Patent Publication Number: US-2020278313-A1

Title: Sensor assembly and method of using same

Description:
The subject application claims benefit under 35 USC § 119(e) of U.S. provisional Application No. 62/587,856, filed Nov. 17, 2017. The entire contents of the above-referenced patent application are hereby expressly incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present disclosure relates to a sensing device which allows for multiple tests to be run concurrently using a small sample volume. 
     SUMMARY OF THE DISCLOSURE 
     In one embodiment, the present disclosure describes a method in which a sample is passed through a fluid flow path of a sensor assembly such that the sample intersects at least one sensor comprising at least three electrodes arranged such that two or more electrodes are opposing and two or more electrodes are beside one another. The sensor is read by a reader monitoring changes to the sensor in the presence of the sample. The reader measures the presence and/or concentration of one or more analytes within the sample based upon data obtained by the reader. 
     In other embodiments, the present disclosure describes a sensor assembly provided with a first substrate, and a second substrate. The first substrate comprises a first base layer, and a first electrical contact, the first base layer having a first surface and a second surface, a first sensor portion on the first surface and connected to the first electrical contact. The second substrate comprises a second base layer, a second sensor portion, and a plurality of second electrical contacts, the second base layer having a first surface and a second surface with the second sensor portion on the first surface of the second base layer. The first substrate and the second substrate are arranged in a layered structure in which the first surface of the first base layer and the first surface of the second base layer border a fluid flow path intersecting the first sensor portion and the second sensor portion, the first sensor portion aligned with the second sensor portion across the fluid flow path to form an electrochemical type of sensor. The second sensor portion includes a first electrode and a second electrode with the first electrode electrically isolated from the second electrode. 
     In yet another embodiment, the present disclosure describes a sensor assembly provided with a first substrate and a second substrate. The first substrate comprises a first base layer, the first base layer having a first surface and a second surface, two spaced apart first sensor portions on the first surface. The second substrate comprises a second base layer, the second base layer having a first surface and a second surface, two spaced apart second sensor portions on the first surface. The first substrate and the second substrate are arranged in a layered structure in which the first surface of the first base layer and the first surface of the second base layer border a fluid flow path, one of the first sensor portions is aligned with one of the the second sensor portions across the fluid flow path to form a first sensor, and the other one of the first sensor portions is aligned with the other one of the second sensor portions across the fluid flow path to form a second sensor. Each of the second sensor portions includes a first recognition element and a second recognition element. 
     In some embodiments, the first recognition element and the second recognition element are electrodes. 
     Additional features and advantages of the disclosure will be made apparent from the following detailed description of illustrative embodiments that proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a top plan view of one embodiment of an exemplary sensor assembly constructed in accordance with the present disclosure. 
         FIG. 2  is a cross-sectional diagram of the sensor assembly of  FIG. 1 , taken along the lines  2 -- 2 . 
         FIG. 3  is a cross-sectional diagram of the sensor assembly of  FIG. 1 , taken along the lines  3 -- 3 . 
         FIG. 4  is a diagrammatic, top plan view of a first substrate and a second substrate utilized to form the sensor assembly depicted in  FIG. 1 . 
         FIG. 5  is a block diagram illustrating a method of using the sensor assembly in accordance with the present disclosure. 
         FIGS. 6A and 6B  are diagrammatic views of incorporating the sensor assembly into a fluidic housing in accordance with the present disclosure. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before explaining at least one embodiment of the inventive concepts disclosed herein in detail, it is to be understood that the inventive concepts are not limited in their application to the details of construction and the arrangement of the components or steps or methodologies set forth in the following description or illustrated in the drawings. The inventive concepts disclosed herein are capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting the inventive concepts disclosed and claimed herein in any way. 
     In the following detailed description of embodiments of the inventive concepts, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. However, it will be apparent to one of ordinary skill in the art that the inventive concepts within the instant disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the instant disclosure. 
     As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherently present therein. 
     As used herein the terms “approximately,” “about,” “substantially” and variations thereof are intended to include not only the exact value qualified by the term, but to also include some slight deviations therefrom, such as deviations caused by measuring error, manufacturing tolerances, wear and tear on components or structures, settling or precipitation of cells or particles out of suspension or solution, chemical or biological degradation of solutions over time, stress exerted on structures, and combinations thereof, for example. 
