Patent Description:
Automated processing of biological samples typically involves the use of sample tube racks that are adapted to hold a relatively large number of sample tubes for processing within a sample preparation or test instrument. Generally, these sample tube racks are configured to enable the sample preparation or test instrument to hold and/or convey the rack, as well as any sample tubes disposed in the rack, throughout the preparation and/or testing process(es).

Sample tubes containing biological sample material are often sealed with a cap to minimize or prevent the possibility of contamination of the samples, other nearby samples and/or exposing instrument operators processing the samples to the biological material in the samples. However, with many known automated sample processing instruments, such sample tube caps must be removed from each sample tube prior to loading a rack of such tubes in the instruments. Of course, removing the caps can result in contamination of samples and/or exposure of instrument operators to the biological material in the samples.

To eliminate the problems associated with having to remove sample tubes caps prior to processing the sample tubes, some automated sample processing instruments are configured to work with sample tubes having penetrable or pierceable caps. In these instruments, disposable pipettes may be used to pierce the sample tube caps, thereby reducing the possibility of sample contamination and/or operator exposure to biological material. While such automated instruments can eliminate significant amounts of mechanical manipulation of the samples and offer a significant improvement in contamination or exposure issues, proper retention of the sample tubes in the rack becomes an important consideration because withdrawal of the pipettes from the pierceable caps may tend to lift the sample tubes out of the rack due to the frictional forces between the caps and the pipettes.

Further, the use of pierceable caps on sample tubes can also result in pressure differentials between the contents of the sample tube and the ambient in which the caps are pierced. For example, if a sample is collected and capped at a relatively low altitude location and subsequently processed (i.e., the cap is pierced) at a higher altitude location, fluid and/or aerosols containing biological material may be expelled out the pierced opening in the cap, thereby potentially contaminating other samples and/or exposing instrument operators to the biological material.

Documents <CIT>, <CIT>, <CIT>, <CIT>, and <CIT> disclose sample tube racks known in the art.

The example sample tube racks described herein may be used to hold a plurality of sample tubes during automated processing of the contents of the sample tubes. The example sample tube racks advantageously employ a cover or retention bar that is configured to hold the sample tubes in a base, a sample tube holder, or a sample tube carrier during automated processing. More specifically, while the example sample tube racks described herein can be used to process sample tubes without caps, when penetrable sample tube caps are used, the retention bar prevents pipettes or the like that have pierced the caps from lifting these capped sample tubes out of the sample tube holder or carrier as the pipettes are withdrawn from the sample tubes and caps. Also, it should be recognized that while various example sample tube racks described herein may be depicted as configured to hold a particular number of sample tubes (e.g., sixteen), the teachings of the examples herein can be readily applied to sample tube racks configured to hold more or fewer sample tubes as needed to suit a particular application.

Example retention bars described herein may advantageously employ one or more features to substantially reduce or prevent contamination of samples and/or exposure of instrument operators to biological material. For example, the retention bar of the invention are pivotally engaged to the sample tube holder to minimize or eliminate any sliding of the retention bar relative to the sample tube holder and, therefore, the tops of the sample tubes loaded in the sample tube holder. By minimizing or eliminating such sliding of the retention bar relative to the sample tube holder, the transfer of biological material from the top of one sample tube to another is substantially reduced or eliminated.

