Abstract:
The present invention relates to diagnostic devices incorporating electrode modules and fluidics for performing chemical analyses. The invented devices consist of a sensor array formed on an electrode module, the sensor array being contained within a fluidic housing. The electrode module is a laminate of a perforated epoxy foil and a photo-formed metal foil with sensor membranes deposited into the perforations. The fluidic housing is an element consisting of a plastic card-like body with fluidic conduits and a sealed fluid reservoir contained in a foil-lined cavity.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation in part of patent application Ser. No. 10/307,481 filed Dec. 2, 2002 and entitled Heterogeneous Membrane Electrodes. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to unit-use diagnostic test cards comprising sensors and fluidics  
         BACKGROUND OF THE INVENTION  
         [0003]    Plastic cards in the general shape and size of credit cards, but with embedded integrated circuit chips are well known in the art. Such devices have appeared as articles of commerce in numerous applications where low cost electronic devices for personal use are required, such as bank cards, phone cards and the like. They are known as smart cards or IC cards. There was no teaching in the prior art concerning the use of card systems of this type that have been modified by removal of the integrated circuit chip and addition of fluidic and sensor elements for use in chemical analysis or in-vitro diagnostics, prior to the following published disclosures which are related to this invention.: Electrode Module U.S. patent Publ. No. US 2002/017944 A1, Point-of-Care In-Vitro Blood Analysis System U.S. patent Publ. No. US 2003/0148530 A1.  
           [0004]    In the co-pending and related patent application entitled Heterogeneous Membrane Electrodes, U.S. patent application Ser. No. 10/307,481 there is disclosed a diagnostic card containing a sensor array on an electrode module comprising a heterogeneous membrane reference electrode and electrochemical indicator electrodes, the disclosed electrode module being contained in a credit card sized fluidic housing. This present patent application now discloses additional inventive components and inventive elements of an electrode module and a diagnostic card incorporating fluidic elements.  
           [0005]    Diagnostic test cards and cartridges for chemical analysis are well known in the art. Diagnostic cards and cartridges incorporating sensors and fluidic elements are known in the art. Early examples are U.S. Pat. No. 4,301,412 that discloses a pair of electrodes in a plastic housing with an orifice for sample introduction and a capillary conduit for sample flow to the electrodes. Similar devices were also disclosed in the capillary flow technology described in U.S. Pat. No. 5,141,868. Diagnostic card devices with sensors and fluidics also incorporating on-board fluids contained in sealed housings within the cartridge were disclosed in U.S. Pat. Nos. 4,436,610 and 4,654,127. The &#39;127 device consisted of a plastic card-like housing with sensors and conduits with a sealed chamber containing a calibrating fluid mounted on the card. In use of this device the seal of the fluid-containing chamber was ruptured when the user manually turned a chamber element and subsequent fluid propulsion to the sensors on the card was by gravity. An improved diagnostic cartridge with sensors, fluid conduits and on-board fluid was disclosed in U.S. Pat. No. 5,096,669. This device consisted of a sensor array on a microfabricated silicon chip in a plastic housing with fluidic conduits, as well as a sealed pouch containing a calibrating fluid. The improvement was that the device was designed so that the fluid containing pouch could be ruptured and calibrating fluid moved to the sensors by the read-out instrument rather than manually. In the use of this device the sample is collected into the card away from the sensors, then subsequently moved to the sensor location by an instrument means. In both the &#39;127 and &#39;669 patents the fluid seal is made by a foil coated element and its rupture is by a piercing element that rips through the foil. U.S. Pat. No. 5,325,853 discloses a diagnostic device with sensors and fluidics with on-board fluid that is not sealed remotely from the sensors.  
           [0006]    Of the devices of the prior art only the &#39;669 device has proven commercially useful for the measurement of a broad range of analytes in parallel in sensor panels. The &#39;669 device incorporates many unique and proprietary designs and special purpose components. The manufacturing processes also are unique to their devices and specialized assembly equipment is required. The &#39;669 device and other prior art diagnostic devices generally require numerous process steps in electrode manufacture and numerous piece-parts and precision assembly steps in the card manufacture. Thus, this technology has proven expensive to manufacture, thereby limiting the broader utilization of the technology.  
           [0007]    There are also performance limitations of the &#39;669 technology. The fluid in the foil-lined and sealed reservoir has very limited shelf stability because the seal lengths are short. Furthermore, the reservoir is pressurized during fabrication and the sealed reservoir is ruptured during use by piercing the foil reservoir under applied pressure. Therefore the fluid in the reservoir is under pressure and, thus, has the potential to be evacuated from the reservoir in an explosive manner causing a potential for segmented fluid flow. Such problems can reduce the reliability of the &#39;669 device. The sample transfer into the sample collection area of the &#39;669 device is not done anaerobically. This may result in errors when measuring dissolved gases such as oxygen and carbon dioxide, particularly in samples which have low buffer capacity for those gases. Furthermore, there is no provision for reliable thermostating of the test fluid adjacent to the sensors.  
           [0008]    There is now a need to provide for simpler and more generic designs and manufacturing procedures for sensor arrays and fluidics in diagnostic-card devices.  
