WO2005096699A2 - Control of liquid droplet stream with electro-nebulizer - Google Patents

Abstract

The invention generates a very rapid velocity stream of nebulized particles which will then impact a target or cryogenic surface to achieve an extremely high temperature gradient at the impact point. An electric field is used to produce and accelerate the nebulized droplet stream.

Description

Description CONTROL OF LIQUID DROPLET STREAM WITH ELECTRO- NEBULIZER CROSS-REFERENCE TO RELATED APPLICATIONS

[1] This application claims the benefit of US Application No. 60/560,182 filed April 6, 2004 and US Application No. 60/560,183 filed April 6, 2004, both of which applications are hereby incorporated herein by reference for all purposes. US Patent No. 6,381,967 is also hereby incorporated herein by reference for all purposes. BACKGROUND OF THE INVENTION

[2] For many years, the scientific community has had a strong desire to develop a method for preserving biological specimens for future use without compromising the utility of the specimen. This has become increasingly important for clinical and scientific applications which include preservation of human oocytes, frozen quarantines of donor eggs to prevent transmission of infectious diseases, long-term storage of embryos, and other tissue preservation.

[3] Common methods for preserving biological specimens often involve freezing the specimens. While some freezing methods have been successful others have had less positive results. Problems associated with current freezing methods include the formation of ice crystals, which may injure the specimens due to the shaφ edges of the crystals, and toxicity introduced into the specimen as a result of the use of cryop- reservation agents.

[4] A document with some relevance to this subject is US Patent No. 6,381,967. SUMMARY OF THE INVENTION

[5] One embodiment of the invention uses an electric field to break a sample fluid into small droplets. The droplets are electrically charged, and then accelerated through an electrostatic field and or gradient onto a cryogenic target. In one embodiment, the sample fluid is injected through a metal needle, and breaks up into small droplets as it emerges from the tip of the needle. Inside the needle, the droplets acquire an electric charge. As the droplets travel between the needle tip and the target they encounter an electric field. The electric field is provided by a voltage generator connected to the metal needle and the metal target, with typical voltage ranging from 1 kilovolt to 50 kilovolts. The droplets accelerate through the electric field to a high velocity, and then impact into the target.

[6] An embodiment of the invention includes a first compartment comprising a source needle electrode with an attached liquid sample injector. Liquid droplets emerge from the source needle electrode as they are accelerated toward a target electrode. A high voltage generator is connected between the source electrode and the target electrode. The device has many variations including those described in more detail below.

[7] One utility of the invention is to convert a liquid sample into small charged droplets. The droplets are then rapidly accelerated by an electrical field onto a target electrode which is held at a cryogenic temperature. The liquid droplets are rapidly frozen upon impact with the cryogenic target.

[8] The invention can also be used to generate samples of water frozen at ultra fast rates, or samples of aqueous solutions ultra-rapidly frozen on the target electrode. Any type of liquid sample that can be driven through this device can be studied in this rapidly frozen state. Liquid sample types include biological materials such as protein solutions, glycoprotein solutions, serum or tissue samples, or live cells. Examples of live cells include red and white blood cells, dissociated tissue culture cells, gamete cells, or embryos.

[9] At first blush, an observer might be concerned with exposing delicate biologic membranes to strong electric fields. While not intending to be bound by any specific theory, it is believed that a particular advantage of freezing live cells or biological samples with this device is the production of droplets within a Faraday cage structure. Liquid droplets contain numerous charged particles or ions. Having the same charge, they will repel each other, and will separate as far as possible from each other by forming an even distribution immediately beneath the surface of the droplet. The outer surface of the droplet is therefore charged, and the interior will have an essentially neutral electric charge so that no substantial electrical field will penetrate the biological specimen.

[10] Accordingly the invention may be further defined by the following mechanistic theory. A liquid is frozen by first transforming the liquid into very small droplets. Next, the very small droplets are charged with an electrical field. The droplets are then rapidly driven with an electrical field onto a refrigerant which is at least partially solidified. Finally, the frozen liquid is collected. BRIEF DESCRIPTION OF THE DRAWINGS

[11] FIG. 1 is an illustration of an overall schematic of one embodiment of the invention.

[12] FIG. 2 A is one embodiment of a liquid sample injector.

[13] FIG. 2B is one embodiment of a liquid sample injector.

[14] FIG. 2C is one embodiment of a liquid sample injector.

[15] FIG. 3 A is one embodiment of a liquid sample injector.

[16] FIG. 3B is one embodiment of a liquid sample injector.

[17] FIG. 3C is one embodiment of a liquid sample injector.

[18] FIG. 4A illustrates an embodiment of a high liquid volume process of the invention.

[19] FIG. 4B illustrates an embodiment of a split needle system. [20] FIG. 5A illustrates an embodiment of a method to control composition, pressure, and flow of the atmosphere for the liquid droplets. [21] FIG. 5B illustrates an embodiment of another method to control composition, pressure, and flow of the atmosphere for the liquid droplets. [22] FIG. 6A illustrates an embodiment of a method to directionally control a stream of liquid droplets. [23] FIG. 6B illustrates an embodiment of a method to directionally control a stream of liquid droplets. [24] FIG. 7A illustrates an embodiment of a method to produce a modified droplet stream. [25] FIG. 7B illustrates an embodiment of a method to produce a modified droplet stream. [26] FIG. 8A is an illustration of droplet stream separation by charge-to-mass ratio.

[27] FIG. 8B is an illustration of droplet stream separation by charge-to-mass ratio.

[28] FIG. 9A is an illustration of an embodiment of a method of droplet stream separation by mass. [29] FIG. 9B is an illustration of an embodiment of a method of deferential separation of the liquid droplet stream. [30] FIG. 10A illustrates an embodiment of a target electrode.

