AU645961B2 - Apparatus and method for the self-levelling of liquid in a container - Google Patents

Description

OPI DATE 07/01/91 PCT AOJP DATE 21/02/91 APPLN- IID 3 /1129 89 PCT NUMBER PCT/US89/023l5 INTERNATIONAL ,r.m ViY l ill V U t i l..i (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 90/15333 GO1N 35/00 Al (43) International Publication Date: 13 December 1990 (13.12.90) (21) International Application Number: PCT/US89/02345 (81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (European pa- (22) International Filing Date: 30 May 1989 (30.05.89) tent)*, DK, FR (European patent), GB (European patent), I' .3uropean patent), JP, LU (European patent), NL (European patent), SE (European patent), US.

(71) Applicant (for all designated States except US): TEe I- CON .INSTRUM .ENTS CORPORATION [US/US]; 511 Benedit Avenue, Tarrytwn, NY 10591 5097 Published With international search report.

(72)Inventor;and Inventor/Applicant (for US only) BOCK, Malcolm, G. [US/ US]; 52 Greenmeadow Lane, New Canaan, CT 06840

(US).

(74) Agents: ROMANO, James, Jr.; 605 Third Avenue, 18th Floor, New York, NY 10158-0072 (US) et al. t M \es Tllc- a7 M 4\v- svw'1-o I 1 E\\clAn~ Zn, a 6'1 u.s. A B u (54) Title: APPARATUS AND METHOD FOR THE SELF-LEVELLING OF LIQUID IN A CONTAINER (57) Abstract New and improved apparatus and method for the self- PROBE levelling of a liquid in a container (10) to a precisely predeter- AC7"T'7I4 O mined level, with a concave meniscus, are provided and com- I prise a plurality of ribs (14, 16) defining with the container 82inner surface (28) one or more capillary pathways formed by the rib-container surface junctures (30, 32, 34, 36) operatively 'y.S SYSTEAI associated with the container (10) and operable upon contact therewith by the liquid within the container (10) to flow liquid out of the container (10) until the liquid has assumed the pre- 72 cisely predetermined level within the container (10) and to pro- 70 /4 12 7 vide a concave liquid meniscus at that level. Central support of 32 78 6 a predetermined volume of an immiscible isolation liquid on the concave meniscus of the liquid in the container (10) of the precisely determined liquid level is also disclosed. I .52 to 32 2 16 52 76 64 70 76 2G See back of page a 645961 1- "APPARATUS AND METHOD FOR THE SELF-LEVELLING OF LIQUID IN A CONTAINER" BACKGROUND OF THE INVENTION 1. Field of the Invention.

This invention relates to new and improved apparatus and method for the self-levelling of a liquid in a container to a precisely predetermined level with a concave liquid meniscus; all particularly adapted to use in contemporary, highly accurate automated sample liquid analysis systems.

2. Description of the Prior Art.

Although a wide variety of self-levelling liquid containers are known in the prior art, none are known which accomplish that function in accordance with the 15 teachings of the apparatus and method of this invention.

Representative of the known prior art self-levelling containers are those disclosed in United States Patent 4,602,995 issued July 29, 1986 to Mr. Michael M.

Cassaday, et al for "Liquid Level Adjusting And Filtering 20 Device," and assigned to the assignee hereof, and United States Patent 4,758,409 issued July 19, 1988 to Mr.

Kenneth F. Uffenheimer for "Microsample Cup," and assigned to the assignee hereof; with both of the same functioning to achieve self-levelling of a liquid in a container essentially at a level coincident with complete container liquid capacity by purposeful over-filling of the container and collecuion of the resultant liquid overflow in a surrounding overflow reservoir. More specifically, in 4,602,995, a separate liquid level adjusting device in addition to the standard liquid container is required, and must be operatively inserted into the latter to pump the liquid therefrom into the device to overfill the same back into the container, thus leaving the liquid in the device at a predetermined level relative to the container and coincident with the capacity of the liquid level adjusting device; while in 4,758,409 direct overfilling of the microsample cup, which can be somewhat difficult due to the

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extremely small size thereof, is required. Both United States Patents 4,602,995 and 4,758,409 do, however, clearly disclose the provision of a concave meniscus on tne liquid at the predetermined liquid level; and 4,602,995 further clearly discloses the emplacement and support on that concave liquid meniscus of a precisely predetermined volume or "lens" of an appropriate immiscible liquid to minimize sample liquid carryover in instances wherein the liquid level adjusting device is used in conjunction with sample liquid containers in an automated sample liquid analysis system as disclosed therein. Self-levelling of the contained liquid to a level essentially coincident with full container capacity as disclosed in United States Patents 4,602,995 and 4,758,409 can, however, prove somewhat 15 problematical in the event of significant mechanical disturbance of the container after that liquid level has been achieved, with resultant liquid spillage from the Scontainer albeit into a surrounding overflow reservoir; it being clear to those skilled in this art that the same would result in a "final" liquid level in the container below that desired.

United States Patents 4,602,995 and 4,758,409 are, in any event, totally devoid of any disclosure of the utilization of capillary action in the self-levelling of a 25 liquid in a container.

United States Patent 4,515,753 issued May 7, 1985 to John L. Smith, Ph.D., et al, for "Integral Reagent Dispenser," and assigned to the assignee hereof, discloses a reagent liquid dispensing well comprising a reagent liquid supply port, and operatively connected, gravity feed reagent liquid supply means; and operates upon aspiration of the reagent liquid from the dispensing well to a level which uncovers the supply port to periodically replenish the reagent liquid from the gravity feed supply means; thiireby maintaining the reagent level within the dispensing w;ll 3 within a narrow range until the available liquid supply is substantially exhausted. This patent does clearly disclose the provision of a concave meniscus on the reagent liquid in the dispensing well, and the central positioning thereon of a precisely predetermined volume or "lens" of an appropriate immiscible isolation liquid for sample liquid carryover minimization purposes.