         SUMMARY OF THE INVENTION  
         [0009]    The current patent teaches designs and manufacturing processes to realize fluidic elements in diagnostic cards consisting of low cost components and manufacturing processes. This approach leads to significantly simpler devices than those of the prior art. There are fewer assembled parts, processes are generic and use generic equipment performing low tolerance assembly processes. The result is that devices according to this invention can be manufactured cost-effectively. Furthermore the diagnostic card of this patent incorporates many new inventive features which address performance limitations of prior art devices.  
           [0010]    The invention provides a diagnostic card for use with a card reader in sensing at least one component concentration of a fluid sample. The diagnostic card includes a card body, at least one component sensor located in a sensor region in the card body, a sealed chamber defined in the card body for containing a fluid, preferably remote from the sensor region, a fluid conduit for fluidically connecting the chamber with the sensor region, a valve for fluidically connecting the chamber to the fluid conduit, and a delivery structure separate and distinct from the valve for forcing fluid from the chamber and into the fluid conduit, when the chamber contains fluid and is fluidically connected to the fluid conduit. In a preferred embodiment, the chamber is a hermetically sealed fluid reservoir, preferably in the form of an aluminum foil-lined cavity. The chamber is preferably filled without pressurization so that the contents of the sealed chamber are not under pressure when the chamber is connected to the fluid conduit by the valve. Furthermore, the valve preferably fluidically connects the chamber to the fluid conduit without simultaneous pressurization of the fluid in the chamber. The valve preferably includes a valve body for rupturing a chamber wall from within the chamber. The valve preferably includes a valve body displaceably received in a valve seat in the card body, the valve body being within the chamber, the valve body and valve seat being shaped and constructed for pinching and rupturing a wall of the chamber upon displacement of the valve body relative to the valve seat. The valve body is preferably a rupture plug and the valve seat is preferably a plug receiving bore in the card body, with the plug and plug receiving bore having cooperating edges for rupturing the chamber wall upon displacement of the plug in the plug receiving bore.  
           [0011]    The invention further provides a sensor array on an electrode module incorporated into a credit-card sized plastic card body. The electrode module preferably includes a thin slab that is a laminate of an epoxy foil with a gold coated copper foil. The upper surface of the module is the epoxy foil which is perforated with holes. The lower surface of the module includes the gold coated copper foil which has been formed into an array of at least two electrodes. Each electrode of the array includes a formed element in the shape of a strip which constitutes an elongated electrical path connecting a contact end or contact pad at one end for connection to an external electrical circuit in a card reader, and a sensor end or sensor region under a hole through the epoxy at its other end. The module preferably comprises an array of such strip electrodes, each having a conductor path, a contact end and a sensor end, each sensor end of the array being located at a different hole in the epoxy foil. A sensor is formed on an electrode of the array when a sensor membrane or membranes are deposited into a hole in the epoxy on the top surface of the module, thus contacting the sensor region of the metal electrode on the bottom surface. In a preferred embodiment, a sensor array is made by depositing a different sensing membrane into each hole of each electrode sensing region of the electrode array.  
           [0012]    The module is sealed to the plastic card body so that its upper epoxy surface including the sensor membranes face a fluidic conduit within the card body and the lower metalized surface faces outward and is exposed for external access to the contact pads. The array of holes with sensor membranes, referred to herein as the sensor region, is preferably a substantially linear region exteding along the center of the module, which region aligns to a substantially linear fluidic conduit in the plastic card body so that fluid flowing through the fluidic conduit during use of the device contacts the sensor membranes of the array in the sensor region. The portion of the module&#39;s epoxy surface not located in the sensor region is sealed off by adhesive between the plastic card body and the module so that fluids are retained within the conduit at the sensor region and do not escape to or around the edge of the module.  
           [0013]    In a preferred embodiment, the metal layer of the electrode module further includes a metal heater element in a heating region on its lower surface that is electrically isolated from the sensor electrodes and intended for contact with a first heater block contained in a card reader. The module&#39;s metal heater element is a formed element in the shape of a split ring which substantially surrounds the sensor region of the sensor array. The ring is split at one, two or more locations, that is to say the metal heater element preferably comprises of two or more shaped metal elements which together form the split ring surrounding the sensor region of the module. Each split represents a connecting gap connecting the sensing and contacting regions of the module. Each electrode of the electrode array now has the conductor path which connects the sensor end of the electrode to the contact end passing through a connecting gap so that the electrodes of the array are electrically isolated from the metal of the heater element. The conductor paths of the electrode array are preferably formed so that they are especially long and thin so that heat transport from the sensor region to the contact region is minimized. In one embodiment, a separate connecting gap is provided for each conductor path. In another preferred embodiment, the contact ends and connecting gaps are distributed about the sensing region so that all conductor paths are of equal length.  
