven (7) milliliters of
`solution per linear foot of membrane. ASupor® 450 mem-
`brane having a pore size of approximately 0.45 microns may
`also be used in place of the Thermopor® and dipped in the
`same solution at the same rate.
`
`The instant invention comprises a reagent solution that
`facilitates end-point testing in a corresponding meter. This
`solution preferably comprises deionized water (700 mL/L),
`citric acid (tri-sodium salt dihydrate, 52.9 g/L), citric acid
`(FAM, 4.2 g/L), MAOS (6.6 g/L), 4-Aminoantipyrine (6.1
`g/L), 10% Gantrez AN-139 (50 mL/L), polyvinylpyrroli-
`done and an enzyme solution (100 mL/L). The enzyme
`solution may include glucose oxidase, peroxidase,
`5-dimethoxyaniline, buffers and stabilizers. The prior solu-
`tion of 4 gms citric acid (free acid monohydrate), 54 g of
`citric acid (otrisodium salt dihydrate), 60 g
`polyvinylpyrrolidone, 50 IU/L catalase, 4g bovin serum
`albumin (BSA), 0.0055 gm O-Tolidine-Hydrochloride,
`0.067 ml. deionized water, 0.0075 gm BSA, 0.0003 gm.
`glycerol, 11.0 lU peroxidase, 9.5 IV glucose oxidase, 0.002
`ml DOSS and 0.003 ml of Gantrez AN-139 may also be used
`if end-point testing is not conducted.
`
`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`Best results are obtained from the reaction membrane
`when it contains, in addition to the specific reagent solution
`noted above, certain conditioning agents which improve the
`performance of the reaction membrane. The conditioning
`agents are generally incorporated into a blend of the reac-
`tants in the solution before the latter are incorporated into the
`reaction membrane. For example, when preparing a reaction
`layer for a glucose test strip, a base solution is prepared with
`citric acid, PVP and BSA. This serves as the base to which
`the chromogen indicator system and other reactants, e.g.
`peroxidase and glucose oxidase, are added. It has also been
`found that the color generation by the reaction is stabilized
`and its readability enhanced by adding a small amount
`(0.0005—0.009 g/ml of solution) of DOSS (dioctyl sulfos-
`uccinate sodium) available from Sigma Chemical Company.
`Gantrez AN 139 (a 2.5 furandione polymer with methoxy—
`ethene otherwise known as a methyl vinyl ether copolymer
`with maleic anhydride) at a level of about 0.0005—0.009
`ml/L of solution may also be added to aid in conditioning the
`membrane.
`
`In use, one places a drop of blood of about 25 microliters,
`from a finger stick for example, into the sample receiving
`port 15 onto the screen surface. The invention can work well
`with a sample volume from 5 to 50 microliters of sample.
`Prior to the end-point test, a rate test was conducted
`whereby reflectance was measured by the meter at
`time
`equal to forty-five (45) seconds. The rate test, however, does
`not provide predictable reliability. The end-point test takes
`reflectance readings at five (5) second increments until
`successive readings differ by less than five percent (5%).
`This ensures that the measurement is taken after the reaction
`has substantially stopped. Since successive measurements
`are taken until the “end-point” of the reaction, the blood
`sample may be applied to the strip 10 outside the meter.
`The color obtained at the reaction viewing port 18 of the
`reaction membrane correlates to the amount of glucose in
`the original sample. The reading can be done by a visual
`comparison to a color chart of varied and defined color
`intensities at various concentrations of glucose. It is pre-
`ferred that a reflectance meter be used to make a reflectance
`reading of the reacted color. The meter performs a computer
`analysis by comparing the reflectance reading to standard
`reflectances obtained on known concentrations of glucose in
`reaction with the membrane reactants.
`The instant invention has been shown and described
`herein in what is considered to be the most practical and
`preferred embodiment. It is recognized, however, that depar-
`tures may be made therefrom within the scope of the
`invention and that obvious modifications will occur to a
`person skilled in the art.
`What I claim is:
`
`1. A diagnostic sanitary test strip device for measuring an‘
`analyte of interest i