United States Patent 4,774,057 issued September 27, 1988 to Mr. Kenneth F. Uffenheimer, et al, for "Dual Liquid Dispenser Package" discloses a reagent dispensing well of essentially the same nature as that disclosed in United States Patent 4,515,753 as described directly hereinabove; but wherein the periodic replenishment of the reagent liquid in the dispensing well is accomplished 15 by periodic rotation of the dispenser package to feed the reagent liquid from the supply means to the dispensing well under the influence of the thusly generated centrifugal forces.

United States Patent 4,515,753 and 4,774,057 are 20 again, in any event, totally devoid of the utilization of

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S: capillary action in the self-levelling of a liquid in a container.

S..The respective disclosure of United States Patents 4,602,995, 4,758,409, 4,515,753 and 4,774,057 are 25 hereby incorporated by reference in the disclosure of this application.

OBJECT OF THE INVENTION It is, accordingly, an object of my invention to provide new and improved apparatus and method for the self-levelling of a liquid in a container.

SUMMARY OF THE INVENTION According to a first aspect of the invention there is provided a liquid container comprising self-levelling means operatively associated with said container, said self-levelling means comprising capillary means operable in response to contact by liquid therewith within the ALHiy container for causing the liquid to assume a 4predetermined level therein.

According to a second aspect of the invention there is provided a method for containment of a liquid in a container comprising the steps of, flowing a liquid into a container to cc -act capillary self-levelling means within said container, and causing said liquid to assume a predetermined level within said container in response to contact thereby with said capillary self-levelling means.

DESCRIPTION OF THE DRAWINGS 15 a.

a 2 The above and other significant objects and advantages of my invention are believed made clear by the following detailed description thereof taken in conjunction with the accompanying drawings wherein: FIG. 1 is a perspective view of a container operatively incorporating therewith new and improved liquid self-levelling means representatively configured and operable in accordance with the teachings of my invention; FIG. 2 is a top plan view of the container of FIG.

a *Z a 1; FIG. 3 is a cross-sectional view taken essentially along line 3-3 in FIG.2; FIG. 4 is an enlarged fragmentary view of a portion 25 of FIG. 2; FIGS. 5 and 6 are respectively cross-sectional views as in FIG. 3, and respectively illustrate the operation of the self-levelling means of my invention essentially at the commencement and completion thereof; FIG. 7 is a top plan view of a container operatively incorporating the self-levelling means of my invention, and excess liquid collection means, therewith; FIG. 8 is a cross-sectional view taken essentially along line 8-8 in FIG. 7, and illustrates the operation of the self-levelling means of my invention essentially 5 at the commencement thereof; FIG. 9 is a cross-sectional view as in FIG. 8 illustrating the operation of the self-levelling means of my invention at the completion thereof, and further illustrates a representative application of he self-levelling means of the invention to use in conjunction with an automated sample liquid analysis system; 15

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o eo e e e e r< FIG. 10 is a perspective view of a container operatively incorporating the self-levelling means of my invention, and new and improved bubble-free liquid introduction means, therewith; FIG. 11 is a top plan view of the container of FIG.

FIG. 12 is a cross-sectional view taken essentially along the 12-12 in FIG. 11 and illustrating the operations of the self-levelling and bubble-free liquid introduction means intermediate the same; and FIG. 13 is a cross-sectional view as in FIG. 12 and illustrating the operations of the self-levelling and bubble-free liquid introduction means at the completion thereof.

DETAILED DESCRXPTION OF THE INVENTION Refe:rring now to FIGS. 1, 2, 3 and 4 of the application drawings, an essentially conventional, opentopped frusto-conical container is shown at 10; and includes new and improved self-levelling means representatively configured and operable in accordance with the teachings of the currently contemplated best mode of the apparatus and method of my invention as indicated generally at 12.

The self-levelling means 12 comprise essentially identical container ribs as indicated at 14 and 16, and which are respectively disposed as snown to opposite sides of the container 10 to be diametrically opposed relative thereto.

Each of the ribs 14 and 16 is formed as shown to commence at, and to be flush with, the interior side wall 18 15 of the container 10 at precisely the sawe level 20 within the container; and to extend therefrom up and across the container top wall or lip 22, and down the container exterior side wall 24 to terminate as shown essentially at the container bottom 26. To this effect with regard to the 20 commencement of the ribs 12 and 14 at precisely the same level 20 on the container interior side wall 18, the latter will be seen to be uniformly bevelled, as shown at 28, commencing at the level 20 and extending upwardly to the top wall or lip 22 of the container t S 25 With the self-levelling means 12 of my invention configured and disposed as described relative to the container 10, it will be clear that four contiguous ribcontainer surface junctures or corners will be provided to respectively extend coextensively with the ribs 14 and 16 as described, on the basis of two contiguous rib-container surface junctures or corners respectively to either side of the rib, from within the container 10 at the level 20 up and accoss the container lip 22 and downwardly therefrom on the exterior of the container essentially to the container bottom 26.

More specifically, and for rib 14, these contiguous rib-container surface junctures or corners, which are in each instance formed by the juncture of the rib surface with the respective surfaces of the bevelled container interior wall portion 28, the container lip 22, and the exterior container wall 24, are indicated at 30 and 32, respectively, to either side of the rib: while, for rib 16, these rib-container surface junctures of corners, formed as described for rib 14, are indicated at 34 and 36, respectively, again to either side of the rib. For purposes of my invention as described in detail hereinbelow, these rib-container surface junctures or corners 30, 32, 34 and 36 are made as sharp as practical in accordance with the 15 particular material(s) chosen for the container 10 and the ribs 14 and 16, and the particular manufacturing technique(s) employed in the fabrication thereof; it being noted in this regard that a juncture or corner radius as indicated at R in the enlarged fragmentary view of FIG. 4 for corners 34 and 36 of 0.002 inch radius maximum has proven satisfactory in these regards.

