Method and apparatus for freezing dispensed droplets of liquid

A method and apparatus for freezing a liquid droplet includes dispensing, by a liquid dispenser (14), a droplet (13) of liquid into a fluid chamber (10) containing a freezing fluid (12). The droplet of liquid is allowed to dwell in the freezing fluid for at least a predetermined dwell time so that the droplet of liquid freezes to a frozen droplet. The method and apparatus further includes injecting, by a gas injector (17), a stream (16) of gas transversely to a surface of the freezing fluid at about where the frozen droplet is located along the surface of the freezing fluid contained in the fluid chamber so that the frozen droplet sinks in the freezing fluid.

FIELD OF THE DISCLOSURE

This disclosure relates to apparatuses and methods for freezing dispensed droplets of liquid in a fluid chamber.

BACKGROUND

Analytical processes of biological fluids, such as blood, typically combine the analyzed fluid with one or more reagents to trigger the occurrence of a detectable property that corresponds to a measured parameter of the analytical process. One example includes combining blood plasma with a reagent to undergo a reaction that changes the color or the visibility of the detectable property, which may be measured by processing equipment. The processing equipment may be supplied with a biological sample and one or more lyophilized reagent pellets that may be reconstituted during the analytical process.

One known method for producing lyophilized reagents includes the step of dispensing liquid reagent droplets of precise volume into a freezing liquid bath in which the liquid droplets freeze and sink to the bottom of the bath. After sinking to the bottom of the bath, the known method includes removing the frozen droplets from the bath and lyophilizing the frozen droplets. In some instances, however, other factors, such as surface tension at the top surface of the freezing liquid, hinder the frozen droplets of liquid reagent from sinking to the bottom of the bath such that the droplets of liquid reagent tend to float near the surface of the freezing liquid. Consequently, subsequent dispensed liquid reagent droplets may combine with the floating droplet, thus resulting in an inaccurate reagent dosage for the combined droplet. Thus, there is a need for improved apparatuses and methods that promote dispensed droplets of liquid to sink to the bottom of a freezing liquid bath.

SUMMARY

The following presents a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview of the subject matter disclosed herein. It is intended to neither identify key or critical elements of the claimed subject matter nor delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

The present disclosure includes various examples of an apparatus for freezing liquid droplets. In accordance with one example, the apparatus comprises a fluid chamber containing a fluid, a liquid dispenser, a gas injector, and a transporter. The liquid dispenser is configured to dispense a droplet of liquid into the fluid chamber. The gas injector is configured to inject a stream of gas transversely to a surface of the fluid contained in the fluid chamber. The transporter is configured to transport at least one of the fluid chamber, the liquid dispenser, and the gas injector relative to each other such that the liquid dispenser dispenses the droplet of liquid on the surface of the fluid contained in the fluid chamber, and the gas injector injects the stream of gas at about where the dispensed droplet of the liquid is located along the surface of the fluid contained in the fluid chamber.

In some examples, the transporter is configured to transport the fluid chamber between a first position below the liquid dispenser and a second position below the gas injector. The liquid dispenser is configured to dispense a droplet of liquid into the fluid chamber when the fluid chamber is in the first position. The gas injector is configured to inject the gas stream transversely to the surface of the fluid contained in the fluid chamber when the fluid chamber is in the second position.

In some examples, the fluid contained in the fluid chamber is a cryogenic liquid configured to freeze the dispensed droplet of liquid to a frozen droplet. In some examples, the cryogenic liquid is liquid nitrogen. In some examples, the transporter comprises a carousel configured to move the fluid chamber about an axis of rotation between the first position and the second position. In some examples, the carousel comprises a drum, and the fluid chamber is disposed within the drum. In some examples, the carousel comprises a spindle configured to rotate about the axis of rotation, and the spindle is coupled to the drum such that the drum is configured to rotate with the spindle about the axis of rotation. In some examples, the carousel comprises a lid coupled to a top end of the drum. In some examples, the lid is removable from the top end of the drum. In some examples, the fluid chamber is disposed beneath the lid, and the lid comprises an opening aligned with the fluid chamber. In some examples, the fluid chamber is removable from the drum. In some examples, the drum is comprised of stainless steel. In some examples, the carousel comprises an insulation layer disposed between the drum and the fluid chamber. In some examples, the insulation layer comprises air.

In some examples, the apparatus comprises multiple fluid chambers, in which the transporter is configured to transport each fluid chamber between the first position below the liquid dispenser and the second position below the gas injector. In some examples, the apparatus comprises multiple liquid dispensers, in which the transporter is configured to transport each fluid chamber to the first position below a respective one of the liquid dispensers. In some examples, the apparatus comprises multiple gas injectors, in which the transporter is configured to transport each fluid chamber to the second position below a respective one of the gas injectors. In some examples, the gas injector comprises a nozzle disposed above the fluid chamber, in which the nozzle is configured to inject the gas stream transversely to the surface of the fluid contained in the fluid chamber. In some examples, the gas injector is configured to inject the gas stream transversely to the surface of the fluid contained in the fluid chamber only when the fluid chamber is in the second position.

In some examples, the apparatus comprises a solenoid valve controlling gas flow to the nozzle and configured to switch between a closed position to shut-off the gas stream from reaching the nozzle and an open position to permit the gas stream to reach the nozzle. In some examples, the apparatus comprises a sensor configured to generate a signal relating to a position of the transporter and a control unit in electrical communication with the sensor and the solenoid valve, in which the control unit is configured to receive the signal from the sensor and transmit a command to the solenoid valve to switch between the open and closed positions based on the signal. In some examples, the transporter is configured to transport the liquid chamber from the first position to the second position at a predetermined dwell time so that the droplet of liquid freezes to the frozen droplet before the gas injector injects the stream of gas transversely to the surface of the fluid contained in the fluid chamber.

