Digital dispense system

Abstract

A digital dispense system and methods for preparing samples for analysis. The digital dispense system includes a fluid droplet ejection system housed in a housing unit. The fluid droplet ejection system contains a fluid droplet ejection head and fluid cartridge containing one or more fluids to be dispensed. A cartridge translation mechanism is provided for moving the fluid droplet ejection head and fluid cartridge back and forth over a sample holder in an x direction. A sample tray translation mechanism moves a sample tray back and forth beneath the fluid droplet ejection head and fluid cartridge in a y direction orthogonal to the x direction.

Claims

1. A digital dispense system for preparing samples for analysis, comprising a fluid droplet ejection system housed in a housing unit, the fluid droplet ejection system including: a fluid droplet ejection head and fluid cartridge containing one or more fluids to be dispensed, a cartridge translation mechanism for moving the fluid droplet ejection head and fluid cartridge back and forth over a sample holder in an x direction; and a sample tray translation mechanism for moving a sample tray back and forth beneath the fluid droplet ejection head and fluid cartridge in a y direction orthogonal to the x direction, wherein the sample tray further comprises a registration device configured to bias glass slides or a micro-well plate in the sample tray against two edges of the sample tray so that the glass slides or micro-well plate are in a predetermined location for fluid droplet ejection.

2. The digital dispense system of claim 1, wherein sample tray further comprises a glass slide adapter for holding one or more glass slides.

3. The digital dispense system of claim 2, wherein the glass slide adapter is selected from the group consisting of an adapter configured to hold one glass slide, an adapter configured to hold two glass slides, and an adapter configured to hold three glass slides.

4. The digital dispense system of claim 1, wherein the sample tray further comprises a micro-well plate adapter for holding a micro-well plate.

5. The digital dispense system of claim 4, wherein the micro-well plate adapter is sized for different size micro-well plates.

6. The digital dispense system of claim 1, wherein the registration device comprises a biasing means to bias the glass slides or micro-well plate in the sample tray to the predetermined location.

7. The digital dispense system of claim 6, wherein the biasing means comprises a spring-loaded lever for positioning glass slides or a micro-well plate in the sample tray.

8. The digital dispense system of claim 7, wherein a distal end of the spring loaded lever abuts a chamfer on one corner of the micro-well plate or a chamfer on one corner of a glass slide adapter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view, not to scale, of a digital dispense system according to an embodiment of the disclosure.

(2) FIG. 2 is an elevational view, not to scale, of a back side of the digital dispense system of FIG. 1.

(3) FIG. 3 is a perspective cutaway view, not to scale, of the digital dispense system of FIG. 1.

(4) FIG. 4 is a schematic view of the digital dispense system of FIG. 1 showing a sample tray and micro-well plate in a position inside the digital dispense system for fluid deposition onto the micro-well plate.

(5) FIG. 5 is a perspective view, not to scale, of a tray for holding samples for use with the digital dispense system of FIG. 1.

(6) FIG. 6 is a perspective view, not to scale, of adapters for glass slides and micro-well plates for use with the tray of FIG. 5.

(7) FIG. 7 is a perspective view, not to scale, of the tray of FIG. 4 holding a micro-well plate for the digital dispense system of FIG. 1.

(8) FIG. 8 is a perspective view, not to scale, of the tray of FIG. 4 holding a glass slide adapter and glass slides for the digital dispense system of FIG. 1.

(9) FIGS. 9A-9C are schematic plan views, not to scale, of a sample tray, and a well plate adapter for holding different sizes of micro-well plates in the sample tray.

(10) FIG. 10 is a perspective view, not to scale of a micro-well plate in a tray according to another embodiment of the disclosure.

(11) FIG. 11 is a plan view, not to scale of the micro-well plate in the tray of FIG. 10.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(12) With reference to FIGS. 1-4 there is shown a digital dispense system 10 for accurately dispensing an amount of one or more fluids into the wells of a micro-well plate, or in some defined pattern of spots on one or more glass slides (commonly referred to as spotting). Unlike the high-end digital dispense devices, the system 10 of the present invention is based on an ejection head and fluid cartridge 12 that moves back and forth in a first direction and a sample tray 14 containing the well plate or slides that moves back and forth in a second direction orthogonal to the first direction, as described in more detail below. The disclosed device 10 can accept open and closed ejection fluid cartridges. The sample tray 14 is adaptable to standard micro-well plates, customized micro-well plates and glass slides. The ejection head on the ejection head and fluid cartridge 12 may be selected from a wide variety of ejection head devices including, but not limited to, thermal jet ejection heads, bubble jet ejection heads, piezoelectric ejection heads, and the like.