[31] FIG. 10B illustrates an embodiment of a target electrode.

[32] FIG. 10C illustrates an embodiment of a target electrode.

[33] FIG. 11 A illustrates an embodiment of a target electrode.

[34] FIG. 1 IB illustrates an embodiment of a target electrode immersed in a liquid, slushed, or solid cryogen. [35] FIG. 11C illustrates an embodiment of a target electrode submerged in a liquid, slushed, or solid cryogen. [36] FIG. 12A illustrates an embodiment of a liquid, slushed, or solid cryogen polled in the depression of a target electrode. [37] FIG. 12B illustrates an embodiment of the target electrode in a pool of liquid, slushed, or solid cryogen. [38] FIG. 12C illustrates an embodiment of a target electrode buried within a solid cryogen. [39] FIG. 13A illustrates an embodiment of a moving target electrode, translational on the x and or y axis. [40] FIG. 13B illustrates an embodiment of a rotational moving target electrode.

[41] FIG. 13C illustrates an embodiment of a rotating drum electrode.

[42] FIGS. 14A-14C illustrate control of the strength of the electric field between the target and source electrodes. DETAILED DESCRIPTION OF THE INVENTION

[43] DEFINITIONS

[44] For the purposes of the present invention, the following terms shall have the following meanings.

[45] A large number of substances can be employed as the refrigerant, depending on the temperature range desired and the composition of the liquid drops to be frozen. It should be understood that "refrigerant" includes substances with a temperature less than or equal to 0 degrees Celsius. When two or more refrigerants are used, the entire system has a temperature less than or equal to 0 degrees Celsius. Refrigerants can be selected from several basic types, including chemical elements and compounds, organic substances or mixtures of these items. Examples of elements include helium (under pressure), hydrogen, nitrogen, argon, neon, krypton, xenon, oxygen, mercury, gallium, and lead. An example of a compound is water and carbon dioxide (under pressure). Examples of organic substances include propane, benzene, ethanol, methanol, and Freon. Mixtures of two or more elements and/or compounds mixed together to alter melting temperature or other physical characteristics can also be used as the refrigerant; e.g. Water+NaCl →Brine, Oxygen+Nitrogen — >Slushed/Solid Air, Ethane+Propane.

[46] Any substance or compound can be used as the refrigerant for this freezing method as long as it can rapidly absorb heat from liquid droplets by its phase change from solid to partially solidified to liquid. The melting temperature of the refrigerant must be lower than the liquid droplet freezing temperature, and the heat of fusion absorbed by the refrigerant (along with some additional heat absorbed by the liquefied refrigerant in some cases) must be greater than the heat of fusion released by the freezing liquid droplets.

[47] A variation of this freezing method involves the use of sublimating compounds as the refrigerant. The phase change from solid to liquid is the basic process for absorption of heat from freezing droplets, but the phase change from solid to gas of the refrigerant can also be used. An example is spraying nebulized liquid droplets directly onto or into the surface of solid carbon dioxide. A disadvantage of this method is the generation of an insulating gas layer around the droplets, which may slow the rate of freezing. This disadvantage can be overcome using devices that rapidly drive the liquid droplets into the solid refrigerant in order to maintain direct contact between their surfaces.

[48] The phase change of the refrigerant from solid to at least partially solidified is a key element of this process. The phrase "at least partially solidified" is intended to encompass completely solid and slush phases. The term "slush" is intended to encompass liquid that has just begun to solidify through equal parts solid and liquid up to the point just before complete solidification. In a slush, the ratio of solid to liquid components is such that movement of particles of solid is controlled by the liquid component. The solid and liquid components of a slush may be the same element or compound or may be different elements or compounds. A slush includes stable mixtures of liquid and solid substantially at equilibrium. When the solid and liquid components are different elements or compounds, the elements or compounds must be compatible in terms of providing an environment suitable for freezing the sample.

[49] The production of solid or slushed refrigerants, especially in the cryogenic temperature range, requires mechanical means or a secondary refrigerant. The mechanical means may be in the form of a refrigeration means or a vacuum chamber. Liquid refrigerant is placed in a vacuum chamber and placed under partial vacuum to achieve at least partial solidification of the refrigerant. The secondary refrigerant can be any heat-absorbing substance held at a temperature lower than the freezing point of the primary refrigerant. A secondary refrigerant is used to freeze the primary refrigerant into a solid or slushed state either by direct contact or by indirect contact through a container. Freezing of the primary refrigerant may be a one-time single event, or can occur as a repetitive or continuous renewal process. Selection of appropriate primary and secondary refrigerants results in production of an optimal slushed primary refrigerant or may be used to change the working temperature of the primary solid refrigerant to maximize liquid droplet freezing rates. For example, frozen argon held at the temperature of liquid helium will absorb much more heat more rapidly from liquid droplets than frozen argon held at liquid nitrogen temperature. Because of the wide range of freezing temperatures for various elemental, compound and organic refrigerants, numerous combinations of primary and secondary refrigerants are possible. The secondary refrigerant for one rapid-freezing application can be used as a primary refrigerant for another application. Several examples of primary and secondary refrigerants are provided in Table 1 of US Patent No. 6,381,967.

[50] The physical size of the sample liquid droplets to be frozen has a significant influence on the freezing rate achieved by this method. In general, the smaller the liquid droplet, the faster it will freeze. Nebulizer type and control can be used to obtain optimal drop or droplet sizes for individual applications of the freezing method. In general, optimum droplet sizes would range from 50 to 700 microns. Examples of biologic materials that the droplets need to be of sufficient size to contain include: the entirety of a human egg cell, a sperm, embryos, red blood cells, and proteins. The content of a droplet may comprise: water, glycol, saline, salt solutions, and other solutions that are isotonic with whatever type of biologic material is desired to be preserved.