Additionally the example retention bars described herein may include lateral walls that form flanges to flank at least a top portion of each sample tube. These flanges can operate to control, reduce or prevent the spread of any fluids and/or aerosols, which may contain biological material(s), to other sample tubes and, more generally, within an automated processing instrument. Further, the retention bars of the invention include openings configured to permit the passage of a pipette therethrough and into respective sample tubes positioned opposite the openings. However, these openings are sized to prevent the sample tubes from being pulled through the retention bar when pipettes that have pierced capped tubes are withdrawn from the capped tubes. To further minimize or prevent sample contamination and/or operator exposure, the openings in the retention bars have at least two aperture sizes or cross-sectional areas. Specifically, one aperture size adjacent to a top surface of the retention bar may be sufficiently large to enable a pipette to pass through the opening, while another aperture size adjacent a bottom surface of the retention bar (and, thus, adjacent the top of a sample tube) may be relatively larger to cover or overlie a substantial portion, if not all, of a pierceable surface of a sample tube cap. In this manner, the openings have stepped profiles that function to capture fluids or aerosols containing biological material that may escape from the sample tubes when, for example, any caps are pierced. In other words, the aperture adjacent the bottom surface of the retention bar may be made just small enough to allow the bottom surface of the retention bar to contact the periphery of the pierceable cap, preventing the cap from entering the lower aperture area while the aperture adjacent the top is relatively smaller and made just large enough to enable the passage of a pipette, thereby minimizing the aperture area through which any fluid(s) and/or aerosols containing biological material can escape to the top surface of the retention bar and sample tube rack.

Example retention bars described herein may also cooperate with the example sample tube holders described herein to facilitate loading and unloading of sample tubes, identification and tracking of the sample tubes and/or racks being processed, and/or the identification of a potential problem with the manner in which the sample tubes are loaded. For instance, in some examples, a latch or lock mechanism may be provided to lock the retention bar against the sample tube holder. Some of the example latches or lock mechanisms enable one-handed operation to facilitate loading and unloading of the sample tube rack. Further, the latches or lock mechanisms may provide visual indicators that the latch or lock is not properly or fully engaged. For instance, a color or feature may be exposed and readily visible to an operator if the latch or lock is not in a fully locked or secured condition. Similarly, the retention bar orientation or position may alternatively or additionally be used to reveal a condition in which the retention bar is not properly or fully engaged with the sample tube holder. For example, the orientation of the retention bar may be canted or angled relative to the sample tube holder when the retention bar is not fully or properly engaged with the sample tube holder. Additionally or alternatively, top portions of one or more loaded sample tubes may be exposed and visible (i.e., not covered or obscured by the flanges of the retention bar) when the retention bar is not fully or properly engaged with the sample tube holder. These exposed top portions of the sample tubes may readily indicate to an operator of an automated sample processing instrument that the retention bar is not fully or properly engaged with the sample tube holder or base and, therefore, may alert the operator to not initiate processing of the sample tubes by the instrument.

The example sample tube racks described herein may also provide identification structures to facilitate the identification of the sample tube racks and/or the sample tubes contained therein. For example, in some examples, the retention bar of a sample tube rack may include a structure to receive a tag that includes indicia identifying the sample tube rack. Such indicia or identifying information may be used, for example, by an automated sample processing instrument to detect the presence of a sample tube rack and, in some cases, whether the sample tube rack is properly loaded and ready for processing. In other words, the automated sample processing instrument may recognize the presence of such indentifying indicia as an indication of the presence of a sample tube rack having a retention bar coupled thereto and, thus, infer that the sample tube rack is loaded with sample tubes for processing.

Further, the sample tube holders or bases or carriers of the invention include openings or apertures to permit viewing of at least a portion of the side(s) or outer surface of each sample tube, thereby enabling manual and/or automatic reading of any indentifying information that may be provided on the sample tubes. For example, such identifying information may correspond to the source of (e.g., a person associated with) the biological sample to be processed.

Now turning in detail to <FIG>, <FIG> and <FIG>, an example sample tube rack <NUM> having a sample tube cover or retention bar <NUM> is illustrated in <FIG>, <FIG> is an exploded view of the example sample tube rack <NUM> of <FIG>, and <FIG> illustrates another view of the sample tube rack <NUM> of <FIG>. The sample tube retention bar <NUM> is removably and pivotally coupled to a base, sample tube carrier or sample tube holder <NUM> via engagement of a protrusion <NUM> with an opening <NUM> of a leg <NUM> that extends downwardly or away from a top portion <NUM> of the retention bar <NUM>. The example sample tube rack <NUM> also includes a guide rail <NUM> that is configured to interface with an automated sample processing instrument to enable the instrument to guide and/or move the sample tube rack <NUM> during processing. Further, the example sample tube rack <NUM> includes a lock or latch mechanism <NUM> that, as described in more detail below, may enable one-hand locking and unlocking of the retention bar <NUM> from the sample tube holder <NUM>.

