Sensor assembly having wicking member for wetting up liquid junction - Patent application

Abstract

A sensor assembly for a body fluid analyzer includes a reference electrode reservoir containing a reference electrode; a membrane capable of or configured to be in fluid communication with the reference electrode reservoir; and a wicking member capable of or configured to be in fluid communication with the reference electrode reservoir, the wicking member configured to draw a reference fluid contained in the reference electrode reservoir toward the membrane when the membrane and the wicking member are exposed to the reference fluid.

Description

[Technical field]

[0001] CROSS REFERENCE TO RELATED APPLICATIONS / INCORPORATION-BY-REFERENCE STATEMENT The subject application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 265,740, filed December 20, 2021. The entire contents of the above-referenced patent applications are expressly incorporated herein by reference. [Background technology]

[0002] Modern hematology analyzers are designed to be used to measure small amounts of a patient's blood. To do so, the analyzer transports the blood from a sampling device to a sensor and ultimately to a waste container. However, the sensors used in conventional hematology analyzers are susceptible to measurement errors due to the presence or formation of air bubbles near the sensor.

[0003] The sensors used for these measurements are ion-specific or ion-selective electrodes (ISEs). These sensors are membrane-type electrochemical transducers that respond to specific ions. Biosensors are used in point-of-care testing devices as well as in traditional clinical laboratory analyzers. Biosensors convert biochemical signals into electrical signals.

[0004] Electrolytes are determined by potentiometry, a form of electrochemical analysis. Potentiometry involves measuring the potential or voltage between two electrodes in a solution. These potentials also arise when a metal and ions of that metal are present in a solution. Different concentrations of ions can be separated by using a membrane that is semi-permeable to the ions. These systems use a reference electrode and a measuring electrode. A constant voltage is applied to the reference electrode; the difference in voltage between the reference and measuring electrodes is used to calculate the concentration of the ion in the solution.

[0005] A typical device for measuring the ion content in a solution includes a reference electrode and another potentiometric or "working" electrode. When immersed in a volume of the solution to be analyzed (i.e., the test solution), the reference electrode and working electrode together constitute an electrochemical cell. The reference electrode provides a constant potential relative to the potential that the working electrode detects from the test solution. The potential difference (i.e., voltage) across the cell (i.e., the potential difference between the working and reference electrodes) is proportional to the activity of the ion in the test solution. This potential difference is in turn related to the concentration of the ion in the test solution, so the concentration can be determined directly as a function of the voltage measured between the reference and working electrodes.

[0006] The electrolyte is confined in an electrolyte reservoir behind a membrane that allows ion transport while restricting the flow of the solution to be analyzed and the electrolyte itself. The electrolyte thus contacts the test solution at a flow-restricting junction, which allows the flow of ions by diffusion but not by convection. The membrane defines the area of ​​the flow-restricting junction. Prior art reference electrodes are typically silver chloride coated silver wires immersed in an electrolyte solution of concentrated potassium chloride (or some equivalent formulation) contained in the electrolyte reservoir. The reference electrode and electrolyte solution are thus contained in the electrolyte reservoir.

[0007] In a typical operating arrangement, the working and reference electrodes are sequentially exposed to a test solution (e.g., a blood sample) and a calibration solution (the calibration solution may follow or precede the blood sample). The calibration solution contains known concentrations of the ions to be measured. By comparison of the potential difference between the reference and working electrodes in response to the sample and reagents, a precisely calibrated value for the ion concentration in the blood sample is determined.

[0008] To prevent salt crystallization and precipitation at the membrane during storage and shipping of the sensor assembly, a plug, cap, or film is employed to keep the membrane sealed from the electrolyte during storage. When ready for use, the electrolyte reservoir can be "wetted up" to perform its operational function by moving the plug to expose the membrane to an electrolyte solution (e.g., a salt solution). However, air bubbles can form between the electrolyte solution and the membrane, thereby preventing the membrane from "wetting up". Furthermore, after the membrane is "wetted up", air bubbles can form on the membrane during use, resulting in undesirable changes or losses in coupling with the reference solution, adversely affecting the flow of ions across the membrane, and therefore resulting in measurement errors. Air bubbles attached at or near the membrane can prevent the electrolyte solution from properly contacting or completely covering the membrane, thereby adversely affecting the maintenance and / or creation of a proper liquid junction in the membrane area, resulting in higher resistance and higher (error) voltage readings. Thus, air bubbles formed at or near the membrane during "wet-up" have adverse consequences for the measurement errors of the sensor assembly. Summary of the Invention [Means for solving the problem]

[0009] To this end, there is a need for a sensor assembly having a reference electrode structure that can be shipped dry, thus providing a long shelf life, but that can be "wetted up" for use without forming air bubbles. In particular, there is a need for a sensor assembly that avoids and / or reduces air bubbles in the region of the sensor membrane, and thus improves the maintenance and / or creation of a liquid junction across the membrane region that eliminates and / or reduces measurement errors. The inventive concepts disclosed herein relate to such sensor assemblies.

[0010] To assist those skilled in the relevant art in making and using the inventive concepts disclosed herein, reference is made to the accompanying drawings and illustrations, which are not intended to be drawn to scale, and for the sake of consistency, the same reference numerals are intended to refer to the same or similar elements. For the sake of clarity, not every component is labeled in every drawing. Certain configurations and certain perspectives of the drawings are shown exaggerated, not to scale, or schematic, for the sake of clarity and conciseness. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view of a blood analyzer having a sensor assembly constructed in accordance with the inventive concepts disclosed herein. [Diagram 2] 2 is an exploded perspective view of the blood analyzer of FIG. 1 showing the sensor assembly removed from the blood analyzer. [Diagram 3] FIG. 2 is a top perspective view of the sensor assembly. [Figure 4] FIG. 4 is a bottom perspective view of the sensor assembly of FIG. 3. [Diagram 5] FIG. 4 is a bottom plan view of the sensor assembly of FIG. 3. [Figure 6] FIG. 2 is a top perspective view of a base of a housing of the sensor assembly. [Figure 7] FIG. 7 is a bottom plan view of the base of FIG. 6 with a pair of covers removed for clarity. [Figure 8] FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 6. [Figure 9] 9 is a cross-sectional view of the base taken along line 9-9 of FIG. 6. [Figure 10] FIG. 2 is an exploded perspective view of the sensor assembly. [Figure 11] FIG. 2 is a partial perspective view of the sensor assembly with the cover removed to reveal a pair of sensor arrays. [Figure 12] 12 is a cross-sectional view taken along line 12-12 of FIG. 3, showing the reference electrode receiving space. [Figure 13A]13A is a cross-sectional view taken along line 13A-13A of FIG. 3, showing the encapsulant in a closed position. [Figure 13B] FIG. 13B is a cross-sectional view showing the encapsulant of FIG. 13A in an open position. [Figure 14A] FIG. 13 is a cross-sectional view of another embodiment of the seal showing the seal in a closed position. [Figure 14B] FIG. 14B is a cross-sectional view showing the encapsulant of FIG. 14A in an open position. [Figure 15A] FIG. 13 is a cross-sectional view of another embodiment of another reference electrode-containing space, sealant, wicking member, and membrane assembly constructed in accordance with the present disclosure. [Figure 15B] FIG. 13 is a cross-sectional view of yet another embodiment of another reference electrode-containing space, sealant, wicking member, and membrane assembly constructed in accordance with the present disclosure. [Figure 15C] FIG. 13 is a cross-sectional view of yet another embodiment of another reference electrode-containing space, sealant, wicking member, and membrane assembly constructed in accordance with the present disclosure. [Figure 15D] FIG. 13 is a cross-sectional view of yet another embodiment of another reference electrode-containing space, sealant, wicking member, and membrane assembly constructed in accordance with the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Before describing at least one embodiment of the inventive concept in detail with illustrative figures, experiments, results, and laboratory procedures, it is to be understood that the inventive concept is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the figures, experiments, and / or results. The inventive concept is capable of other embodiments or of being practiced or carried out in various ways. The words used herein are intended to be given the broadest possible scope and meaning; the embodiments are intended to be illustrative but not exhaustive. It is also to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0013] Unless otherwise defined, scientific and technical terms used in connection with the presently disclosed and claimed inventive concepts shall have the meanings commonly understood by those skilled in the art. Furthermore, unless otherwise required by context, singular terms shall include the plural and plural terms shall include the singular. The techniques and procedures described above are generally carried out according to conventional methods well known in the art and described in various general and more specific references cited and discussed throughout this specification. The nomenclature utilized in connection with analytical chemistry, organic synthetic chemistry, and medicinal chemistry, as well as the laboratory procedures and techniques thereof, described herein are those well known and commonly used in the art. Standard techniques are used for chemical synthesis and chemical analysis.