[51] APPARATUS [52] An embodiment of the invention is illustrated by the diagram in Figure 1. Figure 1 shows a schematic of the device divided into four compartments, 1100, 1200, 1300, and 1400. Compartment 1100 illustrates a source needle electrode (1104) attached to an embodiment of a liquid sample injector (1102) having a plunger (1101). Compartment 1200 illustrates the dynamic movement of liquid sample droplets (1202) emerging from the source needle electrode (1104) as they are accelerated toward the target electrode (1302). A magnification of an individual droplet (1500) illustrates electrical charges distributed uniformly over the outer surface of the spherical shape of the droplet, forming a Faraday cage. Compartment 1300 illustrates the target electrode (1302). Compartment 1400 illustrates a high voltage generator (1402), having a voltage which typically ranges from about one to about 50 kilovolts, with one line (1401) from the generator (1402) attached to the source needle electrode (1104), and the other line (1403) attached to target electrode (1302). The device may have many variations in its components, including those described below.

[53] COMPARTMENT 1100 - SAMPLE DELIVERY

[54] Various embodiments of the liquid sample injectors (1102) utilized in compartment 1100 are illustrated in Figures 2A-2C. Figure 2A illustrates a syringe with manual depression of the plunger (1101) used to force the liquid sample through the source needle electrode (1104). Figure 2B illustrates the same method using a mechanically powered syringe which can better control the volume or rate of injection. Figure 2C illustrates a gravity feed method. In the gravity feed method, the liquid sample is held within an open-ended container which is then allowed to drain by gravity through the source needle electrode (1104).

[55] Additional variations in the type of liquid sample injector (1102) and source needle electrodes (1104) are illustrated in Figures 3A-3B. Figure 3 A illustrates an application of a fractionated liquid sample. In this case, a chromatography or distillation column (3001) is attached to the source needle electrode (1104), and a liquid sample is then separated into its various components by the column before they pass sequentially through the source electrode needle (1104). This fractionated sample variation will be coupled to a method of separating the same droplets as they land on the target electrode (1302). Figure 3B illustrates the use of two or more samples (A and B) injected into the source needle electrode (1104). This could include a primary liquid sample such as a solvent, with entry of a secondary liquid or particulate sample injected into a side port (3003). Figure 3C illustrates the use of two or more liquid samples (A and B) separately injected through two or more source needle electrodes (1104), with the samples combining together during the acceleration phase of Compartment 1200 or combining together at the impact point on the target electrode (1302). An example of the application of this method would be using two liquid samples that would undergo a chemical or physical reaction at room temperature, but would coexist together without reaction at cryogenic temperature after they are deposited on the target electrode (1302). Figure 3C could also be explained as two or more separate samples that are mixed after nebulization.

[56] Figure 4A illustrates an embodiment of the invention where the device is converted to a high liquid volume process. This is done by using multiple parallel source needle electrodes (1104) to allow rapid freezing of large volumes of liquid samples (4004) at a more industrial scale. With respect to this application, a "plurality" of source needle electrodes includes at least two electrodes. In this particular illustration, the individual source needle electrodes (1104) are embedded into a conducting plate (4003) which is then connected to the voltage generator (1402) by line (1401). Other variations may include individual connection of the voltage generator (1402) to each needle electrode (1104). A split needle system is illustrated Figure 4B.

[57] COMPARTMENT 1200 - DROPLET STREAM

[58] Embodiments of how to control of the composition, pressure, and flow of the atmosphere through which the liquid droplets are accelerated in compartment 1200 is illustrated in Figure 5 A and Figure 5B. Figure 5 A illustrates a flow chamber (5002), in which the gas (5006, 5013) surrounding the liquid droplets (5016) is moving parallel to the liquid droplet flow. This gas flow can be either in the same direction (5006) or opposite direction (5013) of the liquid droplets (5016), depending on the particular application. Figure 5B illustrates an enclosed vacuum or pressure chamber (5004) where the content or pressure of the surrounding atmosphere can be controlled. This includes controlling the humidity or ambient gas atmosphere. For instance, carbon dioxide gas can be used as an ambient gas around the droplets (5024) to minimize or prevent electrical arcing between the source (5020) and target (5028) electrodes. Applications that may require a very high ambient pressure or a vacuum around the droplets can also be achieved using this enclosed chamber.

[59] Directional control of the stream of liquid droplets can be achieved by the embodiments of the invention illustrated in Figure 6 A and 6B. Figure 6 A allows voltage plates (6004) to control the direction of a nebulized droplet stream (6006). In Figure 6A, the liquid droplets (6006) emerging from the end of the source needle electrode (6001) have approximately the same electric charge, and therefore will be attracted to or repelled from electrode plates (6004) placed on each side of the flowing droplet stream (6006). Change in the voltage between the electric plates (6004) can be used to move the droplet stream (6006) along an x axis. Figure 6B illustrates multiple voltage plates (6012 and 6014) controlling the direction of the nebulized droplet stream (6013). Figure 6B shows the use of two sets of electrically charged plates (6012) and (6014) placed on each side of the liquid droplet stream (6013), with the axis of the plates per- pendicular to each other. As with Figure 6A, the liquid droplets (6013) emerging from the end of the source needle electrode (6009) in Figure 6B also have approximately the same electric charge, and therefore will be attracted to or repelled from electrode plates (6012 and 6914). This allows control of the droplet stream (6013) direction along the x and the y axis. The voltage applied to the electric plates (6004, 6012, and 6014) from voltage generators (6002, 6010, and 6011) can be variable allowing the droplet stream (6013) to be swept across the target electrode (6016) in a controlled fashion.

