Abstract:
A GigaMatrix plate for holding a large number of small-volume fluid samples includes a base for supporting a plurality of substantially parallel, elongated capillary tubes. Each tube defines a lumen that extends through the base, and each lumen has an aspect ratio greater than about 5:1. Dimensionally, each lumen has an inner diameter that is less than approximately five hundred microns and it has a length greater than about five millimeters. Further, each tube acts to optically distinguish light that is directed toward it from the sample whenever the sample fluoresces inside the tube lumen. Also, however, light from the sample that is directed axially through the tube is emitted therefrom for optical detection of the tube and the sample therein.

Description:
The present application is a continuation-in-part of pending U.S. patent application Ser. No. 09/894,956 filed Jun. 27, 2001, which is a continuation-in-part of pending U.S. patent application Ser. No. 09/687,219, filed Oct. 12, 2000, which is a continuation-in-part of pending U.S. patent application Ser. No. 09/444,112, filed Nov. 22, 1999, which is a continuation-in-part of pending U.S. patent application Ser. No. 08/876,276, filed Jun. 16, 1997; additionally, the present application is a continuation-in-part of pending U.S. patent application Ser. No. 09/636,778, filed Aug. 11, 2000, which application is a continuation and claims the benefit of priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 09/098,206, filed Jun. 16, 1998, which issued as U.S. Pat. No. 6,174,673 on Jan. 16, 2001, which is a continuation-in-part of pending U.S. patent application Ser. No. 08/876,276, filed Jun. 16, 1997, all of the contents of which are incorporated by reference in their entirety herein. 

   FIELD OF THE INVENTION 
   The present invention pertains particularly to plates for holding a large number of relatively small-volume fluid samples. More particularly, the present invention pertains to plates that are formed with a plurality of through-hole wells in which individual samples can be held. The present invention is particularly, but not exclusively, useful as a GigaMatrix™ plate that has a relatively large number of through-hole wells with relatively high aspect ratios, wherein each through-hole well can be optically distinguished from other through-hole wells in the plate. 
   BACKGROUND OF THE INVENTION 
   Plates or trays for holding assays or specimen samples in a fluid solution can be generally grouped into either one of two different types of devices. One type is formed with depressions or wells which have bottoms that support the assay or specimen while it is being processed. The other type incorporates through-hole wells that rely on surface tension to hold the fluid assay or sample in the through-hole well during processing. For example, U.S. Pat. No. 6,027,873 which issued to Schellenberger et al. for an invention entitled “Multi-Through Hole Testing Plate for High Throughput Screening” discloses a holding or testing plate of this second type. Not surprisingly, however, it happens that both types of holding plates have their respective advantages and disadvantages. 
   Insofar as holding plates having through-hole wells are concerned, one advantage they have is that they can be easily filled. Specifically, this can be done by simply immersing a surface of the holding plate into a solution to be analyzed. The through-hole wells are then filled with the solution by capillary action. This, in turn, leads to another advantage which is that a very large number of relatively small volume solution samples can be simultaneously prepared, but individually assayed. 
   As stated above, in addition to their advantages, sample holding plates also have their disadvantages. In particular, there is a significant disadvantage to presently available holding plates with through-hole wells. This disadvantage stems from the fact that the through-hole wells of presently available holding plates have aspect ratios (i.e. a ratio of the length of the well to its inner diameter) that are generally less than 5:1. Accordingly, a significant portion of the solution sample in the through-hole well is exposed to the environment. A consequence of this is that, due to evaporation, such plates can effectively support solution samples for only relatively short periods of time (e.g. minutes or a few hours). The present invention recognizes that through-hole wells having aspect ratios greater than 5:1 can effectively diminish the consequences of evaporation. 
   In addition to the advantages noted above, an attribute that is desirable for all types of holding plates is that they provide the ability to properly process the assays (samples) that are being held by the plate. Specifically, in some instances, it may be desirable or necessary to observe any changes in the sample that take place while it is being held by the plate. Such changes, however, may require several days, or even longer. In the particular case of holding plates with through-hole wells, the observation techniques that are being used must effectively account for the small volumes of the solution samples and their close proximity to each other on the holding plate. If optical techniques are used for these purposes, the individual through-hole wells of the holding plate must also be optically distinguishable. 
