Abstract:
Provided herein is an apparatus for measuring properties of a fluid, the apparatus including: a light emitting unit configured to emit a first light having a first wavelength and a second light having a second wavelength that is longer than the first wavelength, from outside a fluid accommodating unit where the fluid flows in and out to a measurement area inside the fluid accommodating unit; a light receiving unit disposed outside the fluid accommodating unit and configured to receive the first light and second light that passed the measurement area; and a measuring unit configured to measure the properties of the fluid based on an intensity of the first light and second light that the light emitting unit emitted and an intensity of the first light and second light that the light receiving unit received.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to Korean patent application number 10-2014-0067592, filed on Jun. 3, 2014, the entire disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field of Invention 
         [0003]    Various embodiments of the present disclosure relate to an apparatus and method for measuring fluids, and more particularly, to an apparatus and method for measuring a volume ratio of red blood cells to an whole blood. 
         [0004]    2. Description of Related Art 
         [0005]    A conventional blood analysis is made using large equipments, and is thus disadvantageous as it requires a time consuming preliminary operation, large amounts of specimen (blood), a long time for carrying the extracted specimen to an analyzing equipment, and a long time for analyzing the specimen if there are a large number of them to analyze. In order to overcome these disadvantages, there is a need for a small scale analyzing equipment that is capable of analyzing blood right after collecting the blood. By accommodating a small amount of blood in a biochip having a shallow channel (passage) and then putting the biochip into an apparatus that is capable of analyzing blood right away without a time consuming preliminary operation and then analyzing the blood, it is possible to overcome the aforementioned problems. To be used as a blood analyzing device in disease diagnosis in the related field, such an apparatus must have good reproducibility in the measurable concentration range, consume as small amount of power as to drive a battery, cost less in manufacturing, and be stable against environmental changes. Furthermore, it is necessary to develop s biochip analyzing apparatus and method capable of overcoming the problems that occur when there is only a small amount of specimen collected. 
         [0006]      FIG. 1  is a view for explaining the problems in a conventional apparatus for measuring properties of a fluid. A conventional apparatus for measuring properties of a fluid is an apparatus for measuring a hematocrit accommodated in a biochip. A hematocrit is a volume ratio of red blood cells to an whole blood, which is important in diagnosing various diseases including anemia. In general, a low hematocrit indicates anemia, and a healthy male adult would show 42˜45% while a healthy female adult would show 38˜42% hematocrit. When using a conventional large scale analyzing apparatus, a large amount of blood is put into the apparatus, and then red blood cells are separated from the blood by a centrifuge, and then a volume of the whole blood is compared with a volume of the red blood cells. 
         [0007]    In order to measure a hematocrit optically, an electromagnetic absorption ratio must be measured for at least to wavelengths. Referring to  FIG. 1 , a first light having a first wavelength is emitted to a first area (A 1 ), and a second light having a second wavelength is emitted to a second area (A 2 ), and then the electromagnetic absorption ratio for the first wavelength and second wavelength are measured. However, a biochip is generally formed to be thin in order to increase the portability and reduce the manufacturing cost, and thus the ratio of red blood cells may vary depending on the area. That is, when the volume ratios of the red blood cells in the first area (A 1 ) and the second area (A 2 ) are different from each other, the error rate would increase, which is a problem. 
       SUMMARY 
       [0008]    Various embodiments of the present disclosure are directed to an apparatus and method for measuring properties of a fluid that is capable of reducing measurement errors caused by the unhomogeneity of the fluid inside a biochip by emitting a plurality of lights having a plurality of wavelengths to a same area. 
         [0009]    An embodiment of the present disclosure provides an apparatus for measuring properties of a fluid, the apparatus including: a light emitting unit configured to emit a first light having a first wavelength and a second light having a second wavelength that is longer than the first wavelength, from outside a fluid accommodating unit where the fluid flows in and out to a measurement area inside the fluid accommodating unit; a light receiving unit disposed outside the fluid accommodating unit and configured to receive the first light and second light that passed the measurement area; and a measuring unit configured to measure the properties of the fluid based on an intensity of the first light and second light that the light emitting unit emitted and an intensity of the first light and second light that the light receiving unit received. 
         [0010]    Another embodiment of the present disclosure provides a method for measuring properties of a fluid, the method including: accommodating the fluid in a fluid accommodating unit to which the fluid may flow in and out; emitting, by a light emitting unit disposed outside the fluid accommodating unit, a first light having a first wavelength to a measurement area in the fluid accommodating unit; receiving, by a light receiving unit disposed outside the fluid accommodating unit, the first light that passed the measurement area; emitting, by the light emitting unit, a second light having a second wavelength that is longer than the first wavelength to the measurement area; receiving, by the light receiving unit, the second light that passed the measurement area; and measuring the properties of the fluid based on an intensity of the first light and second light that the light emitting unit emitted and an intensity of the first light and second light that the light receiving unit received. 