[60] The size and shape of the impact pattern (7016 and 7034) of the nebulized droplets (1500) can be more accurately controlled by using embodiments of compartment 1200's charged droplet stream that includes a masking system as illustrated in Figure 7 A and Figure 7B. Figure 7 A illustrates the use of target electrode (7008) as a mask, with a pattern (7010) cut into the electrode (in this example a keyhole pattern) through which part of the nebulized droplet stream (7006) will pass. The cross sectional shape of the droplet stream beyond the target electrode (7012) will be determined by the cut pattern (7010). No substantial acceleration occurs beyond the target electrode (7010) because the charged droplets (1500) no longer travel through an electric field in this region. A secondary non-electrode target (7016) is placed behind the target electrode (7012) in order to capture the modified droplet stream (7012). An alternate method of producing a modified droplet stream is illustrated by Figure 7B. In this case, a neutral or minimally charged mask (7026) is placed within the droplet stream (7024, 7023) between the source (7022) and the target electrodes (7036). Some of the nebulized stream (7032) will pass through the pattern cut into the neutral mask (7026), and the cross section of the nebulized droplet stream (7032) beyond the mask will match the same pattern (7028) as it continues on to the target electrode (7034).

[61] Figures 8 A and 8B illustrate embodiments of droplet stream separation by charge- to-mass ratios. Figure 8 A illustrates a separation of the charged liquid droplets (1500) using intermediate charged plates (8004) placed on either side of the stream (8010). Droplets with high charge-to-mass ratios (8011) undergo a greater deflection through the secondary electric field and will impact the target electrode (8014) further away from the direct axis than droplets that have a low charge-to-mass ratio (8009). An alternate method of producing the same result is illustrated by Figure 8B, with a magnetic field, created by magnets (8008) placed on each side of the stream, replacing the electric field as the force used to separate the droplet stream (8012). Liquid droplets with high charge-to-mass ratio (8013) will undergo greater deflection within the magnetic field than those with low charge-to-mass ratios (8015). Embodiments of the magnets (8008) may include fixed magnets or electro magnets.

[62] In yet another embodiment of the invention, the charged plates (8004) could be placed on each side of the droplet stream after it emerges from a target electrode mask like the one illustrated in Figure 7A.

[63] An embodiment of droplet stream separation by mass and gas flow (not charge) is illustrated by Figure 9A. In this instance, flow of the surrounding gas (9004) perpendicular to the droplet stream (9006) will deflect low mass particles (9007) greater than high mass particles (9009) before they impact into the target electrode (9008).

[64] Another embodiment of deferential separation of the liquid droplet stream is illustrated by Figure 9B. In this embodiment there is a dynamic change in the separation of the electrodes by moving the source and or the target electrodes. The distance (9013) between the source electrode (9010) and target electrode (9014) actively changes. This results in changing the distance the droplets travel before impact, the flux of the electric field, the resulting impact speed, and the impact area diameter of the droplets. Part 9016 is an illustration of several of the possible positions for the target electrode (9014) and the source electrode 9010 can be repositioned as well.

[65] COMPARTMENT 1300 - TARGET ELECTRODE

[66] Several embodiments of target electrodes are illustrated in Figures 10A-10C. The size of the target electrode is variable, as illustrated by embodiments Figure 10A and Figure 10B. The embodiment in Figure 10A is an example of a small target electrode and the embodiment in Figure 10B is an example of a large target electrode. The variations in size change the shape and focus of the electric field between the tip (1311) of the source electrode and the surface (1313) of the target electrode. The liquid droplets will follow the lines of the electric field, so the size, shape, and density of the droplet stream will change as the size of the target electrode is altered.

[67] Figure 10C is an illustration of the use of multiple target electrodes (1313A and 1313B) coupled to a single source needle electrode (1311). Separate droplet streams will be produced for each target electrode.

[68] Figures 11 A- 11C illustrate various exemplary embodiments of the surface of the cryogenic target electrode. The cryogenic target in Figure 11 A is the first embodiment, and consists of a solid precooled target electrode (1302), with efficiency improved by thermal insulation around the base of the electrode. The cryogenic target in Figure 1 IB is a second embodiment which illustrates continuous cooling of the target electrode (1302) by partial immersion in a liquid, slush, or solid cryogen (1319). A typical example would be partial submersion of a metallic electrode in a bath of liquid nitrogen or liquid helium. The cryogenic target of Figure 11C is a third embodiment and illustrates the same basic concept, but with a target electrode (1302) submerged below the surface of the liquid, slush, or solid cryogen (1319) so that the liquid droplets (1202) impact onto a cryogen surface (1319) instead of the electrode surface (1302). The resulting frozen droplets could then be washed away continuously.

[69] A further variation in the same concept is illustrated by Figure 12A. A depression in the target electrode of 1322 contains a liquid, solid, or slush cryogen (1321), with a significant part of the liquid droplet stream impacting onto the surface of the cryogen. A more tightly controlled liquid droplet stream can be achieved by the method illustrated in Figure 12B, by submerging a small cross section target electrode (1325) within a cryogen pool of liquid, solid, or slush cryogen in order to narrow the electric field lines (1323) from the source electrode. A sub-variation of this concept is illustrated in Figure 12C, by using a target electrode (1327) immersed within a frozen solid cryogen so that the liquid droplets impact directly upon the surface of the frozen cryogen. The advantage to this method is prevention of the formation of an insulating gas envelope around the impacting liquid droplets which would slow their cooling and freezing rates. Because the phase change of the cryogen would be from solid to liquid (instead of liquid to gas), the liquid cryogen would maintain a high material density with high thermal conductivity at the surface of the liquid droplet as it melts into the solid cryogen.