     As used herein, the term “sample” and variations thereof is intended to include biological tissues, biological fluids, chemical fluids, chemical substances, suspensions, solutions, slurries, mixtures, agglomerations, tinctures, slides, powders, or other preparations of biological tissues or fluids, synthetic analogs to biological tissues or fluids, bacterial cells (prokaryotic or eukaryotic), viruses, singlecelled organisms, lysed biological cells, fixed biological cells, fixed biological tissues, cell cultures, tissue cultures, genetically engineered cells and tissues, genetically engineered organisms, and combinations thereof, for example. The sample can be in a liquid or a gaseous form. 
     Unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). An inclusive or may be understood as being the equivalent to: at least one of condition A or B. 
     In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the inventive concepts. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. 
     Finally, as used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the 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. 
     The inventive concepts disclosed herein are generally directed to the need to minimize the sample volume required to test two or more analytes concurrently. Low sample volumes are desirable when the sample is limited, such as in the case of neonatal patients, or when the sample itself is expensive. As opposed to prior art configurations, which required the volume to increase with the number of analytes being detected, the required sample volume can be greatly reduced when recognition elements of the sensors are arranged in a combination in which two or more recognition elements are facing one another in a sandwich configuration (also referred to as an opposing sensor array) and two or more recognition elements are in a non-opposing configuration which is also referred to herein as a side-by-side configuration or a coplanar configuration. Illustrative opposing and co-planar sensor arrays are discussed in connection with  FIGS. 1-4  below. 
     Referring now to the drawings, and in particular to  FIG. 1 , shown therein and designated by reference numeral  10  is one embodiment of a sensor assembly constructed in accordance with the present disclosure.  FIG. 2  is a cross-sectional view of the sensor assembly  10  taken along the lines  2 - 2 , and  FIG. 3  is another cross-sectional diagram of the sensor assembly  10  taken along the lines  3 - 3  depicted in  FIG. 1 . As will be discussed below, the sensor assembly  10  includes a plurality of sensors  11  positioned within a housing  12 . In  FIG. 1 , three sensors  11  are shown and designated by reference numerals  11   a ,  11   b  and  11   c  by way of example. It should be understood that the sensor assembly  10  may be provided with more or less of the sensors  11 . The sensors  11  can be configured to identify the same analyte of interest or different analytes of interest. For example, the sensor  11 a can be configured to detect an electrolyte, the sensor  1  lb can be configured to detect glucose, and the sensor  11 c can be configured to detect neonatal total bilirubin (nBili). 
     In general, the sensor assembly  10  is provided with a first substrate  14 , and a second substrate  18 , which collectively form the housing  12 . In one embodiment, the first substrate  14  and the second substrate  18  are shaped so as to form a fluid flow path  20  in which the sensors  11   a - c  are disposed. As will be described below, the sensors  11  are formed of multiple electrodes that are spaced apart and electrically isolated from one another. The sensors  11  may be used to identify and/or measure analytes of interest in the analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Each of the sensors  11  is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element (biochemical receptor). 
     The sensors  11  may be classified according to the biological specificity-conferring mechanism or, alternatively, the mode of physicochemical signal transduction. The biological recognition element may be based on a chemical reaction catalysed by, or on an equilibrium reaction with, macromolecules that have been isolated, engineered or present in their original biological environment. In the latter case, equilibrium is generally reached and there is no further, if any, net consumption of analyte(s) by the immobilized biocomplexing agent incorporated into the sensor  11 . The sensors  11  may be further classified according to the analytes or reactions that they monitor: direct monitoring of analyte concentration or of reactions producing or consuming such analytes; alternatively, an indirect monitoring of inhibitor or activator of the biological recognition element (biochemical receptor) may be achieved. 
     The sensors  11  may be of various types. For example, the sensors  11  may be selected from the group comprising an electrochemical sensor, an amperometric sensor, a blood glucose sensor, a potentiometric sensor, a conduct metric sensor, a thermometric sensor, an optical sensor, a fiber optic lactate sensor, a piezoelectric sensor, an immuno-sensor or the like. In certain instances, the sensors  11  may be disposable after one measurement, i.e., single use, and unable to monitor and analyte concentration continuously or at multiple instances of time. In other instances, the sensors  11  may be multi-use in which the sensors  11  are adapted to monitor an analyte concentration continuously or at multiple instances of time. The sensors  11  described herein are integrated devices utilized for detecting analytes of interest, and can be distinguished from an analytical system which incorporates additional separation steps such as high-performance liquid chromatography, or additional hardware and/or sample processing such as specific reagent introduction to identify an analyte of interest. In certain embodiments, the sensors  11  are reagentless analytical devices. 