           [0014]    During use, a diagnostic card in accordance with the invention is inserted into the card orifice of a read-out instrument. The card&#39;s electrode module makes electrical contact at each of the contact pads of the electrode array to a z-action connector contained within the card reader. The card&#39;s electrode module also makes contact at its metal heater region to a first heater block also contained within the card reader. The first heater block is coplanar with the card&#39;s module surface and proximal to it when the card is in the card-reader&#39;s card insertion orifice. The first heater block makes physical contact to the metal heater region of the module, but also extends to cover the entire sensor region and a substantial region of the electrical paths, in close proximity but not in physical contact. This allows efficient heat transfer to the paths, but maintains electrical isolation from them. Thus, the first heater block heats the sensing region of the module and the fluid in the card&#39;s fluidic conduit above the sensing region by direct thermal conduction from the block to the module&#39;s metal heater region, as well as indirectly through an air gap at the sensor region and thence to the sensors and fluids, and indirectly through a thin air gap to the electrical paths of the electrode array. This configuration accomplishes thermal bootstrapping of the electrode paths, which further minimizes the heat transport from the sensor region to ambient along the paths. This configuration thus provides for more uniform temperature control of the sensor region. A second heater block of the card reader is coplanar with the card&#39;s upper surface and proximal to it when the card is in the card-reader&#39;s card insertion orifice. The second heater block makes physical contact to the card&#39;s upper plastic surface. The second heater block covers the sensor area of the card but extends a distance along the direction of the fluidic channel in both directions away from the sensor area. This provides heat to the fluid in the fluidic conduit in the regions immediately upstream of the sensor area and immediately downstream. This minimizes heat flow from the sensor region along the fluidic conduit by effectively thermally bootstrapping the fluid in the conduit. Thus the card&#39;s entire sensor area, the fluidic conduit proximal to the sensor area, the sensors&#39;electrical paths and the fluid in the conduit upstream and downstream of the sensor area are all contained within a thermostatted cavity comprising heater blocks above and below. This arrangement allows rapid heating of a cold sample fluid to its control temperature, and also accomplishes very precise thermostatting to the control temperature.  
           [0015]    In another aspect of the diagnostic card of this invention there is provided a connector means in the read-out device for connection to the card&#39;s electrode module. The connector means is a z-action connector comprising an array of contact elements, being formed metal films on a flex substrate, which flex-substrate is placed on a flexible cantilever, preferably a plastic cantilever. The cantilever is positioned so that when the card is inserted into the card reader&#39;s card insertion orifice the module&#39;s outer surface with its contact pad array is proximal to the contact elements of the flex substrate and the cantilever is depressed so as to apply z-action force between the connector array on the flex substrate and the contact pad array on the module. Because the electrical contacting elements are thin metal films on a flex substrate, the invented flex connector drains far less heat than conventional z-action connector pins used to contact smart cards of the known art. Additionally, the flex substrate and its connector array can also incorporate electronic components of card reader&#39;s electrical circuitry, resulting in a cost reduction of the card reader.  
           [0016]    In still another aspect of the diagnostic card of the invention there is provided an improved design for the sealed calibrator reservoir. In the previously disclosed card of co-pending U.S. patent application Ser. No. 10/307,481 the calibrator reservoir comprised a cavity in the card&#39;s plastic body, which after filling with calibrator fluid was sealed by an overlayer of a metal coated foil element. We have found improved lifetime of the sealed calibrator when the cavity in the plastic card body is clad on both sides with an aluminum foil lamination. The new design comprises a diagnostic card with a sensor array on an electrode module, and a sealed calibrator fluid reservoir, which when the seal is ruptured during the use of the device, becomes fluidically connected to the module&#39;s sensor region. The reservoir comprises a cavity in the card body, a first plastic-film-coated aluminum foil deformed into the cavity so that the foil contacts the plastic surface of the cavity with its aluminum surface facing the plastic of the cavity and the foil extends beyond the perimeter of the cavity, a calibrator fluid in the cavity, and a second plastic-coated aluminum foil element overlaying the first with its plastic surface facing the plastic surface of the first foil element, and a fused plastic-to-plastic seal between the two foil elements which hermetically seals the calibrator fluid, the seal being formed in the region around the perimeter of the cavity. For good room temperature stability of the calibrator fluid in the sealed reservoir, we have preferred that the width of the perimeter seal be at least 3 mm along the entire perimeter, thus providing a long leakage path for material to escape through the fused plastic seam joining the first and second metallized cladding layers.  
           [0017]    In another aspect of the improved calibrator fluid reservoir, there is provided an improved rupture means for automatically rupturing the foil seal upon use of the device, so as to enable the subsequent delivery of calibrator fluid to the measurement cell which is the fluidic cavity above the sensor region of the card&#39;s electrode module. In this improved rupture means there is a plug sealed between the metal foil cladding elements of the calibrator chamber. This plug is caused to move when the card is inserted into the card reader&#39;s card insertion orifice which movement causes rupture of the metal foil cladding. A conduit fluidically connects the calibrator reservoir at its point of rupture to the measurement cell, enabling displacement of calibrator fluid to the measurement cell after rupture of the seal.  
           [0018]    In another aspect of the diagnostic card of the invention there is provided an improved design for the sample entry port. An adhesive gasket around the sample entry hole in the card&#39;s housing permits a reliable fluid- tight seal between a syringe containing sample fluid and the card. A reliable seal results with little skill required by the operator to engage the syringe to the card.  