In accordance with the teachings of my invention, it has been discovered that the contiguous, sharp-cornered rib-container surface junctures 30, 32, 34 and 36 will, under appropriate container material surface energy vis-avis contained liquid surface tension conditions as described in greater detail hereinbelow, function as micro-capilarry tubes, thus providing four capillary pathways as respectively formed by surface junctures 30, 32, 34 and 36, and which extend in each instance as heretofore described from level 20 inside of container 10 upwardly and across the container lip 22 and downwardly therefrom essentially to the bottom 26 of container 10; with each of those capillary pathways being inherently effective under the influence of a contained liquid driving force as provided by capillary rise to flow liquid contained in container 10 above the level out of the container, thereby lowering that liquid precisely to that level within the container 10. In addition, and again in accordance with the teachings of my invention, it has been discovered that this capillary action will inherently provide a concave meniscus on the contained liquid at precisely the level 20 within the container concomitantly with the lowering of that liquid to that level.

With more specific regard to the essential relationships between container material surface energy, contained liquid surface tension, and capillarity, it will be clear to those skilled in this art that, under conditions wherein extraneous forces are negligible, a particle of unconfined liquid will assume a perfectly spherical shape because of the attractive forces between the respective liquid molecules. In the interior of the unconfined liquid particle, each molecule is, of course, surrounded by many others; and, on the average, the attractive forces on each 20 of those molecules are uniform in all directions. At the surface of the unconfined liquid particle, however, there is virtually no outwardly directed attractive force to balance the inwardly directed attractive forces since, for example, with the unconfined liquid particle surrounded by air, there 25 are relatively few molecules surrounding the same. Thus, the molecules at the surface of the liquid particle are subjected to an inwardly dirncted force, while the molecules near but not at the particle surface are also subjected to an inwardly directed force, although of lesser magnitude.

It therefore requires a certain amount of work to bring a molecule from the center of the spherical liquid particle to a point near the particle surface. When the volume of the unconfined liquid particle is increased, as by the introduction of more liquid thereto, molecules will have to be moved from the interior of the spherical particle to the 9 particle surface to account for the increased surface area there, thus requiring the performance of a certain amount of work; with the energy required for the same being proportional to the increase in surface area. This energy, which is expressed in terms of work per unit area as the units of force per unit length, is called surface tension.

Surface tension will always exist whenever there is a density discontinuity at an interface, for example the air-liquid interface between an unconfined liquid particle in air; with the magnitude of the surface tension being dependent in that instance upon the difference in denities between air and the liquid in question. A particularly important aspect of surface tension is the fact that it creates a pressure change across an interface whenever that 15 interface is curved, thus leading to the phenomenon of capillary rise; it having proved convenient to calculate the magnitude of the pressure change in accordance with the concept of surface tension. For an unconfined spherical *e S• liquid particle in air, this pressure cha.nge may be calculated in accordance with the following Equation I: "AP pi po 26/r wherein, P is the pressure change, pi is the pressure at the interior of the liquid 25 particle po is the air pressure outside the liquid particle, is the surface tension of the liquid, and r is the radius of the spherical liquid particle.

In addition to the above, it will be readily understood by those skilled in this art that, when a drop of liquid is placed on a solid surface and surrounded by air, the interface between the liquid drop will be inclined at some. angle to the solid surface. This angle is known as the wetting angle or contact angle and is generally indicated by the term "theta. This wetting or contact angle depernds basically upon the relative attractions of the molecules of three media involved, in this instance, the liquid, the solid which forms the supporting surface, and the surrounding air, and is therefore a function of the relevant physical characteristics of all three of these substances.

In addition, this angle is is very sensitive to contaminants, and ia dependent in part upon whether the liquid is advancing or receding over the solid supporting surface.

These phenomena of surface tension, pressure change, and wetting or contact angle, may be understood to 15 be tho,3e which result in the rise or fall of a liquid as *occur wthen a small diameter tube is dipped into the liquid; it being noted that when the rise or fall of the liquid is much larger than the radius of the tube, the interface or *meniscus separating the liquid from the surrounding medium, normally the ambient air, may be assumed to be nearly spherical, and the extent of the liquid rise or fall relative to the tube closely approximated in accordance with :the following Equation II: *moo*:h z-(2/gre X (cos( theta)) h: is wherein of the rise or fall of the liquid, 6 ris the surf ace tension of the liquid, g is the acceleration of gravity, r is the radius of the tube, eis the density of the liquid, and theta is the contact angle between the 3A~quid and :no tube.

Careful examination of Equation 11 reveals that 11 the 26/r term is pressure change AP across the liquid-air interface as calculated in accordance with the surface tension of the liquid and the radius of the interface from Equation I; while tt:e cos(theta) term is derived from the contact angle of the liquid with the tube in accordance with the relative attractions of the molecules of the three media involved, namely the liquid, the surrounded air, and the solid material of the tube. If the liquid molecules are attracted to the solid tube material molecules, the contact angle at the liquid-tube interface will be less than degrees to result in a positive cos(theta) term, and an attraction or rise in the liquid level in the tube. This will also result in concave meniscus for the liquid. If, on the other hand, the liquid molecules are repulsed by the 15 molecules of the solid tube material, the contact angle at the liquid-tube interface will be, greater than 90 degrees to result in negative cos(theta) term, and a repulsion or fall in toe liquid level in the tube. In this instance, the Smeniscus of the liquid in the tube would be convex. The applicability of Equation II to approximate liquid rise or fall in a tube is limited to situations as described wherein the density of the surrounding medium is much less than the density of the liquid.

With the above in view, reference may now be had 25 to FIGS. 5 and 6 of the application drawings for detailed description of the operation of the self-levelling means 12 of my invention in conjunction with the container 10; it being understood that auch dcacription is in accordance with the containment of a liquid as indicated at 40 in FIGS. ai4 6 which fomfias a wetting or contact angle of less than degrees qit th$e materials of the container 10 and the ribs 14 and 16.