[70] Controlled spread of the droplet deposits onto the target electrode can be achieved by relative movement of the electrodes as illustrated in Figures 13A-13C. In Figure 13 A, the target electrode (1329) can be moved along the x and or y direction to spread the impacted droplets anywhere in the plane. Other similar embodiments would include moving the source needle electrode (in the x and or y direction) of diagram 1328 instead of the target electrode, or moving both the source and target electrodes in the x and or y directions. Variation of this method is illustrated by Figure 13B, using a rotating target electrode (1331). Again, an alternative method would be to move the source needle electrode in a rotational motion, or the source and target electrodes. A third method is illustrated in Figure 13C, using a rotating drum target electrode (1333). Alternate methods would use a converse system of nonmoving target electrode but with lateral, rotational, or radial movement of the source needle electrode.

[71] Nebulized sample particles frozen using this method are easily recovered because t hey remain suspended in the liquefied primary refrigerant at the end of the freezing process. The primary refrigerant liquefies after absorbing heat from the sample, then washes the frozen sample droplets away from the active freezing contact site. Depending on the difference in density between the frozen sample particles and the liquefied refrigerant, the sample particles can be recovered 1) by gravity at the bottom of the refrigerant vessel, 2) by skimming or overflow after floating to the refrigerant surface, or 3) by filtration if suspended within the refrigerant. The ease of sample recovery is a distinct advantage over other prior-art methods, which require scraping frozen samples off cold metal surfaces, removing samples from porous or thin film plates, detaching samples from metal grids, or unsealing samples from tubes or metal canisters. Short or long-term storage of frozen nebulized samples is also greatly simplified by this freezing method, again because the sample remains within the liquefied primary refrigerant after freezing. The primary refrigerant is generally nonreactive and nontoxic, typically liquid nitrogen or a liquefied noble gas, so the frozen sample is subjected to no long-term adverse effects if it remains suspended in the primary refrigerant for storage. An additional advantage is that the sample remains at its freezing temperature indefinitely because there is no need to transfer to another container or medium for storage, so the risk of heating the sample above one of its glass or crystalline transition temperatures is minimized.

[72] Solid or slushed cryogenic "gas" refrigerants used in this method may be noble gases (He, Ne, Ar, etc.) or common industrial cryogens (nitrogen) which are generally chemically nonreactive and nontoxic. This is especially useful when freezing organic or biological materials, or living cells, because the freezing samples come into direct contact with the refrigerants, and some of the refrigerant substance is expected to diffuse into the frozen samples. The use of nonreactive and nontoxic refrigerants is a significant advantage over methods that use organic solvents such as ethane, propane, and butane as liquid refrigerants. Frozen samples are heavily contaminated by these organic solvents, which poison the sample or require removal (usually by a less-toxic organic solvent). Use of noble gases, or in some instances nitrogen, is especially useful for "time stopping" experiments using samples of actively reacting chemicals.

[73] Primary (solid-to-liquid phase) refrigerants and secondary refrigerants (those used to initially freeze the primary refrigerants) are typically inexpensive atmospheric or industrial cryogenic liquefied gases currently mass-produced by efficient industries. They include liquid nitrogen, liquid argon, and liquid helium, and can be extended to more exotic refrigerants such as liquid hydrogen, liquid neon, liquid oxygen, alcohol, or even chilled metals such as mercury. Most of the refrigerants are abundant, easy to ship and handle, and are inert, reducing the cost of purchasing or using the primary raw materials of the process. Waste products generated by the process, typically atmospheric gases or helium, are simply vented or recycled, or for hydrogen, simply burned to produce water vapor, so disposal costs of waste products are minimal or absent.

[74] COMPARTMENT 1402 - ELECTRIC FIELD CONTROL

[75] Control of the strength of the electric field between the target and source electrodes is illustrated in Figure 14A, Figure 14B, and Figure 14C. The voltage to one or more source electrodes or one or more target electrodes can be changed over time in a manner to control the acceleration and pattern of impact of different droplet streams.

[76] Figure 14A illustrates several different model embodiments of voltage with respect to time utilizing one source electrode and one target electrode. In the graph, 1412 represents constant voltage; 1413 is a step switch; 1414 represents increasing voltage; 1415 represents decreasing voltage, 1416 represents variable or programable voltage; and 1417 represents a voltage spike.

[77] Figure 14B illustrates several more model embodiments of voltage with respect to time. This model utilizes two source electrodes A and B, and a target electrode. In the graph, 1422 represents constant equal voltage; 1423 represents alternate switching; 1424 represents Co-switching; 1425 represents constant by different voltage; 1426 represents increasing or decreasing voltages; and 1427 represents variable or programable voltage.

[78] Figure 14C is yet another illustration of model embodiments of voltage with respect to time. This model utilizes a source electrode , and two target electrodes A and B. In the graph, 1432 represents constant equal voltage; 1433 represents alternate switching; 1434 represents constant but different voltages; 1435 represents increasing or decreasing voltages; and 1436 represents variable or programable voltages.

[79] The variations of the components within each compartment described above can be mixed and matched with the different components of any other compartment of this device. This will result in production of a wide variety of device types that can be customized to the individual physical requirements of most applications. The basic concept of this device can therefore be used for a large number of different applications for very rapid freezing of chemical or biological samples.

Claims

Claims

[I] A method for freezing a liquid comprising: transforming a liquid into very small droplets; electrically charging said very small droplets; rapidly driving said very small droplets onto a refrigerant which is at least partially solidified; and collecting the frozen liquid.

[2] 2. The method of claim 1 wherein said refrigerant is solid.

[3] 3. The method of claim 1 wherein said refrigerant is undergoing sublimation.