   In light of the above, it is an object of the present invention to provide a GigaMatrix holding plate with through-hole wells that have relatively high aspect ratios (e.g. greater than 5:1) to limit the effects of evaporation to approximately five percent of solution sample volume per day (5%/day). Another object of the present invention is to provide a GigaMatrix holding plate which allows respective through-hole wells to be optically distinguishable. Still another object of the present invention is to provide a GigaMatrix plate for holding a large number of small volume samples that is easy to use, relatively simple to manufacture and comparatively cost effective. 
   SUMMARY OF THE PREFERRED EMBODIMENTS 
   In accordance with the present invention, a GigaMatrix plate for holding a large number of relatively small solution samples includes a base having a first surface and an opposed second surface that is substantially parallel thereto. Open-ended capillary tubes extend through the base between its first and second surfaces to establish a plurality of substantially parallel through-hole wells. As envisioned for the present invention, the GigaMatrix holding plate can have in excess of a thousand such through-hole wells. 
   Each tube in the holding plate of the present invention has an interior surface that defines a lumen. This lumen further defines a longitudinal axis for the tube. Importantly, each tube has an aspect ratio (i.e. a ratio of lumen diameter to length of tube) that is greater than about 5:1. Within the parameters of such an aspect ratio, the lumen of each tube will have an inner diameter that is less than approximately five hundred microns, and a length that is greater than about five millimeters. 
   A contemplation of the present invention is that the plate will be used for holding samples in respective capillary tubes, and that these samples will fluoresce under appropriate conditions. With this in mind, it is an important aspect of the present invention that the holding plate be structured so that whenever a sample in a tube lumen is excited to become fluorescent, each tube will be independently and optically distinguishable from other tubes in the holding plate. 
   The structure of each tube in the holding plate can be made of a sleeve glass which is embedded in an interstitial material that holds the various tubes of the holding plate together on the base. For each tube, the sleeve glass surrounds the lumen of the tube. In one embodiment of the present invention, the sleeve glass itself is surrounded by a black, extra mural absorption (EMA) glass which absorbs most of the fluorescent light that is directed from the sample toward the tube. In another embodiment, the sleeve glass itself is heat-treated to make it effectively opaque and, thus, light absorptive for the above stated purposes. In yet another embodiment, the sleeve glass and interstitial material can be the same. Further, the glass in this last embodiment may be clear glass, but it should have refractive properties which make each tube optically distinguishable. 
   Additional aspects of the present invention include the fact that the interior surface of each tube lumen can be coated to control the tube&#39;s capillary action, or to provide a surface chemistry in the lumen. Also, a reference indicia can be established on the base of the plate for purposes of positioning and aligning the base, as required. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
       FIG. 1  is a perspective view of a GigaMatrix plate in accordance with the present invention; 
       FIG. 2A  is a top plan view of a portion of the GigaMatrix plate showing one embodiment of a through-hole well for the present invention; 
       FIG. 2B  is a top plan view of a portion of the GigaMatrix plate showing an alternate embodiment of a through-hole well; 
       FIG. 3A  is a cross sectional view of the through-hole well shown in  FIG. 2A  as would be seen along the line  3 — 3  in  FIG. 1 ; 
       FIG. 3B  is a cross sectional view of the through-hole well shown in  FIG. 2B  as would be seen along the line  3 — 3  in  FIG. 1 ; 
       FIG. 4  is a perspective view of an optical fiber that would be suitable for use in manufacturing through-hole wells for the GigaMatrix plate of the present invention; 
       FIG. 5  is a perspective view of the optical fiber shown in  FIG. 4  after it has been drawn down; 
       FIG. 6A  is a perspective view of multis created by stacking sections of the drawn optical fiber shown in  FIG. 5 ; and 
       FIG. 6B  is a perspective view of assembled multis for use in manufacturing the GigaMatrix plate of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1 , a GigaMatrix plate in accordance with the present invention is shown and is generally designated  10 . As shown, the plate  10  includes a base  12  having a generally flat upper surface  14  and an opposed, also generally flat, lower surface  16 . Reference indicia, such as the bumps or rises  18   a  and  18   b  shown in  FIG. 1 , can be used to orient and align the plate  10  as necessary during its use. Most importantly, however, is the fact that the plate  10  is formed with a plurality of through-hole wells  20  that extend through the base  12  between the upper surface  14  and the lower surface  16 . As envisioned for the present invention, these through-hole wells  20  are all substantially parallel to each other, and they have a density of approximately two through-hole wells  20  per square millimeter of area on the surfaces  14 ,  16 . 