In the example of <FIG>, the sample tube holder <NUM> has an elongated body and walls <NUM> defining cavities or apertures <NUM> that are configured to receive respective sample tubes <NUM> and to hold the sample tubes <NUM> in a substantially vertical orientation during processing of the sample tubes <NUM> and the contents therein. The sample tubes <NUM> may be open (i.e., uncovered) and/or covered with, for example, a penetrable or pierceable cap. However, as can be appreciated in light the following detailed description, the features of the example sample tube rack <NUM> are most advantageously applied in connection with covered or capped sample tubes. As shown, the walls <NUM> may have curved surfaces <NUM> that complement the curved outer surfaces of the sample tubes <NUM>. However, the surfaces <NUM> do not necessarily have to be curved and may instead be substantially flat or have any other geometry that maintains the sample tubes <NUM> in a suitable orientation for processing purposes.

The walls <NUM> define elongated openings <NUM>, which extend along at least a portion of a length of each of the sample tubes <NUM> to enable viewing of any indicia or information that may be present on the outer surfaces of the sample tubes <NUM>. Such indicia or information may be used to identify the contents and/or sources of (e.g., persons associated with) the biological samples contained in the sample tubes <NUM>.

As noted above, the elongated retention bar <NUM> is removably and pivotally coupled to the sample tube holder <NUM> via the protrusion <NUM>, which may include a hookshaped feature or undercut area that extends through and engages a surface adjacent the opening <NUM> of the leg <NUM>. The retention bar <NUM> further includes openings <NUM> that are positioned over respective ones of the apertures <NUM> of the sample tube holder <NUM>. The openings <NUM> are sized to prevent removal of the sample tubes <NUM> through the retention bar <NUM>. In other words, during sample processing, with the retention bar <NUM> properly or fully engaged with or locked to the sample tube holder <NUM>, the sample tubes <NUM> are prevented from being pulled out of the sample tube holder <NUM> due to, for example, the frictional force(s) exerted by a pipette on a cap pierced by the pipette as the pipette is withdrawn from the sample tube and cap. The openings <NUM> may further include chamfers or lead-in surfaces <NUM> to facilitate or guide the movement of, for example, a pipette into the sample tubes <NUM>.

The retention bar <NUM> further includes lateral portions or walls <NUM> and <NUM> (<FIG>) that extend downwardly from the top portion <NUM> of the retention bar <NUM> to cover at least a top portion of each of the sample tubes <NUM>. Thus, these lateral portions <NUM> and <NUM> form flanges that, when the retention bar <NUM> is properly and fully engaged with the sample tube holder <NUM>, flank the tops of the sample tubes <NUM> to help prevent or at least reduce contamination due to fluids and/or aerosols containing biological material escaping from one or more of the sample tubes <NUM>.

At an end <NUM> of the retention bar <NUM> opposite the leg <NUM>, the top portion <NUM> of the retention bar <NUM> includes an opening <NUM> to receive a hook <NUM> of the latch mechanism <NUM>. The opening <NUM> is sized to enable the body of the hook <NUM> to pass through the top portion <NUM> of the retention bar <NUM> when the latch mechanism <NUM> is held in an unlocked condition. When the latch mechanism <NUM> is released and, thus, allowed to springably return to a locked condition, a nose or a contoured edge <NUM> of the hook <NUM> extends over a stop surface <NUM> to hold the retention bar <NUM> in engagement or a locked condition with the sample tube holder <NUM> (i.e., to prevent the retention bar <NUM> from being pivoted away from the sample tube holder <NUM>). As shown, the contoured edge <NUM> may have a beveled or tapered surface to facilitate a sliding engagement of the hook <NUM> with the stop surface <NUM>.