[4] 4. The method of claim 1 wherein said refrigerant is a liquid.

[5] 5. The method of claim 1 wherein said refrigerant is a slush comprising a mixture of solid and liquid.

[6] 6. The method of claim 5 wherein said solid and liquids are the same element or compound.

[7] 7. The method of claim 5 wherein said solid and liquids are different elements or compounds.

[8] 8. The method of claim 1 further comprising biologic material contained within said very small droplets.

[9] 9. A method for freezing a liquid comprising: transforming a liquid into very small droplets with an electric field; electrically charging said droplets; rapidly driving said droplets by means of an electrostatic field onto a refrigerant which is at least partially solidified; and collecting the frozen liquid.

[10] 10. The method of claim 9 wherein said refrigerant is solid.

[I I]

11. The method of claim 9 wherein said refrigerant is undergoing sublimation.

[12] 12. The method of claim 9 wherein said refrigerant is a liquid.

[13] 13. The method of claim 9 wherein said refrigerant is a slush comprising a mixture of solid and liquid.

[14] 14. The method of claim 13 wherein said solid and liquids are the same element or compound.

[15] 15. The method of claim 13 wherein said solid and liquids are different elements or compounds.

[16] 16. The method of claim 9 further comprising biologic material contained within said very small droplets.

[17] 17. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a means for transforming the first sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through an outlet onto a refrigerant target.

[18] 18. The apparatus of claim 17 wherein said refrigerant target is liquid.

[19] 19. The apparatus of claim 17 wherein said refrigerant target is solid.

[20] 20. The apparatus of claim 17 wherein said refrigerant target is undergoing sublimation.

[21] 21. The apparatus of claim 17 wherein said refrigerant target is a slush comprising a mixture of solid and liquid.

[22] 22. The apparatus of claim 21 wherein said solid and liquids are the same element or compound.

[23] 23. The apparatus of claim 21 wherein said solid and liquids are different elements or compounds.

[24] 24. The apparatus of claim 17 wherein said first container is a liquid sample injector.

[25] 25. The apparatus of claim 24 wherein the liquid sample injector is a manual syringe.

[26] 26. The apparatus of claim 24 wherein the liquid sample injector is a powered syringe.

[27] 27. The apparatus of claim 17 wherein said first container is an open ended container which drains by gravity into the means for transforming the sample suspension into very small droplets.

[28] 28. The apparatus of claim 17 wherein said first container is a chromatography column.

[29] 29. The apparatus of claim 17 wherein the outlet from which the electrically charged droplets are driven through is an exit point of a source needle electrode.

[30] 30. The apparatus of claim 29 wherein the refrigerant target is a target electrode, and wherein the means for electrically charging said droplets comprises an electrostatic field resulting from a voltage generator connected to the source needle electrode and the refrigerant target electrode.

[31] 31. The apparatus of claim 29 wherein the refrigerant target is a target electrode, and wherein the means for driving the electrically charged droplets comprises an electrostatic field resulting from a voltage generator connected to the source needle electrode and the refrigerant target electrode.

[32] 32. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a means for transforming the first sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through an outlet onto a plurality of refrigerant targets.

[33] 33. The apparatus of claim 32 wherein at least one of the plurality of refrigerant targets is a liquid.

[34] 34. The apparatus of claim 32 wherein at least one of the plurality of refrigerant targets is solid.

[35] 35. The apparatus of claim 32 wherein at least one of the plurality of refrigerant targets is undergoing sublimation.

[36] 36. The apparatus of claim 32 wherein at least one of the plurality of refrigerant targets is a slush comprising a mixture of solid and liquid.

[37] 37. The apparatus of claim 36 wherein said solid and liquids are the same element or compound.

[38] 38. The apparatus of claim 36 wherein said solid and liquids are different elements or compounds.

[39] 39. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a means for transforming the first sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through a plurality of outlets onto a refrigerant target.

[40] 40. The apparatus of claim 39 wherein the first container has an exit point, wherein each of the outlets of the plurality of outlets from which the electrically charged droplets are driven through are exit points of source needle electrodes, and wherein each of the source needle electrodes also have entry points, each of the said entry points of the source needle electrodes being connected to the exit point of the first container.

[41] 41. The apparatus of claim 40 wherein the refrigerant target is a target electrode, and wherein the means for electrically charging said droplets comprises an electrostatic field resulting from a voltage generator connected to the exit point of the first container and the target electrode.

[42] 42. The apparatus of claim 40 wherein the refrigerant target is a target electrode, and wherein the means for driving the electrically charged droplets comprises an electrostatic field resulting from a voltage generator connected to the exit point of the first container and the target electrode.

[43] 43. The apparatus of claim 40 wherein the refrigerant target is a target electrode, wherein each of the plurality of the source needle electrodes are embedded into a conducting plate, and wherein the means for electrically charging said droplets comprises a voltage generator connected to the conducting plate and the target electrode.

[44] 44. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a second sample suspension held in a second container; a means for transforming the first sample suspension and the second sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through an outlet onto a refrigerant target.

[45] 45. The apparatus of claim 44 further comprising a means to combine the first sample suspension and the second sample suspension prior to transforming the first sample suspension and the second sample suspension into very small droplets.

[46] 46. The apparatus of claim 44 further comprising a means to combine the first sample suspension and the second sample suspension after transforming the first sample suspension and the second sample suspension into very small droplets.

[47] 47. The apparatus of claim 44 wherein the outlet from which the electrically charged droplets are driven through is an exit point of a source needle electrode.

[48] 48. The apparatus of claim 47 wherein the refrigerant target is a target electrode, and wherein the means for electrically charging said droplets is comprises an electrostatic field resulting from a voltage generator connected to the source needle electrode and the target electrode.