           [0019]    All inventive aspects of the diagnostic card of the invention are preferably accomplished in a substantially flat credit-card sized form. Being flat enables efficient stacking of the cards during their storage, as well as enabling a simple engagement to two coplanar clamping elements in the card reader&#39;s card insertion orifice.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    Preferred embodiments of the invention will now be described in more detail by way of example only and with reference to the attached drawings, wherein  
         [0021]    [0021]FIG. 1A is a side view schematic of one preferred embodiment of an electrode module and sensor membranes in accordance with the invention;  
         [0022]    [0022]FIG. 1B is a bottom view schematic of another preferred embodiment of an electrode module in accordance with the invention and showing the positioning of the metal foil elements;  
         [0023]    [0023]FIG. 1C is a top view schematic of an electrode module showing the sensor region, the heater region and the contact region of the embodiment of FIG. 1B;  
         [0024]    [0024]FIG. 2A is a top view schematic of one preferred embodiment of a diagnostic card in accordance with the invention including an electrode module and a sealed calibrator fluid chamber with fluidic connections;  
         [0025]    [0025]FIG. 2B is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path BA′ shown in FIG. 2A;  
         [0026]    [0026]FIG. 2C is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the card insertion orifice of the card reader;  
         [0027]    [0027]FIG. 2D is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the partially clamped card insertion orifice of the card reader;  
         [0028]    [0028]FIG. 2E is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the fully clamped card insertion orifice of the card reader;  
         [0029]    [0029]FIG. 3A is a side view schematic of the electrode module embodiment of FIG. 2A embedded in the body of the card of FIG. 2A shown in cross-section taken along line M′ of the electrode module of FIG. 1C, and the position of the card reader&#39;s heater blocks;  
         [0030]    [0030]FIG. 3B is a side view schematic of the electrode module embodiment of FIG. 2A embedded in the body of the card of FIG. 2A shown in cross-section taken along BB′ of the electrode module of FIG. 1C, and the position of the card reader&#39;s heater blocks;  
         [0031]    [0031]FIG. 4A is a top view schematic of the calibrator fluid chamber and valve of the card embodiment of FIG. 2A;  
         [0032]    [0032]FIG. 4B is a side view schematic of the calibrator fluid chamber (before fluid fill) of the card embodiment of FIG. 2A shown in cross-section taken along AA′ shown in FIG. 4A;  
         [0033]    [0033]FIG. 4C is a side view schematic of the calibrator fluid chamber (after fluid fill and seal) of the card embodiment of FIG. 2A shown in cross-section taken along M′ shown in FIG. 4A; and  
         [0034]    [0034]FIG. 4D is a side view schematic of the calibrator fluid chamber (after fluid fill and seal) of the card embodiment of FIG. 2A shown in cross-section taken along BB′ shown in FIG. 4A. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    We describe herein in more detail a preferred embodiment of a diagnostic card in accordance with the invention, formatted for use with a sensor array on an electrode module.  
         [0036]    [0036]FIG. 1A shows a cross-sectional view of an electrode module, fabricated using standard smart-card chip-module technology known in the art. The electrode module is described in detail in U.S. patent Publ. No. US 2002/017944 A1, which is incorporated herein by reference. We now disclose new inventive features of the module and its use as part of the diagnostic card and card reader.  
         [0037]    The module  101  of FIG. 1A comprises an epoxy foil element  102  laminated to a gold coated copper metal foil  103  with optional adhesive  102 A. The epoxy foil element  102  has through-going holes at  104 A and  104 B. The metal foil  103  is formed into an array of electrode elements  130 . The construction of the electrode elements will be discussed in the following by way of a pair of electrode elements  130 A and  130 B. Each electrode element  130 A and  130 B has a connection end  131 A,  131 B for connection to a measuring circuit in a card reader (not shown) and a sensor end  132 A and  132 B under the through-going holes in the epoxy  104 A and  104 B. The electrode module is received from the vendor on a  35  mm web. During manufacture, membranes  105 A and  105 B are applied to the module on the web extending laterally beyond the perimeter of the holes  104 A,  104 B and overlaying the top epoxy surface, and extending through the holes to contact the metal electrodes at the sensor ends  132 A and  132 B. After printing of the membranes, the module is excised from the web using a die cutter, then placed and sealed into a housing in the diagnostic card as described later. In the preferred embodiment, the excised module of the FIG. 1 design is about 11 mm square by  120  micrometers thickness.  
         [0038]    [0038]FIG. 1B shows a bottom view (metal foil side) of a module with eight electrode elements, comprising the laminated epoxy foil  102  and metal foil  103 . This figure shows in more detail the spatial arrangement of the metal electrode elements. As in FIG. 1A, two electrodes  130 A,  130 B, representative of the eight, are labeled to show the relationship between their sensor ends  132 A and  132 B and their connection ends  131 A and  131 B. There is a metal conductor path  133 A,  133 B between each electrode&#39;s sensor end  132  and its connection end  131 , the path  133 A extending between connector end  131 A and sensor end  132 A and the conductor path  133 B extending between the connector end  131 B and sensor end  132 B. The metal conductor paths  133  are generally long and thin to minimize lateral heat transport along them when the module is being heated. Heater contacts  134 A,  134 B of the metal foil  103  are electrically isolated from the eight electrode elements. These regions are for physical contacting by a heater block of the card reader, as described in more detail later.  