To further facilitate alignment between the retention bar <NUM> and the sample tube holder <NUM>, the retention bar <NUM> may also include one or more alignment notches <NUM> along a bottom edge <NUM> of the lateral portions <NUM> and <NUM>. Such alignment notches <NUM> may engage with one or more respective complementary protrusions <NUM> on the sample tube holder <NUM>. In this manner, the cooperation between the alignment notches <NUM> and the protrusions <NUM> maintains alignment of the openings <NUM> relative to the apertures <NUM> when the retention bar <NUM> is fully engaged and/or locked against the sample tube holder <NUM>. In other words, these alignment notches <NUM> and the protrusions <NUM> function to align the relative positions of the retention bar <NUM> and the sample tube holder <NUM> along a longitudinal axis <NUM> of the sample tube rack <NUM>. Likewise, the leg <NUM> includes an inner surface <NUM> that engages an outer surface <NUM> of one of the walls <NUM> at an end of the sample tube rack <NUM> to align the position of the retention bar <NUM> along the longitudinal axis <NUM> of the sample tube rack <NUM>.

To control the lateral alignment (i.e., perpendicular to the longitudinal axis <NUM>) of the retention bar <NUM> relative to the sample tube holder <NUM>, inner surfaces <NUM> of the lateral portions <NUM> and <NUM> of the retention bar <NUM> may engage, or at least are constrained by, surfaces <NUM> of the sample tube holder <NUM> adjacent the lock mechanism <NUM>. Similarly, the leg <NUM> includes lateral walls <NUM>, which extend toward the lock mechanism <NUM>, that engage sides or edges <NUM> of the wall <NUM> at the end of the sample tube rack <NUM>. These lateral walls <NUM> limit the lateral movement of the retention bar <NUM> relative to the sample tube holder <NUM>.

The latch mechanism <NUM> includes an actuator <NUM>, which includes a button <NUM> that is coupled via a slide <NUM> to the hook <NUM>. The actuator <NUM> slidably engages the sample tube holder <NUM> via a slot, channel or groove <NUM> and is springably biased toward a locked condition by a biasing element <NUM> (e.g., a spring). A plug <NUM>, which is fixed to the sample tube holder <NUM> by a screw <NUM> that passes through an aperture <NUM> and into the plug <NUM>, captures the actuator <NUM> in the slot <NUM>. A finger grip <NUM> may be provided as shown to facilitate one-handed operation of the latch mechanism <NUM>. For example, an operator may wrap the forefinger of one hand around the grip <NUM> while using their thumb of the same hand to push the button <NUM> against the biasing element <NUM> toward the unlocked condition (i.e., toward the leg <NUM>). Although not shown, the channel or groove <NUM> may include one or more weep or drain holes to permit any liquid that may enter the channel or groove <NUM> (e.g., during cleaning of the sample tube rack <NUM>) to pass through the rack <NUM>.

In the example of <FIG>, the leg <NUM> of the sample tube rack <NUM> includes a slot or recess <NUM> to receive a tag <NUM> containing indicia or information <NUM> identifying the sample tube rack <NUM> and/or the sample tubes <NUM>. Turning briefly to <FIG>, a more detailed illustration of the tag <NUM> is provided. As shown in <FIG>, the tag <NUM> may have a substantially rectangular body, which may be made of a corrosion resistant metal (e.g., stainless steel) or any other suitable material (e.g., a plastic material), on which an adhesive-backed label <NUM> has been applied. The information or indicia <NUM> may be printed or otherwise applied to the label (e.g., before the label <NUM> is applied to the tag <NUM>), or the information or indicia <NUM> may be applied directly to tag <NUM>. The information or indicia <NUM> may take the form of barcode, text, numerical data, or any other form. However, the use of barcode is particularly advantageous when the sample tube rack <NUM> is used with an automated sample processing instrument because such barcode can be automatically read and interpreted by such an instrument.