[49] 49. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a second sample suspension held in a second container; a means for transforming the first sample suspension and the second sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through a plurality of outlets onto a refrigerant target.

[50] 50. The apparatus of claim 49 further comprising a means to combine the first sample suspension and the second sample suspension prior to transforming the first sample suspension and the second sample suspension into very small droplets.

[51] 51. The apparatus of claim 50 wherein the plurality of outlets from which the electrically charged droplets are driven through is an exit point of each of a plurality of source needle electrodes, said plurality of source needle electrodes also having an entrance point, said entrance point of the source needle electrodes connected to the means to combine the first sample suspension and the second sample suspension.

[52] 52. The apparatus of claim 49 further comprising a means to combine the first sample suspension and the second sample suspension after transforming the first sample suspension and the second sample suspension into very small droplets.

[53] 53. The apparatus of claim 49 wherein the plurality of outlets from which the electrically charged droplets are driven through is an exit point of each of a plurality of source needle electrodes.

[54] 54. The apparatus of claim 53 wherein the refrigerant target is a target electrode, wherein each of the plurality of the source needle electrodes are embedded into a conducting plate, and wherein the means for electrically charging said droplets comprises an electrostatic field resulting from a voltage generator connected to the conducting plate and the target electrode.

[55] 55. The apparatus of claim 53 wherein the refrigerant target is a target electrode, wherein each of the plurality of the source needle electrodes are embedded into a conducting plate, and wherein the means for driving the electrically charged droplets comprises an electrostatic field resulting from a voltage generator connected to the conducting plate and the target electrode.

[56] 56. An apparatus for freezing a sample suspension, including biological samples, comprising: a first sample suspension held in a first container; a means for transforming the first sample suspension into very small droplets; a means for electrically charging said droplets; a means for driving the electrically charged droplets through an outlet onto a target; and said target being cooled by a refrigerant.

[57] 57. The apparatus of claim 56 wherein the outlet from which the electrically charged droplets are driven through is an exit point of a source needle electrode.

[58] 58. The apparatus of claim 57 wherein the target is an electrode, and wherein the means for electrically charging said droplets comprises an electrostatic field resulting from a voltage generator connected to the source needle electrode and the target electrode.

[59] 59. The apparatus of claim 57 wherein the target is an electrode, and wherein the means for driving the electrically charged droplets comprises an electrostatic field resulting from a voltage generator connected to the source needle electrode and the target electrode.

[60] 60. The apparatus of claim 59 wherein the target electrode is immersed in the refrigerant.

[61] 61. The apparatus of claim 59 wherein the refrigerant is a liquid.

[62] 62. The apparatus of claim 59 wherein said refrigerant is solid.

[63] 63. The apparatus of claim 59 wherein said refrigerant is undergoing sublimation.

[64] 64. The apparatus of claim 59 wherein said refrigerant is a slush comprising a mixture of solid and liquid.

[65] 65. The apparatus of claim 64 wherein said solid and liquids are the same element or compound.

[66] 66. The apparatus of claim 64 wherein said solid and liquids are different elements or compounds.

[67] 67. The apparatus of claim 59 wherein the target electrode is submerged in the refrigerant.

[68] 68. The apparatus of claim 67 wherein the refrigerant is a liquid.

[69] 69. The apparatus of claim 67 wherein said refrigerant is solid.

[70] 70. The apparatus of claim 67 wherein said refrigerant is undergoing sublimation.

[71] 71. The apparatus of claim 67 wherein said refrigerant is a slush comprising a mixture of solid and liquid.

[72] 72. The apparatus of claim 71 wherein said solid and liquids are the same element or compound.

[73] 73. The apparatus of claim 71 wherein said solid and liquids are different elements or compounds.

[74] 74. The apparatus of claim 59 wherein the target electrode contains a poled refrigerant.

[75] 75. The apparatus of claim 74 wherein the refrigerant is a liquid.

[76] 76. The apparatus of claim 74 wherein said refrigerant is solid.

[77] 77. The apparatus of claim 74 wherein said refrigerant is undergoing sublimation.

[78] 78. The apparatus of claim 74 wherein said refrigerant is a slush comprising a mixture of solid and liquid.

[79] 79. The apparatus of claim 78 wherein said solid and liquids are the same element or compound.

[80] 80. The apparatus of claim 78 wherein said solid and liquids are different elements or compounds.

[81] 81. The method of claim 1 further characterized in that the very small droplets are driven in a path toward an area, the method further comprising the step of placing a mask in the path whereby droplets impinge upon less than all of the area.

[82] 82. The method of claim 81 wherein the mask is an electrode.

[83] 83. The method of claim 81 wherein the mask is not an electrode.

[84] 84. The method of claim 9 further characterized in that the very small droplets are driven in a path toward an area, the method further comprising the step of placing a mask in the path whereby droplets impinge upon less than all of the area.

[85] 85. The method of claim 84 wherein the mask is an electrode.

[86] 86. The method of claim 84 wherein the mask is not an electrode.

[87] 87. The method of claim 1 further comprising the step of applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops.

[88] 88. The method of claim 87 wherein the first transverse field is an electric field.

[89] 89. The method of claim 87 wherein the first transverse field is a magnetic field.

[90] 90. The method of claim 87 further comprising the step of applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field.

[91] 91. The method of claim 90 wherein the second transverse field is perpendicular to the first transverse field.

[92] 92. The method of claim 91 wherein the first transverse field is an electric field and the second transverse field is an electric field.

[93] 93. The method of claim 91 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field.

[94] 94. The method of claim 9 further comprising the step of applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops.

[95] 95. The method of claim 94 wherein the first transverse field is an electric field.

