Patent Application
20110186428
Electrochemical biosensors are known. They have been used to determine the concentration of various analytes from biological samples, particularly from blood. Electrochemical biosensors are described in U.S. Pat. Nos. 5,413,690; 5,762,770; 5,798,031; 5,997,8171; 7,073,246; 7,195,705; and 7,473,398 and U.S. Patent Application Publication No. 2005/0016844, the disclosure of each of which is expressly incorporated herein by reference.
For example, as the number of patients suffering from diabetes and similar medical conditions increases, self-monitoring of blood glucose wherein the patient monitors his or her blood glucose levels has become a common practice. The purpose of monitoring the blood glucose level is to determine the concentration level and then to take corrective action, based upon whether the level is too high or too low, to bring the level back within a normal range. The failure to take corrective action can have serious medical implications. Glucose monitoring is a fact of everyday life for diabetic individuals. Failure to test blood glucose levels properly and on a regular basis can result in serious diabetes-related complications, including cardiovascular disease, kidney disease, nerve damage and blindness.
A number of biosensors employ electrochemical analysis to determine the blood glucose level by measuring a current related to an analyte concentration. Such biosensors may employ a capillary channel with an electrode substrate providing a working electrode area in the capillary channel. The current response of the electrochemical cell is directly proportional to the working electrode area. However, variations in the working electrode area are created during the manufacture and assembly of the components of the biosensor that define the capillary channel. Variations in the working electrode area in the capillary channel from one biosensor to another are undesirable since the variation in electrode area introduces imprecision in the measured analyte concentration. Therefore, biosensor arrangements which minimize variations in the working electrode area in the manufacture of the biosensor are desirable.
The present invention relates to a biosensor. The biosensor includes a support substrate, electrodes positioned on the support substrate, a spacer substrate positioned on the support substrate, and a cover positioned on the spacer substrate. The cover cooperates with the support substrate to define a capillary channel. The electrodes include at least one working electrode defining a working electrode area in the capillary channel. The working electrode is configured to minimize variation of the effective working electrode area in the capillary channel due to variations in the spacer substrate placement relative to the working electrode while also maximizing the effective working electrode area within the capillary channel.
According to one aspect, a biosensor comprises a support substrate extending between opposite first and second ends and opposite first and second edges; a spacer substrate positioned on the support substrate that includes an inner edge extending along the support substrate between the first and second ends and the first and second edges; a cover cooperating with the spacer substrate so that the inner edge of the spacer substrate defines a boundary of a capillary channel; and at least one working electrode in the capillary channel. The working electrode includes a width and a main body portion extending along a length transversely to the width between opposite ends of the main body portion. The main body portion includes at least two working electrode portions positioned along the length of the main body portion in the capillary channel with the at least two working electrode portions connected by at least one connecting portion. The working electrode further includes at least one connective neck extending from at least one of the opposite ends of the main body portion and across the inner edge of the spacer substrate. The two working electrode portions each define a minimum or least width that is greater than a maximum or greatest width of the connective neck, and the connecting portion defines a maximum or greatest width that is less than a minimum or least width of the connective neck.
In one refinement of the aspect, the capillary channel includes an inlet at the first end of the support substrate and the main body portion of the working electrode is located entirely within the capillary channel.
In a further refinement of the aspect, the working electrode includes a second neck extending from the other of the opposite ends of the main body portion in the capillary channel, the second neck extending across the inner edge of the spacer substrate.
In a further refinement of the aspect, the working electrode includes first and second connecting portions extending between and connecting the at least two working electrode portions to one another in the capillary channel. The first and second connecting portions each include a maximum or greatest width that is less than the minimum or least width of the connective neck, and the first and second connecting portions are separated from one another by a non-conductive space between the connecting portions and working electrode portions.
In another refinement of the aspect, the at least one connecting portion of the working electrode includes a plurality of rows of connecting portions extending between the at least two working electrode portions of the working electrode. Adjacent pairs of the rows of connecting portions are separated from one another by a non-conductive space, and each row of the connecting portions includes a maximum or greatest width that is less than the minimum or least width of the at least one connective neck.