FIG. 5 illustrates the filling of the container substantially to capacity at the container lip 22 with the liquid 40, for example by the simple manual pouring of the liquid triereinto. in instances wherein liquid spillage over the container lip 22 is of no consequence, or wherein additional~ provision is made for liquid, spillage containment externally of the container 10 as described in detail hereinbelow, filling of the container to capacity as illustrated in FIG. 5 may be readily accomplished by simply pouring the liquid thereinto until the liquid perhaps slightly overflows the container lip 22 thus insuring that the container~ is full; and this, of course, negates any 0 requirement that the liquid 40 be initially introduced to the container 10 with any degree of time-consuming precisio-n and care to "fill" the container to any predetermined level.

With thie container 10 filled to capacity by the liquid 40 as illustrated in FIG. 5, it will be clear that a 5 convex meniscus as indicated at 42 will initially be formed by the liquid, 0000 0~ S SO S 5e

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Filling of the con .iner 10 with the liquid 40 as shown in FIG. 5 will, of course, result in the immediate wetting by the liquid of the container interior, including those portions of the capillary pathways formed as described by the rib-container surface junctures 30 and 32, and 34 and 36, respectively to opposite sides of the ribs 14 and 16, which are within the container 10 and coincident witn the bevelled interior contain~er wall portion 28; and the 25 virtually concomitant commincament in each instance of the flow of the liquid 40 under capillary action as described essentially at right angles to the juncture radii R along those capillary pathways upwardly from the interior of the container 10 across the container lip 22 and downwardly along the exterior of the container 10 essentially to the container bottom 26; with the pres-sure drop or "head" between the height of what becomes the source liquid 40 in container 10 above the level 20, and the height of the cont~ainer bottom 26, functioning to provide siphon effect to maintain flow of the liquid 40 along the capillary 13 pathways. This is to say tnat, once flow of the liquid from the container 10 in the capillary pathways formed by rib-container surface junctures 30, 32, 34 and 36 is commenced as described by capillary rise up and across the container lip 22 and down the container exterior, this siphon effect will operate to insure the continuation of the same along those capillary pathways. Liquid flow is shown by the flow arrows in FIG. Flow of the liquid 40 along the sharp-cornered capillary pathways provided by the rib-container surface junctures 30, 32, 34 and 36 from the container interior will continue as described until the liquid level in the container drops essentially to in reality an extremely short distance below-- the level 20, as illustrated in FIG.

15 6, at which liquid level flow will, of course, cease since there is no longer any liquid present at what are in essence the inlets to the capillary pathways at the points whore the ribs 14 and 16 respectively become flush with the interior container wall 18. In addition, and as also clearly illustrated by FIG. 6, the meniscus 42 of the liquid 40 in the container 10 will be flipped from convex to concave in accordance with the wetting of the container and rib material(s) by the liquid and the phenomenon of capillary rise as described, attendant this reduction in liquid level essentially to the level 20 in the container 10. Thus, and in full accordance with the stated objects of the apparatus and method of my invention, it will be immediately clear to those skilled in this art that the level of the liquid 40 in the container 10 is inherently fixed at a precisely predeterminable level in the container interior below the container lip and virtually coincident with the extent of the ribs 14 and 16 into the container interior, and that the liquid 40 will inherently exhibit a concave meniscus at that level; all totally without requirements for any particular degrees of skiil, precision, care, or time expenditures, in the initial filling of the container 2or moving parts, or for the conduct of operations of any nature beyond the relatively siaple initial filling of the container as described with the liquid A container assembly representatively configured and operable in accordance with the teachings of the apparatus and method of my invention for use in automated, successive sample liquid analysis systems of the type heretofore described with regard to United States Patents 4,602,995, 4,678,641, 4,758,409 and 4,774,057 is indicated generally at 50 in FIGS. 7, 8 and 9; and will immediately be seen to comprise the container 10 with the self-levelling means 12 as again formed by the ribs 14 and 16 configured and operatively associated therewith as heretofore described. The container assembly 50 further includes an outer container member 52 joined as illustrated from the outer surfaces 54 and 56 of the ribs 14 and 16 to the *Y container 10 to be spaced from and surround the same at the container sides and bottom. This provides arcuate liquid Zlow passages as indicated at 58 and 60 between the exterior side wall 24 of the container 10 and the interior side wall 62 of th outer container member 52, as divided by the ribs 14 and 16, and provides a liquid collection space 64 between the exterior wall 66 of the bottom 26 of the container 25 and the interior wall 68 of tfe bottom 70 of the outer container member of the outer container member 52; it being immediately clear that the liquid collection space 64 will be in liquid flow communication with each of the flow passages 58 and 60, and with each of the capillary pathways which are formed as described by the sharp-cornered ribcontainer surface junctures 30, 32, 34 and 36, respectively.

In addition to the above, it will be clear that the outer container member 52, which preferably extends as seen in FIGS. 8 and 9 some distance above the top surfaces 70 and 72 of the ribs 14 and 16, can function to advantageously facilitate handling of the container assembly and the operative emplacement thereof in sample liquid analysis system container indexing means by presenting a smooth and uniform surface for the assembly; and/or to render more effective the operable emplacement of a suitable evaporation cover to inhibit sa.aple liquid evaporation over one or more of the container assemblies by effectively preventing contact by the ambient air with the sample liquid suface( a).

FIG. 8 depicts the container assembly S0 of my invention immediately upon the completion of the simple filling of the container 10 as heretofore described essentially to capacity with a sample liquid, as indicated at 76, including an initially convex meniscus as indiacted at 78; and makes clear that, within reason, any spillage of the sample liquid 76 as may have occured during the filling of container 10 and overflowed the same will have been effectively contained by the upper wall portions of the outer container member 52 which extend as shown above the lip 22 of the container 10 for downward flow through arcuate flow passages 58 and 60, and containment as representatively illustrated in the collection space 64.