     The sensors  11  will be described herein by way of example as an electrochemical type of sensor. It should be understood, however, that the skilled artisan will understand how to create other types of sensors  11  based upon the teachings within the present disclosure. 
     The electrochemical type of sensor  11  is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element (biochemical receptor) which is retained in direct spatial contact with an electrochemical transduction element. The electrochemical type of sensor  11  may be based upon the principle of a transfer of charge from an electrode to another electrode based upon an oxidation or reduction process. During this process, chemical changes take place at the electrodes and the charge is conducted through the sample. By measuring the transfer of charge, a determination of the presence and/or the amounts of analytes of interest may be made. Electrochemical types of sensors  11  may be based upon several principles, such as potentiometric, amperometric, or conductivity measurements. Also, the electrochemical type of sensors  11  may have the ability to be repeatedly calibrated without any reagent addition. 
     As will be discussed below, the electrochemical type of sensor  11  is provided with at least three recognition elements in the form of electrodes, that may be classified as a working electrode, a counter electrode, and a reference electrode. When the electrochemical type of sensor  11  is based upon potentiometric principles, a voltage potential difference between certain of the electrodes (e.g., a working electrode and a counter electrode) forming the electrochemical type of sensor  11  is read and interpreted. When the electrochemical type of sensor  11  is based upon amperometric principles, a current that is dependent upon the concentration of an analyte is read and interpreted. In some instances, the amount of the current is linearly dependent upon the concentration of analyte. Conductometric sensors are based on the measurement of electrolyte conductivity, which varies when the sensor is exposed to different environments. The electrodes of the electrochemical type of sensor  11 , in general, are fabricated of predetermined materials, dopings and/or coatings to provide analyte selectivity to the electrochemical type of sensor  11 . For example, the biological receptors, i.e. enzymes, antibodies, cells or tissues, with high biological activity, can be immobilized in a thin layer at the transducer surface by using different procedures, such as entrapment behind a membrane, entrapment within a polymeric matrix, entrapment of biological receptors within self-assembled monolayers or bilayer lipid membranes, covalent bonding of receptors on membranes or surfaces activated by bifunctional groups of spacers, or bulk modification of entire electrode material. Receptors may be immobilized either alone or may be mixed with other proteins, such as bovine serum albumin (BSA), either directly on the electrode, or on a polymer membrane covering the electrode. In the latter case, preactivated membranes can be used directly for the enzyme or antibody immobilization without further chemical modification of the membrane or macromolecule. 
     In accordance with the present disclosure, the first substrate  14  is provided with a first base layer  22 , and a plurality of first electrical contacts  26  (three of the first electrical contacts  26  being depicted in  FIG. 2  by way of example and designated by reference numerals  26   a ,  26   b , and  26   c ). The first base layer  22  may be made from, for example, ceramic, polymer, foil, or any other type of material known to someone of ordinary skill in the art. The first electrical contacts  26  are electrically isolated and may be constructed of an electrically conductive material, such as copper, aluminum, silver, gold, carbon nanotubes, or the like. The first base layer  22  may be provided with a first surface  30 , and a second surface  32 . The first surface  30  may be a planar surface, i.e., in the form of a plane. In other embodiments, the first surface  30  may be in the form of an arc, or include a combination of planar and arc shaped portions. The first electrical contacts  26  may extend through the first base layer  22  from the first surface  30  to the second surface  32  as shown in  FIG. 2  so that a reader (not shown) can be connected to the first electrical contacts  26 . In other embodiments, the first electrical contacts  26  may extend across portions of the first surface  30  and/or the second surface  32  so long as the first electrical contacts  26  may be connected to a reader. 