In some examples, the liquid dispenser comprises a nozzle, in which the nozzle is configured to dispense the droplet of liquid into the fluid chamber. In some examples, the nozzle of the liquid dispenser comprises a tip located above the surface of the fluid contained in the fluid chamber at a predetermined distance. In some examples, the predetermined distance between the tip of the nozzle of the liquid dispenser and the surface of the fluid contained in the fluid chamber is set from about ¾ of an inch to about 2 inches.

In another example, a method for freezing liquid droplets comprises a step (a) of dispensing a droplet of liquid into a fluid chamber containing a freezing fluid, a step (b) of allowing the droplet of liquid to dwell in the freezing fluid for at least a predetermined dwell time so that the droplet of liquid freezes to a frozen droplet, and a step (c) of injecting a stream of gas transversely to a surface of the freezing fluid at about where the frozen droplet is located along the surface of the freezing fluid so that frozen droplet sinks in the freezing fluid. In some examples, step (a) further comprises using a liquid dispenser to dispense the droplet of liquid into the fluid chamber containing the freezing fluid. In some examples, step (c) further comprises using a gas injector to inject the stream of gas transversely to the surface of the freezing liquid.

In some examples, step (c) further comprises monitoring the predetermined dwell time and automatically injecting the stream of gas transversely to the surface of the freezing fluid after the predetermined dwell time. In some examples, the method further comprises the step of transporting the fluid chamber by a transporter from a first position below a liquid dispenser to a second position below a gas injector. In some examples, the method comprises the steps of monitoring a position of the transporter and automatically injecting the stream of gas when the fluid chamber is at a position beneath the gas injector. In some examples, the method further comprises the step of transporting the fluid chamber by the transporter from the second position below the gas injector back to the first positon below the liquid dispenser. In some examples, the method further comprises, after the step of returning the fluid chamber back to the first position, the step of dispensing a second droplet of liquid into the liquid chamber.

In some examples, the fluid chamber is integrally attached to the transporter. In some examples, the fluid chamber is removably coupled to the transporter. In some examples, the transporter comprises a carousel, and the step of transporting further comprising rotating, by the carousel, the fluid chamber about an axis of rotation from the first position to the second position. In some examples, the carousel comprises a drum and the liquid chamber is disposed within the drum. In some examples, the carousel comprises a lid coupled to a top end of the drum. In some examples, the lid is removable from the top end of the drum.

In some examples, the method comprises, before step (a), moving a liquid dispenser over the fluid chamber to align the liquid dispenser with a target zone located along the surface of the freezing fluid contained in the fluid chamber. In some examples, step (a) further comprises dispensing, by the liquid dispenser, the droplet of liquid at the target zone. In some examples, the method comprises, after step (a) and before step (c), moving a gas injector over the fluid chamber to align the gas injector with the target zone located along the surface of the freezing fluid contained in the fluid chamber. In some examples, step (c) further comprises injecting, by the gas injector, the stream of gas at the target zone. In some examples, the fluid chamber comprises a stationary bath containing the freezing fluid.

In some examples, the method further comprises after step (c), collecting, by a retainer basket, the frozen droplet sinking toward a bottom of the fluid chamber. In some examples, the method further comprises after the step of collecting the frozen droplet, drying the frozen droplet. In some examples, the step of drying the frozen droplet comprises lyophilizing the frozen droplet.

In accordance with another example, the apparatus comprises a fluid chamber containing a fluid, a liquid dispenser, and a gas injector. The liquid dispenser is configured to move relative to the fluid chamber so that the liquid dispenser is aligned above a target zone located along the surface of the fluid contained in the fluid chamber. The liquid dispenser is configured to dispense a droplet of liquid into the fluid chamber at the target zone. The gas injector is configured to move relative to the fluid chamber so that the gas injector is aligned above the target zone located along the surface of the fluid contained in the fluid chamber. The gas injector is configured to inject a gas stream transversely to the surface of the fluid contained in the fluid chamber at the target zone.

In some examples, the fluid chamber comprises a stationary bath containing the fluid. In some examples, the liquid dispenser is configured to move in a longitudinal direction along the bath and dispense multiple droplets of liquid at multiple target zones arranged in the longitudinal direction along the surface of the fluid contained in the bath. In some examples, the liquid dispenser is configured to move in a lateral direction along the bath and dispense multiple droplets of liquid at multiple target zones arranged in the lateral direction along the surface of the fluid contained in the bath. In some examples, the gas injector is configured to move in a longitudinal direction along the bath and inject multiple streams of gas transversely to the surface of the fluid contained in the bath at multiple target zones arranged in the longitudinal direction along the surface of the fluid contained in the bath. In some examples, the gas injector is configured to move in a lateral direction along the bath and inject multiple streams of gas transversely to the surface of the fluid contained in the bath at multiple target zones arranged in the lateral direction along the surface of the fluid contained in the bath. In some examples, the gas injector is configured to wait for at least a predetermined dwell time after the liquid dispenser dispenses the droplet of liquid at the target zone before injecting the stream of gas at the target zone.

Other features and characteristics of the subject matter of this disclosure, as well as the methods of operation, functions of related elements of structure and the combination of parts, and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.

DETAILED DESCRIPTION

While aspects of the subject matter of the present disclosure may be embodied in a variety of forms, the following description and accompanying drawings are merely intended to disclose some of these forms as specific examples of the subject matter. Accordingly, the subject matter of this disclosure is not intended to be limited to the forms or embodiments so described and illustrated.

Unless otherwise indicated or the context suggests otherwise, as used herein, “a” or “an” means “at least one” or “one or more.”