FIG. 9 depicts tits container assembly 50 upon the Se completion of the flow of that portion of the sample liquid 25 76 in container 10 above the level 20, up and out of tne container interior, across the. lip 22, and down the container exterior, along the respective capillary pathways formed by the sharp-cornered rib-container surface junctures 32, 34 and 36, all as heretofore described in detail with regard to FIG. 6, with attendant flip of the sample liquid meniscus 78 from convex to concave; and FIG. 9 makes immediately clear that this portion of the sample liquid 76 will also be containted in the collection space 64 as illustrated along with the sample liquid spillage,, if any, upon the flow of that liquid portion into that collection 16 space from those capillary pathways as indicated by th~e sample liquid flow arrows in FIG. 9 at the lower extremities of those capillary pathways.

Under all of the above circumstances, 4L~ Will be clear that, again within reason with regard to tho initial filling to capacity of the container 10, no contd.iinating leakage of the sample liquid 76 from the container assembly of my invention should occur; and this will be readily understood by those skilled in this art to be of particular contemporary importance in those instances wherein the sample liquid 76 is constituted by a biological liquid which may contain h~.ghly and readily communicable infectious agent(s).

With the level of the sample liquid 76 in the container 10 of the container assembly 50 essentially coincident as illustrated and described with regard to FIG.

9 with the level 20, and thus at precisely the same readily reproducible lovel in each of the plurality of the container assemblies So as would be employed in an automated, successi.ve sample liquid analysis 3ystem as heretofore described, it will be readily apparent to those skilled i this art. that successive sample liquid presentations to the precisely operable sample liquid analysis system probe means, as shown at 80 in FIG. 9, at precisely the same liquid level, is assured. This, as described in some detail in United Statiss Patents 4,602,995 and 4,758,409, is of particular importance with regard to insuring precisely the same probe residence time in the liquids 76 in each of the sample liq%;id, container assemblies 50 as the probe means are moved in each instance, under the control of probe moans actuator means as depicted schematically at 82 in FIG. 9, from thiv probe means position depicted in phantom lines wherein the same are without the sample liquid container assembly 50, to the probe means position depicted in solid lines wherein the inlet end 83 of the probe means is 0 17 immersed in the sample liquid 76 for sample liquid aspiration and supply as indicated to the sample liquid analysis system; thus in turn insuring the aspiration by the probe means 80 and supply to the sample liquid analysis system of precisely the same volume of sample liquid 76 from each of the successively presented sample liquid container assemblies 50; all to particularly significant advantage with regard to the overall and consistent accuracy of the sample liquid analysis results.

The probe means 80 may, for example, take the general form of those disclosed in United States Patent 4,121,466 issued October 24, 1978 to Mr. Allen Reichler, et al for "Liquid Dispenser With An Improved Probe;" in which instance the probe means 80 would include means to coat the 15 same with a thin layer of an immiscible isolation liquid as set forth in some detail in United States Patent 4,121,466, the disclosure of which is hereby incorporated by reference in this specification.

In addition to the above, and with the..meniscus 78 20 of the sample liquid 76 in the container 10 of the container assembly 50 flipped as heretofore described to concave attendant the reduction of the level of the sample liquid essentially to the level 20, it will be clear that an appropriate, predetermined volume of an immiscible isolation 25 liquid, or "lens" thereof as the same is commonly termed, as indicated at 84, may be emplaced in any suitable manner, for example by operatively associated, precisely operable isolation liquid dispenser means as indicated schematically at 85 in FIG. 8, on the concave meniscus 78 of the sample liquid as seen in FIG. 9; it being clear that the isolation liquid dispenser means 85 would only be operable to emplace the isolation liquid lens 84 on the concave liquid meniscus after the same had come into being, and prior to operation of the probe means 80 as hereinafter described in detail.

The surface tension of the sample liquid 76 will function to 18 retain the isolation liquid lens atop the meniscus 78, and the concavity of that meniacus will function to retain the lens 84 precisely certrally disposed relative to the container 10, and thus relative to probe means 80. Thus, and for use as described of a successive plurality of the container assemblies 50 in an automated sample liquid analysis system, and with the isolation liquid lens 84 constituted in each instance by precisely the same volume of the isolation liquid, it will immediately be clear that precisely the same thickness of the isolation liquid lens 84, and thus precisely the same isolation liquid volume, will be presented to the probe means 80 for aspiration therethrough preceding sample liquid aspiration upon movement as described of the probe means into the respective 15 sample liquids 76 in each of the successively presented Goo: sample liquid container assemblies Although described in some detail in United States Patents 4,121,466, 4,515,753, 4,678,641 and 4,602,995, it is reiterated in this specification that, for use with sample 20 liquids 76 which are essentially aqueous, the immiscible S..isolation liquid, for example a fluorinated hydrocarbon liquid, functions to selectively wet the hydrophobic analysis system components, including probe means 80, to the substantial exclusion of the sample liquids under analysis, 25 thus substantially preventing the adherence of those sample liquids to the analysis system components. This significantly reduces sample liquid "carryover," i.e. the contamination of the succeeding sample liquid by the residue of a preceding sample liquid, with resultant maximization of the accuracy of the successive sample liquid analysis results. Thus, the provision as described in accordance with the teachings of my invention of precisely the same volume of the isolation liquid from lens 84 for aspirstion by probe means 80 preceding the aspiration in each instance of the sample liquids 76 in turn from ,he successively 19 presented container assemblies 50 is also of significant advantage in, on the one hand, insuring that a predetermined, precisely sufficient volume of the isolation liquid as required by the sample liquid analysis system for the carryover minimization task at hand for each sample liquid, is provided; while, on th, other hand, insuring that excess and wasteful volumes of the isolation liquid, which are quite expensive and which can adversely affect the accuracy of t'10 sample liquid analysis results, are not provided.

A container assembly representatively configured and operable in accordance with the teachings of the currently contemplated best mode of the apparatus and method of my invention for theL accomplishment of both the ready and 15 convenient, bubble-free tilling of a container, and the subsequent adjustment in the level of the liquid in the 00 thusly filled container to a precisely predetermined level 0 0 as heretofore described in detail, is indicated generally at 100 in FIGS. 10, 11, 12 and 13 of the application drawings.