     The first substrate  14  is also provided with a plurality of first sensor portions  36  connected to and on the first surface  30 . The first sensor portions  36  extend over and cover at least a portion of the first surface  30 . Although it should be understood that in some embodiments the first sensor portions  36  do not directly contact the first surface  30 . Rather, one or more layers of material may be positioned between the first sensor portions  36  and the first surface  30 . In addition, in some embodiments, the first surface  30  is devoid of any reaction wells or other areas designed to retain a liquid around the first sensor portions  36 . In one embodiment, each of the first sensor portions  36  forms a part of one of the electrochemical sensors  11 . By way of example, three of the first sensor portions  36  are depicted and labeled with reference numerals  36   a ,  36   b  and  36   c . The first sensor portions  36  are spaced apart and electrically isolated from one another. Although the first sensor portions  36  are shown spaced apart in a generally linear arrangement, it should be understood that other arrangements and patterns of the first sensor portions  36  can be used in an effort to maximize the density of the first sensor portions  36 . For example, the first sensor portions  36  can be arranged in a staggered arrangement. In the example depicted in  FIGS. 2 and 4 , the first sensor portion  36   a  is spaced apart from the first sensor portion  36   b  and electrically isolated therefrom. Likewise, the first sensor portion  36   b  is spaced apart from the first sensor portion  36   c  and electrically isolated therefrom. Although only three of the first sensor portions  36  are depicted, it should be understood that the first substrate  14  can be provided with more or less of the first sensor portions  36 . The first sensor portions  36  can be made of an electrically conductive material using any suitable methodology, such as a thick film approach (e.g., screen printing, rotogravure, pad printing, stenciling conductive material such as carbon, Cu, Pt, Pd, Au, and/or Nanotubes, etc) or a thin film approach (e.g., by sputtering, thermal spraying, and/or cold spraying conductive material). While the first sensor portions  36  in  FIG. 4  are depicted as being rectangular, it should be understood that this is an exemplary configuration only. The first sensor portions  36  could be constructed in various shapes, such as a line, a circle, a triangle or the like. 
     Respective ones of the first electrical contacts  26  are connected to the first sensor portions  36 . Thus, for example, the first electrical contact  26   a  is connected to the first sensor portion  36   a  ; the first electrical contact  26   b  is connected to the first sensor portion  36   b  ; and the first electrical contact  26   c  is connected to the first sensor portion  36   c.    
     In accordance with the present disclosure, the second substrate  18  is provided with a second base layer  50 , and a plurality of second electrical contacts  52  (six of the second electrical contacts  52  being depicted in  FIG. 2  by way of example and designated by reference numerals  52   a ,  52   b ,  52   c ,  52   d ,  52   e  and  52   f ). The second base layer  50  may be made from, for example, ceramic, polymer, foil, or any other type of material known to someone of ordinary skill in the art. The second electrical contacts  52  are electrically isolated and may be constructed of an electrically conductive material, such as copper, aluminum, silver, gold, carbon nanotubes, or the like. It should be understood that in some embodiments the first electrical contacts  26  and the second electrical contacts  52  are optional. For instance, the the first electrical contacts  26  and the second electrical contacts  52  may not be included when the sensor  11  is an optical type of sensor that can be read by an optical reader, such as a reflectance meter or a photodetector. The second base layer  50  may be provided with a first surface  56 , and a second surface  60 . The second electrical contacts  52  may extend through the second base layer  22  from the first surface  56  to the second surface  60  as shown in  FIG. 2  so that a reader (not shown) can be connected to the second electrical contacts  26 . In other embodiments, the second electrical contacts  52  may extend across portions of the first surface  56  and/or the second surface  60  so long as the second electrical contacts  52  may be connected to a reader. 
     The second substrate  18  is also provided with a plurality of second sensor portions  64  on the first surface  56 . The second sensor portions  64  extend over and cover at least a portion of the first surface  56 . Although it should be understood that in some embodiments the second sensor portions  56  do not directly contact the first surface  56 . Rather, one or more layers of material may be positioned between the second sensor portions  36  and the first surface  56 . In addition, in some embodiments, the first surface  56  is devoid of any reaction wells or other areas designed to retain a liquid around the second sensor portions  64 . Although it should be understood that the first surface  36  can be shaped to form one or more reaction wells encompassing respective ones of the second sensor portions. In one embodiment, a combination of the first and second sensor portions  64  forms one of the electrochemical sensors  11 . By way of example, three of the second sensor portions  64  are depicted and labeled with reference numerals  64   a ,  64   b  and  64   c . The second sensor portions  64  are spaced apart and electrically isolated from one another. Although the second sensor portions  64  are shown spaced apart in a generally linear arrangement, it should be understood that other arrangements and patterns of the second sensor portions  64  can be used in an effort to maximize the density of the second sensor portions  64  on the first surface  56 . For example, the second sensor portions  64  can be arranged in a staggered arrangement. In the example shown, the second sensor portion  64   a  is spaced apart from the second sensor portion  64   b  and electrically isolated therefrom. Likewise, the second sensor portion  64   b  is spaced apart from the second sensor portion  64   c  and electrically isolated therefrom. Although only three of the second sensor portions  64  are depicted, it should be understood that the second substrate  18  can be provided with more or less of the second sensor portions  64 . The second sensor portions  64  can be made of an electrically conductive material using any suitable methodology, such as a thick film approach (e.g., screen printing, rotogravure, pad printing, stenciling conductive material such as carbon, Cu, Pt, Pd, Au, and/or Nanotubes, etc. . . . ) or a thin film approach (e.g., by sputtering, thermal spraying, and/or cold spraying conductive material). 