(13) The ejection head and fluid cartridge 12 is moved back and forth in an x direction by a cartridge movement mechanism 16 (FIG. 3) both of which are contained in a rectangular prism-shaped box 18. An activation switch 20 is included on the box 18 for activating the system 10. A rear side 22 of the box 18 includes an opening 24 for movement of the sample tray 14 through the box 18 in the second direction orthogonal to the x direction to dispense fluid into the micro-well plate or slides. A USB port 26 is provided on the rear side 22 of the box 18 to connect the digital dispense system 10 to a computer or a digital display device. Power is provided to the system 10 through a power input port 28 on the rear side 22 of the box 18. FIG. 4 illustrates a view through the box 18 of the digital dispense system 10 showing the sample tray 14 containing a micro-well plate in position within the system for fluid deposition thereto. A sample tray movement mechanism 30 provides movement of the sample tray 14 in a direction through the system that is orthogonal to the movement of the ejection head and fluid cartridge 12.

(14) The sample tray 14 and adapters 32 and 34 for the sample tray 14 are illustrated in FIGS. 5 and 6. The adapters 32 and 34 are unique aspects of the disclosed embodiments that enable much more flexibility in the use of the system 10 to deposit fluids on a variety of surfaces. The adapter 32 is particularly suitable for holding two glass slides 36 as shown, however, an adapter to hold only one glass slide or three glass slides may also be used. Adapter 40 is specifically designed to hold a micro-well plate 38. Both adapters 32 and 34 are configured to fit into an adapter holding space 40 in the sample tray 14. In some embodiments, as described in more detail below, the micro-well plate 38 is disposed directly in the holding space 40 of the tray 14 in the absence of the adapter 34. FIG. 7 illustrates a micro-well plate 38 containing a plurality of wells 42 disposed directly in the holding space 40 (FIG. 5) of the tray 14. FIG. 8 illustrates glass slides 36 on the glass slide adapter 32 in the sample tray 14.

(15) In some embodiments, as illustrated in FIGS. 9A-9C, different size micro-well plates 38A, 38B, or 38C may be used to prepare and analyze samples using the digital dispense system 10 described above. In order to accommodate various micro-well plate sizes, a sample tray 44 specifically designed to accommodate a well plate adapter 46 may be used. The well plate adapter 46 may contain a gate 50 that may be used to restrict the position of the micro-well plate 38A, 38B and 38C in well plate adapter 46 as shown. In some embodiments, the gate is molded into the well plate adapters 46. In other embodiments, the gate 50 is adjustable with respect to the well plate adapter 46 so as to accommodate a wide variety and sizes of micro-well plates 38A-38C.

(16) In order for the system 10 to deposit fluids in the precise well locations on the micro-well plate 38, an embodiment of the disclosure provides a device for urging a micro-well plate 38 or glass-slide adapter 32 into a pre-determined registration position within a sample tray 54 is illustrated in FIGS. 10-11. FIG. 10 is a perspective view of the tray 54 having a registration device 56 for urging the micro-well plate 38 into the predetermined registration position so that the micro-well plate 38 abuts edges 58 and 60 of the tray 54. The registration device 56 may be a spring-loaded lever that has a distal end 62 that abuts a chamfer 64 of the micro-well plate 38 in order to urge the micro-well plate 38 toward edges 58 and 60 of the tray 54. Accordingly, the registration device 56 may be rotated clockwise in the direction of arrow 66 to load the micro-well plate 38 into the tray 54. Once the micro-well plate 38 is loaded into the tray 54, the registration device 56 is released and a spring (not shown) causes the registration device 56 to rotate in a counter-clockwise direction indicated by arrow 68 so that the distal end 62 of the registration device 56 abuts the chamfer 64 of the micro-well plate 38 thereby urging the micro-well plate 38 in the direction of arrows 70 and 72. Accordingly, the registration device 56 enables precise deposition of fluid into the wells 42 of the micro-well plate 38.

(17) For a given volume of fluid to be deposited on a glass slide 36 or into wells 42 of a micro-well plate 38 using the system 10 described above, the number of drops required to dispense a given volume of fluid is defined as (volume/drop size). For example, if a drop size is selected as 10 pico-liters, and it is required to dispense 10 micro-liters, then the ejection head and fluid cartridge 12 will have to dispense 10/10.sup.e-6 or 1,000,000 drops. Now that the number of drops is determined for the given volume, the area can be calculated. Most inkjet printers print on a grid that has a specific resolution, for example 600H×1200V DPI (drops per inch). If the target area is a square that is 0.5 inches×0.5 inches, then the maximum number of drops that can be dispensed in that area with one pass of the ejection head and fluid cartridge 14 can be calculated as follows:
Area=0.5*0.5=0.25 inches'
Maximum drops in one pass=Area*(600×1200)=180,000 drops.
Finally, the total number of passes required to spread this volume over the selected area can be calculated as follows:
1,000,000/180,000=5.56 passes.
Accordingly, the ejection head and fluid cartridge 12 will need to make 5 full passes, and then a ‘remainder’ pass that is not entirely full to dispense the volume of fluid calculated over a given area. Each of the passes will spread the drops consistently over the area.