Returning to <FIG>, the sample tube rack <NUM> also includes the rail <NUM> to facilitate use of the sample tube rack <NUM> with one or more different sample processing instruments. The rail <NUM> may be specifically adapted to work with a particular sample processing instrument or may be adapted to work with a number of different sample processing instruments. The rail <NUM> is depicted as a separate piece that is coupled to the bottom of the sample tube holder <NUM> via fasteners <NUM> (e.g., screws). However, the rail <NUM> may, alternatively, be integrally formed with the sample tube holder <NUM>. The example rail <NUM> also includes openings <NUM> to enable any liquid(s) that may be present in the sample tube rack <NUM> to pass through the bottom of the sample tube rack <NUM>.

The various components of the example sample tube rack <NUM> may be made of identical, similar and/or different materials to suit the needs of particular applications. In some examples, the retention bar <NUM> and the sample tube holder <NUM> are made of plastic while the guide rail <NUM> is made of metal. Such a material selection provides a rugged rail, which can be replaced as needed due to wear or changed to enable adaptation of the sample tube rack <NUM> to different processing instruments. Further, the use of lighter, plastic materials for the retention bar <NUM> and the sample tube holder <NUM> while metal is used for the guide rail <NUM> provides a relatively lower center of mass and, thus, increased stability of the rack <NUM>, particularly when the rack <NUM> is loaded with the sample tubes <NUM>. However, in other applications, the guide rail <NUM> may be made of plastic rather than metal. Further, the various components (e.g., a surface of the sample tube holder <NUM>) may be flame treated to facilitate adhesion of a label to the component.

<FIG> is an enlarged cross-sectional view of a portion of the sample tube rack <NUM> of <FIG> showing a pipette <NUM> penetrating a cap <NUM> through one of the openings <NUM> in the retention bar <NUM>. As depicted in <FIG>, each of the openings <NUM> has a stepped profile that functions to reduce or avoid contamination due to fluid(s) and/or aerosols escaping from one or more of the sample tubes <NUM>. More specifically, the stepped profile may be composed of at least two different aperture sizes. For example a lower aperture <NUM> adjacent a bottom surface <NUM> of the retention bar <NUM> is relatively larger (e.g., has a larger diameter, cross-sectional area, etc.) than another, upper aperture <NUM> that is adjacent the top portion <NUM> of the retention bar <NUM>. In this example, the upper aperture <NUM> is sized to be only sufficiently large enough to enable passage of the pipette <NUM> through the retention bar <NUM>, whereas the lower aperture <NUM> is relatively larger and substantially overlies or covers a pierceable portion <NUM> of the sample tube cap <NUM>. Such an arrangement of aperture sizes enables the lower aperture <NUM> to be sufficiently large to facilitate the capture of any fluids and/or aerosols that may escape from the sample tube <NUM> when the pipette <NUM> pierces the cap <NUM> while the relatively smaller upper aperture <NUM> substantially reduces or restricts the area or path through which any such escaped fluids or aerosols may pass to the ambient and/or other sample tubes <NUM>.

<FIG> generally illustrate the mechanical interaction between the retention bar <NUM> and the sample tube holder <NUM>. In particular, <FIG> shows the example sample tube rack <NUM> with the retention bar <NUM> removed. In <FIG>, the sample tubes <NUM> have been loaded into respective ones of the apertures <NUM> of the sample tube holder <NUM>. In this particular example, all of the apertures <NUM> have been loaded with a sample tube <NUM> and all of the sample tubes <NUM> are depicted as having the pierceable cap <NUM>. However, in other example uses, one or more of the apertures <NUM> may not have a sample tube <NUM> loaded therein and one or more of the sample tubes <NUM> may not be capped (i.e., may be open).