[0014] All of the articles, compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. Although the articles, compositions and methods of the inventive concept have been described in terms of specific embodiments, it will be apparent to one skilled in the art that modifications can be made to the articles, compositions and / or methods, and to the steps or sequence of steps of the methods described herein, without departing from the concept, spirit and scope of the inventive concept. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the inventive concept as defined by the appended claims.

[0015] As utilized in the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings:

[0016] When used in conjunction with the term "comprising" in the claims and / or specification, the use of the words "a" or "an" can mean "one," but is also consistent with the meanings of "one or more," "at least one," and "one or more."

[0017] Use of the term "or" in the claims is used to mean "and / or," unless expressly indicated to refer to alternatives only or the alternatives are not mutually exclusive, however, the present disclosure supports a definition that refers to alternatives only and "and / or."

[0018] Throughout this application, the term "about" is used to indicate that a value includes the inherent variation of error for the device, the method employed to determine the value, or the variation that exists among testing subjects.

[0019] Use of the term "at least one" will be understood to include any amount of two or more, including but not limited to not only one, but 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 100, etc. The term "at least one" can range up to 100 or 1000 or more, depending on the term to which it is attached; in addition, an amount of 100 / 1000 should not be considered limiting, as higher limits may also provide satisfactory results. Additionally, use of the term "at least one of X, Y, and Z" will be understood to include X only, Y only, and Z only, as well as any combination of X, Y, and Z.

[0020] As used in the specification and claims, the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include"), or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0021] As used herein, the term "or combinations thereof" refers to all permutations and combinations of the items listed before the term. For example, "A, B, C, or combinations thereof" is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and, where order is important in a particular context, BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing the example, combinations including one or more repeats of an item or term are expressly included, such as BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, etc. One of skill in the art will understand that there is typically no limit to the number of items or terms in any combination, unless otherwise clear from the context.

[0022] As used herein, the term "sample" and variations thereof are intended to include, for example, biological tissue, biological fluid, chemical fluid, chemical substance, suspension, solution, slurry, mixture, aggregate, tincture, slide, powder, or other preparation of biological tissue or fluid, synthetic analogs of biological tissue or fluid, bacterial cells (prokaryotic or eukaryotic), viruses, single-cell organisms, lysed biological cells, fixed biological cells, fixed biological tissue, cell cultures, tissue cultures, genetically modified cells and tissues, genetically modified organisms, and combinations thereof.

[0023] As used herein, the term "wet-up" will be understood to refer to the hydration process (e.g., of a membrane) from the placement of a sensor in a fluid analyzer to the point at which a stable signal is obtained from a calibration reagent (e.g., a reference fluid). A stable signal is obtained when a junction is formed and maintained. Air bubbles that form at or near the membrane during wet-up can adversely affect signal stability by preventing the formation or maintenance of a junction. Thus, the wet-up improvements described herein include obtaining and / or maintaining a stable signal and thus a junction in a bubble-free or reduced bubble membrane.

[0024] As used herein, the phrase "capable of or configured to be in fluid communication" refers to direct or indirect fluid communication between two elements / compartments that allows for fluid flow between them. In addition, the phrase "capable of or configured to be in fluid communication" includes cases where the flow point between the two elements / compartments is sealed or otherwise blocked, but the two elements / compartments are capable of having fluid flow between them by puncturing, piercing, or otherwise removing a sealant / plug formed therein or between.

[0025] In the following detailed description of the embodiments of the present invention summary, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. However, it will be apparent to those skilled in the art that the inventive concepts within the scope of the present disclosure may be practiced without these specific details. In other instances, well-known configurations have not been described in detail to avoid unnecessarily complicating the present disclosure.

[0026] Finally, as used herein, any reference to "one embodiment" or "an embodiment" means that a particular element, configuration, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0027] The inventive concepts disclosed and / or claimed herein generally relate to a sensor assembly for a body fluid analyzer. The sensor assembly includes a reference electrode container including a reference electrode; a membrane capable of or configured to be in fluid communication with the reference electrode container; and a wicking member capable of or configured to be in fluid communication with the reference electrode container. The wicking member is configured to draw a reference fluid contained in the reference electrode container toward the membrane when the membrane and wicking member are exposed to the reference fluid (i.e., when the membrane and wicking member are in fluid communication with the reference electrode container). When the membrane and wicking member are not exposed to the reference fluid (i.e., sealed from the reference fluid), the membrane and wicking member are not in fluid communication with the reference electrode container. The membrane and wicking member can be located within the reference electrode container or can be located outside the reference electrode container but in fluid communication with the reference electrode container.

[0028] In another aspect, the inventive concepts disclosed and claimed herein generally relate to a fluid analyzer including a sample receiving assembly having a sample probe with a fluid inlet and a fluid outlet, a fluid disposal assembly; and a sensor assembly in fluid communication with the sample receiving assembly and the fluid disposal assembly. The sensor assembly includes a reference electrode container including a reference electrode; a membrane capable of or configured to be in fluid communication with the reference electrode container; and a wicking member capable of or configured to be in fluid communication with the reference electrode container. The wicking member is configured to draw a reference fluid contained in the reference electrode container toward the membrane when the membrane and wicking member are exposed to the reference fluid (i.e., when the membrane and wicking member are in fluid communication with the reference electrode container). When the membrane and wicking member are not exposed to the reference fluid (i.e., sealed from the reference fluid), the membrane and wicking member are not in fluid communication with the reference electrode container. The membrane and wicking member can be located within the reference electrode container, or can be located outside the reference electrode container but in fluid communication with the reference electrode container.

[0029] In another aspect, the inventive concepts disclosed and claimed herein generally relate to a method of forming a sensor assembly for a body fluid analyzer, the method including positioning a membrane including a reference electrode and configured to contain a reference fluid and in fluid communication with a reference electrode reservoir, and positioning a wicking member to draw the reference fluid toward the membrane when the membrane and wicking member are exposed to the reference fluid, the membrane and wicking member being located inside or outside the reference electrode reservoir.

[0030] Described herein and shown in the accompanying drawings are several non-limiting embodiments of the presently claimed and disclosed inventive concept apparatus used in conjunction with a collection syringe and a liquid sample analyzer to remove air or other gas bubbles from a fluid sample for analysis by the fluid sample analyzer. The fluid sample is generally from a biological source. By "fluid" is meant any substance that does not have a fixed shape and that readily yields to an external pressure.

[0031] Referring now to the drawings, and more particularly to FIGS. 1 and 2, an exemplary hematology analyzer 10 for analyzing one or more samples for one or more target analytes is illustrated. In certain embodiments, the hematology analyzer 10 is a point-of-care analyzer or hematology analyzer as known in the art. Exemplary point-of-care analyzers are available from Siemens Healthcare Diagnostics, Inc. and are sold under the trademarks RAPIDLab 1200, RapidLab 348EX, RAPIDPoint 500, RAPIDLab 248 / 348, RAPIDPoint 400 / 405, and RAPIDPoint 340 / 350 systems. Other commercially available point-of-care devices are available from Roche Molecular Systems Inc., Medica Corp., Radiometer Medical (Denmark), and Nova Biomedical Corp.