         [0011]    Various aforementioned embodiments of the present disclosure have an effect of providing an apparatus and method for measuring properties of a fluid that is capable of reducing measurement errors caused by the unhomogeneity of the fluid inside a biochip by emitting a plurality of lights having a plurality of wavelengths to a same area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in is different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art. 
           [0013]    In the drawing figures, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout. 
           [0014]      FIG. 1  is a view for explaining problems of a conventional apparatus for measuring properties of a fluid; 
           [0015]      FIG. 2  is a view for explaining a concept of an apparatus for measuring properties of a fluid according to an embodiment of the present disclosure; 
           [0016]      FIG. 3  is a view for explaining a light focusing unit of the apparatus for measuring properties of a fluid according to the embodiment of the present disclosure; 
           [0017]      FIG. 4  is a view for explaining a concept of an apparatus for measuring properties of a fluid according to another embodiment of the present disclosure; 
           [0018]      FIG. 5  is a view for explaining a concept of a light receiving unit of the apparatus for measuring properties of a fluid according to the another embodiment of the present disclosure; 
           [0019]      FIG. 6  is a view for explaining a concept of a light receiving unit of the apparatus for measuring properties of a fluid according to the another embodiment of the present disclosure; 
           [0020]      FIG. 7  is a flowchart for explaining a method for measuring properties of a fluid according to an embodiment of the present disclosure; and 
           [0021]      FIGS. 8 and 9  are flowcharts for explaining emitting a light in the method for measuring properties of a fluid according to the embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Hereinafter, embodiments will be described in greater detail with reference to the accompanying drawings. Embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments should not be construed as limited to the particular shapes of regions illustrated herein but may include deviations in shapes that result, for example, from manufacturing. In the drawings, lengths and sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
         [0023]    Terms such as ‘first’ and ‘second’ may be used to describe various components, but they should not limit the various components. Those terms are only used for the purpose of differentiating a component from other components. For example, a first component may be referred to as a second component, and a second component may be referred to as a first component and so forth without departing from the spirit and scope of the present disclosure. Furthermore, ‘and/or’ may include any one of or a combination of the components mentioned. 
         [0024]    Furthermore, a singular form may include a plural from as long as it is not specifically mentioned in a sentence. Furthermore, “include/comprise” or “including/comprising” used in the specification represents that one or more components, steps, operations, and elements exist or are added. 
         [0025]    Furthermore, unless defined otherwise, all the terms used in this specification including technical and scientific terms have the same meanings as would be generally understood by those skilled in the related art. The terms defined in generally used dictionaries should be construed as having the same meanings as would be construed in the context of the related art, and unless clearly defined otherwise in this specification, should not be construed as having idealistic or overly formal meanings. 
         [0026]    It is also noted that in this specification, “connected/coupled” refers to one component not only directly coupling another component but also indirectly coupling another component through an intermediate component. On the other hand, “directly connected/directly coupled” refers to one component directly coupling another component without an intermediate component. 
         [0027]      FIG. 2  is a view for explaining a concept of an apparatus for measuring properties of a fluid according to an embodiment of the present disclosure. The measuring apparatus  100  includes a light emitting unit  120 , light receiving unit  150  and measuring unit (not illustrated), and when there is a fluid accommodating unit (biochip)  110  inserted into the measuring apparatus  100 , the measuring apparatus  100  may measure properties of the fluid (F) accommodated in the fluid accommodating unit  110 . The fluid accommodating unit  110  includes an inlet  111 , outlet  112 , and a passage  113  that connects the inlet  111  and outlet  112 , and the fluid accommodating unit  110  may accommodate the fluid (F). In order to prevent vortex from occurring that interrupts flow of the fluid, it is desirable that a laminar flow is formed in the fluid flowing through the passage  113 . A thickness of the passage  113  may desirably be 1 to 500 μm. Fabricating the passage  113  to have a thickness of 1 μm is very difficult due to fabricating errors, and the fluid may not flow smoothly. Furthermore, when fabricating the passage  113  to have a thickness of above 500 μm, vortex may be generated in the fluid, and measurement errors may increase, significantly reducing the reliability of the measurement. Furthermore, a thickness of the fluid accommodating unit  110  may desirably be 1 to 10 mm. When the thickness of the fluid accommodating unit  110  is less than 1 mm, areas where passages are formed may be damaged by impact, and when the thickness of the fluid accommodating unit  110  is less than 10 mm, the price may increase and the portability may decrease. For optical measurement, the fluid accommodating unit  110  may desirably be made of a transparent material. The emitting unit  120  emits a first light having a first wavelength and a second light having a second wavelength that is longer than the first wavelength to a measurement area (MA) in the fluid accommodating unit  110 . The light receiving unit  150  receives the first light and second light that passed the measurement area (MA), and the measuring unit (not illustrated) measures properties of the fluid based on an intensity of the first light and second light that the light emitting unit  120  emitted and an intensity of the first light and second light that the light receiving unit  150  received. 