This description may use relative spatial and/or orientation terms in describing the position and/or orientation of a component, apparatus, location, feature, or a portion thereof. Unless specifically stated, or otherwise dictated by the context of the description, such terms, including, without limitation, top, bottom, above, below, under, on top of, upper, lower, left of, right of, in front of, behind, next to, adjacent, between, horizontal, vertical, diagonal, longitudinal, transverse, radial, axial, etc., are used for convenience in referring to such component, apparatus, location, feature, or a portion thereof in the drawings and are not intended to be limiting.

Furthermore, unless otherwise stated, any specific dimensions mentioned in this description are merely representative of an exemplary implementation of a device embodying aspects of the disclosure and are not intended to be limiting.

The use of the term “about” applies to all numeric values specified herein, whether or not explicitly indicated. This term generally refers to a range of numbers that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numeric values (i.e., having the equivalent function or result) in the context of the present disclosure. For example, and not intended to be limiting, this term can be construed as including a deviation of ±10 percent of the given numeric value provided such a deviation does not alter the end function or result of the value. Therefore, under some circumstances as would be appreciated by one of ordinary skill in the art a value of about 1% can be construed to be a range from 0.9% to 1.1%.

As used herein, the term “group” refers to a collection of one or more objects. Thus, for example, a group of objects can include a single object or multiple objects. Objects of a group also can be referred to as members of the group. Objects of a group can be the same or different. In some instances, objects of a group can share one or more common properties.

As used herein, the term “adjacent” refers to being near or adjoining. Adjacent objects can be spaced apart from one another or can be in actual or direct contact with one another. In some instances, adjacent objects can be coupled to one another or can be formed integrally with one another.

As used herein, the terms “substantially” and “substantial” refer to a considerable degree or extent. When used in conjunction with, for example, an event, circumstance, characteristic, or property, the terms can refer to instances in which the event, circumstance, characteristic, or property occurs precisely as well as instances in which the event, circumstance, characteristic, or property occurs to a close approximation, such as accounting for typical tolerance levels or variability of the embodiments described herein.

As used herein, the terms “optional” and “optionally” mean that the subsequently described, component, structure, element, event, circumstance, characteristic, property, etc. may or may not be included or occur and that the description includes instances where the component, structure, element, event, circumstance, characteristic, property, etc. is included or occurs and instances in which it is not or does not.

The term “reagent” means one or more reagents or components necessary or desirable for use in one or more reactions or processes, for example, one or more components that in any way affect how a desired reaction can proceed. The reagent can comprise a reactive component. However, it is not necessary that the reagent participate in the reaction. The reagent can comprise a non-reactive component. The reagent can comprise a promoter, accelerant, or retardant that is not necessary for a reaction but affects the reaction, for example, affects the rate of the reaction. The reagent can comprise one or more of a solid reagent for reaction and a fluid reagent for reaction.

The term “fluid communication” means either direct fluid communication, for example, two regions can be in fluid communication with each other via an unobstructed fluid processing passageway connecting the two regions or can be capable of being in fluid communication, for example, two regions can be capable of fluid communication with each other when they are connected via a fluid processing passageway that can comprise a valve disposed therein, wherein fluid communication can be established between the two regions upon actuating the valve, for example, by dissolving a dissolvable valve disposed in the fluid processing passageway.

The term “cryogenic liquid” refers to a liquefied gas that keeps its liquid state at substantially low temperatures. In one example, the term “cryogenic liquid” refers to a liquefied gas having a normal boiling point below about −75° C. In another example, the term “cryogenic liquid” refers to a liquefied gas having a normal boiling point below about −150° C. Examples of cryogens include argon (Ar), helium (He), hydrogen gas (H2), nitrogen gas (N2), oxygen (O2), methane (CH4), and carbon monoxide (CO).

The term “lyophilization” refers to a dehydration process that is typically used to preserve a perishable material and/or facilitate transport thereof. Conditions for lyophilization may include subjecting a liquid material and/or a vessel containing the liquid material to freezing conditions while reducing the surrounding pressure to allow the frozen water within the material to sublimate directly from the solid phase to the gas phase. Such freezing conditions may include cooling the material below the lowest temperature at which the solid and liquid phases thereof can coexist (known in the art as the “triple point”). Usually, the freezing temperatures are between −50° C. and −80° C., however, one of skill in the art can determine the appropriate freezing temperature to lyophilize the reagent for use in the automated biochemical assay.

FIGS.1and2illustrate a method50for freezing liquid droplets in a fluid chamber10containing a freezing liquid12according to an example. The method50includes a step, or process,51of dispensing a droplet of liquid13into the fluid chamber10containing the freezing fluid12having a surface18. In one example, the freezing fluid12is a cryogenic liquid, such as liquid nitrogen, and the droplet13is dispensed by a liquid dispenser14. The liquid dispenser14is configured to drop individual liquid droplets of reagent solution, whereby each droplet is of substantially uniform size.

Once the droplet of liquid is received on the surface18of the freezing fluid12, the method50includes a step52of allowing the droplet of liquid13to dwell in the freezing fluid12for at least a predetermined dwell time ΔT so that the droplet of liquid13freezes to a frozen droplet15. In some non-limiting examples, the predetermined dwell time ΔT includes at least the period of time between when the dispensed liquid droplet13initially contacts the surface of the freezing fluid12and when the dispensed liquid droplet13fully submerges under the surface of the freezing fluid12. In some examples, the predetermined dwell time ΔT is calculated from a number of parameters, including the composition of liquid solution dispensed from the liquid dispenser14, the mass and volume of the liquid droplet13, the composition of the freezing fluid12, the temperature of the freezing fluid12, and the pressure of the fluid chamber10. The predetermined dwell time ΔT may be extended to account for possible air bubbles trapped inside of the dispensed liquid droplet13, interaction between the dispensed liquid droplet13and the surface of the freezing fluid12, and temperature differentials between the dispensed liquid droplet13and the temperature of the freezing fluid12. Accordingly, the predetermined dwell time ΔT may vary based on the composition selected for the liquid dispensed into the fluid chamber, the composition selected for the freezing fluid contained in the fluid chamber, and the interaction between the dispensed liquid droplet13and the freezing fluid12. In some examples, the predetermined dwell time ΔT is one minute or less.