(18) The input data that is created by the foregoing calculations is effectively an image representing both X and Y axes, but also introducing a Z axis that represents volume. In addition, when dispensing more than 1 channel or fluid at once, a 4.sup.th dimension is introduced to track the different channels or fluids.

(19) The foregoing assumes an ejection head on the ejection head and fluid cartridge 12 has a length of 0.5 inches and can cover the entire area. This is not always be the case, so an additional variable must be introduced, which is the length of the ejection head. For example, if we continue the example from above, but assume that ejection head has a length of 0.25 inches, this introduces a requirement to move either the ejection head and fluid cartridge 12 over the slide or well plate in the x direction to fill in the area correctly. Furthermore, there may be reasons in certain applications to increase the number of passes beyond what is the minimum required. Some examples could include: To improve some aspect of the output (coverage, uniformity, etc.) To artificially limit the maximum volume per pass for experimental reasons.
Variations may be achieved by setting an artificial minimum number of passes for the job. This becomes a multiplier to be used with the required number of passes. So, if the minimum number of passes of 2, then a 50% maximum limit can be set on the number of drops in each pass, which will multiply the total number of passes by 2 overall.

(20) The foregoing method provides benefits over traditional digital dispense systems which may print the entire volume of fluid into a micro-plate well in a single operation. The foregoing method spreads the volume of fluid to be dispensed over multiple dispense head passes and multiple fluid ejectors along a dispense head array of an ejection head. This will minimize the impact of missing or poorly performing fluid ejectors. Depending on the desired dispense accuracy and probability of ejectors not functioning correctly, a minimum number of fluid ejectors to use can be specified or calculated.

(21) In fields such as hematology it may be desirable to deposit or print multiple stains or buffers over a defined area of a substrate such as a glass slide. When printing layers of fluid, the test may be improved by controlling the rate at which the fluid is deposited. The digital dispense system 10 described herein will enable a user to better control the deposition rate.

(22) In some embodiments, the digital dispense system 10 according to the disclosure enables a volume of fluid to be spread consistently over an area/shape that is specified. It also enables a mode to be defined that minimizes variations by distributing ejector head nozzle usage over the entire ejection head. A minimum number of passes of the ejection head and fluid cartridge 12 can be specified along with a maximum volume per pass. If the maximum volume per pass exceeds a defined flow rate, additional passes can be added to the operation mode. The dispense system 10 can be scaled to dispense one or more fluids onto a glass slide or micro-well plate.

(23) In some embodiments, the sample tray 14 described above can be use with glass slides to dispense fluids on the glass slides to analyze body fluids such as blood. The glass slides with bloods smears may be stained with multiple stains and other fluid types selectively or simultaneously using the digital dispense system 10 according to the disclosure in order to create stained slides for studying cells types in blood samples. The use of stains to identify the blood cells has been used for a long time, but the technique for putting stains on slides is very tedious.

(24) Romanowsky type stains have been used to identify red blood cell (RBC) and white blood cell (WBC) from blood smears on glass slides. Most laboratories use some form of Romanowsky type stain (e.g. Wright-Giemsa). These stains give excellent results but the method to put the stains on slides is cumbersome. In the conventional method, the slides with blood smears are dipped in stains for a period of time. However, dipping slides is labor and time intensive. As described above, the digital dispense system 10 provides an improved technique for creating stained slides for studying cell types in blood samples by depositing precise amounts of fluids in defined locations on the slides.

(25) In some embodiments, stains such as Giemsa stain for May Grunwald and Giemsa stain or any other type of stains and a buffer solution may then be deposited simultaneously or selectively onto the glass slides. The digital dispense system 10 provides the flexibility of either jetting one, two or more stains and buffer solutions simultaneously or selectively. The amount of stains used by this method is much less compared to the dipping technique. The use of this technique is not limited to Giemsa and May Grunwald stains. It can be used with any other fluid that meets the requirements of fluid ejection technology. A predetermined volume of each fluid can be deposited onto a sample using the dispense system 10 described above.

(26) It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items

(27) For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

(28) While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.