         [0028]    The light emitting unit  120  includes a first light generating unit  121  that generates the first light, a second light generating unit  122 , a light shield wall  124  and a light focusing unit  130 . The first light generating unit  121  generates the first light, and the second light generating unit  122  generates the second light and is adjacent to the first light generating unit  121 . The first light and second light are emitted alternately, and the light shield wall  124  prevents the first light and second light from being mixed together. The light focusing unit  130  focuses the first light generated by the first light generating unit  121  and the second light generated by the second light generating unit  122  to be emitted to a same measurement area (MA). Details of such a structure will be explained hereinafter. 
         [0029]    The light receiving unit  150  may receive the first light and second light that passed the measurement area (MA), and the light receiving unit  150  may include a photo diode, CIS, or CCD. 
         [0030]    The measuring unit (not illustrated) stores a math equation and correcting constant, and measures properties of the fluid (F) based on an intensity of the first light and second light that the light emitting unit  120  emitted and an intensity of the first light and second light that the light receiving unit  150  received. In a case where the fluid (F) is blood, it is possible to measure a volume ratio of red blood cells to an entirety of the blood by optical measurement. Since the first light and second light are emitted alternately, the measuring unit (not illustrated) may determine whether or not the received light is the first light or second light based on a time when the light is received by the receiving unit  150 . 
         [0031]    An electromagnetic transmission rate (A) of the first light and second light may be calculated through the math equation shown below. 
         [0000]    
       
         
           
             
               
                 
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         [0032]    Herein, T represents the transmission rate, I 1  represents an intensity of the light (first light or second light) after it has been transmitted through the fluid is accommodating unit  110 , I 0  represents an intensity of the light before it is transmitted through the fluid accommodating unit  110 , α represents a damping constant per mol, 1 represents a transmission passage, c represents a concentration, and A represents an electromagnetic absorption ratio. In a hematocrit measurement, light having a wavelength of 570 nm or light having a wavelength of 880 nm may be used. After obtaining the electromagnetic absorption ratio of each light, a hematocrit may be calculated through the math equation shown below. 
         [0000]    
       
         
           
             
               
                 
                   HCT 
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                           880 
                         
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         [0033]    Herein, HCT is a volume ratio of red blood cells to an whole blood, A 570  and A 880  are light absorption ratios at 570 nm and 880 nm, respectively, c 570  and c 880  are correcting constants at 570 nm and 880 nm, respectively. That is, the measuring unit (not illustrated) stores math equation 1, math equation 2, c 570  and C 880 . 
         [0034]      FIG. 3  is a view for explaining a light focusing unit of the apparatus for measuring properties of a fluid according to the embodiment of the present disclosure. Referring to  FIG. 3 , the light focusing unit  130  includes a light focusing inlet  131 - 1 ,  131 - 2 , light focusing outlet  132 , and light focusing passage  133 . 
         [0035]    The light focusing inlet  131 - 1 ,  131 - 2  includes a first light focusing inlet  131 - 1  where the first light is emitted and a second light focusing inlet  131 - 2  where the second light is emitted, and the light focusing outlet  132  transmits the first light and second light to the measurement area (MA). 