[0032] Hematology analyzer 10 includes a housing 12 for containing and supporting a number of sample analysis components and / or modules. These components may include a sample receiving assembly 14, a fluid tubing assembly 16, a sensor assembly 18, and a reagent assembly 20. Housing 12 may also support a display screen 22 for showing the progress of a test.

[0033] The fluid sample introduced into the blood analyzer 10 may include any biological material collected from a subject, such as, for example, bodily fluids, pathogens, or abscesses collected from a subject by suitable methods and devices known in the art. Bodily fluids include, but are not limited to, urine, whole blood, serum, plasma, saliva, spinal fluid, pleural fluid, dialysate, nasopharyngeal swabs, vaginal swabs, tears, tissues, and the like. The sample further includes any suitable buffers, diluents, and the like, as required or desired for the particular sample. In certain embodiments, the sample includes a blood sample, which may be: a whole blood sample including plasma and whole blood cells; a plasma sample; or a serum sample. In certain embodiments, the sample includes a whole blood sample. The whole blood sample may include red blood cells, platelets, and the like. In other embodiments, the blood sample includes a plasma sample. To obtain a plasma sample, the sample has been processed to remove a plurality of whole blood cells using known methods and components, such as centrifugation or commercially available porous membranes.

[0034] The sample receiving assembly 14 is adapted to introduce a liquid sample from a transport container (not shown) to the sensor assembly 18 for analysis. An example of the sample receiving assembly 14 is disclosed in U.S. Pat. No. 10,928,409, which is expressly incorporated herein by reference. In one example, the sample receiving assembly 14 includes a sample probe 24 that may be rotatable to a selected position so that the sample probe 24 can receive a fluid sample from different types of sample transport containers. Examples of sample transport containers include syringes, vacutainers, and capillary tubes (not shown). The sample probe 24 is also oriented in a standby mode (e.g., vertically) to seal the fluid outlet 26 of the reagent assembly 20, thereby using the sample receiving assembly 14 to transport fluid from the reagent assembly 20 to the sensor assembly 18.

[0035] The reagent assembly 20 holds a number of reagent fluids used in the testing. The reagents are provided in reservoirs such as sealed bags or bottles (not shown). The reagent assembly 20 may include one or several reservoirs pre-filled with processing fluids of known composition (known to those skilled in the art: QC1, QC2, QC3, CRL3 (S1940), CRL2 (S1930), RINSE / CAL1 (S1920)). Those skilled in the art will understand that other chemicals may be provided depending on the exact test desired.

[0036] The reagent assembly 20 may include, for example, a rubber nipple (not shown) defining a fluid outlet 26 such that when in sealing engagement with the sample receiving assembly 14, the reagent assembly 20 is in fluid communication with the sensor assembly 18 to allow reagent fluid to flow from the reagent assembly 20 to the sensor assembly 18. The reagent assembly 20 may be integrated as a member of the blood analyzer 10 or may otherwise be configured to be removable / disposable.

[0037] The sensor assembly 18 includes a sensor that is used to contact the fluid sample. The sensor assembly 18 may be integrated into the blood analyzer 10 or may be a removable / disposable modular unit. The sensor assembly 18 may communicate directly or indirectly with a computing unit (not shown) that may collect, store, and analyze analytical test results from the sensors according to known methods. After delivering the fluid sample to the sensor assembly 18, the blood analyzer 10 may introduce fluid from the reagent assembly 20 to prepare the blood analyzer 10 for the introduction of a subsequent fluid sample.

[0038] 3-14, the sensor assembly 18 is shown removed from the housing 12 of the blood analyzer 10. In one non-limiting embodiment, the sensor assembly 18 includes a housing 30 (FIGS. 3-13), at least one sensor 32 (FIGS. 3, 9, and 10), a reference electrode 34 (FIG. 12), a reference fluid 36 (FIGS. 12, 13A, 13B, 14A, and 14B), a sealant such as a membrane 150 (FIGS. 13A-13B and 14A-14B), a plug 40 (FIGS. 13A and 13B) or a pierceable barrier 170 (FIGS. 14A and 14B) that defines the area of ​​the liquid junction 38, and a wicking member 42 (FIGS. 13A-13B and 14A-14B).

[0039] The housing 30 is configured to define a fluid inlet 44, a fluid outlet 46, and a fluid flow path 48 extending between the fluid inlet 44 and the fluid outlet 46. The housing 30 has a sensor-containing space 50 (also referred to as a sensor receptacle 50) and a reference electrode-containing space 52 (also referred to as a reference electrode receptacle 52) separated from one another. The housing 30 supports various components for performing a chemical (e.g., electrochemical) assay on a fluid sample.

[0040] As shown in Figure 3, in one non-limiting embodiment, the housing 30 is shown to be generally rectangular in shape. However, one of ordinary skill in the art will readily appreciate that the housing 30 may be any shape capable of accomplishing the presently disclosed and / or claimed inventive concept, including, but not limited to, circular, triangular, square, pentagonal, hexagonal, heptagonal, octagonal, nonagonal, decagonal, or any polygonal shape. Additionally, the housing 30 is constructed of any suitable material, including opaque and / or transparent and / or translucent materials, including, but not limited to, synthetic polymers and / or naturally occurring or naturally derived polymers (both organic and / or inorganic), such as, by way of example only, thermoplastic polymers, thermoset polymers, elastomers, and / or synthetic fibers, such as low density polyethylene, high density polyethylene, polystyrene, polyvinyl chloride, styrene butadiene, polyacrylic, polyvinyl acetate, acrylic, acrylic acid, and acrylate polymers, and combinations thereof.

[0041] The housing 30 is constructed from several different components assembled together. In one non-limiting embodiment of the presently disclosed and / or claimed inventive concepts, the housing 30 includes a base 54, a cover 56, and a plug assembly 58 (FIG. 12). The base 54 serves as a substrate for an integrated analyte detection system, which may include an electrochemical system. In one non-limiting embodiment, with reference to FIGS. 5 and 6, the base 54 has a top surface 62 and a bottom surface 64. The top surface 62 allows and / or facilitates fastening of additional components to the base 54. The base 54 may include the fluid inlet 44 of the housing 30. The fluid inlet 44 extends through the base 54 from the bottom surface 64 to the top surface 62 and intersects with the fluid flow path 48 (FIGS. 13A, 13B) for the fluid sample.

[0042] In one non-limiting embodiment, the base 54 can define a portion of the fluid flow path 48. More specifically, the fluid inlet 44 can intersect one end of a groove 66 (FIG. 6) that extends along the top surface 62 of the base 54. At the other end of the groove 66, a port 68 (FIG. 7) extends from the top surface 62 to the bottom surface 64, where the port 68 intersects one end of a cross groove 70 (FIG. 7) formed in the bottom surface 64 of the base 54. The cross groove 70 extends along a portion of the bottom surface 64 of the base 54. The cross groove 70 is covered by a cover 72 (FIG. 5) to define a cross channel. A port 74 (FIG. 7) extends from the other end of the cross groove 70 from the bottom surface 64 to the top surface 62, where the port 74 intersects one end of a groove 76 (FIG. 6) that extends along the top surface 62 of the base 54. The groove 76 can extend in a parallel relationship to the groove 66.

[0043] At the other end of the groove 76, a port 78 (FIGS. 7 and 8) extends from the top surface 62 to the bottom surface 64, where the port 78 intersects one end of a groove 80 formed in the bottom surface 64 of the base 54. The groove 80 extends along a portion of the bottom surface 64, where the other end of the groove 80 intersects with a port 82 (FIGS. 7 and 8) that extends from the bottom surface 64 to the top surface 62. The top surface 62 of the base 54 within the reference electrode receiving space 52 includes a protrusion 84 (FIGS. 6 and 8). The port 82 extends to a distal end of the protrusion 84. The distal end of the protrusion 84 has a slot 86, where the port 82 intersects one end of the slot 86 (FIGS. 6 and 7). The other end of the slot 86 intersects one end of a port 88 that extends from the top surface 62 to the bottom surface 64, so that the port 82, the slot 86, and the port 88 define a generally U-shaped flow path (FIG. 8).

