DIGITAL DISPENSE SYSTEM

[0001] This application claims priority to provisional application Ser. No. 62/788,290, filed Jan. 4, 2019, now pending.

[0002] The disclosure is directed to analytical instruments and in particular to instruments that are used to dispense fluids for analytical purposes.

[0003] In the medical field, in particular, there is a need for automated sample preparation for analysis. The analysis may be colorimetric analysis or require the staining of samples to better observe the samples under a microscope. Such analysis may include drug sample analysis, blood sample analysis and the like. In the analysis of blood, for example, blood is analyzed to provide a number of different factors that are used to determine the health of an individual. When there are a large number of patients that require blood sample analysis, the procedures for preparing the samples for analysis may be extremely time consuming. Also, there is a need for accurate preparation of the samples so that the results can be relied on. There are many other situations that require sample preparation in the medical field and in other fields that can benefit from the use of analytical instruments that provide accurate and reproduceable results, such as micro-titration of multiple samples.

[0004] Well plates, slides and other substrates are used for many experiments and laboratory procedures. The process of filling the wells or spotting is often performed manually or using expensive lab equipment. In some cases, the wells are filled with hand operated pipettes. In other cased, high-end automated devices based on pipette technology are used to fill the well plates. Such automated devices accommodate an open well dispense head only. The open well dispense head is a dispense head where a small amount of fluid must be deposited into an opening in the dispense head before use. The fluid is typically deposited manually using a pipette or similar means. The dispense head is held stationary while moving the microplate in both X and Y directions. These high end devices are extremely expensive. Accordingly, there is a need for a digital dispense system that can be used in a wide variety of analytical situations for analysis and digital titration of samples that is much less expensive to purchase. There is also a need for readily visualizing the volume of fluid in each well of a well tray or the amount of fluid that is applied to a predetermined area of a slide.

[0005] In view of the foregoing, an embodiment of the disclosure provides a digital dispense system and method of preparing samples for analysis. The system includes a fluid droplet ejection system housed in a compact 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 for moving the fluid droplet ejection head and fluid cartridge back and forth over a sample holder in an x direction; and a sample holder translation mechanism for moving a sample back and forth beneath the fluid droplet ejection head and fluid cartridge in a y direction orthogonal to the x direction. A digital display device is attached to the fluid droplet ejection system for displaying fluid volume information to a user. The fluid volume information is selected from relative fluid volume, absolute fluid volume, and a combination of relative and absolute fluid volumes.

[0006] In another embodiment there is provided a method for staining slides without dipping or immersing slides in a dye. The method includes providing a digital fluid droplet ejection system housed in a compact 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 for moving the fluid droplet ejection head and fluid cartridge back and forth over a slide holder in an x direction, and a slide holder translation mechanism for moving one or more slides back and forth beneath the fluid droplet ejection head and fluid cartridge in a y direction orthogonal to the x direction. A digital display device is attached to the digital fluid droplet ejection system. Fluid is ejected from the fluid droplet ejection head and fluid cartridge in one or more locations on the slide. Fluid volume information is displayed to a user on the digital display device. The fluid volume information is selected from relative fluid volume, absolute fluid volume, and a combination of relative and absolute fluid volumes.

[0007] In some embodiments, the fluid volume information is displayed by a bar graph representation of fluid in a particular location on a slide or fluid in a well of a well plate. In another embodiment, the digital display has a relative volume graphic for each fluid dispensed to a well in a well plate or to a slide location on a slide. In other embodiments, the digital display has both an absolute volume graphic of fluid dispensed and a relative volume graphic for each fluid dispensed to a well in a well plate or to a slide location on a slide.

[0008] In some embodiments, the fluid droplet ejection system further comprises a processor and a memory for storing fluid droplet information and for transferring the fluid droplet information to the digital display device. In other embodiments, the digital display devices is a portable or laptop computer.