After allowing the droplet of liquid13to dwell in the freezing fluid12for at least the predetermined dwell time ΔT so that the droplet of liquid13freezes, the method50includes a step53of injecting, by a gas injector17, a stream of gas16transversely to the surface18of the freezing fluid12at about where the frozen droplet is located along the surface of the freezing fluid12. The impulse of the gas stream16contacting the frozen droplet15breaks the surface tension between the freezing fluid12and the frozen droplet15so that the frozen droplet15sinks in the freezing fluid12. Preferably, the stream of gas16is injected substantially orthogonally to the surface of the freezing fluid12. Thus, step53of the method50ensures that the dispensed droplet of liquid13freezes completely to a frozen droplet15and that the frozen droplet15sinks to the bottom of the fluid chamber10.

During the method50, in some examples, the fluid chamber10may move with respect to the liquid dispenser14and the gas injector17, as indicated by arrow A inFIG.1. In some examples, the liquid dispenser14and the gas injector17may move with respect to the fluid chamber10, as indicated by arrow B inFIG.1. In one example, the method50includes holding the fluid chamber10at the same position during all three steps51,52, and53of the method50whereby the liquid dispenser14is positioned above the fluid chamber10in step51and the gas injector17is then positioned above the fluid chamber10in step53. In one example, the method50may be automated such that step53further includes monitoring the predetermined dwell time ΔT and automatically injecting the stream of gas16transversely to the surface of the freezing fluid12after the predetermined dwell time ΔT.

In another example, the method includes the step of transporting the fluid chamber10by a transporter from a first position below the liquid dispenser14to a second position below the gas injector17. In one example, the fluid chamber10may be transported from the first positon to the second position during the step52of allowing the droplet of liquid13to dwell in the freezing fluid12for at least the predetermined dwell time ΔT. In one example, the method50may be automated such that step53includes monitoring a position of the transporter and the steps of automatically injecting the droplet13when the fluid chamber10is at the first position beneath the liquid dispenser14and automatically injecting the stream of gas16when the fluid chamber10is at the second position beneath the gas injector17. In one example, the method50includes a control unit and a sensor to monitor the positon of the transporter and command the gas injector17to inject the stream of gas16.

In one example, after the step53of injecting the stream of gas16transversely to the surface of the freezing fluid, the method50further includes the step of transporting the fluid chamber10by the transporter from the second position below the gas injector17back to the first position below the liquid dispenser14so that another droplet of liquid13may be dispensed into the fluid chamber10.

In other examples, the fluid chamber10comprises a bath (not shown) of freezing fluid12. In some examples, the bath extends in a longitudinal direction from a first end to a second end and a lateral direction from a first side to a second side. In some examples, step51of method50further comprises moving the liquid dispenser14over the bath of freezing fluid12in the longitudinal direction such that multiple droplets of liquid13are dispensed into the bath of the freezing fluid12at multiple target zones (not shown) spatially arranged along the bath of freezing fluid12in the longitudinal direction. In some examples, step53of method50further comprises moving the gas injector17in the longitudinal direction such that a gas stream16is injected transversely to the surface18of the freezing fluid12at about each target zone. In some examples, step51of method50further comprises moving the liquid dispenser14over the bath of freezing fluid12in a lateral direction such that multiple droplets of liquid13are dispensed into the bath of the freezing fluid12at multiple target zones spatially arranged along the bath of freezing fluid12in the lateral direction. In some examples, step53of method50further comprises moving the gas injector17in the lateral direction such that a gas stream16is injected transversely to the surface18of the freezing fluid12at about each target zone. In some examples, step51further comprises moving the liquid dispenser14in a longitudinal direction after dispensing multiple droplets of liquid13in the lateral direction along the bath of freezing fluid12such that multiple rows of target zones are arranged along the bath of freezing fluid. In some examples, step53further comprises moving the gas injector17in a longitudinal direction after injecting multiple streams of gas16transversely to the surface18of the freezing fluid12in the lateral direction such that a stream of gas16is injected at about each target zone.

In some other examples, the method50includes dispensing and freezing multiple droplets of liquid15simultaneously in the bath of the freezing fluid12. In some examples, step51further comprises dispensing multiple droplets of liquid13simultaneously at multiple target zones with multiple liquid dispensers14arranged along the bath of freezing fluid12in the longitudinal direction. In some other examples, step53further comprises injecting multiple gas streams16transversely to the surface18of the freezing fluid12at about each target zone with multiple gas injectors17arranged along the bath of freezing fluid12in the longitudinal direction.

In some examples, the method50further comprises the step of collecting the frozen droplets15that sink towards the bottom of the fluid chamber10. In some examples, the frozen droplets15are collected by providing a retainer basket (FIG.9) disposed in the fluid chamber10. In some examples, the retainer basket is configured to receive and hold the sunken frozen droplets15without retaining frozen fluid12. In some examples, the step of collecting the frozen droplets15includes removing the retainer basket holding the frozen droplets15from the fluid chamber10.

In some examples, the method50further comprises the step of drying the frozen droplet15after the step of collecting the frozen droplets15such that reagent material stored in the frozen droplet15is preserved and portable. The step of drying the frozen droplets may include any process to dehydrate the moisture content of the frozen droplets. In some examples, the step of drying the frozen droplets comprises lyophilizing the frozen droplet.

