Abstract:
A device is constructed so as to define a capillary channel that draws a body fluid form a proximal portion of the capillary channel toward a distal portion. A counterbore defining a “ledge” not substantially normal to the center line of channel causes the meniscus of body fluid to be “biased” into a non-radially-symmetric shape. In one example, the bias draws the body fluid toward a testing element that is set into a groove in the main body of the device. In another example, hydrophilic and/or hydrophobic regions are created on or in device to produce the biasing effect. In certain configurations, device requires less blood to be drawn into the capillary channel for a successful test than if the biasing effect were not created.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/436,331, filed Dec. 24, 2002 (Attorney Docket No. 7404-453), which is hereby incorporated by reference in its entirety. 
     
    
     
       BACKGROUND  
         [0002]    The present invention generally relates to the medical field, and more specifically, but not exclusively, relates to the sampling of bodily fluids.  
           [0003]    The acquisition and testing of body fluids is useful for many purposes, and continues to be of importance for use in medical diagnosis and treatment, and in other diverse applications. In the medical field, it is desirable for lay operators to perform tests routinely, quickly and accurately outside of a laboratory setting, with rapid results and a read-out of the resulting test information. Testing can be performed on various body fluids, and for certain applications, it is particularly related to testing of blood and/or interstitial fluid. Such fluids can be tested for a variety of characteristics of the fluid or analytes contained in the fluid, in order to identify medical conditions, determine therapeutic responses, assess progress of treatments and the like.  
           [0004]    A common medical test is the measurement of blood glucose levels. The glucose level can be determined directly by analysis of the blood, or indirectly by analysis of other fluids, such as interstitial fluid. Diabetics are generally instructed to measure their glucose levels several times a day, depending on the nature and severity of their diabetes. Based upon observed patterns in the measurement of glucose levels, the patient and physician can determine the appropriate level of insulin to be administered, also taking into account such issues as diet, exercise and other factors.  
           [0005]    In testing for the presence of analytes such as glucose in a body fluid, test systems are commonly used which take advantage of oxidation/reduction reaction, which occurs using an oxidase/peroxidase detection chemistry. The testing reagent is exposed to a sample of the body fluid for a suitable period of time, and there is a color change if analyte (glucose) is present. Typically, the intensity of the change is proportional to the concentration of analyte in the sample. The color of the reagent is then compared to a known standard, which enables one to determine the amount of analyte present in the sample. This determination can be made, for example, by visual check or by an instrument, such as a spectrophotometer at a selected wave length, or a blood glucose meter. Electrochemical and other systems are also well known for testing body fluids for properties of constituents. Typically, a fingertip or some other body location of a patient is lanced with a lancet in order to obtain a body fluid sample.  
           [0006]    Although fingertips generally provide an ample supply of blood, repeated lancing of fingertips can be quite painful due to the high concentration of nerve endings in the fingertips. Therefore, there has been a trend towards sampling fluids from alternate sites on the body, where the nerve concentrations are lower, such as the forearm. As should be appreciated, since alternate sites have lower nerve concentrations, the patient experiences less pain when lancing the alternate site. However, these alternate sites usually produce less fluid as compared to fingertips. Consequently, it has been a goal to reduce the amount of fluid needed for a successful test. To achieve this goal, it is desirable to ensure that as much fluid as possible is transported from the incision to the test area so as to minimize waste.  
           [0007]    Thus, there remains a need for improvement in this field.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is an isometric view of a portion of an example apparatus according to the present invention.  
         [0009]    [0009]FIG. 2A is an end view of the apparatus of FIG. 1.  
         [0010]    [0010]FIG. 2B is a side view of the apparatus of FIG. 1.  
         [0011]    [0011]FIG. 2C is a cross-sectional view taken along line  2 C- 2 C of FIG. 2B.  
         [0012]    [0012]FIG. 3 is a side view of the apparatus of FIG. 1 disposed above body fluid on a tissue surface.  
         [0013]    [0013]FIG. 4 is a side view illustrating the apparatus of FIG. 1 displaying the initial capillary action.  