[0009] In some embodiments, two or more fluids are ejected on a slide simultaneously. In other embodiments two or more fluids are ejected on a slide sequentially.

[0010] In digital dispense procedures as described herein, it may be necessary to provide a user of the digital dispense system with an indication of how much of each fluid is applied to specific locations on a slide or deposited in each well of a well plate. In other situations, it may be necessary for the user to know the relative volume of each fluid that is dispensed to a slide or well plate. While only a small number of slides may be processed at one time in the digital dispense system, each well plate may have 96, 384, or 1536 wells or may have a customized number of wells depending on the application and analysis to be performed. Accordingly, a user interface for the digital dispense system would be useful so that the user can readily see if the appropriate amounts of fluids are being dispensed. Thus, an embodiment of the disclosure provides a suitable user interface in combination with the digital dispense system described herein.

[0022] With reference to FIGS. 1-9 there is shown a digital dispense device 10 for accurately dispensing an amount of one or more fluids into the wells of a well plate, or in some defined pattern of spots on a slide (commonly referred to as spotting). Unlike the high-end digital dispense devices, the device 10 of the present invention is based on an ejection head and fluid cartridge 14 that moves back and forth in a first direction and a tray 12 containing the wells 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 dispense heads rather than just open dispense head. The tray 12 is adaptable to both standard micro-well plates as well as glass slides and other substances. The ejection head on the ejection head and fluid cartridge 14 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.

[0023] The ejection head and fluid cartridge 14 and head movement mechanism 16 (FIG. 3) are contained in a rectangular prism-shaped box 18. An activation switch 20 is included on the box 18 for activating the device 10. A rear side 22 of the box 18 includes an opening 24 for movement of the tray 12 through the box 18 in the second direction to dispense fluid to the well plate or slides. A USB port 25 is provided on the rear side 22 of the box 18 to connect the digital dispense device 10 to a digital display device 27. Power is provided to the device 10 through a power input port 29 on the rear side 22 of the box 18. In other embodiments, information from the digital dispense device 10 may be transmitted wirelessly to the digital display device 27.

[0024] The tray 12 and adapters 26 and 30 for the tray are illustrated in FIGS. 4 and 5. The adapter 26 is sized to hold glass slides 28 and the well plate adapter 30 is sized to hold a micro-well plate 32. The tray 12 has an adapter holder 34 for holding the adapters 26 and 30 for dispensing fluids thereon. FIG. 6 illustrates a well plate on the adapter 30 in the tray 12. FIG. 7 illustrates slides 28 on the slide adapter 26 in the tray 12. As shown in FIG. 7, the tray 12 may include gear teeth 36 for indexing the tray 12 in the second direction as the tray moves through the box 18.

[0025] FIGS. 8-9 illustrate methods for calculating an optimized print pattern for dispensing fluid into a microplate, glass slide or other substrate. The method formats data for a digital dispense system 10 where the input is a volume of fluid to be delivered over a defined area.

[0026] For a given volume, the number of drops required to dispense that volume of fluid is defined as (volume/drop size).

[0027] 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 14 will have to dispense 10/10^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 inches²

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.

[0028] Accordingly, the ejection head and fluid cartridge 14 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.

[0029] 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 as show schematically in FIG. 8. In addition, when dispensing more than 1 channel or fluid at once, a 4^th dimension is introduced to track the different channels or fluids.

[0030] The foregoing assumes an ejection head on the ejection head and fluid cartridge 14 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 14 over the slide or well plate in the Y 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:

[0031] To improve some aspect of the output (coverage, uniformity, etc.)

[0032] 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.

[0033] 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.

[0034] 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. This method will allow the user to better control the deposition rate. FIG. 9 illustrates a hypothetical 4 pass example with a “remainder” fourth pass showing that the first three passes have the same drop count, but the fourth pass has a lower drop count as indicated by the lighter color. The fourth pass finishes the remaining number of drops required.