In another refinement of the aspect, the at least two working electrode portions of the main body portion of the working electrode includes a plurality of working electrode portions spaced along the plurality of rows of connecting portions to form a grid-shaped pattern for the main body portion of the working electrode.
According to another aspect, a biosensor comprises a support substrate extending between opposite first and second ends and opposite first and second edges; a spacer substrate positioned on the support substrate that includes an inner edge extending along the support substrate with the inner edge being located between the first and second ends and the first and second edges of the support substrate; a cover cooperating with the spacer substrate so that the inner edge of the spacer substrate defines a boundary of a capillary channel; and at least one working electrode. The at least one working electrode includes a main body portion defining a width and a length transverse to the width between opposite ends of the main body portion. The length and width are sized so that the main body portion is located in the capillary channel. The working electrode further includes first and second connective necks each extending from a respective one of the opposite ends of the main body portion and across the inner edge of the spacer substrate. The main body portion defines a minimum or least width that is greater than a maximum or greatest width of each of the first and second necks. Each of the first and second connective necks extends from the main body portion to an electrode lead on the support substrate so that each of the first and second connective necks provides an electrical connection with the working electrode.
In one refinement of the aspect, the main body portion of the working electrode includes a maximum width at a center of the main body portion and tapers in width from the center toward each of the first and second connective necks.
In another refinement of the aspect, the first connective neck extends to an electrode lead that extends along the support substrate to an electrode contact, and the second connective neck extends to an electrode looping portion located outside the capillary channel. The electrode looping portion joins the second connective neck to the electrode lead so that the working electrode forms a continuous loop located within and outside the capillary channel.
According to another aspect, a biosensor comprises a support substrate extending between opposite first and second ends and opposite first and second edges; a spacer substrate positioned on the support substrate that includes an inner edge extending along the support substrate, the inner edge extending from the first edge to the second edge adjacent the first end of the support substrate; a cover cooperating with the spacer substrate so that the inner edge of the spacer substrate defines a boundary of a capillary channel; and at least one working electrode in the capillary channel. The working electrode includes a main body portion with a length that extends toward the first and second edges within the capillary channel. The working electrode further includes a connective neck extending from an end of the main body portion toward the second end of the support substrate. The inner edge is spaced from the main body portion and extends across the connective neck where the connective neck is oriented to extend toward the second end of the support substrate.
In one refinement of the aspect, the main body portion of the working electrode is located entirely within the capillary channel.
In another refinement of the aspect, the working electrode includes first and second connective necks extending from opposite ends of the main body portion toward the second end of the support substrate and the inner edge extends across each of the first and second connective necks where the first and second connective necks are oriented toward the second end of the support substrate.
In another refinement of the aspect, the main body portion includes a minimum or least width along a substantial portion of the length and the connective neck includes a maximum or greatest width as measured in a direction toward the first and second edges of the support substrate, the minimum width of the main body portion being greater than the maximum width of the connective neck.
According to another aspect, a method for manufacturing a biosensor comprises: providing a support substrate; forming at least one working electrode on the support substrate, the working electrode including a main body portion and at least one connective neck extending from an end of the main body portion, wherein a width of the at least one connective neck is greater than a minimum or least width of part of the main body portion of the working electrode; and positioning a spacer substrate on the support substrate, the spacer substrate including an inner edge that defines a boundary of a capillary channel, the inner edge extending across the at least one connective neck of the working electrode so that the part of the main body portion defining the minimum width is located entirely within the capillary channel.
According to another aspect, a method for manufacturing a biosensor comprises: providing a support substrate; forming at least one working electrode on the support substrate, the working electrode including a main body portion defining a substantially constant width along a substantial portion of a length of the main body portion, the working electrode including a central portion projecting outwardly from the width; and positioning a spacer substrate on the support substrate so that opposite portions of an inner edge of the spacer substrate extend across opposite lateral portions of the main body portion and the central portion of the working electrode is positioned entirely within a capillary channel defined by portions of the inner edge, wherein the central portion occupies less than half of the length of the main body portion between the portions of the inner edge.
Further aspects, embodiments, forms, features, benefits, objects, and advantages shall become apparent from the detailed description and figures provided herewith.