         [0014]    [0014]FIG. 5 is a side view illustrating the apparatus of FIG. 1 displaying biased capillary action.  
         [0015]    [0015]FIG. 6 is a side view of a portion of an alternative example apparatus according:to the present invention displaying another form of biased capillary action.  
         [0016]    [0016]FIG. 7 is a side view of the apparatus of FIG. 6 illustrating a test strip disposed within a groove in the apparatus.  
         [0017]    [0017]FIG. 8 is a side view of a portion of another alternative example apparatus according to the present invention.  
         [0018]    [0018]FIG. 9 is a side view of the apparatus of FIG. 8 displaying another form of biased capillary action.  
         [0019]    [0019]FIG. 10 is a side view of the apparatus of FIG. 8 illustrating a test strip disposed within a groove in the apparatus.  
         [0020]    [0020]FIG. 11 is a side view of a portion of yet another alternative example apparatus according to the present invention.  
         [0021]    [0021]FIG. 12 is an isometric view of a portion of another example apparatus according to the present invention.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]    Provided below is a written description of examples embodying the invention and examples of making and using the same. The scope of the invention is not limited to these examples, but rather is defined solely by the numbered claims that appear at the end of this document, and the invention includes alterations, modifications, and further applications that fall within the claims. The written description uses full, clear, concise, and exact terms to enable any person skilled in the art to which the invention pertains to make and use the invention. The best mode contemplated by the inventor of carrying out the invention is also set forth herein.  
         [0023]    All the information set forth in the following patent applications is incorporated by reference, as if fully set forth herein: U.S. patent application Ser. No. 10/054,270, filed Jan. 22, 2002, entitled LANCET DEVICE HAVING CAPILLARY ACTION; and U.S. patent application Ser. No. 10/165,101, filed Jun. 7, 2002, entitled SAMPLING DEVICES AND METHODS UTILIZING A HORIZONTAL CAPILLARY TEST STRIP.  
         [0024]    The present invention generally concerns a sampling device that is configured to bias the flow of body fluid in the device so as to reduce the amount of fluid needed for sampling. In one embodiment, the device has a capillary channel that is structured to bias a miniscus of the fluid in a radially asymmetric manner. Specifically, the capillary channel has an angled counter bore that biases the meniscus of the fluid in a radial asymmetric manner. In another embodiment, the capillary channel includes hydrophobic and hydrophillic portions that bias the flow of fluid.  
         [0025]    [0025]FIG. 1 illustrates one example of a device  100  for sampling body fluid (not shown), comprising a main body  110  defining a capillary channel  120 . The capillary channel  120  is preferably dimensioned to draw a body fluid into the capillary channel  120  through capillary action, as described more fully in the above-incorporated patent applications. In this example the capillary channel  120  is further dimensioned to form an angled counterbore  130 .  
         [0026]    Though the device  100  is shown in FIG. 1 as cylindrical with an annular cross-section, this is just one example geometry. Any geometry can be used for device  100 , as long as device  100  provides a capillary channel  120  dimensioned to draw a body fluid into said capillary channel  120  through capillary action. For example, one or more portions of device  100  and/or capillary channel  120  could independently have square, rectangular, triangular, oval, U-shaped, amorphous, or any other shape cross-sections. Device  100  may comprise any material and may be made by any means, such as the materials and methods of manufacture set forth in the above-incorporated patent applications.  
         [0027]    [0027]FIGS. 2A, 2B and  2 C further illustrates the example of FIG. 1. The device, or apparatus,  100  comprises a body  110  defining a capillary channel  120  having a first region  140  and a second region  150  and a proximal portion  160  and a distal portion  170 . In the example shown in FIGS.  1 - 5 , the second region  150  of the capillary channel  120  defines a counterbore  130  ending in a surface non-normal to the longitudinal axis  180  of the capillary channel  120  by angle α.  