Referring toFIGS.3and4, an example of the apparatus for implementing the process described with respect toFIGS.1and2is indicated by reference number1000and includes a transporter100, a liquid dispenser200, a gas injector300, and one or more fluid chambers126(openings to the fluid chambers126are shown inFIG.3). In general, each fluid chamber126contains a freezing fluid, such as a cryogenic liquid (e.g., liquid nitrogen), and the transporter100is configured to transport each fluid chamber between a first position below the liquid dispenser200and a second position below the gas injector300. The liquid dispenser200is configured to dispense a droplet of liquid into a respective fluid chamber126when the respective fluid chamber126is in the first position. The gas injector300is configured to inject a gas stream transversely to a surface of the freezing fluid contained in the respective fluid chamber126when the respective fluid chamber126is in the second position.

In one example, the transporter100comprises a carousel configured to move each fluid chamber126about an axis of rotation between the first position and the second position. As shown inFIGS.3and4, the carousel may comprise a drum110, a lid cover120enclosing an upper end of the insulated drum110, and a base130enclosing a bottom end of the insulated drum110. In some examples, the drum110is comprised of stainless steel and houses the fluid chambers126. In some examples, the lid cover120is removably coupled to the drum110. Referring toFIGS.4and7, the carousel further comprises a spindle132projecting through the base130and aligned with a central opening122of the lid cover120. As shown inFIG.4, the apparatus1000comprises a motor150disposed underneath the base130and coupled to the spindle132such that the axis of rotation of the carousel extends through the spindle132. The motor150is configured to drive rotation of the spindle132, thereby triggering rotation of the carousel such that the base130, the drum110, and the lid cover120rotate about the axis of rotation. In one example, the motor150is configured to rotate the carousel at a rate about 1.5 revolutions per minute (RPM).

In some examples, the fluid chambers126are disposed in the drum110and arranged around the central opening122and the spindle132. In some examples, the carousel comprises an insulation layer (not shown) disposed between the drum110and the fluid chambers126to minimize heat transfer between the freezing fluid and the ambient air outside the drum110. The insulation layer may be comprised of air, a noble gas (e.g., argon), or a material having a low thermal conductivity (e.g., polymeric foam). In one example, each fluid chamber126comprises a tube disposed beneath the lid cover120. In another example, each fluid chamber126comprises a cylindrical wall integrally fixed to a lower surface of the lid cover120. As shown inFIGS.3and5, the lid cover120includes an opening for each fluid chamber126spaced around the central opening122, in which each opening is aligned with a respective fluid chamber126to provide access to the respective fluid chamber. In the illustrative example, the openings are shaped as circles having one inch diameters. In other examples, the openings may have other shapes or different sizes to accommodate for dispensed liquid droplets of various sizes.

Referring toFIG.5, in one example, the openings of the fluid chambers126may be arranged in groups. As shown inFIG.5, one group of openings126is indicated by annotated box A-A shown inFIG.5and includes four openings of fluid chambers126. In the illustrative example, each opening is displaced from the center of the lid cover120by a different radius r1, r2, r3, or r4, in which each respective radius r1, r2, r3, and r4is measured from the center of the central opening122to the center of the respective opening of the fluid chamber126. In the illustrative example shown inFIG.5, an edge of one of the openings in the group closest to the central opening122is set such that the edge is separated from the center of the central opening122at a first predetermined radius, and an edge of another one of the openings in the group furthest from the central opening122is set such that the edge is separated from the center of the central opening at a second predetermined radius. Accordingly, all the openings of the group are located between the first predetermined radius and second predetermined radius. In one example, the first predetermined radius defined from the edge of the opening closest to the central opening122to the center of the central opening is set at about 2 inches, and the second predetermined radius defined from the edge of the opening furthest from the central opening122to the center of the central opening122is set at about 5 inches.

In some examples, the transporter100further comprises a pellet collector disposed in the drum110, whereby the pellet collector is configured to receive the frozen droplets that sink toward the bottom of the fluid chambers126. In some examples, the pellet collector comprises a strainer basket that includes a plurality of holes to permit freezing fluid to pass through the strainer basket while retaining the sunken frozen droplets. In one example, as shown inFIGS.3and4, the pellet collector may comprise a handle rod140extending through the central opening122of the lid cover120. The handle rod140is configured to be grasped so that the pellet collector may be removed from the drum110to collect the sunken frozen droplets. In some examples, the strainer basket is disposed in the fluid chamber126and extends along the interior surface of the fluid chamber126to receive frozen droplets. In some examples, the strainer basket is disposed in the drum110and beneath the fluid chambers126such that a bottom of each fluid chamber126opens into the strainer basket to receive frozen droplets.

Freezing fluid is supplied to each fluid chamber126such that the surface level of the freezing fluid remains within a predetermined distance from the lid cover120. In some examples, the predetermined distance between the surface level of the freezing fluid and the lid cover120is set between about ⅛ of an inch to one inch. In some examples, the surface level of freezing fluid in each fluid chamber126is monitored to account for the volatility of the freezing fluid. Accordingly, if the surface level of freezing fluid lowers due to evaporation, more freezing fluid is supplied to the freezing fluid chambers126.

Referring toFIGS.3and4, in one example, the liquid dispenser200is mounted to a mounting post220arranged along a side of the transporter100. The gas injector300is mounted to a mounting post320arranged along the side of the transporter100and spatially separated from the mounting post220. In one example, mounting post220comprises an upright post210fixed to a mounting base212, a lateral bracket222connected to an end of the upright post210, and a nozzle bracket224extending laterally from a free end of the lateral bracket222. In one example, mounting post320comprises an upright post310fixed to a mounting base312, a lateral bracket322connected to an end of the upright post320, and a nozzle bracket324extending laterally from a free end of the lateral bracket322.