         [0039]    [0039]FIG. 1C shows the module of FIG. 1B in top view (epoxy foil side). The position of the electrodes on the underside of the module is shown in the narrow dashed line. The electrodes are not labeled for reasons of clarity. Also shown is the position of the through-going holes  104  in the epoxy relative to the underside metal electrodes. As shown diagrammatically, the layout of the module comprises three distinct regions. The central region of the module is the sensor region  12 . This region of the module is proximal to a fluidic conduit in the card when the module is assembled into the diagnostic card, as described later. The region proximal to the location of the lower heater block of the card reader when the card is in the card reader&#39;s card insertion orifice is the heater contact region  13 . More details of the relationship of the heater blocks of the card reader to the module in the card are given later. The region on the periphery of the module where electrical contact is made by the card reader to the metal electrodes on the underside of the module is the contact region  14 . Those skilled in the art will appreciate that the same standard module fabrication technology can be used to make modules with many different electrode numbers and geometries. They differ only in the tooling to provide different locations of the through-going holes  104  (see FIGS. 1A and 1B), and the mask art-work used to photolithographically define different spatial arrangements of the formed metal elements  103 . The general arrangement of any module according to this invention will include a sensor region  12  approximately centrally located, a heater contact region  13  at least partially adjacent the sensor region, and an electrical contact region  14  toward the module&#39;s periphery.  
         [0040]    [0040]FIG. 2A shows a top plan view and FIGS.  2 B-E show cross-sectional schematic views of a preferred embodiment of a diagnostic card in accordance with the invention, including a sensor array on an electrode module, including the card&#39;s relationship to elements of the card reader&#39;s card insertion orifice when the card is in the card insertion orifice during the use of the card. FIG. 2B shows one cross-sectional schematic taken along the fluidic path AA′ of FIG. 2A, the fluidic path extending from a calibrator fluid chamber  220  along a fluidic channel  210 , through the measurement cell  211  to a waste channel  241 . FIGS.  2 C-E show schematics along the fluidic path BA′ of FIG. 2A, being along a fluidic path from the sample entry port  251  through the measurement cell  211  to the waste channel  241 .  
         [0041]    Referring to FIGS. 2A and 2B, the diagnostic card in the preferred embodiment is formed from a credit-card sized (85 mm ×53 mm ×1 mm thick) molded plastic card body  200  with an electrode module  101  as generally described above with reference to FIGS. 1A-1C embedded in the lower surface of the card body. The electrode module comprises an epoxy foil element  102  with die-cut through-going passages, the epoxy element being laminated with a metal foil that has been formed into eight electrode elements. Two electrode elements  130 A,  130 B are shown in FIG. 2B which have a sensor end  132 A and  132 B respectively and a contact end  131 A,  131 B respectively as are shown in the side-view schematic diagram. Membranes  207  and  208  are shown on the top surface of the module and contacting underside metal elements at the sensor ends  132 A and  132 B through the passages in the epoxy. The card body  200  also contains molded features (grooves, trenches and holes) on both its upper (solid lines in the top view schematic) and lower (dotted lines in the top view schematic) surfaces which molded features, when sealed by other laminating elements, form fluidic channels and a sealed fluid reservoir. Laminations are made to the lower and upper surface of the housing by label elements  201  and  202  and by metal foil elements  223 A and  223 B. Elements  201 ,  202  on the lower and upper surfaces of the card are label elements die-cut from an adhesive coated polymer sheet. Elements  223 A and  223 B are a lamination of two elements which are die-cut from a sheet of metal foil coated with polyethylene for heat sealing.  
         [0042]    There are two trenches side by side on the lower surface of the plastic body. When clad by laminating elements  223 A and  223 B they form a reservoir chamber  220  with a volume of about 150 microliters. There is an orifice  221 A through the plastic body  200  through which a calibrator fluid  224  is injected from the upper surface of the body to fill the chamber  220  during card manufacture, with another orifice  222 , also through the body  200 , for venting of air during the filling process. The chamber walls are defined by a pair of opposite foil elements  223 A and  223 B made of a plastic coated meal foil. The chamber  220 , after filling with fluid, is completely sealed when the orifices  221  and  222  are closed-off during the lamination of foil elements  223 A and  223 B as is described in more detail later with reference to FIGS.  4 B-D.  