         [0028]    [0028]FIG. 3 illustrates the device  100  positioned above a drop of body fluid  310  issuing from an incision  305  in body tissue  300 . The body fluid  310  may be produced by puncturing the body tissue  300 , or by any other means, including as described in the above-incorporated patent applications. FIG. 4 illustrates the device  100  lowered toward the body tissue  300  until the proximal portion  160  of the capillary channel  120  is in fluid communication with the body fluid  310 . The body fluid  310  is then drawn into the capillary channel  120  by capillary action, as represented in FIGS. 4 and 5. As shown in FIGS. 4 and 5, the body fluid  310  flows in the capillary channel  120  from the proximal portion  160  toward the distal portion  170 . However, when the body fluid  310  reaches the angled counterbore  130 , the meniscus  320  of the body fluid  310  is biased radially asymmetrically about the centerline  180  toward one side of capillary channel  120 , as shown in FIG. 5.  
         [0029]    Capillary mechanics dictate that the step or offset created by the angled counterbore  130  causes the first region  140  to have an effectively stronger capillary attraction to body fluid  310  than the second region  150  when the body fluid  310  flows in the capillary channel  120  from the proximal portion  160  toward the distal portion  170 . Though an angled counterbore  130  is shown as an example, any geometry including a step or other shape can be used that has the capillary biasing effect of biasing the forces of capillary action acting on body fluid  310  so that they are radially asymmetric about the centerline  180 , such as by tending to favor one side of capillary channel  120 .  
         [0030]    This difference in capillary attraction pulls or biases the meniscus  320  radially asymmetrically about the centerline  180 , toward the first region  140  and away from the second region  150 , thus biasing the body fluid  310  toward a first side  122  of the capillary channel  120 , and away from a second side  124  of the capillary channel  120 . Subject to the materials and dimensions used in device  100  and their interaction with a particular body fluid  310 , increasing the angle α tends to increasingly bias the body fluid  310  toward a first side  122  of the capillary channel  120 , and away from a second side  124  of the capillary channel  120 .  
         [0031]    [0031]FIG. 6 shows a device  100 ′ that is similar to device  100 , but has a counterbore  130 ′ with an increased angle α′. As shown in FIG. 6, increasing the angle from α to α′ tends to increase the bias of the meniscus  320  radially asymmetrically about the centerline  180 , thus tending to increase the bias of the body fluid  310  toward a first side  122  of the capillary channel  120 , and away from a second side  124  of the capillary channel  120 .  
         [0032]    [0032]FIG. 7 shows the device  100 ′ of FIG. 6 further including a testing element  700  disposed within a groove  710  in the main body  110 ′ of the device  100 ″. When body fluid  310  has moved up first side  122 , as shown, the testing element  700  is in spatial communication with body fluid  310  through one or more passageways  720 , so that the testing element  700  may be used to test various aspects of the body fluid  310 , for instance as described in the above-incorporated patent applications. Testing element  700  may be any testing means that interfaces with body fluid  310 , such as a test strip or other chemistry, for instance as described in the above-incorporated patent applications.  
         [0033]    Since the body fluid  310  tends to bias toward the first side  122  of the capillary channel  120 , passageways  720  are shown formed in the first side  122  of the capillary channel  120 . Passageways  720  are filled with body fluid  310 , even though the adjacent portion of the capillary channel  120  is only partially filled with body fluid  310  due to the biasing effect described above. Thus, the device  100 ″ is capable of communicating body fluid  310  to testing element  700  using less body fluid  310  than would be required without the capillary biasing effect described herein.  
         [0034]    [0034]FIG. 8 illustrates another example device  100 ″ configured to create a capillary biasing effect without requiring an angled counterbore  130  or any geometry such as a step or other shape in the capillary channel  120 . Instead, the first side  122  of the capillary channel  120  includes a hydrophilic region  800 . The hydrophilic region  800  is hydrophilic relative to one or more adjacent regions of the capillary channel  120 , such as the second side  124 . The hydrophilic region  800  need only be relatively hydrophilic; for instance, the hydrophilic region  800  may be defined by providing hydrophobic surrounding regions. A relatively hydrophilic region  800  may be created by forming portions of the capillary channel  120  from hydrophilic or hydrophobic materials, or by treating portions to be relatively hydrophilic or hydrophobic, for instance in the manners described in the above-incorporated patent applications.  