As shown inFIG.3, the liquid dispenser200includes one or more dispenser nozzles230extending through retention holes formed in the nozzle bracket224. In some examples, each dispenser nozzle230is positioned above the lid cover120at a radius r1, r2, r3, or r4corresponding to the positions of the openings to the fluid chambers126such that each nozzle230is aligned with a center of a respective fluid chamber126when fluid chamber126is set at the first position. In other examples, the dispenser nozzles230may be located above the lid cover120whereby each dispenser nozzle230is aligned with any position within the diameter of the hole of a respective fluid chamber126when set at the first position. As shown inFIGS.3and6, the gas injector300includes one or more injector nozzles330extending through retention holes formed in the nozzle bracket324. In some examples, each injector nozzle330is positioned above the lid cover120at a radius r1, r2, r3, or r4corresponding to the positions of the openings to the fluid chambers126such that the each nozzle330is aligned with a center of the opening of a respective fluid chamber126when the fluid chamber is set at the second position. In other examples, the injector nozzles330may be located above the lid cover120whereby each injector nozzle330is aligned with any position within the diameter of the hole of a respective fluid chamber126when set at the second position.

In one example, the dispenser nozzles230and injector nozzles330are disposed within the respective nozzle bracket224,324in an arrangement corresponding to the arrangement of the openings of fluid chambers126as shown in box A-A ofFIG.5. Referring toFIG.3, the liquid dispenser200comprises a set of four dispenser nozzles230aligned with a respective group of openings of fluid chambers126that is positioned beneath the nozzle bracket224. Referring toFIGS.3and6, the gas injector300comprises a set of four dispenser nozzles330aligned with another respective group of openings of fluid chambers126that is positioned underneath the nozzle bracket324. Accordingly, as the transporter100rotates, a first group of openings of the fluid chambers126becomes aligned with the set of dispenser nozzles230when positioned beneath the nozzle bracket224, and a second group of openings of the fluid chambers126becomes aligned with the set of injector nozzles330when positioned beneath the nozzle bracket324. In other examples, the dispenser nozzles230, the injector nozzles330, and the openings of the fluid chambers126may be set in other arrangements that simultaneously allow a set of dispenser nozzles230to dispense fluid into a first group of openings of fluid chambers126and a set of injector nozzles330to inject gas into a second group of openings of fluid chambers126.

The liquid dispenser200includes a liquid feed line240(e.g., hoses, tubes, etc.) connecting each dispenser nozzle230to a liquid reservoir (not shown). The gas injector300includes a gas feed line340(e.g., hoses, tubes, etc.) connecting each injector nozzle330to a source of compressed gas (not shown).

In some examples, the liquid reservoir contains an aqueous solution of reagents, and the liquid dispenser200includes a pump system (not shown) that conveys the liquid reagent from the liquid reservoir to the liquid dispenser through the associated liquid feed line. The pump system allows the liquid dispenser200to control the flow rate of liquid reagent passing through the liquid feed line240and the frequency of liquid droplets dispensed into the fluid chambers. The liquid dispenser200is configured to dispense individual drops of liquid reagent from the dispenser nozzle230into the openings of the fluid chambers126. The dispenser nozzle230includes an orifice (not shown) that is configured to provide substantially uniform drop size. A variety of dispenser nozzles230may be used so long as sufficient uniformity of drop size is provided. The dispenser nozzles230may be made of Trifluoroethylene or some other polymer with equivalent rigidity and surface characteristics. The size of the orifice in the dispenser nozzle230will depend upon the composition of the liquid reagent and the operating pressure used to pump the reagent. In one example, the dispenser nozzle230is tapered, and a wall thickness of the dispenser nozzle230may vary based on the properties of the liquid reagent being dispensed.

The tip of the dispenser nozzle230is preferably located a sufficient distance above the surface of the freezing fluid contained in the fluid chamber to permit the dispensed liquid droplet to form a sphere before landing on the surface of the freezing fluid. However, spacing the tip of the dispenser nozzle230too great a distance above the surface of the freezing fluid surface permits the dispensed liquid droplet to break up into multiple droplets prior to contacting the freezing fluid. Furthermore, if the tip of the dispenser nozzle230is too close to the surface of the freezing fluid, then the dispensed liquid droplet freezes too rapidly once contacting the freezing fluid or promotes splashing of the freezing fluid. Accordingly, in some examples, the tip of the dispenser nozzle230is positioned between about ¾ of an inch and about 2 inches above the surface of the freezing fluid. The precise distance between the tip of the dispenser nozzle230used will depend upon the particular design of the apparatus, the design of the dispenser nozzle230used, and characteristics of the liquid to be dispensed. This distance can be determined by minimal experimentation once other design variables are specified. In some examples, the tips of the liquid dispenser nozzle230and the injector nozzle330are located about ½ inch above the lid cover120having a thickness about ¼ of an inch, whereby the surface of the freezing fluid is set about ⅛ of an inch to about 1 inch below a bottom surface of the lid cover120.

FIG.8illustrates a schematic diagram of a gas delivery and control system400according to one example. The system400comprises an injector nozzle410, a source of compressed gas (e.g., a tank or a compressor)420, and a feed line430connecting the injector nozzle410to the source of compressed gas420. The source of compressed gas420is configured to generate a stream of gas that is conveyed via the feed line430to the nozzle410. The system400may include an isolation valve440(e.g., ball valve) disposed along the feed line430and configured to selectively stop the stream of gas along the feed line430(e.g., for maintenance purposes or detection of a leak). The system400may include a pressure regulator450disposed along the feed line430and downstream of the isolation valve440. The pressure regulator450is configured to control the pressure of the gas flow along the feed line430. The system400may include a solenoid valve460disposed along the feed line430and downstream of the pressure regulator450. The solenoid valve460is configured to control the gas flow to the nozzle410by switching between a closed position to shut-off the gas stream from reaching the nozzle410and an open position to permit the gas stream to reach the nozzle410. The system400may include a flow valve470disposed along the feed line430and downstream of the solenoid valve460and configured to control the flow rate of the gas stream reaching the injector nozzle410. The combination of the pressure regulator450and flow valve470allow the control of supply pressure at the injector nozzle410. The supply pressure to the injector nozzle410is regulated to inject a stream of gas with enough pressure to adequately disturb the surface tension of the freezing fluid. The supply pressure to the injector nozzle410is further regulated to limit the pressure such that the stream of gas does not promote splashing of the freezing fluid. In one example, the injector nozzle410is configured to inject a stream of gas at a supply pressure range of about 10 to 40 pounds per square inch (PSI). In some preferred examples, the injector nozzle410is configured to inject a stream of gas a supply pressure range of about 20 to 30 PSI.