         [0043]    There is a fluidic channel  210  connecting the calibrator fluid chamber  220  to the measurement cell  211  at the electrode module&#39;s sensor region, and then to a waste channel  241 . The diagnostic card also includes a sample inlet port  251  which is in fluid communication with a second channel  250  connecting the sample inlet port  251  to the measurement cell  211 . There is a chamber outlet valve  230  for fluidically connecting the calibrator fluid chamber  220  with the connecting channel  210  between the measurement cell  211  and the calibrator fluid chamber without pressurizing fluid contained within the chamber. This means the valve structure is operated/operable independent of any pressurization of fluid in the chamber. The valve is preferably a rupturing structure for rupturing the wall of the sealed chamber at the connection with the connecting conduit for fluidically connecting the chamber to the conduit. In this preferred embodiment, the chamber rupturing structure includes a bore  233  through the body  200  and a rupture element, in this case plug  234 , located in the bore and within the chamber  220  between the two metal foil elements  223 A and  223 B. The plug is slightly smaller in diameter than the bore, rendering it capable of axial movement therein, in this case upwards. The plug  234  is positioned so that a region of the metal foil element  223 A on the peripheral edge of the plug ( 295  of FIG. 2D) ruptures when the plug is pushed upwards. Any other structures useful for the controlled opening of the chamber  200  for connection with the channel  210  when the card is in the card reader can also be used to function as the valve  230 , as long as they do not lead to a pressurization of the chamber  220  during opening of the chamber. The diagnostic card further includes a delivery structure for forcing fluid from the chamber  220  under pressure, when the chamber contains fluid, and into the connecting conduit  210 . In the preferred embodiment, the delivery structure is a portion of the chamber walls which is sufficiently flexible to be deformed, preferably from the exterior of the card and while the card is inserted in the card reader. Of course, the delivery structure can also be any other structure usable for reliably forcing fluid from the chamber when the chamber is fluidically connected to the connecting conduit..  
         [0044]    FIGS.  2 C-E schematically show the card in the card orifice of a card reader (the card reader preferably including a circuit board with detectors, amplifiers and other circuit components, as described in co-pending U.S. patent Publn. No. 2003/0148530A1) and illustrate the spatial relationship between elements of the card and elements of the cardreader&#39;s orifice during use of the device. In use, the card is first inserted into a card reader&#39;s card insertion orifice (FIG. 2C). The orifice comprises a lower generally planar mating element  280  which is co-planar with and proximal to the card&#39;s lower surface, and an upper generally planar mating element  290  which is co-planar with and proximal to the card&#39;s upper surface.  
         [0045]    The card reader&#39;s card insertion orifice has a guide (not shown) to locate the features on the card with their respective mating features on the card reader insertion orifice&#39;s planar mating elements during card insertion. After insertion, the two mating elements of the card reader insertion orifice are moved toward each other, thus clamping the card between them. The construction and function of the card reader is described in detail in co-pending U.S. patent Publn. No. 2003/148530A1, incorporated herein by reference. As the lower surface of the card is brought into contact with the lower mating element  280  of the card reader&#39;s card orifice, a pin element  282  provided on the mating element  280  first contacts the card at the calibrator fluid chamber outlet valve  230 . The pin  282  pushes plug  234  upwards. This lifts the metal foil laminate above the plug causing foil  223 A to break at location  295  (FIG. 2D), thus fluidically opening the calibrator fluid chamber. At the same time, the electrode module is electrically contacted by a contacting means of the card reader which comprises a contacting array of eight metal contact elements formed in a metal film or foil  286  on an insulating flex connector substrate  287 . Two of the eight pins are shown in the side view schematics of FIG. 2C-E. Each has a contact end  283 A,  283 B for making z-action contact to the module&#39;s electrode contact locations  131 A,  131 B on the lower surface of the electrode module, and an end  284 A,  284 B for connection to an electrical circuit elsewhere in the card reader. The flex connector at its module contacting end is mounted on the movable end of a set of flexible cantilevers  285 A and  285 B, preferably made of plastic, whose other end is embedded in the lower mating element  280  of the card reader orifice The cantilevers, with the flex connector mounted on it, are in their at-rest position raised above the plane of the lower mating element  280  at the location of contact to the module, so that as the card is clamped to the lower mating element of the card reader orifice the cantilevers are depressed, thus providing z-action contact force to the electrical contacts made between the flex connector of the card reader and the electrode module of the card. At the same time the card&#39;s electrode module is thermally contacted by a lower heater block  289  and the top of the diagnostic card above the measurement chamber by an upper heater block  291 . The lower heater block  289 , which is mounted in the card reader orifice&#39;s lower mating element  280 , makes thermal contact with the module on its lower surface directly under the measurement chamber  211 , making physical contact to the module&#39;s ‘split ring’ heater contact metal elements  134 A,  134 B, while being in close proximity to the other metal elements elsewhere on the module, but electrically isolated from them. At the same time, the upper heater block  291 , which is mounted in the card reader orifice&#39;s upper mating element, makes thermal contact to the card directly above the measurement chamber  211 . Each heater block contains a heater element and a temperature measuring element each in intimate thermal contact with the block (not shown). The blocks&#39; heater elements and temperature measuring elements are also connected to the card reader&#39;s electrical circuit. The lower mating element  280  of the card reader also includes an actuator element  281  positioned to be opposite the calibrator fluid chamber  220  when the card is inserted into the card reader&#39;s card orifice. As the card continues to be clamped between the mating surfaces, the actuator element  281  now engages the delivery structure of the calibrator fluid chamber  220 , deforming the chamber wall  223  and compressing the chamber  220 , thereby pressurizing the chamber contents and causing delivery of fluid out of the chamber along fluidic channel  210  to measurement chamber  211  (FIG. 2E). When the card is fully clamped in the card reader orifice (FIG. 2E) there is a period of time during which the module, the sensors and the fluid in the measurement cell are heated, preferably to 37.4° C., followed by a period of time during which the module&#39;s sensors are calibrated. After this calibration period, the card-reader prompts the user to supply sample fluid to the diagnostic card. The user engages a syringe containing sample fluid to the card&#39;s sample entry port ( 251  of FIGS. 2A and 2B). The syringe tip forms a seal with an adhesive element  253  surrounding the entry port. The sample port  251  may optionally be reversibly sealed with a closure flap which can be part of the label  202 . The user delivers sample fluid from the syringe to the measurement cell  211  along channel  250 , thus displacing calibrator fluid out of chamber  211  to waste channel  241 . The module&#39;s sensors now generate sensor signals derived from the sample fluid, which electrical signals are extracted from the electrode module via the card reader&#39;s electrical flex connector  287  to an electrical circuit in the reader. After completion of the measurement cycle, the card is unclamped and withdrawn from the card reader&#39;s orifice.  