Container assembly 100 comprises a central,generally cylindrical container 102 in the nature of container 10 as heretofore described with regard to FIGS. 1 through 9, and a generally cylindrical outer container :member 104 which surrounds container 100 generally concentrically thereof, and which is spaced therefrom as shown to provide a torous-like space generally indicated at 106 therebetween. vertical dividing walls as indicated at 108 and 110 extend readially as shown between the respective side walls of container 102 and outer container member '-,74 at a 1800 interval thereby dividing space 106 into arcuate spaces 116 amd 118. As best seen in FIG. 10, the side wall of container 102 is divided essentially along the container diameter as indicated at 120 to form semi- cylindrical container side wall portions 122 and 124, with the former being of significantly less height than the latter.

A generally semi-circular bottom wall 126 extends generally horizontally as shown between the higher container side wall portion 124, intermediate the same, and the side wall of outer container member 104 thereby forming, in conjunction with that container side wall portion, the outer container side wall, and the dividing walls 108 and 110, an open-topped arcuate liquid chamber 128, which is coincident with space 116; while a gsnerlly semi-circular bottom wall 129 extends as shown generally horizontally between the lower edge of the lower container side wall portion 122 and the lower portion of the side wall of outer container member 104 thereby forming, in conjunction with that container side wall portion, the outer container side wall, and dividing walls 108 and 110, an open topped arcuate liquid chamber 130 which is coincident with space 118.

For reasons made clear hereinbelow, it is of particular inportance to the operation of the container assembly 100 of my invention that the level of bottom wall 126 of liquid chamber 128 be above the level of the upper 20 edge or lip 132 if the lower portion 122 of the side wall of container 102.

Automatically operable means for the ready and Sconvenient, oubble-free filling of container 102 with liquid and liquid chamber 128 are indicated generally at 134; and take the form of a rib 136 operatively associated with both the container 102 and the liquid chamber 128 and which, in the manner heretofore described in detail with regard to riba 14, and 16 of FIGS. 1 through 10, foCrm' contiguous, sharp-cornered rib-container surface junctures with the container 102. More specifically, rib 136 extends as best seen in FIGS. 12 and 13 along the exterior surface of the side wall portion 124 of container 102 substantially from the intersection of the bottom wall 126 of liquid chamber 128 therewith upwardly as shown and over and across the upper edge or lip of the container side wall portion 124, 21 and downwardly therefrom along the interior surface of that container side wall portion substantially to the bottom wall 140 of container 102; thereby forming contiguous ribcontainer surface junctures, as respectively indicated at 142 and 144 to either side of rib 136, extending in each instance substantially from the bottom of liquid chamber 128 to the bottom of container 102. This, as heretofore described in some detail, provides capillary pathways coextensivea with those rib-container surface junctures for liquid flow from liquid chamher 128 into container 102.

self-levelling meann configured and operable in accordance with the teachings of the method and apparatus of my invention for the automatic adjustment of the liquid level in container 102 to a precisely predetermined level is are indicated generally at 146 in -FIGS. 10 through 13 and, 44 1.in the manner of self-levelling means 12 as heretofore described in detail with regard to FIGS. 1 through 9, comprise a rib 148, diametrically opposed to rib 136 via-avia container 102, which again forms sharp-cornered rib- 20 container surface junctures with the container10. Mr specifically, rib 148 extends as best seen in FIGS. 12 and 13 from a precisely predetermined level 150 on the interior a. surface of the sid* wall portion 122 of container 102 upwardly as shown and over and across the upper edge or lip 132 thereof, and downwardly therefrom along the exterior surface of that container side wall portion substantially to the bottom wall 129 of the liquid chamber 130; thereby forming contiguous rib-container surface junctures 152 and 154 respectively to either side of rib 148, extending in each instance from level 150 in container 102 substantially to the bottom of liquid chamber 130, and providing, as heretofore described, capillary pathways coextensive therewith for liquid flow from level 150 in container 102 into the liquid chamber 130. FIGS. 12 and 13 make clear that the level 150 in container 102 is significantly above 0 22 the level of the bottom 129 of liquid chamber 130; while FIGS. 11 through 13 make clear that the respective volumes of liquid chambers 128 and 130 are, in each instance, greater than the volume of container 102.

In use of the container assembly 100 for the ready and convenient filling of container 102 essentially to the level 150 with completely bubble-free liquid from liquid chamber 128, and with the liquid in question of course being one which readily wets the container assembly materials by forming a contact angle of less than 900 therewith as heretofore described, it may be understood that liquid chamber 128 is initially filled in any convenient manner, for example by the simple pouring or dispensing of a liquid as indicated at 156 in FIGS. 12 and 13 thereinto, always to somewhat less than the full capacity thereof below the upper edge or lip 132 of containpr side wall portion 124 to prevent overflow of the liquid 156 from chamber 128 directly into container 102; and this again makes clear as described in some detail hereinabove with regard to the initial 20 filling of container 10 that no particular degree of skill or care need be exercised, nor inordinate amount of time expended, in the initial filling of the chamber 128 with the liquid 156 to any precisely predetermined level. In addition, and to further significant advantage as described 25 in detail hereinbelow, it may be understood that, within reason, no care of any nature need be taken to insure that the liquid introduced as described to chamber 128 is at all bubble-free.