For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
The present invention relates to a biosensor and a method for manufacturing a biosensor that reduces sensitivity of the effective working electrode area to manufacturing variations. The present invention improves precision and accuracy of current measurements in electrochemical analysis of an analyte positioned in a capillary channel of the biosensor in contact with the effective working electrode area. The biosensor and method for manufacturing are relatively low in cost since the advantages are achieved without necessarily requiring significant additional steps or materials in the manufacturing process, such would be involved in screen printing of insulating overlays to define the working electrode area. Aspects of the invention are presented in
Biosensor 10 is shown as rectangular in shape, it being understood, however, that biosensor 10 can be provided in any one of a number of shapes in accordance with principles of this disclosure. Furthermore, biosensor 10 can be any one of a substantial quantity of biosensors produced from rolls of material, sheets of material, or other material stock in accordance with the principles of this disclosure. In one embodiment, the selection of materials for the construction of biosensor 10 includes a stock sufficiently flexible for roll processing, but still rigid enough to give a useful stiffness to finished biosensor 10. The biosensor arrangement and method for manufacturing the biosensor described herein minimizes variations in effective working electrode area from one biosensor to the next, improving precision and accuracy of current readings measured by the working electrode during electrochemical analysis of a fluid sample.
Variation in effective working electrode area can be caused by imprecision in forming the working electrode, or at least the portion of the working electrode exposed within the capillary channel. However, the variation problem attempted to be solved by the present invention is caused by imprecision in forming the capillary channel itself where the effective working area is exposed. For a biosensor which utilizes a spacer layer to define the capillary channel, imprecision may lie in the inner edge or edges formed in the spacer layer to define the capillary channel. This affects effective working electrode area where the working electrode extends across that inner edge, wherein deviation of the inner edge of the spacer at that location directly increases or decreases the exposed portion of the working electrode within the capillary channel, thereby increasing or decreasing the effective working electrode area. Thus, the present invention relates to working electrode configurations designed to minimize the overall impact of imprecision of the inner edge on the total working electrode area exposed in the capillary channel.
The electrode-support substrate 12 is shown in
Electrodes 14, 16, 18 are formed from conductor 13 provided on first surface 24 of support substrate 12. Non-limiting examples of material suitable for electrical conductor 13 include aluminum, carbon (such as graphite), cobalt, copper, gallium, gold, indium, iridium, iron, lead, magnesium, mercury (as an amalgam), nickel, niobium, osmium, palladium, platinum, rhenium, rhodium, selenium, silicon (such as highly doped polycrystalline silicon), silver, tantalum, tin, titanium, tungsten, uranium, vanadium, zinc, zirconium, mixtures thereof, and alloys, oxides, or metallic compounds of these elements. In one specific embodiment, electrodes 14, 16, 18 are isolated from the rest of the electrical conductor 13 by laser ablation or laser scribing, and electrodes 14, 16, 18 are created by removing the electrical conductor 13 from an area extending around the electrodes either broadly, such as by broad field ablation, or minimally, such as by line scribing. Other embodiments contemplate other techniques for forming electrodes 14, 16, 18 as would occur to those of ordinary skill in the art, such as lamination, screen-printing, or photolithography.
Electrodes 14 and 18 define reference or counter electrode 60 and electrode 16 defines working electrode 70, at least a portion of each of which are located in capillary channel 25. Leads 62, 64 extend away from the counter electrode 60, and lead 72 extends away from working electrode 70. Leads 62, 64, 72 extend from the electrodes 60, 70 to contacts 36, 38, 40, respectively, at the second end 30 of the electrode-support substrate 12. Contacts 36, 38, 40 provide an electrical connection with a meter (not shown) or other device when biosensor 10 is positioned therein. It is contemplated that the leads 62, 64, 72 extending from the electrodes 60, 70 can be formed to have any suitable length and extend to any suitable location on the electrode-support substrate 12. It is further contemplated that the configuration of the electrodes, the number of electrodes, as well as the spacing between the electrodes may vary in accordance with this disclosure and that more than two electrodes may be formed as illustrated and discussed further herein.