   It is an important aspect of the present invention that the plate  10  be formed with a plurality of through-hole wells  20 . For the present invention, this plurality may include as many as a thousand or more such wells  20 . Structurally, the through-hole wells  20  are preferably any one of three possible embodiments. The first such embodiment, shown as the through-hole well  20 ′ in  FIG. 2A , is formed with a lumen  22  that is surrounded and defined by the interior surface  24  of an interior wall  26 . Additionally, the through-hole well  20 ′ ( FIG. 2A ) includes an outer wall  28  that surrounds the interior wall  26 . For the second embodiment, shown as the through-hole well  20 ″ in  FIG. 2B , there is no outer wall  28 . The difference in these structures, as more fully disclosed below, stems from the optical characteristics exhibited by the interior wall  26 . Regardless, for both of these embodiments, the plate  10  includes an interstitial material  30  in which the through-hole well  20 ′ (or  20 ″) is embedded and held together in the base  12  with the other through-hole wells  20  of the plate  10 . For the third embodiment, the interior wall  26 , outer wall  28  and interstitial material  30  may all be the same. 
   As mentioned above, differences between the various embodiments for through-hole well  20  are dependent on the optical properties of their respective interior walls  26 . For the through-hole well  20 ′ ( FIG. 2A ) the interior wall  26  is preferably made of a sleeve glass that is of a type well known in the pertinent art. This sleeve glass alone, however, may not have the light absorptive properties that are preferred for the plate  10 . If so, the outer wall  28  can be added and used to achieve the desired result. For this purpose, the outer wall  28  is preferably made of an extra mural absorptive (EMA) glass. On the other hand, for the through-hole well  20 ″ ( FIG. 2B ) it is possible that the interior wall  26  be made of a sleeve glass which, after being heat-treated, will become substantially opaque. In either of these two cases, it is preferable that the through-hole wells  20  (either  20 ′ or  20 ″) have light absorptive characteristics that will minimize “cross-talk” (i.e. light interference) between adjacent through-hole wells  20  in the plate  10 . Furthermore, if the inner wall  26 , outer wall  28  and interstitial material  30  are all the same, it is important that the refractive properties of the material be such that the individual lumens  22  of the through-hole wells  20  can be optically distinguished from the material of the holding plate  10 . 
   Dimensionally, the through-hole wells  20  of the plate  10  have several salient aspects. In all, there are two paramount aspects of the plate  10  that are particularly important. First is that the through-hole wells  20  function as capillary tubes that can be effectively filled by a wicking action. Second, and of equal importance, is that the through-hole wells  20  be configured to minimize the effects of evaporation. For the plate  10  of the present invention, both of these aspects are addressed by properly dimensioning the configuration of the through-hole wells  20 . 
   As perhaps best appreciated by cross referencing  FIGS. 2A and 2B  with  FIGS. 3A and 3B , the through-hole wells  20  are preferably cylindrical in shape and define a longitudinal axis  32  (FIG.  3 A). The cross-section of the through-hole wells  20 , however, may be oval or rectangular. With these structures, each through-hole well  20  has a length  34  and an inner diameter  36 . Specifically, the inner diameter  36  is the diameter of lumen  22 . Importantly, these dimensions define an aspect ratio, “A”, that for a through-hole well  20  is the ratio of its length  34  to its diameter  36 . As intended for the present invention, “A” will be greater than approximately 5:1, and may be as much as 30:1, or more. Within the values of these parameters for “A”, the length  34  is preferably in a range of about five to ten millimeters (5-10 mm) and the inner diameter  36  of the through-hole well  20  is preferably less than about five hundred microns (500 μm). 
   Manufacturing a GigaMatrix plate  10  in accordance with the present invention begins by providing a single elongated optical fiber  38 , such as shown in FIG.  4 . Specifically, the optical fiber  38  will have an initial length  40 , and will include a cylindrical shaped core glass  42  that is surrounded by a concentric layer of sleeve glass. More specifically, this sleeve glass will eventually comprise the interior wall  26  of a through-hole well  20 . As shown in  FIG. 5 , the outer wall  28 , if used, and the interstitial material  30 , in all instances, will be included in the optical fiber  38 . 