[0044] Port 88 intersects one end of a groove 90 (FIG. 8) formed in bottom surface 64 of base 54. Groove 90 extends along a portion of bottom surface 64, and the other end of groove 90 intersects with a port 92 (FIG. 9) that extends from bottom surface 64 to top surface 62. Grooves 80 and 90 are covered by a cover 94 (FIG. 5) to define a pair of channels.

[0045] The port 92 intersects one end of a groove 96 (FIG. 9) that extends along a portion of the top surface 62 and the other end of the groove 96 intersects the fluid outlet 46 that extends from the top surface 62 to the bottom surface 64 of the base 54 .

[0046] 9-11, in one non-limiting embodiment, the at least one analyte sensor 32 may be a member of a pair of sensor arrays 100a and 100b. However, it should be understood by one of ordinary skill in the art that the sensor assembly 18 may include any number of analyte sensor arrays. The sensor arrays 100a and 100b may be the same or different, both in configuration and in the electrochemical assays / measurements performed. In addition, although the sensor arrays 100a and 100b are shown in FIGS. 9 and 11 as being on the top surface 62 of the base 54, they may be on the same or different surfaces to achieve the inventive concepts presently disclosed and / or claimed. For example, the sensor array 100a may be on the top surface 62 of the base 54 and the sensor array 100b may be on the bottom surface 64 of the base 54; or, alternatively, both the sensor arrays 100a and 100b may be on the bottom surface 64.

[0047] One example of a suitable sensor array is disclosed in WO 2020 / 05692 and WO 2020 / 005697, both of which are expressly incorporated herein by reference. The sensor arrays 100a and 100b may include a sensor panel 102 having an upper surface and a lower surface. In some embodiments, one or more analyte sensors 108 are located on the sensor panel 102. The sensor panel 102 may be made from materials including, but not limited to, ceramic, plastic, and / or the like.

[0048] In some embodiments, the sensor arrays 100a and 100b may include an adhesive layer 110 having an upper surface 112 and a lower surface 114. A pair of slots 116 may span the length of the adhesive layer 110. The upper surface 112 of the adhesive layer 110 is adhesively secured to the lower surface 106 of the sensor panel 102. The lower surface 114 of the adhesive layer 110 is secured to the upper surface 62 of the base 54 with the slots 116 aligned with the grooves 66 and 76. In some embodiments, the adhesive layer 110 may be optional.

[0049] Sensor arrays 100a and 100b are secured over grooves 66 and 76, respectively, and define a portion of a fluid flow path 48. Fluid flow path 48 is configured for a test sample or fluid sample to pass along grooves 66 and 76 to contact one or more analyte sensors 108.

[0050] 3, 10, and 12-14, the cover 56 of the housing 30 is secured to the base 54 with the sensor arrays 100a and 100b sandwiched therebetween. The cover 56 has a first end 130, a second end 132, a first side 134, a second side 136, and a bottom surface 138. The bottom surface 138 is configured to couple to the top surface 62 of the base 54 with the sensor arrays 100a and 100b located therebetween such that the cover 56 defines a sensor-receiving space 50 adjacent the first end 130 of the cover 56. The bottom surface 138 of the cover 56 can have a number of openings 140 corresponding to the analyte sensors 108 to allow electrical pins (not shown) to contact the analyte sensors 108.

[0051] The reference electrode-receiving space 52 of the housing 30 is defined adjacent the second end 132 of the cover 56 by a plurality of side walls 142a-142d. The side wall 142d separates the sensor-receiving space 50 from the reference electrode-receiving space 52. The reference electrode-receiving space 52 is sealed by a cap 144. The cap 144 can support the reference electrode 34 such that the reference electrode 34 extends into the reference electrode-receiving space 52 (FIG. 12). The reference electrode 34 can be, for example, a silver wire coated with silver chloride. The reference fluid 36 is disposed within the reference electrode-receiving space 52 such that the reference fluid 36 contacts the reference electrode 34. The reference fluid 36 can be an electrolyte solution, such as an aqueous potassium chloride solution (or an equivalent formulation).

[0052] The reference fluid 36 contacts (e.g., forms an ionic and / or electrical connection with) the fluid sample in the fluid flow path 48 at a flow restriction region, such as a membrane, film, barrier, constriction, or boundary region. The reference fluid 36 forms a junction 38 with the fluid sample at or near the flow restriction region. A junction is a boundary between two electrolyte solutions of different composition (e.g., the reference fluid 36 and the fluid sample) at which a potential difference, called the junction potential, occurs. The flow restriction region may be a porous region (having one or more pores or holes) that allows ion flow by diffusion but restricts fluid flow to define a limited diffusion type junction. In one non-limiting embodiment, the flow restriction region includes a membrane 150 (FIGS. 13A-13B and 14A-14B) located between the reference electrode receiving space 52 and the fluid flow path 48 and defines the region of the junction 38. Thus, the membrane 150 fluidly separates (i.e., restricts or prevents the flow of fluids but allows the flow of ions) the reference electrode-containing space 52 from the sensor-containing space 50. The membrane 150 is positioned around the protrusion 84 of the base 54 to cover the slot 86. The protrusion 84 extends up through an opening provided through the bottom surface 138 of the cover 56 in the base 54. The membrane 150 may be disk-shaped and is secured around the protrusion 84 by a fastening member, such as an O-ring 152.

[0053] The membrane 150 is formed and / or treated (e.g., coated) with one or more suitable materials, such as, for example, polymeric materials. In one non-limiting embodiment, all or a portion of the membrane 150 may be a hydrophilic material. In yet another embodiment, all or a portion of the membrane 150 is treated (e.g., coated) with a hydrophilic material. A membrane formed of or including a hydrophilic material advantageously strengthens the membrane 150 to "wet up" to perform its operational function and helps prevent bubble formation, thus helping to maintain stability of the liquid junction in the membrane 150. Examples of suitable non-exclusive materials for the membrane 150 or membrane coating include, for example, polypropylene, polyethylene, polyvinyl chloride, and modified polyvinyl chloride, as well as any similar hydratable polymer membranes known to those skilled in the art. Examples of other suitable non-exclusive materials may be cellulose acetate, or porous glass, or ceramic, etc. Instead of a homogeneous membrane, a heterogeneous membrane may also be used. The term heterogeneous membrane as used herein refers to a membrane formed from and / or treated (e.g., coated) with at least two different materials. In one exemplary embodiment, to enhance "wet-up," the surface of the membrane 150 facing the fluid flow passage 48 has a higher hydrophilicity than the surface of the membrane 150 facing the reference electrode-accommodating space 52, which may include a hydrophobic material or a material that has a lower hydrophilicity compared to the surface of the membrane 150 facing the fluid flow passage 48. Alternatively, in another embodiment, the surface of the membrane 150 facing the reference electrode-accommodating space 52 has a higher hydrophilicity than the surface of the membrane 150 facing the fluid flow passage 48.

[0054] The reference electrode receiving space 52 is configured to receive the reference fluid 36. The sensor assembly 18 may or may not be stored and shipped with the reference fluid 36 located in the reference electrode receiving space 52, but in either embodiment, the membrane 150 is sealed to prevent contact with the reference fluid 36 until operationally desired. In one embodiment shown in FIG. 12, a plug assembly 58 is provided to seal the membrane 150. The plug assembly 58 may include a lever 154 (FIG. 10) pivotally connected to the cover 56 and a bladder 156 (FIG. 10) connected to one end of the lever 154. A plug 40 (FIGS. 10-13B) is connected to the other end of the lever 154. The plug 40 may be a rigid or semi-rigid cap. Actuation of the bladder 156 by an actuator (not shown) causes the lever 154 to move the plug 40 from a closed position (FIG. 13A), in which the plug 40 seals the junction 38 (e.g., the membrane 150) from the reference fluid 36, to an open position (FIG. 13B), in which the reference fluid 36 is in fluid communication with the fluid flow path 48 to form the junction 38 at or near the membrane 150.