Spacer substrate 20 of biosensor 10 includes a first member 40 extending between the edges 32, 34 of the electrode-support substrate 12. It is contemplated that spacer substrate 20 may be comprised of a single member or a plurality of members. First member 40 includes an inner edge 50 facing the capillary channel 25 and defining a boundary of capillary channel 25. In the illustrated embodiment of
When spacer substrate 20 is coupled to support substrate 12, electrodes 60 and 70 are positioned to lie within the capillary channel 25 formed by spacer substrate 20 between support substrate 12 and cover 22. Any variation in the width of the capillary channel 25 defined by inner edge 50 introduces variation in the effective area of working electrode 70 that is located in capillary channel 25, resulting in imprecision of the current measured related to an analyte concentration. Biosensor 10 is arranged to maximize the effective area of working electrode 70 certain to be exposed when spacer substrate 20 is positioned on support substrate 12 relative to the effective area of working electrode 70 that may be unintentionally exposed or covered by spacer substrate 20.
Spacer substrate 20 is formed from an insulative material, such as, for example, a flexible polymer including an adhesive coated polyethylene terephthalate (PET)-polyester. A non-limiting example of a suitable material includes a white PET film, both sides of which are coated with a pressure-sensitive adhesive. It is contemplated that spacer substrate 20 may be constructed of a variety of materials and includes an inner surface 44 that may be coupled to support substrate 12 and an outer surface 46 coupled to the cover substrate 22 using any one or combination of a wide variety of commercially available adhesives. Additionally, when surface 24 of support substrate 12 is exposed and not covered by electrical conductor 13, spacer substrate 20 may be coupled to support substrate 12 by welding, such as heat or ultrasonic welding. It is also contemplated that first surface 24 of support substrate 12 may be printed with, for example, product labeling or instructions (not shown) for use of biosensor 10.
Cover substrate 22 is coupled to upper surface 46 of spacer substrate 20. Cover substrate 22 includes an inner surface 58 facing spacer substrate 20 and an outer surface 59. In addition, cover substrate 22 includes opposite first and second ends 61, 63 and edges 66, 68 extending between the first and second ends 61, 63. When biosensor 10 is assembled, cover 22 cooperates with the spacer support substrate 20 and the electrode-support substrate 12 to define a sample receiving chamber or capillary channel 25. Cover substrate 22 is generally rectangular in shape; it is appreciated, however, that the cover substrate 22 may be formed in one of a variety of shapes and sizes in accordance with the principles of this disclosure. Cover substrate 22 may be formed from a flexible polymer and preferably from a polymer such as a polyester or polyimide. A non-limiting example of a suitable polymer is a hydrophilic polyester film.
Referring now to
It is further contemplated that electrochemical reagents can be positioned on counter and working electrodes 60, 70. The reagents provide electrochemical probes for specific analytes. The choice of specific reagents depend on the specific analyte or analytes to be measured, and are well known to those of ordinary skill in the art. An example of a reagent that may be used in biosensor 10 is a reagent for measuring glucose from a whole blood sample.
One arrangement of counter electrode 60 and working electrode 70 in capillary channel 25 is further shown in
Furthermore, measurement accuracy is improved by both connective necks 76 providing connectivity of working electrode 70 to contact 40 through at least lead 72. An electrode looping portion 78 extends under spacer substrate 20 from connective neck 76 on one side of working electrode 70 and is joined to lead 72 extending from the other connective neck 76 at a location adjacent to the capillary channel 25.
To the extent a biosensor comprising an electrode looping portion 78 is a desirable basic embodiment, the connective necks 76 further enable minimizing the effective area of the looping portion which minimizes the susceptibility of the electrode, particularly the working electrode, to electromagnetic interference.
Working electrode 270 includes a main body portion with a pair of working electrode portions 274a, 274b spaced along its length. Working electrode portion 274a, 274b each have a minimum width W1 transverse to the length, and are sized to be located entirely in capillary channel 25. Necks 276 extend from the opposite ends of respective ones of the working electrode portions 274a, 274b and include sufficient lengths to extend across inner edge 50 to a location outside capillary channel 25. One of the necks 275 is a terminal neck, meaning generally that it terminates outside the capillary channel and does not extend or lead to another portion of the electrode 16, while the other neck 276 is connected with a lead that extends to at least one contact 40 on support substrate 12. Necks 276 each have a maximum width W2 that is substantially less than minimum width W1.