         [0035]    [0035]FIG. 9 illustrates the device  100 ″ of FIG. 8 positioned near body tissue  300  so that the proximal portion  160  of the capillary channel  120  is in fluid communication with a small drop of body fluid  310  issuing from an incision  305  in body tissue  300 , the body fluid  310  being drawn into the capillary channel  120  by capillary action. When the body fluid  310  reaches the relatively hydrophilic region  800 , the body fluid  310  is disproportionately attracted to the hydrophilic region  800 . This difference in capillary attraction pulls or biases the meniscus  320  radially asymmetrically about the centerline  180 , thus biasing the body fluid  310  toward the relatively hydrophilic region  800  of the first side  122  of the capillary channel  120 , and away from the relatively hydrophobic second side  124  of the capillary channel  120 .  
         [0036]    [0036]FIG. 10 shows the device  100 ″ of FIG. 9 further including a testing element  700  disposed within a groove  710  in the main body  110 ″ of the device  100 ″. The testing element  700  is in spatial communication with body fluid  310  through one or more passageways  720 , so that the testing element  700  may be used to test various aspects of the body fluid  310 , as set forth above. Since the body fluid  310  tends to bias toward the hydrophilic region  800  on the first side  122  of the capillary channel  120 , passageways  720  are shown formed in the first side  122  of the capillary channel  120 . Passageways  720  are filled with body fluid  310 , even though the adjacent portion of the capillary channel  120  is only partially filled with body fluid  310  due to the biasing effect described above. Thus, the device  100 ″ is capable of communicating body fluid  310  to testing element  700  using less body fluid  310  than would be required without the capillary biasing effect described herein.  
         [0037]    [0037]FIG. 11 shows a device  100 ′″ including by way of example both an angled counterbore  130  and a relatively hydrophilic region  800  in the capillary channel  120 , and further including an integrated lancet  1100  for forming the incision  305 . The integrated lancet  1100 , or any other structure, may be used in conjunction with devices incorporating the capillary biasing effect described herein. For instance, devices including an integrated lancet  1100  can include any or all of the structure set forth in the above-incorporated patent applications. In this example, an angled counterbore  130  works in conjunction with a relatively hydrophilic region  800  to bias body fluid  310  toward testing element  700  using less body fluid  310  than would be required without the capillary biasing effect described herein.  
         [0038]    [0038]FIG. 12 illustrates a capillary tube  1200  according to another embodiment of the present invention. In the illustrated embodiment, the capillary tube  1200  has a stepped-end counterbore  1202  for biasing the fluid in a specified direction inside the capillary tube.  
         [0039]    Various alternatives to the structures and details described herein are available, and could be implemented without undue experimentation by those skilled in the art. For example, a plurality of sites on a testing device might be used for testing the same or different characteristics of the body fluid. Those sites might be spaced around the circumference of the device at approximately the same distance from the proximal end, or they might be situated at different distances from the proximal end. They may be on the same side of the device, opposite sides of the device, or in some other relative configuration.  
         [0040]    Further, various test methods may be implemented at the one or more test sites, including for example optical, magnetic, and chemical tests as would occur to one skilled in the art given the disclosure herein, which includes the matter incorporated by reference above.  
         [0041]    Furthermore, a wide variety of techniques might be used to bias the body fluid toward the testing site(s). These techniques might include (but are not limited to) the angled-end counterbore and hydrophobic/hydrophilic wall techniques discussed above; chemically treating or coating one or more portions of the inner wall of the capillary tube with one or more different hydrophobic, hydrophilic, or other chemicals known in the art; the stepped-end counterbore  1202  as shown in FIG. 12; roughening the inner wall of the capillary tube in one region relative to another; and forming longitudinal grooves in certain portions of the inner wall (or more grooves in certain portions than in others).  
         [0042]    While examples embodying the invention have been illustrated and described in detail in the drawings and foregoing description, which includes material incorporated by reference, these examples are illustrative and not restrictive in character, it being understood that only certain examples have been shown and described and that all changes and modifications that come within the spirit of the invention are to be protected.