         [0046]    Referring again to FIG. 2, the card is assembled as follows in three principle steps. Step  1 : sealing the electrode module  100  to plastic card body  200 . Step  2 : forming the metal foil cladding around chamber  220  by laminating first lamination  223 A and second  223 B lamination of metal foil elements with insertion of the rupture plug  234  between these laminations; filling of the clad calibrator chamber  220  with calibrator fluid  224 ; then sealing calibrator fluid and plug into the clad chamber. Step  3 : laminate top  202  and bottom  201  labels. Steps  1  and  2  will now be described in more detail.  
         [0047]    [0047]FIG. 3A and B show in more detail the electrode module assembled into the plastic card body  200  in step  1  of the assembly process. Referring to FIG. 3A, the molded plastic card body  200 , as received from the vendor, is first laminated with the electrode module  100  whose epoxy foil upper surface  102  faces the card body and is recessed into it and sealed with adhesive  303 . The adhesive is applied to the outer area of the module&#39;s epoxy surface perimetric to the module&#39;s central sensor region. As shown in FIGS. 3A and 3B the adhesive is applied to the entire top epoxy surface, except the sensor region (region  12  shown in FIG. 1C). The module, when embedded in the card, is coplanar with the card body with the module&#39;s upper sensor surface proximal to the card body&#39;s fluid measurement cell  211  and the module&#39;s lower metal surface  103  facing the outside.  
         [0048]    [0048]FIGS. 3A and 3B also show in more detail the location of the card reader&#39;s heater blocks relative to the card and its electrode module when the card is clamped in the card reader&#39;s card insertion orifice. FIG. 3A shows a cross-section along AA′ of the electrode module shown in FIG. 1C, which is in the direction orthogonal to the card&#39;s fluidic channel over the electrode module. FIG. 3B shows a cross-section along BB′ of the electrode module shown in FIG. 1C, which is in the direction along the path of the card&#39;s fluidic channel over the electrode module. As shown in FIG. 3A, the lower heater block  289  physically contacts the electrode module at the locations  134 A and  134 B which are the electrode module&#39;s heater contact metal elements. The lower heater block  289  is in close proximity to (thus thermally connected with) but electrically isolated from, other metal elements of the electrode module  100 , including the sensor ends  132  and contact ends  131  of the electrodes and the metal paths  133  between them. The lower heater block  289  extends a distance beyond the width of the fluidic measurement chamber  211 . As shown in FIG. 3B the lower heater block is in close proximity to the metal paths  133  connecting the electrodes&#39; sensor ends  132  to their contact ends  131  but not in physical contact with them. The upper heater block  291  makes contact to the card&#39;s upper plastic label. It too extends beyond the width of the measurement chamber  211  (FIG. 3A), but also extends a distance along the fluidic channel beyond the electrode module on both sides (FIG. 3B). We have found that when the upper heater extends about 5 mm beyond the module there is satisfactory thermal bootstrapping of the fluid beyond the sensor region of the module, thus assuring excellent thermal control of the temperature of the sensor region.  
         [0049]    We have found that when the card is fully clamped in the card reader&#39;s orifice, at which time the lower heater block  289  contacts the electrode module&#39;s heater contacts  134 , the regions of the heater block not in contact with, but in proximity to the module, should be spaced about 25 micrometers from the module&#39;s metal surface: At this distance there is still satisfactory heat transfer from heater block to module, but there is also reliable electrical isolation during repeated use of the card reader. In general, the rate of heat transfer from the heater block to the module increases with decreasing spacing. The preferred range of spacing is 10 to 50 micrometers. However, the person skilled in the art will appreciate that a spacing below 10 micrometers may be usable as long as reliable electrical insulation of the heater block from the sensing and contacting regions of the module is ensured. A spacing above 50 micrometers is usable, but the heat transfer rate will be low.  