[0055] In one non-limiting embodiment, the bottom surface 138 of the cover 56 includes a well or pocket 160 in which the membrane 150 sits to control ion diffusion. A portion of the plug 40 can mate with the pocket 160 to seal the membrane 150 from the reference fluid 36. Due to the small fluid space used by the sensor assembly 18, when the plug 40 is moved to an open position to expose the membrane 150 to the reference fluid 36, air bubbles can form between the reference fluid 36 and the membrane 150, thereby preventing the membrane 150 from "wetting up" and resulting in measurement errors for the sensor assembly 18.

[0056] The wicking member 42 is configured to be in fluid communication with the reference electrode receiving space 52 (e.g., but not limited to, being located in the reference electrode receiving space 52) and is arranged to contact a surface of the membrane 150. The wicking member 42 is configured to be sealed from the reference fluid 36 when the plug 40 is in the closed position, and the wicking member 42 is configured to draw the reference fluid 36 into contact with the membrane 150 when the plug 40 is in the open position. In the open position, the wicking member 42 is configured to maintain contact between the reference fluid 36 and the membrane 150, and thus to maintain the liquid junction 38.

[0057] In Figures 13A-13B and 14A-14B, the wicking member 42 is illustrated as a strip located in the pocket 160, where one end or surface of the wicking member 42 is in contact with the membrane 150. However, it will be understood that the wicking member 42 can be constructed in a variety of shapes and sizes. Also, in one embodiment, two or more wicking members 42 can be employed. One or more wicking members are positioned to contact at least a portion of the surface of the membrane 150 that faces the reference electrode receiving space 52. The wicking member 42 absorbs the reference fluid 36 and draws the reference fluid 36 to the surface of the membrane 150. By contacting the reference fluid 36 with the membrane 150, the wicking member 42 helps prevent the formation of air bubbles, thus helping to maintain and / or create a liquid junction at the membrane 150, thereby reducing measurement errors. In one embodiment, the wicking member 42 is a hydrophilic material or is coated with a hydrophilic material. Alternatively, the wicking member 42 may be formed and / or coated with a combination of hydrophobic and hydrophilic materials, with the hydrophilic material portion being exposed to the reference fluid 36 during the method of operation of the sensor assembly 18. As used herein, "wicking member" refers to any substance or material, matrix, mixture, or composite having an open structure, such as an open mesh. For example, the wicking member may be formed of woven and / or nonwoven (extruded) materials made from filament fibers, or may be formed of sintered materials (e.g., non-fibrous materials made from multiple pellets, such as polymer or metal pellets). Other non-limiting exemplary materials include, for example, cellulose, polyester, nylon, aramid, polyethylene, and / or glass fibers, which may be utilized among many available fibers as appropriate for the application. Suitable materials for the wicking member 42 are Hi-Flow™ Plus Membrane and SureWick® Pad Materials available from EMD Millipore Corporation, Billerica, Massachusetts.

[0058] To seal the wicking member 42 when in the closed position, the plug 40 may be hollow and have an open bottom through which the wicking member 42 sits, as shown in Figures 13A-13B. The wicking member 42 is attached to the inside of the pocket 160, such as by attachment to the surface of the membrane 150 with a suitable adhesive or by interference or capture of the member.

[0059] In another embodiment shown in Figures 14A and 14B, instead of the plug 40 or plug assembly 58, the sealant can be a pierceable barrier 170, such as a film or coating, located on the bottom surface 138 of the cover 56 in the closed position (Figure 14A) to seal the liquid junction 38 (e.g., the membrane 150) from the reference fluid 36. In the closed position (i.e., not pierced or broken), the pierceable barrier 170 is configured to sealably separate the membrane 150 and the wicking member 42 from the reference fluid 36. In one embodiment, the pierceable barrier 170 extends across the pocket 160 containing the membrane 150 and the wicking member 42 to seal the membrane 150 and the wicking member 42, as shown in Figure 14A. The pierceable barrier 170 may or may not be in direct contact with the surface of the wicking member 42. In one embodiment, the pierceable barrier 170 may be a hydrophobic material to further help prevent the reference fluid 36 from contacting the membrane 150 and / or the wicking member 42 when the pierceable barrier 170 is in the closed position.

[0060] When the sensor assembly 18 is activated, the pierceable barrier 170 (e.g., a film or coating) is broken or perforated such that the pierceable barrier 170 is in an open position ( FIG. 14B ). The pierceable barrier 170 can be broken or perforated by tearing or puncturing the pierceable barrier 170 to form a liquid junction 38 where the reference fluid 36 is in fluid communication with the fluid flow path 48. In an exemplary embodiment, the pierceable barrier 170 is broken or perforated by a mechanical perforator (not shown), such as a piercing or puncturing element attached to the housing 30 and configured to be actuated or moved (e.g., by a user or actuator) toward the pierceable barrier 170 when the sensor assembly 18 is activated. Alternatively or additionally, the pierceable barrier 170 is ruptured or perforated by an electroporator, such as, for example, a spark, impact, or vibration (e.g., ultrasonic) signal, which is configured to rupture the pierceable barrier 170 when the sensor assembly 18 is activated, exposing the membrane 150 to the reference fluid 36. Thus, the piercing or rupturing of the pierceable barrier 170 by a tearing or piercing element (not shown) exposes the wicking member 42 to the reference fluid 36, thereby facilitating the attraction of the reference fluid 36 to the membrane 150 for enhanced "wet-up" and reduced bubble formation.

[0061] In the embodiment shown in Figures 13A-13B and 14A-14B, the wicking member 42 and the membrane 150 are located inside the reference electrode-containing space 52. However, what is important is that a portion of the wicking member 42 is disposed to contact a portion of the membrane 150, and that the wicking member 42 and the membrane 150 are configured to be sealed by a sealant (e.g., a plug or a pierceable barrier) to prevent fluid communication or contact with the reference fluid 36 contained in the reference electrode-containing space 52 until operationally desired. Thus, it is within the scope of the present disclosure for the wicking member and the membrane to be located outside or external to the interior of the reference electrode-containing space, as shown in Figures 15A-15D. In one alternative embodiment, as shown in Figure 15A, a portion of the wall 180 of the reference electrode-containing space 52a (e.g., a portion of the bottom wall 180) has a gap or opening 182 that is covered by a sealant 184 (e.g., a plug or a pierceable barrier). A first end 186 or surface of the wicking member 42a is configured to contact the sealant 184 located in or otherwise extending across the gap 182. The wicking member 42a extends from its first end 186 away from the reference electrode-containing space 52a (e.g., away from the bottom wall 180 of the reference electrode-containing space 52a) toward a second end 188 or surface of the wicking member 42a opposite the first end 186. The second end 188 of the wicking member 42a is positioned to contact at least a portion of a surface 190 of the membrane 150a that faces the reference electrode-containing space 52a. In this embodiment, the sealant 184 (e.g., a plug or pierceable barrier) may be similar to the sealant of the plug 40 and pierceable barrier 170 of Figures 13A-13B and Figures 14A-14B, except that the sealant 184 is configured to seal a gap 182 or opening in a portion of the wall 180 of the reference electrode accommodating space 52a (e.g., a portion of the bottom wall 180) when in a closed position, and to expose the gap 182, and thus the wicking member 42a located therein, and to allow the reference fluid to contact the membrane 150a when the sealant 184 (e.g., a plug or pierceable barrier) is in an open position.