<FIG> shows the example sample tube rack <NUM> with the retention bar <NUM> pivotally engaging the sample tube holder <NUM> via the leg <NUM> and, in particular, via the protrusion <NUM> and the opening <NUM>. The pivoting action of the retention bar <NUM> is substantially devoid of any sliding action relative to the sample tube holder <NUM> as well as the tops of the sample tubes <NUM>. The substantial elimination of any sliding action of the retention bar <NUM> relative to the sample tubes <NUM> further reduces the possibility of moving any biological material or other contaminates from the top of one of the sample tubes <NUM> to another one of the sample tubes <NUM>.

<FIG> shows the example sample tube rack <NUM> of <FIG> with the retention bar <NUM> not fully or properly engaged with the sample tube holder <NUM>. As can be clearly seen in <FIG>, the configuration of the lateral portions <NUM> and <NUM> is such that when the retention bar <NUM> is not fully engaged with the latch mechanism <NUM> and, more generally, with the sample tube holder <NUM>, one or more of the caps <NUM> (or tops if one or more caps are not present) of the sample tubes <NUM> are exposed as indicated at reference number <NUM>. In this manner, the retention bar <NUM> is configured to provide a clear visual indication of whether the retention bar <NUM> is fully and/or properly secured, engaged and/or locked to the sample tube holder <NUM>. Specifically, a skewed orientation (e.g., an angle) of the retention bar <NUM> relative to the sample tube holder <NUM> is plainly visible, particularly due to the varying exposure of the top portions of one or more of the sample tubes <NUM>.

<FIG> illustrates another example sample tube holder <NUM> that may be used to implement various sample tube racks having retention covers. The sample tube holder <NUM> is similar in principal to the sample tube holder <NUM> described above but employs different mechanisms to engage or lock a retention bar or cover. More specifically, the example sample tube holder <NUM> does not use a retention bar that pivots relative to the sample tube holder <NUM> as the retention bar is being secured or locked against the sample tube holder <NUM>. Rather, sample tube holder <NUM> is configured to receive a retention bar by vertically placing the retention bar across a handle <NUM> at one end of the sample tube holder <NUM> and a post <NUM> at an opposite end of the sample tube holder <NUM> and then sliding the retention bar across the handle <NUM> and the post <NUM> to engage one or more features of the retention bar (e.g., a keyhole opening) with complementary features of the handle <NUM> and the post <NUM>.

In the example of <FIG>, the handle <NUM> includes a lug or key <NUM> that protrudes away from the handle <NUM>, which may have a T-shaped profile. In addition, the handle <NUM> may include a depression <NUM>, which facilitates gripping of the handle <NUM> by, for example, an operator's thumb or other finger(s). Still further, the handle <NUM> may include visual unlocked and locked indicators <NUM> and <NUM>, respectively, which may be colored areas, textured areas, etc. that, as described in more detail below, can be used to indicate whether a retention bar is properly and/or fully engaged or locked to the sample tube holder <NUM>. The post <NUM> also has a T-shaped portion <NUM>, which is configured to lockably engage a retention bar.

Walls <NUM> of the sample tube holder <NUM> may include posts <NUM>-<NUM> that are configured to receive o-rings (not shown), for example, to facilitate stabilization of any sample tubes loaded in the rack <NUM>. Such o-rings may be selected to frictionally engage outer surfaces of sample tubes to limit or prevent movement of the sample tubes once loaded in the sample tube rack <NUM>.

<FIG> illustrate a latch mechanism <NUM> that may be used to lock a retention bar <NUM> to the example sample tube holder <NUM> of <FIG>. As shown in <FIG>, the retention bar <NUM> includes a latch plate <NUM> having an opening or keyhole <NUM>, an actuation handle or plate <NUM>, and bias members or fingers <NUM> and <NUM>, where each of the fingers <NUM> and <NUM> includes a respective detent mechanism <NUM> and <NUM>.