         [0050]    [0050]FIG. 4 shows in more detail the metal foil clad calibrator fluid chamber  220  and the foil rupturing plug, and its forming, filling and sealing processes which together are step  2  of the card assembly procedure. Referring to FIG. 4A which is a top view schematic of the card&#39;s calibrator fluid reservoir region and FIG. 4B which is a cross-section through the embodiment of FIG. 4A taken along line M′, being along the fluidic path from the calibrator fluid fill hole  221  along the calibrator fluid reservoir  220 , its connecting channel  405  to the vent hole  222 . The card body  200  in the calibrator fluid reservoir region of the card features a molded calibrator fluid reservoir cavity  401  (shown here as two parallel cavities fluidically connected), a molded trench  405  connecting the cavity  401  to a rupture-plug bore  233  and a second trench  210  connecting the rupture-plug bore to the measurement cell  211  (see FIG. 2A). A first metal foil element  223 A has a pressure sensitive adhesive on one side of the metal and approximately 25 micrometers thickness polyethylene coating on the other. The element  223 A, which is die cut from a sheet and placed with its adhesive side down onto the card body, extends over the calibrator fluid reservoir cavity  401 , the connecting channel  405  and the rupture-plug bore  233 , overlaying all these features and extending to a perimeter beyond them. When high air pressure is applied to the foil element  223 A it deforms taking the contour of the card body&#39;s reservoir cavity  401 , connecting channel  405  and rupture-plug hole  233 , being then attached to the body&#39;s surface by the pressure sensitive adhesive. The polyethylene coated surface of foil element  223 A faces the inside of the reservoir cavity. The foil deforming procedure is similar to the blow-molding process well known in the art. In manufacture, a tool with an air pressurizable cavity is engaged to the foil on the card body and sealed to it about the cavity, preferably by an elastomeric gasket. When high pressure air is introduced into the tool&#39;s cavity, the air blow-deforms the metal foil to take the contour of the card body. It will be readily apparent to the person skilled in the art that other methods of shaping the foil element  223 A to take on the contour of the card body may also be used, such as hydroforming. A rupture-plug element  234 , which is a rigid disc approximately the same thickness as the card body with a diameter somewhat smaller than the diameter of the rupture-plug bore  233 , is placed onto the foil element  223 A in the depression in the foil formed over the rupture-plug bore  233 . The foil element  223 A is pierced at the bottom of fluid fill hole  221  and vent hole  222 . A second polyethylene coated metal foil element  223 B is laminated over the first foil element  223 A with its polyethylene coating facing the polyethylene coating of element  223 A. A heat seal is made between foil elements  223 A and  223 B, by fusing the two polyethylene coating layers, everywhere except in the fill and vent regions  415  and  416  adjacent the fluid fill and vent holes  221  and  222  respectively. At this stage, the foil clad calibrator fluid reservoir is sealed except for the fill and vent holes  221 ,  222  as shown in FIG. 4B and is now ready to receive fluid. Calibrator fluid  224  is introduced through fill hole  221  into chamber  220  filling it and partially filling the channel  405  while expelling air from the chamber through vent hole  222 . In the final step, once the chamber  220  is filled, the fill and vent regions  415  and  416  near the fill and vent holes  221 ,  222  are then sealed in a secondary heat seal process, thus entirely sealing the calibrator fluid and rupture plug within the two foil elements as shown in FIGS. 4C and 4D. Lamination of the card body  200  with an upper pressure sensitive adhesive coated label element  202  now forms a channel  210  which fluidically connects the region  450  of the calibrator chamber where the rupture of the foil takes place (FIG. 4D) with the measurement cell  211  (see FIG. 2A). A second lower label lamination  201  which leaves the lower surface of the electrode module  100  exposed completes the card assembly.  
         [0051]    Using the above recited fluid chamber design and manufacturing procedure we have achieved a remarkably long period of calibrator fluid storage stability. The mean time to failure of a sealed fluid used for sensor calibration is the time for the carbon dioxide partial pressure to drop from its initial value in the fluid to an unacceptably low level as the gas permeates out through the heat fused polyethylene seam. We have found that we can achieve greater than 6 months room temperature storage stability in which time the partial pressure of carbon dioxide changes from it&#39;s average value by less than 0.5 mm Hg. To achieve this we have designed the perimeter seal width to be greater than 3 mm width at all locations along the perimeter. This high level of stability is in marked contrast to other devices of the known art, which must be stored in the refrigerator to achieve extended lifetime. Using the above recited fluid chamber design with incorporated rupture plug we have achieved a simple foil rupturing method which opens the foil-sealed chamber during the use of the device, but before the calibrator fluid in the chamber is pressurized to expel it from the chamber and to the measurement cell. This achieves a high level of reliability and control in the calibrator fluid delivery step of the device&#39;s operation.  
         [0052]    Those skilled in the art will recognize that the various inventive elements of the diagnostic card can be used together as they are in the card of this disclosure, or they can be used separately in different card designs. For example, the sealed fluid chamber and its valve structure means can be incorporated into diagnostic cards comprising micro-porous fluidic elements such as those as disclosed in U.S. patent application Ser. No. 10/649,683. In this case the sealed fluid is used for priming the micro-porous pump elements rather than for sensor calibration purposes. The inventive fluidic arrangements and sealed fluid chamber can be advantageously used with electrode modules comprising foil laminates as described in this disclosure, but they can also be used with sensor modules of other kinds, including the many types of sensor modules of the known art which are fabricated on a planar insulating substrates (microfabricated chips, planar circuit boards and the like) and including sensor modules incorporating non-electrochemical sensing means such as optical, chemiluminescence or fluorescence, as are known in the art. Indeed, these inventive fluidic components will be useful in any unit-use diagnostic card incorporating an on-board fluid.