[0062] 15A, the wicking member 42a extends into a gap 182 in the wall 180 of the reference electrode-containing space 52a such that a first end 186 of the wicking member 42a is substantially flush with the inner surface of the wall 180 of the reference electrode-containing space 52a, and the wicking member 42a in the gap 182 is then covered by a sealant 184 that is within the reference electrode-containing space 52a. However, it will be understood that the scope of the present disclosure includes positioning the wicking member and sealant anywhere inside, internal, external, or outside of the reference electrode-containing space.

[0063] Instead of the sealant extending across the gap in the bottom wall of the reference electrode-containing space, the sealant is positioned to seal a mating member that is coupled to or extends through the gap until operationally desired. The mating member may be a well or pocket in which at least a portion of the wicking member (e.g., a first end) is located and in which the sealant can matingly engage with the mating member (e.g., an upper surface of the well or pocket) to seal the wicking member and membrane from fluid communication with the reference fluid until the sealant is released. The mating member may be similar in design and function to the well or pocket 160 described in Figures 13A-13B and 14A-14B, except that at least a portion of the mating member is located outside the reference electrode-containing space and aligned with the gap in the wall of the reference electrode-containing space.

[0064] In one non-limiting embodiment (FIG. 15B), the engagement member (e.g., a well of a pocket) can be coupled to an outer wall of the reference electrode-containing space and extend away from the interior of the reference electrode-containing space, where the sealant is configured to extend across the gap along the outer wall of the reference electrode-containing space. As seen in FIG. 15B, the wicking member 42b is located outside and exterior of the reference electrode-containing space 52b. The sealant 184b is disposed on a first end 186b of the wicking member 42b and covers the gap / opening 182b in the wall 180b of the reference electrode-containing space 52b. The fitting member 192 extends downward (i.e., away from the reference electrode accommodating space 52b) from and around at least a portion of the side of the first end 186b of the wicking member 42b such that at least a portion of the wicking member 42b (i.e., the first end 186b) is located within the fitting member 192 (i.e., within the sidewall of the fitting member 192). The sealant 184b is positioned to extend across the sidewall of the fitting member 192 such that the first end 186b of the wicking member 42b and the gap / opening 182b are sealed in the closed position when fluid communication between the reference electrode accommodating space 52b and the wicking member 42b is not desired.

[0065] In another non-limiting embodiment (FIG. 15C), the engagement member (e.g., well of pocket) is flush with the wall of the reference electrode-containing space and extends from the gap toward the exterior of the reference electrode-containing space, where the sealant is flush with or aligned with the interior of the bottom wall of the reference electrode-containing space. In FIG. 15C, the wicking member 42c is disposed in the gap 182c such that the first end 186c of the wicking member 42c is disposed inside the wall 180c. In addition, the sealant 184c covers the first end 186c of the wicking member 42c, and the engagement member 192c extends to its side to close the gap / opening 182c in the wall 180c of the reference electrode-containing space 52c.

[0066] In yet another embodiment (FIG. 15D), the fitting member (e.g., a well of a pocket) is positioned to extend through the gap such that a first end of the fitting member is located inside the reference electrode-accommodating space and a second end of the fitting member is located outside the reference electrode-accommodating space. In this embodiment, the wicking member is located both inside and outside the reference electrode-accommodating space such that a first end of the wicking member is located inside the reference electrode-accommodating space and can contact the sealant, while a second end of the wicking member is located outside the reference electrode-accommodating space and contacts the membrane. In particular, in FIG. 15D, the wicking member 42c extends through and into the gap 182d in the wall 180d of the reference electrode-accommodating space 52d. The sealant 184d covers the first end 186d of the wicking member 42d, and the fitting member 192d covers at least a portion of the side of the wicking member 42d that extends through the wall 180d of the reference electrode-accommodating space 52d. In all of Figures 15A-15D, the second ends 188 / 188b / 188c / 188d of the wicking members 42a / 42b / 42c / 42d, as well as the membranes 150a / 150b / 150c / 150d, are outside the reference electrode receiving spaces 52a / 52b / 52c / 52d.

[0067] In use, the sensor assembly 18 is inserted and secured within the housing 12. The sealant (e.g., plug 40, pierceable barrier 170, or sealant 184) is moved or actuated from a closed position to an open position, exposing the wicking member 42 and membrane 150 to the reference fluid 36, thereby "wetting up" the membrane. The wicking member 42 aids and enhances the "wetting up" of the membrane 150 for an improved method of actuation of the sensor assembly 18. For example, the wicking member 42 enhances the "wet up" cycle of the sensor assembly 18 as the wicking member 42 draws the reference fluid 36 towards the membrane 150 and / or pocket 160, reducing or preventing air bubble formation on the membrane 150, thereby preventing air bubble formation as well as improving complete fluid coverage of the area surrounding the membrane 150 and / or pocket 160 which helps displace any formed air bubbles from the membrane 150, improving the "wet up" of the membrane 150. Because the wicking member 42 draws the reference fluid 36 towards the membrane 150, the wicking member 42 advantageously promotes and maintains contact between the reference fluid 36 and the membrane 150, thereby improving the creation and maintenance of the liquid junction 38 in the open position. The presence of the wicking member 42 can reduce or prevent bubble formation above the membrane 150 during a test cycle of the sensor assembly 18 due to the hydrophilic nature of the wicking member 42 material. The wicking member 42 can also reduce or prevent bubble formation by eliminating and / or reducing convective fluid motion above the membrane 150, which can disadvantageously introduce gas (and thus bubbles) as the reference fluid 36 heats up (e.g., to 37° C.) during a test cycle. Heating the reference fluid 36 can alter (i.e., decrease) gas solubility, which can lead to the evolution of gas (e.g., oxygen and nitrogen) from the reference fluid 36, thereby disadvantageously encouraging bubble formation at or near the membrane 150. After testing a predetermined number of fluid samples, the sensor assembly 18 can be removed from the housing 12 as a modular unit. EXAMPLES

[0068] The following examples serve to illustrate certain useful embodiments and aspects of the presently disclosed and claimed inventive concepts and are not to be construed as limiting the scope thereof. EXAMPLES

[0069] Four sensor cartridges without a wicking member were tested. Each of the sensor assemblies exhibited poor wet-up. Each of the sensor assemblies formed air bubbles on the membrane within 24 hours. The potential difference signal began to drift and eventually a measurement was recorded indicating a loss of baseline. EXAMPLES

[0070] Three sensor assemblies, each with a wicking member, were tested. None of the sensor assemblies failed during the initial wet-up, and none of the sensor assemblies failed during the one week operation period. In this example, a cellulose wicking material was used as the wicking member. However, as mentioned above, it should be understood that any material having wicking properties may be used as the wicking member.

[0071] From the above description, it is apparent that the inventive concepts disclosed herein are well adapted to carry out the objects and obtain the advantages set forth herein, as well as those inherent in the inventive concepts disclosed herein. While exemplary embodiments of the inventive concepts disclosed herein have been described for purposes of this disclosure, it will be understood that numerous modifications will be readily suggested to one skilled in the art and may be effected without departing from the scope of the inventive concepts disclosed herein and defined by the appended claims.

[0072] Non-Limiting Exemplary Embodiments The following is a list of non-limiting exemplary embodiments of the inventive concepts disclosed herein.

[0073] An exemplary sensor assembly for a body fluid analyzer, comprising: a reference electrode reservoir including a reference electrode and configured to contain a reference fluid; a membrane configured to be in fluid communication with the reference electrode reservoir; and a wicking member configured to be in fluid communication with the reference electrode reservoir and configured to draw the reference fluid toward the membrane when the membrane and the wicking member are exposed to the reference fluid.

[0074] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the wicking member is in contact with the membrane.

[0075] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the wicking member comprises a hydrophilic material.

[0076] An exemplary sensor assembly as described in any one of the preceding exemplary embodiments, further comprising a sealant located within the reference electrode container and operable from a closed position to an open position, wherein in the closed position, the wicking member and the membrane are sealed from the reference fluid and, in the open position, the wicking member and the membrane are exposed to the reference fluid.