         [0036]    The light focusing passage  133  connects the light focusing inlet  131 - 1 ,  131 - 2  to the light focusing outlet  132 , and the light focusing passage  133  includes a light stem unit  134  of which one end is connected to the light focusing outlet  132 , a first light branch unit  135 - 1  of which one end is connected to the first light focusing inlet  131 - 1  and another end connected to a portion of another end of the light stem unit  134 , and a second light branch unit  135 - 2  of which one end is connected to the second light focusing inlet  131 - 2  and another end connected to at least a portion of the another end of the light stem unit  134  not connected to the first light branch unit  135 - 1 . A portion of the surface of the light focusing passage  133  that is connected to the light focusing inlet  131 - 1 ,  131 - 2  and light focusing outlet  132  may transmit light, but at least a portion of the rest of the surface maximizes the amount of the first light and second light arriving at the light receiving unit  150  by reflecting the first light and second light. For example, at least one selected from glass, PMMA (polymethyl methacrylate), PI (Polyimide), PC (Polycarbonate) and COC (cyclo olefin copolymer) may constitute the light focusing passage  133 , and in a case where the surface of the light focusing passage  133  is a curved surface that is not bent, the light focusing passage  133  may reflect the first light and second light due to the difference of refractive index of air and the light focusing passage  133 . Alternatively, at least one selected from Au, Ag and Al may constitute the surface of the light focusing passage  133 , and due to optical characteristics of the surface of the light focusing passage  133 , the light focusing passage  133  may reflect the first light and second light. At least one selected from glass PMMA (polymethyl methacrylate), PI (Polyimide), PC (Polycarbonate) and COC (cyclo olefin copolymer) may constitute the rest of the light focusing passage  133  besides the surface thereof. 
         [0037]    The first light generated by the first light generating unit  121  is emitted to the first light focusing inlet  131 - 1 , passes the first light branch unit  135 - 1  and light stem unit  134 , and arrives at the light focusing outlet  132 . The second light generated by the second light generating unit  122  is emitted to the second light focusing inlet  131 - 2 , passes the second light branch unit  135 - 2  and light stem unit  134 , and arrives at the light focusing outlet  132 . Therefore, the light focusing unit  134  focuses the first light and second light generated in different areas and emits the focused light to the measurement area (MA). 
         [0038]      FIG. 4  is a view for explaining a concept of an apparatus for measuring properties of a fluid according to another embodiment of the present disclosure;  FIG. 5  is a view for explaining a concept of a light receiving unit of the apparatus for measuring properties of a fluid according to the another embodiment of the present disclosure; and  FIG. 6  is a view for explaining a concept of a light receiving unit of the apparatus for measuring properties of a fluid according to the another embodiment of the present disclosure. Hereinafter, explanation will be made with reference to  FIGS. 4 to 6 . 
         [0039]    A measuring apparatus  200  includes a light emitting unit  220 , light receiving unit  250 , and measuring unit (not illustrated). In a case where there is a fluid accommodating unit  210  inserted in the measuring apparatus  200 , the measuring apparatus  200  may measure properties of a fluid (F) accommodated in the fluid accommodating unit  210 . The fluid accommodating unit  210  is the same as the fluid accommodating unit  110  of  FIG. 2 , and thus detailed explanation will be omitted. The light emitting unit  220  includes a broadband light source that emits a broadband light that includes both a first light and second light. The broadband light may be transmitted through the measurement area (MA) and arrive at the light receiving unit  250 . 
         [0040]    The light receiving unit  250  includes a plurality of light receiving areas  251  that includes a first light receiving area  251 - 1 , second light receiving area  251 - 2 , third light receiving area  251 - 3 , and fourth light receiving area  251 - 4 , and a light division unit  252 . The light division unit  252  receives the broadband light, and transmits a light having a different wavelength to each of the light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4 . Each of the light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4  may include a photodiode, CIS, or CCD. 
         [0041]    The measuring unit (not illustrated) is very similar to the measuring unit (not illustrated) explained with reference to  FIG. 2 , and thus detailed explanation will be omitted. In  FIG. 2 , the first light and second light are emitted alternately, and thus a wavelength of the light received is determined by the measuring unit based on a time when the light is received in the light receiving unit  150 . However, in  FIG. 5 , the light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4  receive lights of different wavelengths, and thus the measuring unit (not illustrated) may determine the wavelength of the light that each light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4  receives based on an index  1 ,  2 ,  3 , and  4  of each of the light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4 . 
         [0042]    Referring to  FIG. 5 , the light division unit  252  includes a plurality of filters  252 - 1 ,  252 - 2 ,  252 - 3 , and  252 - 4  corresponding to the plurality of light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4 . Each of the plurality of filters  252 - 1 ,  252 - 2 ,  252 - 3 ,  252 - 4  transmits only a certain wavelength and delivers it to each of the plurality of light receiving areas  251 - 1 ,  251 - 2 ,  251 - 3 , and  251 - 4 . The first filter  252 - 1  transmits a light having a first wavelength to the first light receiving area  251 - 1 , the second filter  252 - 2  transmits a light having a second wavelength to the second light receiving area  251 - 2 , the third filer transmits a light having a third wavelength to the third light receiving area  251 - 3 , and the fourth filter  252 - 4  transmits a light having the fourth wavelength to the fourth light receiving area  251 - 4 . Herein, the first wavelength, second wavelength, third wavelength and fourth wavelength are all different from one another. 