Immediately upon contact by the liquid 156 with the capillary pathways formed as heretofore described in chamber 128 by the sharp-cornered rib-container surface junctures 142 and 144 to opposite sidea of rib 136, and the wetting thereof by the liquid, it will be clear that flow of the liquid 156 along those capillary pathways from liquid chamber 128 into container 102 will commence in accordance with the head provided by the difference in height between chamber 128 and container 102. Since the flow of air along the capillary pathways provided by rib-container surface junctures 142 and 144 is not possible, it will be readily understood by those skilled in this art that completely bubble-free liquid 156, only, will flow as described from chamber 128 to container 102; and this despite the fact that the liquid 156 as initally introduced into chamber may very well contain some measure of air bubbles.

immediately upon contact by the thusly flowed liquid from chamber 128 into container 102, and the contact therewith and wetting thereby o~f, thie capillary pathways *formed by the rib-container surface junctures .152 and 154 to 1-pposite sides of rib 148 within containe~r 102, it wrill be i 5 claar that flow of the liquid 156 along those capillary 9 pathways from container 102 to liquid chamber 130 will also *9commence in accordance with the head provided by the 9: difference in height between the container 102 and, the chamber 130; thereby providing concomitant flow c:f the liquid 156 from chamber 128 to container 102; and) from container 102 to chamber 130, respectively. FI1G. 12 illustrates this stage in the operation of the container 9 assembly 100 of my invention; with the flow arrows adjacent the capillary pathway formed by the sharp-cornered surface juncture 142 of rib 136 with side wall portion 124 of container 102 illustrating the flow of liquid 156 from chamber 128 into container 102; and the flow arrows adjacent the capillary pathway formed by the sharp-cornered surface juncture 152 of rib 148 with side wall portion 122 of container 102 illustrating the concomitant flow of the liquid 156 from container 102 to chamber 130.

Operation of the container assembly 100 of my inviention continues as deacribad until all available liquid 156 from chamber 128 has flowed, totally without air bubble 3 content, into container 102, and all available liquid 156 in

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container 102 above level 150 has flowed in turn from that container for collection in chamber 130; thus, and in accordance with the provision of a normally anticipated "fill" volume for cha~mber 128 which is clearly greater than the volume of container 102 below level 150, insuring that, upon completion of all flow of the liquie jq6 as described, true container 102 will contain that liquid totally bubblefree, and at a level essentially coincident with level 150.

FIG. 13 illustrates this final, insofar as flow of the liquid 156 is concerned, condition of the container assembly 100, and makes clear that the meniscus 158 of the liqui.d 156 in container 102 will again be concave.

The container assembly 100 of FIGS. 10 through 13 is particularly adapted for use as a microsampl *e cup of the nature disclosed in United Stalas Patent 4,758,409 in an automated, successive sample liquid analysis system. For :0 to such use, and with the meniscus 158 of would be a sample liquid 156 in container 102 concave, it will be clear to those skilled in this art that a precisely predetermined volume or "lens" of an appropriate isolation liquid -3 CC indicated at 160 in FIG. 13. may be disposed on the liq--..d 156 in container 102 and maintained centrally thereof by the concave meniscus 158, to significant advantage with regard :to the effective minimization of sample liquid carryover as too.": 25 heretofore described in some detail with regard to isolation liquid lens 84 of FIG. 9.

For use of the container assembly 100 as a microsample cup, it will be understood by those s) k.led in~ this art that the volume of container 102, would bt U4it& small, for example 10Q. microl~iters, while the inner diaiteter of the container 102 at the upper @:3g6 or lip 132 thereof would, for example, be as small as 0.15 inches. Under these circumstances, it will be clear that direct filling of tne container 102 in the manner disclosed for the filling of the microsaample cup of United States Patent 4,758,409 can sometimes prove difficult, even through use of an appropriately small pipette, due of course to the very small inner container diameter in question. In addition, the tendency of microbubbles to form and be contained in the very small sample liquid volumes under discussion, especially upon the handling and dispensing thereof by pipette into an extremely small container, can also prove problematical; it being clear to those skilled in this art that the presence of such microbubbles in the sample liquid contained in a microsample cup of the nature disclosed in United States Patent 4,758,409 can adversely impact upon the overall accuracy of the sample liquid analysis results by lessening the actual volume of samplo liquid aspirated from the microsample cup by the probe means for supply to the 15 sample liquid analysis system, and/or by interfering with the essentially central placement, and thus aspirated volume, of an isolation liquid lens as may be emplaced thereon as described.

Under the above circumstances, and for use of the 20 container assembly 100 of my invention as a microsample cup, it will be clear that configuration of the same to provide for a substantially larger accessible area of the liquid S"chamber 128 vis-a-vis the accessible area of the container 102 will render the "filling" of that liquid chamber, as by S 25 pipette, much more readily and conveniently accomplishable •than direct "filling" of the container 102; while the problem of microbubble content in the sample liquid 156 in container 102 is rendered non-existent.

Representative materials for use in the formation of the container of my invention for operation as described with essentially aqueous liquids, for example human blood sera sample liquids, are glass-filled plastics such as polyvinylchloride or polyethylene, with which such liquids will form a contact angle of less than 900 to readily "wt" the same as required for capillary action. The advantages of these glass-filled plastics are ready availability, relatively low cost, general chemical inertness, and suitable strength characteristics. In addition, the same are readily injection moldable, which is a preferred method for tie fabrication of the container of my invention.

Possible alternatives to glass-filled plastics as described for use in the formation of the container of my invention for operation with essentially aqueous liquids are plastics, again for example polyvinylchloride, to which an appropriate surfactant, for example ethlylene oxide, has been added, or which have been plasma treated in the presence, for example, of oxygen to, in either instance, raise the surface energy of the plastic in question to an extent sufficient to insure the formation therewith by essentially aqueous liquids of a 15 contact angle of less than 90° as required for capillary 0 action to occur. A non-plactic material which is E particularly suitable for use in the formation of the container of my invention for operation as described with essentially aqueous .iquids is glass which, is readily 20 "wettable" by those liquids.

SFor use of the container of my invention as representatively disclosed with sample liquids in an 00 automated sample liquid analysis system, wherein the *9 container is of course readily and economically disposable 0* 25 after but a single use, the container is preferably fabricated as an integral unit; bute for other and different applications of the container it is not beyond the scope of the apparatus and method of my invention that the ribs be fabricated separately from the container member(s) and simply emplaced thereon, or affixed thereto in any appropriate manner, prior to ntilization of the container.