Furthermore, working electrode portions 274a, 274b are connected to one another by a connecting portion 278 having a maximum width W3 that is less than a minimum width of either of necks 276. Since the effective area of the working electrode portions 274a, 274b certain to be located in capillary channel 25 is substantially greater than the variation in the effective area of necks 276 caused by inner edge 50, variation in the effective working electrode area in capillary channel 25 is minimized.
Working electrode portions 274a″, 274b″ each include an oval shape that extends between the respective neck 276 and connecting portion 278. In one embodiment, the increased area of the working electrode portions is formed by adding electrode material to the location between neck 276 and connecting portion 278. In another embodiment, the increased area of the electrode portion is formed by removing or covering sufficient electrode material between and around main body portions 274a″, 274b″ to form connecting portion 278 and necks 276. For example, insulator material could be printed, or adhesive and/or spacer material placed, in capillary channel 25 to cover sufficient conductor material to form the desired shape and configuration of the main body portion.
In one embodiment, lateral portions 276a″, 276b′ extend along at least 50% of the overall length of working electrode 270′″ between the opposite sides of inner edge 50. In another embodiment, lateral portions 276a″, 276b′ extend along at least 75% of the overall length of working electrode 270′″ between the opposite sides of inner edge 50. The outwardly projecting central body portion 274a′″ increases the effective area of the working electrode 270′ certain to be located in capillary channel 25, reducing the effect of variability in the effective working electrode area created by inner edge 50. Central body portion 274a′″ is formed in one embodiment by including additional conductor material to the working electrode between lateral portions 276a′″, 276b′″ to increase the width at or near the center of working electrode 270′″. Rather than include additional conductor material, the spacer may be configured (or insulative material added) so that the exposed width of lateral portions 276′″ is reduced, with the unreduced portion of the width forming central body portion 274a′″.
One useful aspect of certain of these embodiments is that the at least one connective portions of the embodiments of
In the
One useful aspect of certain of these embodiments having the “open” areas or non-conductive portions of the working electrode that are completely or at least partially surrounded by conductive portions of the electrode, such as shown in
In the illustrated embodiment, working electrode portions 578 each include a substantially circular shape. Other embodiments contemplate other node-like shapes for working electrode portions 578, including oval, square, rectangular, polygonal, and non-circular shapes, for example. In the illustrated embodiment, the plurality of nodes include five node-shaped working electrode portions and the connecting portion includes four connecting portions, and adjacent pairs of the working electrode portions are connected by respective ones of the four connecting portions. Other embodiments contemplate two or more node-shaped portions with an appropriate number of connecting portions connecting the node-shaped portions.
Working electrode 660 includes a main body portion 674 extending laterally between toward the side edges of support substrate 612, and opposite connective necks 676 that extend transversely from main body portion 674 toward the end of biosensor 10 opposite capillary channel 625. Spacer substrate 612 is positioned so that inner edge 650 extends across connective necks 676 and so that main body portion 674 is located entirely within capillary channel 625. This arrangement maximizes the area of working electrode 670 certain to be located in capillary channel 625 relative to the variation in effective working electrode area that may result due to the placement location of inner edge 650 along connective necks 676 and/or due to any irregularities in the boundaries of capillary channel 625 formed by inner edge 650.
In
The embodiment of
In
In use, a number of the biosensors are typically packaged in a vial, usually with a stopper or other arrangement formed to seal the vial. It is appreciated, however, that the biosensors may be packaged individually, or biosensors can be folded upon one another, rolled in a coil, stacked in a cassette magazine, packed in blister packaging. In another embodiment, the packaging is formed as a card with removable individual segments comprised of biosensors, examples of which may be found in U.S. application Ser. No. 12/198,197 entitled “BIOSENSOR TEST STRIP CARDS,” the contents of which are incorporated herein by reference in its entirety. Since the biosensors include the herein described arrangements to maximize the area of the working electrode certain to be located in the capillary channel relative to the area of the portion of the working electrode affected by placement of the inner edge of the spacer substrate, the precision of the analyte measurements taken with the biosensors is improved.