     When the sensor assembly  10  is assembled, the first substrate  14  and the second substrate  18  are arranged in a layered structure in which the first surface  30  of the first base layer  22  extends over and covers the first surface  56  of the second base layer  50 . The first surface  30  of the first base layer  22  and the first surface  56  of the second base layer  50  also border the fluid flow path  20 . The first substrate  14  can be bonded to the second substrate  18  in a variety of manners, such as using a cohesive, an adhesive, pressure sensitive adhesive, ultraviolet adhesive, thermal adhesive, ultrasonic welding, thermal tacking procedures, or mechanical coupling (e.g., tongue and groove construction). When the first substrate  14  and the second substrate  18  are bonded, the first sensor portions  36  are aligned with the second sensor portions  64  and spaced apart there from so that the sample can flow between the first sensor portions  36  and the second sensor portion  64 . In some embodiments, the first sensor portion  36  can be characterized as a single electrode  70 . The first sensor portion  36  and the second sensor portion  64  of each electrochemical type of sensor  11  is spaced apart vertically an amount sufficient to electrically isolate the first sensor portion  36  from the second sensor portion  64  in the absence of a sample contacting the first sensor portion  36  and the second sensor portion  64 , while permitting the first sensor portion  36  and the second sensor portion  64  to work together to identify an analyte of interest in the presence of the sample. To prevent interference between the electrochemical type of sensors  11 , the electrochemical type of sensors  11  are spaced laterally from one another the amount of spacing can be determined based upon the types of sensors  11 , the types of samples anticipated to be analyzed, and a desired useful life of the sensor. For example, when the sensors  11  will be used for identifying analytes of interest in blood, and have a desired useful life of  30  days, then a  1 mm spacing between sensors  11  can be used. If a shorter useful life is desired, then the sensors  11  can be spaced closer together. 
     The second sensor portions  64  are provided with two or more electrodes. In  FIG. 2 , the second sensor portions  64  include a first electrode  72  and a second electrode  74  with the first electrode  72  electrically isolated from the second electrode  74  in the absence of a sample contacting the first electrode  72  and the second electrode  74 . The first electrode  72  and the second electrode  74  are spaced apart a sufficient distance to maintain electrical isolation in the absence of a sample contacting the first electrode  72  and the second electrode  74 , while establishing fluidic contact in the presence of the sample to permit the first and second electrodes  72  and  74  to work together to assist in identifying the analyte of interest. The spacing between the first electrode  72  and the second electrode  74  can vary depending upon a type of dielectric between the first electrode  72  and the second electrode  74 , as well as a type of sample anticipated to be used with the first electrode  72  and the second electrode  74 . In this example, each of the electrochemical type of sensors  11  include a single electrode  70  residing on the first surface  30  of the first base layer  22 , and the first electrode  72 , and the second electrode  74  residing on the first surface  56  of the second base layer  50 . 
     While the first and second electrodes  72  and  74  in  FIG. 4  are depicted as being rectangular, it should be understood that this is an exemplary configuration only. The first and second electrodes  72  and  74  of the second sensor portions  64  could be constructed in various shapes, such as a line, a circle, an arc shape, a triangle or the like. In  FIG. 2 , the first surface  56  of the second base layer  50  is a planar surface. In this example, the first and second electrodes  72  and  74  are arranged in a co-planar configuration. Thus, the electrodes  70 ,  72  and  74  of the electrochemical type of sensors  11  are arranged in a combination in which two or more electrodes (e.g., the electrodes  70  and  74 ) are connected to different support structures (in this case the electrode  70  is connected to the first substrate  14  and the electrode  74  is connected to the second substrate  18 ) and face one another in a sandwich configuration (also referred to as an opposing sensor array) across the fluid flow path  20 , and two or more electrodes (e.g., the electrodes  72  and  74 ) are connected to a same surface of a support structure (in this example the first surface  56  of the second substrate  18 ) in a coplanar configuration. In one embodiment, the electrode  70  can be a reference electrode, the electrode  72  can be a working electrode, and the electrode  74  can be a counter electrode. In other embodiments, one or more of the electrochemical sensors  11  could also have an inactive working electrode. In this instance, the inactive working electrode would be a part of the second sensor portion  64 . 