   Once an optical fiber  38  has been selected, it is drawn down in a manner well known in the pertinent art to create an optical fiber having a length  44 . As will be appreciated by comparing  FIG. 4  with  FIG. 5 , the length  44  is much longer than the length  40 . The drawn optical fiber  38  ( FIG. 5 ) is then cut into a plurality of sections  46 , of which the sections  46   a, b, c . . . w  and  x  are only exemplary. Next, the individual sections  46  are stacked together to create a so-called multi  48 . As best seen with reference to  FIGS. 6A and 6B , the sections  46  are stacked together in a substantially parallel arrangement, such as shown for the exemplary multis  48   a  and  48   b . After the multis  48  have been created, they are then pressed together as indicated by the arrow  50 , and heated to fuse the interstitial material. Although only the multis  48   a  and  48   b  are shown in  FIG. 6A , it is to be appreciated that many such multis  48  can be fused together. Also, the process can be repeated to create multi-multis. Regardless how the multis  48  are made, the result is a unit assembly  52  that serves as a precursor for the plate  10 . 
   After a plurality of the multis  48  have been pressed together, the resultant unit assembly  52  is carefully heated to fuse the interstitial material  30  between adjacent sections  46 . For example, in order to avoid structural damage to materials in the unit assembly  52 , this heating may be accomplished at relatively slow rates. Specifically, this is done to bond the sections  46  into an integral unit assembly  52 . After cooling, the unit assembly  52  is cut and ground to establish a substantially same predetermined length for each of the sections  46 . As a consequence of this, the surfaces  14  and  16  of the plate  10  are created with a distance between them that is preferably about six millimeters. 
   An important step in the manufacture of the GigaMatrix plate  10  of the present invention is that, after the unit assembly  52  has been cut and its surfaces  14  and  16  smoothed by grinding, the whole assembly  52  is immersed into an acid bath (not shown). This is specifically done to etch the core glass  42  from the assembly  52  to create the GigaMatrix plate  10 . For the embodiment of plate  10  wherein the through-hole well  20 ″ does not include the outer wall  28  of EMA glass, a final step in the manufacture of plate  10  can require heat-treating the plate  10  to make the sleeve glass of interior wall  26  substantially opaque. 
   In use, a surface  14  or  16  of the plate  10  is immersed into a container (not shown) that is holding samples  54  in a liquid solution  56 . As intended for the present invention, this action wicks the samples  54  along with the liquid solution  56  into the through-hole wells  20  by a capillary action. The samples  54  are then held in the through-hole wells  20  to be subsequently assayed. Although the aspect ratio “A” that is manufactured for the through-hole wells  20  of plate  10  will act to minimize the effects of evaporation, this feature of the present invention can be supplemented. Specifically, as shown in  FIG. 3B , a cap  58  can be used to cover the through-hole wells  20 . Alternatively, a membrane (not shown) can be used for this purpose. Also, a wax, or a high vapor pressure fluid  60 , can be inserted into the through-hole wells  20  to retard evaporation. Further, an obvious step for further reducing the effects of evaporation on the liquid solution  56  is to place the plate  10  in a humidified environment. 
   With the construction of the plate  10  as disclosed herein, it is possible to detect individual samples  54  in separate through-hole wells  20  if the samples  54  can be somehow excited to be fluorescent. Specifically, due to the light absorptive characteristics of the outer wall  28 , or an appropriately heat-treated interior wall  26 , each through-hole well  20  (capillary tube) will act as a light channel. On the other hand, to a lesser degree, the material of the holding plate  10 , by itself, can have refractive properties that will allow the individual lumens  22  in the plate  10  to be optically distinguishable. With reference back to  FIG. 3A , it can be seen that when fluorescent light is emitted by the sample  54 , and is directed toward the interior surface  24  of the lumen  22 , (e.g. as indicated by the arrow  62 ), the light will be refracted by the outer wall  28 . One important consequence of this is that this refracted light can be distinguished from the light that is emitted from sample  54  and directed along the axis  32  will emerge from the through-hole well  20  (e.g. as indicated by the arrow  64 ). This light can then be used for the optical detection of the sample  54 . Also, this light is sufficient to optically distinguish the particular through-hole well  20  in which the sample  54  is located from adjacent through-hole wells  20 . 
   While the particular GigaMatrix Holding Tray Having Through-Hole Wells as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.