Many fluid sample types may be analyzed using the biosensors discussed herein. For example, human body fluids such as whole blood, plasma, sera, lymph, bile, urine, semen, cerebrospinal fluid, spinal fluid, lacrimal fluid and stool specimens as well as other biological fluids readily apparent to one skilled in the art may be measured. Fluid preparations of tissues can also be assayed, along with foods, fermentation products and environmental substances, which potentially contain environmental contaminants. Preferably, whole blood is assayed with the biosensor.
A user of the biosensor places a finger having a blood collection incision or puncture against the inlet to the capillary channel. Capillary forces pull a liquid blood sample flowing from the incision or puncture into and through the capillary channel across the reagents and the electrodes in the capillary channel. The liquid blood sample dissolves the reagents and engages the electrodes in the capillary channel where the electrochemical reaction takes place.
Sometime after the reaction has begun, a power source (e.g., a battery) applies a potential difference between the electrodes respectively. When the potential difference is applied, the amount of oxidized form of the mediator at the reference or counter electrode and the potential difference must be sufficient to cause electro-oxidation of the reduced form of the mediator at the surface of the working electrode. A current measuring meter (not shown) measures the current generated by the oxidation of the reduced form of the mediator at the surface of the working electrode. The biosensors discussed herein minimize the variation in the working electrode area in the capillary channel, improving the accuracy and precision of the measured current from one biosensor to the next.
An example of a biosensor configured for use with electrochemical techniques is the ACCU-CHEK® Aviva test strip, which is described more fully in U.S. Patent Application Publication No. 2005/0016844, the disclosure of which is hereby incorporated herein by reference in its entirety. This exemplary test element is distributed in the United States by Roche Diagnostics Corporation of Indianapolis, Ind.
One illustrative method for manufacturing a biosensor includes providing a support substrate; forming at least one working electrode on the support substrate, the working electrode including a main body portion and at least one connective neck extending from an end of the main body portion, wherein a width of the at least one connective neck is greater than a minimum width of part of the main body portion of the working electrode; and positioning a spacer substrate on the support substrate, the spacer substrate including an inner edge that defines a boundary of a capillary channel, the inner edge extending across the at least one connective neck of the working electrode so that the part of the main body portion defining the minimum width is located entirely within the capillary channel.
In one refinement, the method may also include positioning a cover on at least the spacer substrate to form the capillary channel between the support substrate and the cover. In a further refinement of the method, the biosensor is a glucose sensor.
In another refinement of the method, the main body portion of the working electrode includes first and second working electrode portions and a connecting portion extending between the first and second working electrode portions, the connecting portion defining the part of the main body portion and first and second working electrode portions each define a minimum width in the capillary channel that is greater than the maximum width of the at least one connective neck. In a further refinement of the method, the connecting portion includes a plurality of connecting portions forming rows extending between the first and second working electrode portions, each of the connecting portions defining a width that corresponds to the minimum width. In yet a further refinement of the method, the first and second working electrode portions include a plurality of working electrode portions spaced along the plurality of connecting portions to form a grid-like pattern for the main body portion of the working electrode.
Another illustrative method for manufacturing a biosensor includes providing a support substrate; forming at least one working electrode on the support substrate, the working electrode including a main body portion defining a substantially constant width along a substantial portion of a length of the main body portion, the working electrode including a central portion projecting outwardly from the width; and positioning a spacer substrate on the support substrate so that opposite portions of an inner edge of the spacer substrate extend across opposite lateral portions of the main body portion and the central portion of the working electrode is positioned entirely within a capillary channel defined by portions of the inner edge, wherein the central portion occupies less than half of the length of the main body portion between the portions of the inner edge. In a refinement of the method, the central portion occupies less than one fourth of the length of the main body portion between the portions of the inner edge.
Further details and examples of conventional blood glucose meters and related electrical and optical components and their respective measurement techniques are described in U.S. Pat. Nos. 5,352,351; 4,999,482; 5,438,271; 6,645,368; 5,997,817; 6,662,439; RE 36,268; 5,463,467; 5,424,035; 6,055,060; 6,906,802; and 5,889,585; the disclosures of which are hereby incorporated herein by reference in their entireties.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.