     Respective ones of the second electrical contacts  52  are connected to the second sensor portions  64 . Thus, for example, the second electrical contact  52   a  is connected to the electrode  72  of the electrochemical type of sensor  11 a; the second electrical contact  52   b  is connected to the electrode  74  of of the electrochemical type of sensor  11   a ; the second electrical contact  52   c  is connected to the electrode  72  of the electrochemical type of sensor  11   a ; the second electrical contact  52   d  is connected to the electrode  74  of the electrochemical type of sensor  11   b ; the second electrical contact  52   e  is connected to the electrode  72  of the electrochemical type of sensor  11   c ; and the second electrical contact  52   f  is connected to the electrode  74  of the electrochemical type of sensor  11   c.    
     As shown in  FIGS. 3 and 4 , the second substrate  18  may also be provided with two spaced apart side walls  80 ,  82 , and end walls  83 ,  84  extending between the first surface  30  of the first base layer  22  and the first surface  56  of the second base layer  50  to define the fluid flow path  20 . In this embodiment, the first surface  30  of the first base layer  22 , the first surface  56  of the second base layer  50 , the sidewalls  80 ,  82 , and the end walls  83 ,  84  border the fluid flow path  20 . In the example shown, the sidewalls  80 ,  82 , and the end walls  83 ,  84  may be integrally formed with the second base layer  50  to form a unitary structure. In other embodiments, the sidewalls  80 ,  82 , and end walls  83 ,  84  may be applied onto the first surface  30  of the first base layer  22 , or the first surface  56  of the second base layer  50 . The sidewalls  80 ,  82 , and end walls  83 ,  84  are designed so as to not interfere with the reactions (e.g., electrochemical reactions) caused by an interaction with the sample and the electrochemical type of sensors  11 . In one embodiment, the sidewalls  80 ,  82 , and end walls  83 ,  84  are either constructed with a dielectric material, or coated with a dielectric material. It should also be understood that the sidewalls  80 ,  82 , and end walls  83 ,  84  may be integral with or bonded to the first base layer  22 . When the sidewalls  80 ,  82 , and end walls  83 ,  84  are not integral with the first base layer  22  or the second base layer  50 , the sidewalls  80 ,  82 , and end walls  83 ,  84  may be referred to herein as a dielectric layer having an opening  85  (see  FIG. 4 ) forming the fluid flow path  20  and being closed by the first base layer  22  or the second base layer  50 . 
     As shown in  FIG. 1 , the sensor assembly  10  is also provided with a first end  86  and a second end  88 . In the example shown, the fluid flow path  20  extends generally between the first end  86  and the second end  88 , but is separate from (i.e., does not intersect) either one of the first end  86  or the second end  88 . For example, as shown in  FIG. 4 , the first base layer  22  may be provided with an inlet  90  and an outlet  92  that intersect the fluid flow path  20  when the first substrate  14  is bonded to the second substrate  18 . In this example, the inlet  90  and the outlet  92  extend through the first base layer  22  from the first surface  30  to the second surface  32  to permit a sample to be disposed within the fluid flow path  20  and flow from the inlet  90  to the outlet  92 . As will be appreciated by a person skilled in the art, inlet  90  and/or outlet  92  may be formed in a variety of ways. For example, inlet  90  and/or outlet  92  may be openings in the side of the sensor assembly  10 , may be ports (e.g., apertures) formed in one or more layers of first and second substrates  14  and  18 . In addition, the first and second substrates  14  and  18  can be designed for the fluid flow path  20  to intersect either one or both of the first end  86  or the second end  88 . In some embodiments, the first and second substrates  14  and  18  can be designed to provide two or more fluid flow paths  20 , e.g., with one or more of the electrochemical sensors  11  in one or more of the fluid flow paths  20 . 