[0035] Accordingly, the dispense device according to the invention 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 14 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 any number of fluids dispensed by the system.

[0036] FIGS. 10A-12B illustrate the use of the dispense system 10 to dispense one or more fluids on glass slides to analyze body fluids such as blood. The glass slides 10A and 10B with bloods smears are 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.

[0037] 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 present invention 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.

[0038] Multiple types of stains and a buffer solution may be placed in chambers of an ejection head and fluid cartridge 14. Stains such as Giemsa stain for May Grunwald and Giemsa stain or any other type of stain and the buffer solution can then be jetted simultaneously or selectively onto the glass slides. The dispense system 10 provides the flexibility of either jetting one, two or more stains and buffer solutions simultaneously or selectively. In some embodiments, there are three or more fluid chambers and fluid types that are ejected from each ejection head and fluid cartridge 14. 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 jetted with this invention. The dispense technique has been successful in identifying white and red blood cells from stained glass slides with blood smears as shown in FIGS. 10A and 10B.

[0039] FIGS. 11A and 11B illustrate slides wherein two or three fluid types are simultaneously jetted onto the slides to improve the uniformity of the stained slides. FIGS. 12A and 12B illustrate a technique of selectively staining slides in a sequential manner using the dispense system 10 of the disclosure.

[0040] With reference to FIGS. 13-15, there are illustrated a visual representations of fluid volumes dispensed by the digital dispense system 10 and that are displayed on the digital display device 27 to provide a user interface with the digital dispense device 10. The user interface may give a user clear knowledge of the volume in each well of the micro well plate or spot of fluid on a glass slide as well as provide a means to select how much fluid is dispensed in each location of a slide 28 or well plate 32.

[0041] When dispensing fluids in applications where volume is an important input, such as medical well plates or slides, it's important to be able to display to the user a useful visual representation of the volume of each fluid being used. Since some wells can hold a significant volume, a relative volume display that uses the fluid with the highest volume as a maximum and scales the rest of the fluids to the highest volume fluid is one way to compare the fluids to each other. An absolute volume scale may not be useful for fluids in a large well since the amount of fluid may not be sufficient to provide visually useful information.

[0042] In FIG. 13, bar graphs 38 and 40 for two fluids represent a relative volumes of each fluid on a slide 28 or in a single well of a well plate 32, while 42 represents the absolute total volume of the fluids dispensed. In FIG. 14, bar graphs 38 and 40 of two fluids again represent the relative volumes of each fluid on a slide or in a single well of a well plate 32, however, an expanding circle 44 may be used to represent the total relative volume of all fluids that are dispensed into a well or onto a slide 28. The user interface for display on a digital display device 27 may be configured to provide both types of visual representation shown in FIGS. 13 and 14 by selecting a desired visual representation from a drop down menu in the user interface. Likewise, the user interface may be configured to show the absolute or relative volumes in a single well or in multiple wells of a well plate 32.

[0043] FIG. 15 illustrates a visual representation of the fluids in wells of a well plate using bar graphs 38, 40 and 46 and relative volume circles 47. The bar graph 46, representing the largest volume of fluid, is used to scale the other fluids in order to provide a good comparison of fluid volumes in each well. Only a small portion of the well plate 32 is represented by the visual display in FIG. 15 providing a visual display of the fluid in the wells in rows A-E and in columns W-Z. The amount of each fluid dispensed may vary by row, by column, or by individual cell. The digital dispense device may be programmed by use of the digital display device to deposit predetermined amounts of fluids in predetermined locations of a well plate 32 or slide 28.

[0044] It will be appreciated that the visual representations described above may be used provide the same information for applications using glass slides and spotting of liquid on the glass slides. In the glass slide application, a fluid is dispensed onto a planar substrate rather than into segregated wells. The foregoing digital representations give a user the ability to use the same digital dispense device and interface to eject fluid into wells or onto slides.

[0045] 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

[0046] 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.

[0047] 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.