The delivery and control system400may allow the injector nozzle410to inject gas into a fluid chamber in short bursts only when the fluid chamber is positioned beneath the injector nozzle410or may allow the injector nozzle410to dispense a constant stream of gas, whereby the fluid chambers move in and out of the stream of gas by relative movement between the fluid chamber and the injector nozzle410. Referring toFIG.8, in some examples, the delivery and control system400comprises a control unit480in communication with the solenoid valve460to control operation of the solenoid valve460. In one example, the system400is configured to inject gas only when a fluid chamber is disposed beneath the injector nozzle410, so the control unit480is configured to open the solenoid valve460based on a detected position of the injector nozzle410with respect to a fluid chamber. In one example, the system400may include a sensor490that monitors the position of the transporter100and communicates to the control unit480to open the solenoid valve460when the transporter100is in a position placing a fluid chamber126beneath the nozzle410.

In one example, the control unit480includes one or more processors, computer storage media (e.g., volatile and non-volatile memory), and one or more connectors, receivers, transmitters, and transceivers linked to the sensor490and the solenoid valve460. The control unit480is in electrical communication with the sensor490and is configured to receive the signal from the sensor480. The control unit480is configured to determine the rotation rate or the angular position of the transporter100(e.g., the base130or drum110) based on the received signal. The control unit480is in electrical communication with the solenoid valve460and configured to transmit a command to the solenoid valve460to switch between the open and closed positions based on the rotation rate or angular position of the transporter100. Accordingly, the control unit480allows the gas injector400to selectively inject the gas stream based on the rotation rate or angular positon of the transporter100.

In one example, the control unit480controls the gas injector400to inject the gas stream transversely to the surface of freezing fluid contained in a respective fluid chamber only when the respective fluid chamber is in the second position. In one example, the gas injector400starts injecting the stream of gas once a leading edge of the fluid chamber is positioned below the injector nozzle410and continues injecting the stream of gas until a trailing edge of the fluid chamber is positioned below the injector nozzle410, such that the stream of gas strikes the surface of the freezing fluid transversely along the entire diameter of the fluid chamber. After the trailing edge of the fluid chamber moves away from the injector nozzle410, the control unit480commands the solenoid valve460to switch to the closed position, thereby terminating the gas flow until a leading edge of another fluid chamber is positioned underneath the injector nozzle410. In other examples, the gas injector400is configured to inject the gas stream continuously while the carousel is moving each fluid chamber between the first and second positions.

In one example, the sensor490is an optical sensor disposed beneath the base130of the transporter100and comprises a transmitter (492) configured to transmit a light beam494and a receiver (496) configured to receive the light beam. Interference of the received light beam triggers the sensor490to generate a signal. In one example, as shown inFIG.7, the transporter100includes a plurality of projections134spatially arranged along a perimeter of the base130, whereby each respective projection134is configured to rotate between the transmitter492and the receiver496of the sensor490, thereby triggering the sensor490to generate a signal when one of the projections134blocks the light beam494. The sensor490is configured to generate a signal that indicates the angular position of the transporter100. In one example, the angular separation between the projections134along the perimeter of the base130corresponds to the angular separation between each group of openings of the fluid chambers126(e.g., as shown in box A-A ofFIG.5) along the lid cover120such that each projection134corresponds to a respective group of openings of fluid chambers126. Accordingly, each projection134is configured to trigger the sensor490when a respective group of openings of fluid chambers126is aligned with a set of injector nozzles330and another respective group of openings of fluid chambers126is aligned with a set of dispenser nozzles230. In another example, the angular displacement between each pair of projections134corresponds to a respective group of openings of fluid chambers126such that detection of one of the projections134by the sensor490triggers the dispenser nozzle230to stop dispensing liquid droplets and the injector nozzle330to stop injecting a stream of gas.

Process for Preparation of Frozen Reagent Spheres

A non-limiting exemplary process for producing and collecting frozen reagent spheres is described herein. In some non-limiting examples, the method50and apparatus1000described above may be implemented for the exemplary process of producing and collecting frozen reagent spheres, as described herein. In one example, a bulk liquid reagent may be prepared in a bulk reagent bottle. The bulk liquid reagent was dispensed in aliquots (e.g., 24 μL sample size) by a liquid dispenser, such as the liquid dispenser200shown inFIGS.3and4, into a freezing fluid (e.g., cryogenic liquid). The bulk liquid reagent may be supplied to the liquid dispenser by a pump (e.g., an IVEK™ pump). In one example, the pump comprises four separate feed lines that are each configured to independently transfer an aliquot of the bulk reagent through a liquid dispenser nozzle, such as the liquid dispenser nozzle230shown inFIGS.3and4, and into a fluid chamber, such as the fluid chamber126shown inFIG.3, containing liquid nitrogen (LN2). The dispensing rate of aliquots may vary based on several factors, such as the configuration of the LN2 bath, the physical parameters of the droplet, and the rotation speed of the fluid chambers. In one example, an aliquot of liquid may be dispensed at a rate of about every 3.2 seconds.