[0077] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the sealant is a plug.

[0078] An exemplary sensor assembly as described in any one of the preceding exemplary embodiments, wherein the reference electrode container has a pocket, the plug engages with the pocket in the closed position, and the wicking member is positioned within the pocket between the plug and the membrane.

[0079] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the sealing material is a pierceable barrier configured to be pierced.

[0080] An exemplary sensor assembly as described in any one of the preceding exemplary embodiments, wherein the reference electrode container has a pocket, the piercable barrier covers the pocket in the closed position, and the wicking member is positioned within the pocket between the piercable barrier and the membrane.

[0081] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member is located inside the reference electrode reservoir.

[0082] The exemplary sensor assembly of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member are located outside the reference electrode reservoir.

[0083] An exemplary sensor assembly as described in any one of the preceding exemplary embodiments, wherein a first end of the wicking member is located inside the reference electrode container and a second end of the wicking member is located outside the reference electrode container, and the second end of the wicking member contacts the membrane, and the membrane is located outside the reference electrode container.

[0084] The exemplary sensor assembly of any one of the preceding exemplary embodiments, further comprising a housing having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the housing including a reference electrode reservoir and a sensor reservoir fluidly separated from the reference electrode reservoir by a membrane, one side of the membrane facing the reference electrode reservoir and the other side of the membrane facing the fluid flow path.

[0085] The exemplary sensor assembly of any one of the preceding exemplary embodiments, further comprising at least one analyte sensor positioned in a sensor receptacle in fluid communication with the fluid flow path.

[0086] An exemplary sensor assembly as described in any one of the preceding exemplary embodiments, wherein the membrane includes at least one pore, and the wicking member is configured to maintain a liquid junction in the membrane when exposed to a reference fluid.

[0087] An exemplary fluid analyzer including: a sample receiving assembly having a sample probe having a fluid inlet and a fluid outlet; a fluid disposal assembly; and a sensor assembly in fluid communication with the sample receiving assembly and the fluid disposal assembly, the sensor assembly including: a reference electrode reservoir including a reference electrode and configured to contain a reference fluid; a membrane configured to be in fluid communication with the reference electrode reservoir; and a wicking member configured to be in fluid communication with the reference electrode reservoir and configured to draw the reference fluid toward the membrane when the membrane and the wicking member are exposed to the reference fluid.

[0088] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the wicking member is in contact with the membrane.

[0089] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the wicking member comprises a hydrophilic material.

[0090] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the sensor assembly further includes a sealant located within the reference electrode container and operable from a closed position to an open position, wherein in the closed position the wicking member and the membrane are sealed from the reference fluid and in the open position the wicking member and the membrane are exposed to the reference fluid.

[0091] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the sealant is a plug.

[0092] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the reference electrode container has a pocket, the plug engages with the pocket in the closed position, and the wicking member is positioned within the pocket between the plug and the membrane.

[0093] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the sealant is a pierceable barrier configured to be pierced.

[0094] An exemplary fluid analyzer as described in any one of the preceding exemplary embodiments, wherein the reference electrode container has a pocket, the piercable barrier covers the pocket in the closed position, and the wicking member is positioned within the pocket between the piercable barrier and the membrane.

[0095] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member is located inside the reference electrode reservoir.

[0096] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member is located outside the reference electrode reservoir.

[0097] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein a first end of the wicking member is located inside the reference electrode container and a second end of the wicking member is located outside the reference electrode container, and the second end of the wicking member contacts the membrane, and the membrane is located outside the reference electrode container.

[0098] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the sensor assembly further includes a housing having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the housing including a reference electrode reservoir and a sensor reservoir fluidly separated from the reference electrode reservoir by a membrane, one side of the membrane facing the reference electrode reservoir and the other side of the membrane facing the fluid flow path.

[0099] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the sensor assembly further includes at least one analyte sensor positioned in a sensor receptacle in fluid communication with the fluid flow path.

[0100] The exemplary fluid analyzer of any one of the preceding exemplary embodiments, wherein the membrane includes at least one pore, and the wicking member is configured to maintain a liquid junction in the membrane when exposed to a reference fluid.

[0101] An exemplary method of forming a sensor assembly for a body fluid analyzer, the exemplary method including: positioning a membrane such that it is fluidly connectable with a reference electrode container including a reference electrode and configured to contain a reference fluid; and positioning a wicking member to draw the reference fluid toward the membrane when the membrane and wicking member are exposed to the reference fluid.

[0102] The exemplary method of any one of the preceding exemplary embodiments, wherein the step of positioning the wicking member further comprises contacting the wicking member with the membrane.

[0103] The exemplary method of any one of the preceding exemplary embodiments, further comprising sealing the membrane and wicking member from the reference fluid prior to positioning the reference fluid in the reference electrode reservoir.

[0104] An exemplary method as described in any one of the preceding exemplary embodiments, wherein the sealing step further includes sealing the membrane and wicking member with a plug operable from a closed position to an open position, wherein in the closed position, the wicking member and membrane are sealed from the reference fluid and in the open position, the wicking member and membrane are exposed to the reference fluid when the reference electrode container contains the reference fluid.

[0105] The exemplary method of any one of the preceding exemplary embodiments, wherein the step of positioning the membrane and the wicking member further comprises positioning the membrane and the wicking member in a pocket of a reference electrode container.

[0106] An exemplary method as described in any one of the preceding exemplary embodiments, wherein the sealing step further includes mating a plug with the pocket such that the wicking member is positioned within the pocket between the plug and the membrane.

[0107] An exemplary method as described in any one of the preceding exemplary embodiments, wherein the sealing step further includes sealing the membrane and wicking member with a pierceable barrier operable from a closed position to an open position, wherein in the closed position, the wicking member and membrane are sealed from the reference fluid and in the open position, the wicking member and membrane are exposed to the reference fluid when the reference electrode container contains the reference fluid.

[0108] The exemplary method of any one of the preceding exemplary embodiments, wherein the step of positioning the membrane and the wicking member further comprises positioning the membrane and the wicking member in a pocket of a reference electrode container.

[0109] An exemplary method as described in any one of the preceding exemplary embodiments, wherein the sealing step further includes covering the pocket with a pierceable barrier such that the wicking member is positioned within the pocket between the pierceable barrier and the membrane.

[0110] The exemplary method of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member is located inside the reference electrode container.

[0111] The exemplary method of any one of the preceding exemplary embodiments, wherein the membrane and / or wicking member is located outside the reference electrode container.

[0112] An exemplary method as described in any one of the preceding exemplary embodiments, wherein a first end of the wicking member is located inside the reference electrode container and a second end of the wicking member is located outside the reference electrode container, and the second end of the wicking member contacts the membrane, and the membrane is located outside the reference electrode container.

[0113] The exemplary method of any one of the preceding exemplary embodiments, wherein the reference electrode reservoir is defined by a housing further including a sensor reservoir having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the sensor reservoir being fluidly separated from the reference electrode reservoir by a membrane, and the step of positioning the membrane in the reference electrode reservoir further includes positioning the membrane such that one side of the membrane faces the reference electrode reservoir and the other side of the membrane faces the fluid flow path.

[0114] The exemplary method of any one of the preceding exemplary embodiments, further comprising positioning at least one analyte sensor in a sensor receptacle in fluid communication with the fluid flow path.

[0115] An exemplary method as described in any one of the preceding exemplary embodiments, wherein the step of positioning the membrane further includes a membrane including at least one pore, and the wicking member maintains a liquid junction at the membrane when exposed to the reference fluid.