         [0043]    Referring to  FIG. 6 , the light division unit  252 - 5  includes a fine structure unit (not illustrated). The fine structure unit (not illustrated) may transmit only a plurality of certain wavelengths. Furthermore, in a case where a size and material of the fine structure unit (not illustrated) may be adequately adjusted, a light emitted to the light division unit  252 - 5  may be divided to have a different passage depending on its wavelength. Accordingly, a light having a fifth wavelength, sixth wavelength, seventh wavelength, or eighth wavelength that are different from one another may be transmitted to each of the light receiving areas  251 - 5 ,  251 - 6 ,  251 - 7 , and  251 - 8 . 
         [0044]      FIG. 7  is a flowchart for explaining a method for measuring properties of a fluid according to another embodiment of the present disclosure, and  FIGS. 8 and 9  are flowcharts for explaining emitting light of the method for measuring properties of a fluid according to the another embodiment of the present disclosure. Hereinafter, explanation will be made with reference to  FIGS. 2 ,  3 ,  7 ,  8 , and  9 . 
         [0045]    Referring to  FIG. 7 , a method for measuring properties of a fluid according to an embodiment of the present disclosure includes accommodating the fluid (S 110 ), emitting the first light (S 120 ), receiving the first light (S 130 ), emitting the second light (S 140 ), receiving the second light (S 150 ), measuring (S 160 ), (S 170 ), and moving the light emitting unit and light receiving unit (S 180 ). 
         [0046]    At the step of accommodating the fluid (S 110 ), the fluid (F) is accommodated in the fluid accommodating unit  110  that includes the inlet  111 , outlet  112 , and the passage  113  connecting the inlet  111  and outlet  112 . Furthermore, the fluid accommodating unit  110  is inserted in the measuring apparatus  100 . 
         [0047]    At the step of emitting the first light (S 120 ), the first light generating unit  121  generates the first light having the first wavelength (S 121 ). Then, the first light is focused as it passes the first light focusing inlet  131 - 1 , first light branch unit  135 - 1 , light stem unit  134  and light focusing outlet  132  (S 122 ), and then emitted to the measurement area (MA) inside the fluid accommodating unit  110 . 
         [0048]    At the step of receiving the first light (S 130 ), the light receiving unit  150  receives the first light that passed the measurement area (MA). Since the time the light receiving unit  150  received light corresponds to the time when the first light generating unit  121  generated the first light, the measuring unit (not illustrated) determines that the light received in the light receiving unit  150  is the first light. 
         [0049]    At the step of emitting the second light (S 140 ), the second light generating unit  122  generates the second light having the second wavelength that is longer than the first wavelength (S 141 ). Then, the second light is focused as it passes the second light focusing inlet  131 - 2 , second light branch unit  135 - 2 , light stem unit  134  and light focusing outlet  132  (S 142 ), then emitted to the measurement area (MA) inside the fluid accommodating unit  110 . 
         [0050]    At the step of receiving the second light (S 150 ), the light receiving unit  150  receives the second light that passed the measurement area (MA). In the same manner as in the step of receiving the first light, the measuring unit (not illustrated) determines that the light received in the light receiving unit  150  is the second light. 
         [0051]    At the step of measuring (S 160 ), the measuring unit (not illustrated) stores the math equation and correcting constant, and measures properties of the fluid (F) based on the intensity of the first light and second light that the light emitting unit  120  emitted and the intensity of the first light and second light that the light receiving unit  150  received. The math equation and correcting constant stored in the measuring unit (not illustrated) and the method of measuring the properties of the fluid were explained hereinabove. 
         [0052]    At the step (S 170 ), in a case where it is necessary to move the measurement area (MA) for the same fluid (F) and perform an additional measurement, the step of moving the light emitting unit and light receiving unit is performed (S 180 ), and in a case where it is not necessary to move the measurement area (MA) nor perform an additional measurement, the method for measuring the properties of the fluid (S 100 ) ends. Before or during performing the method for measuring the properties of the fluid (S 100 ), the position and number of the measurement area (MA) may be input by the user. 
         [0053]    At the step of moving the light emitting unit and light receiving unit (S 180 ), the light emitting unit  120  and light receiving unit  150  are moved so that the input measurement area (MA) may be measured. After the step of moving the light emitting unit and light receiving unit (S 180 ), the step of emitting the first light for measurement (S 120 ) is performed. 
         [0054]    Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.