In <FIG>, the retention bar <NUM> is shown in an unsecured condition in which the latch mechanism <NUM> is not locked. This unlocked condition is clearly indicated by the exposure of the indicator <NUM> through the opening or keyhole <NUM> in the latch plate <NUM>. To lock the latch <NUM> and fully secure the retention bar <NUM> to the sample tube holder <NUM>, an operator may push the actuator plate <NUM> in a direction away from the depression <NUM>. As the lock plate <NUM> is moved, the detent mechanisms <NUM> and <NUM> spread the fingers <NUM> and <NUM> away from the key <NUM> to allow the detent mechanisms <NUM> and <NUM> to pass over the key <NUM> and then springably return the fingers <NUM> and <NUM> to the locked state shown in <FIG>. The locked condition is clearly indicated by the presence of the indicator <NUM>. In addition to using the lock indicators <NUM> and <NUM>, an operator could, of course, also determine whether or not the retention bar <NUM> is properly and/or fully engaged or locked by assessing whether or not apertures <NUM> in the retention bar <NUM> are aligned with the sample tubes <NUM> (see, e.g., <FIG>).

<FIG> illustrate alternative latch mechanisms <NUM> and <NUM> that may be used to lock the example retention bar <NUM> to the example sample tube holder <NUM> of <FIG>. The alternative latch mechanisms <NUM> and <NUM> are similar to those of <FIG>. However, the latch mechanisms <NUM> and <NUM> use alternative detent mechanisms <NUM> and <NUM>, respectively. The detent mechanisms <NUM> and <NUM> are configured to travel over the top of the key or lug <NUM>.

<FIG> illustrates another example sample tube rack <NUM> having o-rings <NUM> to stabilize the sample tubes <NUM>. <FIG> is an exploded view of the sample tube rack <NUM> of <FIG> is an enlarged partial view of the sample tube rack <NUM> of <FIG> showing the o-rings <NUM> stabilizing the sample tubes <NUM> with caps and sample tubes <NUM> without caps. Referring to <FIG>, the example sample tube rack <NUM> includes a sample tube holder or carrier <NUM>, a guide rail <NUM> and a retention cover or bar <NUM>.

The retention bar <NUM> may be vertically coupled or locked to the sample tube holder <NUM> via buckle structures <NUM> and <NUM>, which are located at opposite ends of the sample tube rack <NUM>. As can be most clearly seen in <FIG>, each of the buckles <NUM> and <NUM> includes a respective female buckle portion <NUM>, <NUM> and male buckle portion <NUM>, <NUM> that may be pushed together to lock the retention bar <NUM> to the sample tube holder <NUM>. The male buckle portions <NUM> and <NUM> include tangs or fingers <NUM>-<NUM> that form a snap-fit coupling with openings <NUM>-<NUM>. To remove the retention bar <NUM> from the sample tube holder <NUM>, an operator presses the fingers <NUM>-<NUM> inwardly (i.e., toward a longitudinal axis of the sample tube rack <NUM>) and pulls upwardly on the retention bar <NUM> to lift the retention bar <NUM> away from the sample tube holder <NUM>. The locking and removal of the retention bar <NUM> may be facilitated by use of a handle or lift tab <NUM>. Additionally, the example sample tube rack <NUM> may include a tag <NUM> on which identifying indicia or information may be placed for use during processing of the sample tube contents.

<FIG> illustrates another example sample tube rack <NUM> having a buckle-type latch mechanism <NUM>. <FIG> is an exploded view of the sample tube rack <NUM> of <FIG>. With reference to <FIG> and <FIG>, the example sample tube rack <NUM> includes a sample tube holder <NUM>, a retention bar <NUM>, and a frame assembly <NUM>. The frame assembly <NUM> includes a guide rail portion <NUM> and end plates <NUM> and <NUM>. One of the end plates <NUM> also includes a handle or tab <NUM> to facilitate handling of the rack <NUM> during, for example, loading of the sample tubes and/or securing or locking of the retention bar <NUM>.

The latch mechanism <NUM> includes a buckle lever <NUM> and a loop or hasp <NUM> that engages and pulls downwardly on a lip <NUM> of the retention bar <NUM> to the lock the retention bar to the rack <NUM>. At the end of the rack <NUM> opposite the latch <NUM>, the retention bar <NUM> includes a slot <NUM> to receive a hooked end <NUM> of the end plate <NUM>.