Claims

1. 1. A sensor assembly for a body fluid analyzer comprising: a reference electrode container including a reference electrode and configured to contain a reference fluid; a membrane configured to be in fluid communication with the reference electrode reservoir; a wicking member configured to be in fluid communication with the reference electrode reservoir and configured to draw the reference fluid toward the membrane when the membrane and the wicking member are exposed to the reference fluid; The sensor assembly comprising:

2. The sensor assembly of claim 1 , wherein the wicking member is in contact with the membrane.

3. The sensor assembly of claim 1 , wherein the wicking member comprises a hydrophilic material.

4. 10. The sensor assembly of claim 1, further comprising a seal located within the reference electrode container and operable from a closed position to an open position, wherein in the closed position the wicking member and membrane are sealed from the reference fluid and in the open position the wicking member and membrane are exposed to the reference fluid.

5. The sensor assembly of claim 4 , wherein the sealant is a plug.

6. 6. The sensor assembly of claim 5, wherein the reference electrode container has a pocket, the plug mates with the pocket in the closed position, and the wicking member is positioned within the pocket between the plug and the membrane.

7. The sensor assembly of claim 4 , wherein the encapsulant is a pierceable barrier configured to be pierced.

8. 8. The sensor assembly of claim 7, wherein the reference electrode container has a pocket, the pierceable barrier covers the pocket in the closed position, and the wicking member is positioned within the pocket between the pierceable barrier and the membrane.

9. The sensor assembly of claim 1 , wherein the membrane and the wicking member are located inside the reference electrode container.

10. The sensor assembly of claim 1 , wherein the membrane and the wicking member are located outside the reference electrode container.

11. 2. The sensor assembly of claim 1, wherein a first end of the wicking member is located inside the reference electrode container and a second end of the wicking member is located outside the reference electrode container, and the second end of the wicking member contacts the membrane, the membrane being located outside the reference electrode container.

12. a housing having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the housing further including a reference electrode reservoir and a sensor reservoir fluidly separated from the reference electrode reservoir by a membrane; 2. The sensor assembly of claim 1, wherein one side of the membrane faces the reference electrode reservoir and the other side of the membrane faces the fluid flow path.

13. The sensor assembly of claim 12 , further comprising at least one analyte sensor positioned in a sensor reservoir in fluid communication with the fluid flow path.

14. The sensor assembly of claim 1 , wherein the membrane includes at least one pore, and the wicking member is configured to maintain a liquid junction at the membrane when exposed to a reference fluid.

15. 1. A fluid analyzer comprising: a sample receiving assembly having a sample probe with a fluid inlet and a fluid outlet; a fluid disposal assembly; a sensor assembly in fluid communication with the sample receiving assembly and the fluid waste assembly, the sensor assembly comprising: a reference electrode container including a reference electrode and configured to contain a reference fluid; a membrane configured to be in fluid communication with the reference electrode reservoir; a wicking member configured to be in fluid communication with the reference electrode reservoir and configured to draw the reference fluid toward the membrane when the membrane and the wicking member are exposed to the reference fluid; The fluid analyzer comprising:

16. 16. The fluid analyzer of claim 15, wherein the wicking member is in contact with the membrane.

17. 16. The fluid analyzer of claim 15, wherein the wicking member comprises a hydrophilic material.

18. The sensor assembly:

16. The fluid analyzer of claim 15, further comprising a seal located within the reference electrode container and operable from a closed position to an open position, wherein in the closed position the wicking member and membrane are sealed from the reference fluid and in the open position the wicking member and membrane are exposed to the reference fluid.

19. 20. The fluid analyzer of claim 18, wherein the sealant is a plug.

20. 20. The fluid analyzer of claim 19, wherein the reference electrode container has a pocket, the plug mates with the pocket in the closed position, and the wicking member is positioned within the pocket between the plug and the membrane.

21. 20. The fluid analyzer of claim 18, wherein the sealant is a pierceable barrier configured to be pierced.

22. 22. The fluid analyzer of claim 21, wherein the reference electrode container has a pocket, the pierceable barrier covers the pocket in the closed position, and the wicking member is located within the pocket between the pierceable barrier and the membrane.

23. 16. The fluid analyzer of claim 15, wherein the membrane and wicking member are located inside the reference electrode reservoir.

24. 16. The fluid analyzer of claim 15, wherein the membrane and wicking member are located outside the reference electrode reservoir.

25. 16. The fluid analyzer of claim 15, wherein a first end of the wicking member is located inside the reference electrode reservoir and a second end of the wicking member is located outside the reference electrode reservoir, and the second end of the wicking member contacts the membrane, the membrane being located outside the reference electrode reservoir.

26. The sensor assembly includes: a housing having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the housing further including a reference electrode reservoir and a sensor reservoir fluidly separated from the reference electrode reservoir by a membrane; 16. The fluid analyzer of claim 15, wherein one side of the membrane faces the reference electrode reservoir and the other side of the membrane faces the fluid flow path.

27. 26. The fluid analyzer of claim 25, wherein the sensor assembly further comprises at least one analyte sensor positioned in a sensor reservoir in fluid communication with the fluid flow path.

28. 16. The fluid analyzer of claim 15, wherein the membrane includes at least one pore, and the wicking member is configured to maintain a liquid junction in the membrane when exposed to a reference fluid.

29. 1. A method of forming a sensor assembly for a body fluid analyzer, comprising: positioning the membrane in fluid communication with a reference electrode reservoir configured to contain a reference electrode and to contain a reference fluid; positioning the wicking member to draw the reference fluid toward the membrane when the membrane and the wicking member are exposed to the reference fluid; The method comprising:

30. 30. The method of claim 29, wherein the step of positioning the wicking member further comprises contacting the wicking member with the membrane.

31. 30. The method of claim 29, further comprising sealing the membrane and wicking member from the reference fluid prior to positioning the reference fluid in the reference electrode reservoir.

32. 32. The method of claim 31 , wherein the sealing step further comprises sealing the membrane and wicking member with a plug operable from a closed position to an open position, wherein in the closed position the wicking member and membrane are sealed from the reference fluid and in the open position the wicking member and membrane are exposed to the reference fluid when the reference electrode container contains the reference fluid.

33. 33. The method of claim 32, wherein the step of positioning the membrane and wicking member further comprises positioning the membrane and wicking member in a pocket of a reference electrode reservoir.

34. 33. The method of claim 32, wherein the sealing step further comprises mating a plug with the pocket such that the wicking member is positioned within the pocket between the plug and the membrane.

35. 32. The method of claim 31 , wherein the sealing step further comprises sealing the membrane and wicking member with a pierceable barrier movable from a closed position to an open position, in which the wicking member and membrane are sealed from the reference fluid and in which the wicking member and membrane are exposed to the reference fluid when the reference electrode container contains the reference fluid.

36. 36. The method of claim 35, wherein the step of positioning the membrane and wicking member further comprises positioning the membrane and wicking member in a pocket of a reference electrode container.

37. 36. The method of claim 35, wherein the sealing step further comprises covering the pocket with a pierceable barrier such that the wicking member is positioned within the pocket between the pierceable barrier and the membrane.

38. 30. The method of claim 29, wherein the reference electrode reservoir is defined by a housing further including a sensor reservoir having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet and configured to transport a sample fluid, the sensor reservoir being fluidly separated from the reference electrode reservoir by a membrane, and wherein the step of positioning the membrane in the reference electrode reservoir further includes positioning the membrane such that one side of the membrane faces the reference electrode reservoir and the other side of the membrane faces the fluid flow path.

39. 30. The method of claim 29, wherein the membrane and wicking member are located inside the reference electrode container.

40. 30. The sensor assembly of claim 29, wherein the membrane and wicking member are located outside the reference electrode container.

41. 30. The sensor assembly of claim 29, wherein a first end of the wicking member is located inside the reference electrode container and a second end of the wicking member is located outside the reference electrode container, the second end of the wicking member contacting the membrane, and the membrane is located outside the reference electrode container.

42. 30. The method of claim 29, further comprising positioning at least one analyte sensor in a sensor reservoir in fluid communication with the fluid flow path.

43. 30. The method of claim 29, wherein the step of positioning the membrane further comprises a membrane including at least one pore, and wherein the wicking member maintains a liquid junction at the membrane when exposed to the reference fluid.

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