[96] 96. The method of claim 94 wherein the first transverse field is a magnetic field.

[97] 97. The method of claim 94 further comprising the step of applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field. [98] 98. The method of claim 97 wherein the second transverse field is perpendicular to the first transverse field. [99] 99. The method of claim 98 wherein the first transverse field is an electric field and the second transverse field is an electric field. [100] 100. The method of claim 98 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field. [101] 101. The method of claim 1 further comprising the step of applying a transverse megnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [102] 102. The method of claim 9 further comprising the step of applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [103] 103. The method of claim 1 further comprising the step of applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [104] 104. The method of claim 9 further comprising the step of applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [105] 105. The method of claim 1 further comprising the step of moving the refrigerant transversely while the drops impinge upon it. [106] 106. The method of claim 9 further comprising the step of moving the refrigerant transversely while the drops impinge upon it. [107] 107. The method of claim 1 further comprising the step of rotating the refrigerant in a transverse plane while the drops impinge upon it. [108] 108. The method of claim 9 further comprising the step of rotating the refrigerant in a transverse plane while the drops impinge upon it. [109] 109. The method of claim 1 further comprising the step of rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [110] 110. The method of claim 9 further comprising the step of rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [I l l] 111. The apparatus of claim 17 further comprising the means applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [112] 112. The apparatus of claim 111 wherein the first transverse field is an electric field. [113] 113. The apparatus of claim 111 wherein the first transverse field is a magnetic field. 114. The apparatus of claim 111 further comprising means applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field. 115. The apparatus of claim 114 wherein the second transverse field is perpendicular to the first transverse field. 116. The apparatus of claim 115 wherein the first transverse field is an electric field and the second transverse field is an electric field. 117. The apparatus of claim 115 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field. 118. The apparatus of claim 32 further comprising the means applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. 119. The apparatus of claim 118 wherein the first transverse field is an electric field. 120. The apparatus of claim 118 wherein the first transverse field is a magnetic field. 121. The apparatus of claim 118 further comprising means applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field. 122. The apparatus of claim 121 wherein the second transverse field is perpendicular to the first transverse field. 123. The apparatus of claim 122 wherein the first transverse field is an electric field and the second transverse field is an electric field. 124. The apparatus of claim 122 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field. 125. The apparatus of claim 44 further comprising the means applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. 126. The apparatus of claim 125 wherein the first transverse field is an electric field. 127. The apparatus of claim 125 wherein the first transverse field is a magnetic field. 128. The apparatus of claim 125 further comprising means applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field. 129. The apparatus of claim 128 wherein the second transverse field is perpendicular to the first transverse field. [130] 130. The apparatus of claim 129 wherein the first transverse field is an electric field and the second transverse field is an electric field. [131] 131. The apparatus of claim 129 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field. [132] 132. The apparatus of claim 56 further comprising the means applying a first transverse field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [133] 133. The apparatus of claim 132 wherein the first transverse field is an electric field. [134] 134. The apparatus of claim 132 wherein the first transverse field is a magnetic field. [135] 135. The apparatus of claim 132 further comprising means applying a second transverse field to the rapidly driven drops, the second transverse field in a direction non-identical to the direction of the first transverse field. [136] 136. The apparatus of claim 135 wherein the second transverse field is perpendicular to the first transverse field. [137] 137. The apparatus of claim 136 wherein the first transverse field is an electric field and the second transverse field is an electric field. [138] 138. The apparatus of claim 136 wherein the first transverse field is a magnetic field and the second transverse field is a magnetic field. [139] 139. The apparatus of claim 17 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [140] 140. The apparatus of claim 32 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [141] 141. The apparatus of claim 39 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [142] 142. The apparatus of claim 44 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [143] 143. The apparatus of claim 49 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [144] 144. The apparatus of claim 56 further comprising means applying a transverse magnetic field to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops, each drop deflected as a function of the ratio of its charge to mass. [145] 145. The apparatus of claim 17 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [146] 146. The apparatus of claim 32 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [147] 147. The apparatus of claim 39 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [148] 148. The apparatus of claim 44 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [149] 149. The apparatus of claim 49 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [150] 150. The apparatus of claim 56 further comprising means applying a transverse air flow to the rapidly driven drops, whereby the drops are deflected transversely to the direction of driving of the drops. [151] 151. The apparatus of claim 17 further comprising means moving the refrigerant transversely while the drops impinge upon it. [152] 152. The apparatus of claim 32 further comprising means moving the refrigerant transversely while the drops impinge upon it. [153] 153. The apparatus of claim 39 further comprising means moving the refrigerant transversely while the drops impinge upon it. [154] 154. The apparatus of claim 44 further comprising means moving the refrigerant transversely while the drops impinge upon it. [155] 155. The apparatus of claim 49 further comprising means moving the refrigerant transversely while the drops impinge upon it. [156] 156. The apparatus of claim 56 further comprising means moving the refrigerant transversely while the drops impinge upon it. [157] 157. The apparatus of claim 17 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [158] 158. The apparatus of claim 32 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [159] 159. The apparatus of claim 39 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [160] 160. The apparatus of claim 40 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [161] 161. The apparatus of claim 44 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [162] 162. The apparatus of claim 49 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [163] 163. The apparatus of claim 56 further comprising means rotating the refrigerant in a transverse plane while the drops impinge upon it. [164] 164. The apparatus of claim 17 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [165] 165. The apparatus of claim 32 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [166] 166. The apparatus of claim 39 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [167] 167. The apparatus of claim 44 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [168] 168. The apparatus of claim 49 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it. [169] 169. The apparatus of claim 56 further comprising means rotating the refrigerant about an axis transverse to the direction of driving the drops, while drops impinge upon it.