       FIG. 5  shows a process  100  of measuring the presence and/or concentration of an analyte in accordance with the presently disclosed concepts. In use, the sample is passed through the fluid flow path  20  as indicated by a block  102 . This can be accomplished by introducing the sample into the fluid flow path  20  and using a motive force, such as a pump or capilarry action, to move the sample through the fluid flow path  20  to intersect the sensors  11   a ,  11   b  or  11   c  as shown in block  104 . As shown in block  106 , as the sample intersects the sensors  11  (or a delay from when the sample intersects the sensors  11 ), the sensors  11  can be read by a reader. For example, the first electrical contacts  26  and the second electrical contacts  52  can be read by a reader when certain ones of the sensors  11  are of the electrochemical type. Or, light emitted from the sensors  11  that are of an optical type (e.g., fluoresce in the presence of an analyte of interest) can be detected by an optical detector, such as a photodetector or a grid of photodetectors. In either case, the reader(s) receive the information (e.g., changes in voltage, amperage, or conductivity, optical signals, or the like), and uses the information to measure the presence and/or concentration of one or more analytes within the sample as indicated by block  108 . 
     While the present disclosure has been described in connection with the exemplary embodiments of the various figures, it is not limited thereto and it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiments for performing the same function of the present disclosure without deviating therefrom. 
     For example,  FIGS. 6A and 6B  depict an embodiment in which sensor assembly  10  is incorporated into a fluidic housing  110 . Fluidic housing  110  may be made of molded plastic and/or polymer and have microfluidic and/or macrofluidic channels  112  incorporated therein (represented by the dashed arrows/box). The sensor assembly  10  can then be inserted into an opening  114  into the housing  110  such that the fluid flow path(s)  20  are placed in fluidic contact with the microfluidic and/or macrofluidic channels  112  such that liquid flows through from the channels  112  into the sensor assembly  10  and back into the channels  112  in the direction of the fluid flow path  20 . 
     Sensor assembly  10  can be bonded to the fluidic housing  110  via, for example, adhesive, ultrasonic welding, thermal sealing, and solvent bonding, etc. 
     In certain embodiments, the present disclosure describes a method in which a sample is passed through a fluid flow path of a sensor assembly such that the sample intersects at least one sensor comprising at least three electrodes arranged such that two or more electrodes are opposing and two or more electrodes are beside one another. The sensor is read by a reader monitoring changes to the sensor. The reader measures the presence and/or concentration of one or more analytes within the sample based upon data obtained by the reader. 
     In other embodiments, the present disclosure describes a sensor assembly provided with a first substrate, and a second substrate. The first substrate comprises a first base layer, and a first electrical contact, the first base layer having a first surface and a second surface, a first sensor portion on the first surface and connected to the first electrical contact. The second substrate comprises a second base layer, a second sensor portion, and a plurality of second electrical contacts, the second base layer having a first surface and a second surface with the second sensor portion on the first surface of the second base layer. The first substrate and the second substrate are arranged in a layered structure in which the first surface of the first base layer and the first surface of the second base layer border a fluid flow path intersecting the first sensor portion and the second sensor portion, the first sensor portion aligned with the second sensor portion across the fluid flow path to form an electrochemical type of sensor. The second sensor portion includes a first electrode and a second electrode with the first electrode electrically isolated from the second electrode. 
     In yet another embodiment, the present disclosure describes a sensor assembly provided with a first substrate and a second substrate. The first substrate comprises a first base layer, the first base layer having a first surface and a second surface, two spaced apart first sensor portions on the first surface. The second substrate comprises a second base layer, the second base layer having a first surface and a second surface, two spaced apart second sensor portions on the first surface. The first substrate and the second substrate are arranged in a layered structure in which the first surface of the first base layer and the first surface of the second base layer border a fluid flow path, one of the first sensor portions is aligned with one of the the second sensor portions across the fluid flow path to form a first sensor, and the other one of the first sensor portions is aligned with the other one of the second sensor portions across the fluid flow path to form a second sensor. Each of the second sensor portions includes a first recognition element and a second recognition element. 
     In some embodiments, the first recognition element and the second recognition element are electrodes. 
     Therefore, the present disclosure should not be limited to any single embodiment, but rather should be construed in breadth and scope in accordance with the appended claims. Also, the appended claims should be construed to include other variants and embodiments of the disclosure, which may be made by those skilled in the art without departing from the true spirit and scope of the present disclosure.