The LN2 may be held in a stainless steel drum enclosed with a lid cover, such as the drum110and cover120shown inFIGS.3and4. The drum may comprise a bath (e.g., 50 gallon bath) configured to hold the LN2. The lid cover may comprise a plurality of bored holes, which form the fluid chambers. The plurality of fluid chambers may be arranged in groups of four fluid chambers, such as the group of fluid chambers126shown inFIG.5, whereby each respective fluid chamber in the group is aligned with a respective liquid dispenser nozzle when the group of fluid chambers is set in a first position. To increase throughput, the fluid chambers and the LN2 bath may be rotated by rotating the drum about a spindle so that the first group of fluid chambers each receive a first dispensed aliquot of liquid reagent. Sometimes, the dispensed aliquot of liquid reagent may float on the surface of the LN2 before sinking to the bottom of the LN2 filled bath. To ensure that the first dispensed aliquot of liquid reagent sinks below the surface of the LN2 before dispensing a second aliquot of liquid reagent, the first group of fluid chambers may be rotated from the first position to a second position, in which the first group of fluid chambers are disposed under a set of gas injector nozzles. As the first group of fluid chambers move toward the second position, a second group of fluid chambers are moved to be aligned with the liquid dispense nozzles. Accordingly, a second aliquot of liquid reagent may then be dispensed into the second group of fluid chambers. The second group of fluid chambers may then be rotated to the second position such that the fluid chambers of the second group are disposed underneath the gas injector nozzles. The cycle of dispensing aliquot of liquid reagent into fluid chambers of a respective group and transporting the fluid chambers of the respective group to a second position may be repeated to prepare a batch of frozen liquid reagent spheres.

The rotational rate of the drum and the dispensing rate of the pump may be coordinated by providing projections attached to the base of the drum, such as the base130shown inFIG.7, a transmitter, and a sensor, such as the sensor490shown inFIG.4. In some examples, the lid cover is connected to the drum, such as the lid cover120and drum110shown inFIG.3, so that the lid cover may rotate with the drum about the axis of rotation defined by the spindle. Coordinating the lid cover rotation rate with the pump dispenser rate ensures that the dispensed aliquot of liquid reagent drops into the fluid chambers. In some examples, a motor, such as the motor150shown inFIG.4, is coupled to the base of the drum by the spindle so that the rotational rate of the drum may be controlled by controlling the speed of the motor.

The lid cover may rotate at a rate of about 1.5 RPM. The rotational rate may be selected based on a radius defined between the fluid chambers and a central point of the lid cover. Because the average dwell time of the dispensed liquid reagent in the freezing fluid is calculated to be about 10 seconds in some examples, the rotational speed (e.g., RPM) of the motor is selected to provide adequate time for most of the dispensed aliquots of liquid reagent to fall below the surface of the LN2 before the fluid chamber rotates back to the first position under the liquid dispense nozzle and receives a second aliquot of liquid reagent.

However, for a number of reasons, not all dispensed aliquots of liquid reagents will sink below the surface of the LN2 within a single revolution. Accordingly, in some examples, a gas injector, such as the gas injector300shown inFIG.3, is disposed adjacent to the drum, and the gas injector comprises plurality of gas injector nozzles arranged to align with each group of fluid chambers when set at the second position. In some examples, the gas injector comprises a tank containing pressurized oxygen, four gas feed lines, and an injector nozzle connected to each gas feed line, such as the gas delivery system shown inFIG.8. The gas injector nozzles may be placed to inject a stream of air transverse to a surface of the fluid contained in the fluid chamber at about 10 seconds after the fluid chamber initially rotates away from the first position under the liquid dispense nozzle. In some examples, the time interval between when the fluid chamber initially rotates away from the first position to the second position and when the gas injector injects a stream of gas is set to be longer than the average dwell time. The gas injector may be configured to deliver a burst of air when the fluid chamber reaches the second position, in which the fluid chamber is aligned with the nozzle of the gas injector. In some examples, the gas delivery system further comprises a pressure gauge, pressure regulator, solenoid and flow valves, and a control unit, such as the gas delivery system shown inFIG.8, to ensure that the injection of air from the gas injector is properly timed with the positioning of the fluid chamber.

In some examples, the plurality of gas injector nozzles are each configured to inject a stream of air transversely to the surface of the fluid contained in the fluid chamber to disrupt the surface tension of the LN2. Accordingly, any aliquot of liquid reagent floating on the surface of the LN2 will sink into the LN2 before the fluid chamber returns to the first position under the fluid dispense nozzle to receive a second dispensed aliquot of liquid reagent.

Following a number of cycles, the liquid and air burst dispensing may be stopped, and the rotation of the drum and the lid cover may be stopped. The fluid contained in the fluid chambers freeze the aliquots of dispensed liquid reagents into frozen spheres, which sink toward the bottom of the fluid chamber. To recover the frozen spheres, a strainer basket may be disposed along a bottom interior of the drum. For example, as shown inFIG.9, a strainer basket142disposed within drum110may be attached to a basket recovery shaft that extends through a central opening of the lid cover, such as the handle rod140(also shown inFIG.3). Accordingly, frozen reagent spheres15captured by the strainer basket142may be collected by grasping and pulling the handle rod140such that the strainer basket142is removed from the drum110. Once removed from the LN2, the frozen reagent spheres15may be transferred to a lyophilization tray to undergo a lyophilization process.

In the appended claims, the term “including” is used as the plain-English equivalent of the respective term “comprising.” The terms “comprising” and “including” are intended herein to be open-ended, including not only the recited elements, but further encompassing any additional elements. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(b), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.

While the subject matter of this disclosure has been described and shown in considerable detail with reference to certain illustrative embodiments, including various combinations and sub-combinations of features, those skilled in the art will readily appreciate other embodiments and variations and modifications thereof as encompassed within the scope of the present disclosure. Moreover, the descriptions of such embodiments, combinations, and sub-combinations is not intended to convey that the claimed subject matter requires features or combinations of features other than those expressly recited in the claims. Accordingly, the scope of this disclosure is intended to include all modifications and variations encompassed within the spirit and scope of the following appended claims.