<FIG> depict an alternative latch mechanism <NUM> that may be used with the example sample tube rack <NUM> of <FIG>. The example latch mechanism <NUM> uses an end plate <NUM> having an end <NUM> with notches <NUM> that provide a snap-fit arrangement with an opening or slot <NUM> in the retention bar <NUM>. In this manner, securing or locking the retention bar <NUM> to the rack assembly <NUM> is performed by pushing the retention bar <NUM> vertically onto the end plate <NUM>. Alternatively, removing the retention bar <NUM> involves pulling the retention bar <NUM> away from the end plate <NUM> with sufficient force to cause the edges of the opening or slot <NUM> to pull out of the notches <NUM> to allow the end <NUM> of the plate <NUM> to be pulled out of the retention bar <NUM>.

<FIG> illustrates another example sample tube rack <NUM> and <FIG> is an exploded view of the example sample tube rack <NUM> of <FIG>. The example sample tube rack <NUM> employs a modular construction in which wall sections <NUM> may be snap-fit or otherwise plugged into openings <NUM> of a base <NUM>, which has an integral rail feature <NUM>. Some of the wall sections <NUM> may include posts <NUM> having ends <NUM> that plug or snap-fit into respective openings or slots in a retention cover or bar <NUM>.

<FIG> illustrates an exploded view of another sample tube rack <NUM>. The example sample tube rack <NUM> employs a retention bar <NUM> that plugs or snap-fits onto end wall sections <NUM>.

<FIG> illustrates yet another example sample tube rack <NUM>, and <FIG> is an exploded view of the example sample tube rack <NUM> of <FIG>. The example rack <NUM> of <FIG> includes a u-shaped structure <NUM> having upright legs <NUM> with slots <NUM> to slidably receive a retention bar <NUM>.

<FIG> illustrates an example sample tube rack <NUM> having a retention bar <NUM> that pivots laterally relative (e.g., along the direction of arrow <NUM>) to a sample tube holder portion <NUM> of the rack <NUM>.

<FIG> illustrates an example one-piece sample tube rack <NUM> in which sample tubes are side-loaded. The example sample tube rack <NUM> includes a plurality of fingers or grips <NUM> that are spaced apart (at least at the ends of the fingers or grips <NUM>) to be a distance apart that is smaller than, for example, the diameter of the sample tubes. In this manner, the sample tubes can be captured by the fingers or grips <NUM> by pushing the tubes to spread the fingers or grips <NUM> and into holding apertures <NUM>, which may be sized to be somewhat larger than the diameter of the tubes. Removing sample tubes involves an operator pulling the tubes away from the rack <NUM> back through the fingers or grips <NUM>.

Claim 1:
A rack for holding sample tubes, comprising:
a sample tube carrier (<NUM>) including an elongated body having a first end and a second end opposite the first end and walls (<NUM>) defining apertures (<NUM>), each of the apertures configured to receive a respective one of the sample tubes (<NUM>), wherein the walls (<NUM>) define elongated openings (<NUM>), each of which corresponds to a respective one of the sample tubes and extends along at least a portion of a length of the respective sample tube, the elongated openings (<NUM>) to enable viewing of information on the outer surfaces of the sample tubes; and
a retention bar (<NUM>) including an elongated body having a first end and a second end opposite the first end, the retention bar (<NUM>) pivotally coupled to one end of the sample tube carrier (<NUM>) , the retention bar (<NUM>) having openings (<NUM>), each of which is positioned over a respective one of the apertures (<NUM>), wherein the openings (<NUM>) are dimensioned to prevent removal of the sample tubes from the sample tube carrier through the retention bar (<NUM>),
wherein the retention bar (<NUM>) is removably coupled to the sample tube carrier (<NUM>), and each of the openings (<NUM>) has a stepped profile (<NUM>, <NUM>, <NUM>) to reduce contamination due to material escaping from one or more of the sample tubes .