In accordance with the teachings of the apparatus and method of my invention, it will be immediately clear to those skilled in this art that the level to which the liquid in the container is adjusted -as determined of course by 27 the level at which the sharp-cornered rib (s)-container surface junctures, and thus the provided capillary pathways for liquid flow out of the container, commence on the interior side wall of the container-- may as a practical matter be freely chosen in the fabrication of the container and ribs to range from a level immediately below the full capacity level of the container at the relevant container lip, to a level immediately above the container bottom. This advantageously provides wide latitude in the choice of that level in accordance with the relevant requi _enents of the particular application(s) to which the container is to be put; and, in all instances as representatively disclosed herein wherein that level is measureably below full container 15 capacity, provides the additionally significant advantage of inhibiting spillage and attendant reduction in that _level upon significant mechanical disturbance of the container, for example by incautious container handling, after that level has been assumed by the contained liquid.

20 Since the liquid flow rate(s) both out of and into the container in instances wherein the latter is relevant -in all applications of my invention will depend in large measure upon the number or ribs, thus of capillary pathways provided, the liquid "head" in question which 25 drives that liquid flow in each instance, and the respective lengths of the capillary pathways, it will be immediately clear to those skilled in this art that each of those parameters may be readily varied from those as representatively disclosed herein. Thus, for example, the container 10 of FIGS. 1 through 6 could include only one rib, or could alternatively include more than two of the same; while whatever number of ribs are provided need not extend completely to the container bottom 26. Too, <0

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28 although the liquid flow rate(s) will vary in accordance with those parameters specified, it may be understood that the capillary liquid flow, whicn commences immediately upon relevant surface wetting as described, is in reality quite rapid, thus providing for a representative total operational time for the apparatus and method of my invention of under seconds once "filling" of the container or liquid chamber, as the case may be, is completed.

Although representatively disclosed herein as applied to the containment of sample liquids for use in automated sample liquid analysis systems, it is clear that the apparatus and method of my invention are by no means limited to use with sample liquids, or to use in conjunction with liquid analysis systems.

15 Various changes may of course be made in the apparatus and method of my invention as disclosed herein without departing from the spirit and scope of that S' invention as defined in the appended claims.

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Claims (19)

1. A liquid container comprising self-levelling means operativ.ely associated with said container, said self-levelling means comprising capillary means operable in response to contact by liquid therewith within the container for causing the liquid to assume a predetermined level therein.

2. A liquid container as in claim 1, said self-levelling means further comprising means for flowing liquid out of said container.

3. A liquid container as in claim 1, said self-levelling means further comprising means for establishing said predetermined liquid level below the full liquid level of said container. 15 4. A liquid container as in claim 1, said self-levelling means further comprising means for forming a concave meniscus on the liquid in the container. A liquid container as in claim 1, said self-levelling means further comprising means for forming 20 a capillary pathway for liquid flow out of said container.

6. A liquid container as in claim 1, said self-levelling means being immovable relative to said container.

7. A liquid container as in claim 1, said 25 self-levelling means being integral with said container.

8. A liquid container as in claim 2 further comprising means operatively associated with said self-levelling means for collecting liquid flowed out of said container by said self-levelling means.

9. A liquid container as in claim 4 further comprising, means operatively associated with said container for disposing a predetermined volume of an immiscible isolation liquid on said concave liquid meniscus for retention thereon generally centrally of said concave liquid meniscus. A liquid container as in claim 5, wherein said capillary pathway for liquid flow out of said container S6 U U C C S S S S C* 30 extends contiguously from a level within said container essentially coincident with said predetermined liquid level to a level outside of said container which is below said predetermined liquid level.

11. A liquid container as in claim 5, said means for forming a capillary pathway for liquid flow out of said container comprising means for torming a sharp-cornered surface juncture with the surface of said container.

12. A liquid container as in claim 5, said means for forming a capillary pathway for liquid flow out of said container comprising means for forming a plurality of separate and distinct capillary pathways.

13. A liquid container as in claim 5, said container being formed of a material with which the liquid will 15 form a contact angle of less than 900.

14. A liquid container as in claim 5, wherein the liquid is essentially aqueous, said container being formed of a glass-filled plastics material.

15. A liquid container as in claim 5 wherein the liquid 20 is essentially aqueous, said container being formed of a plastics material to which a. surfactant has been added to raise the surface energy thereof.

16. A liquid container as in claim 5 wherein the liquid is essentially aqueous, said container being formed of a plastic material which has been plasma treated to raise the surface energy thereof.

17. A liquid container as in claim 5, wherein the liquid is essentially aqueous, said container being formed of glass.

18. A method for the containment of a liquid in a container comprising the steps of, flowing a liquid into a c-ntainer to contact capillary self-levelling means within said container, and causing said liquid to assume a predetermined level within said container in response to contact thereby with said capillary self-levelling means. y 19. A method as in claim 18, wherein the step of UJ u( NAli 31 causing said liquid to assume a predetermined level within said container comprises the flowing of liquid out of said container. A method as in claim 18, wherein said predetermined level is below the full liquid level of said container.

21. A method as in claim 18, further comprising the step of forming a concave meniscus on said liquid.

22. A method as in claim 19, further comprising the step of collecting the liquid flowed out of said container.

23. A method as in claim 19, wherein the step of flowing liquid out of said container comprises flowing

606. the liquid by capillary action. S.24. A method as in claim 19, wherein the step of 15 flowing liquid out of sa4d container comprises flowing the liquid to a level outside of said container which is s ee below said predetermined liquid level. A methcd as in claim 21, further comprising the step of disposing a predetermined volume of an immiscible liquid on said concave liquid meniscus for retention thereon centrally of said concave liquid meniscus. *66666 26. A method as in claim 23, wherein the step of flowing liquid by capillary action comprises providing a t: 5: capillary pathway which extends contiguously from a level 25 within said container essentially coincident with said predetermined liquid level %o a level outside of said container which is below said predetermined liquid level, and flowing liquid along the thusly provided capillary pathway. 27. A method as in claim 23, wherein the provision of said capillary pathway comprises forming sharp-cornered surface junctures between the surfaces of said self-levelling means and said container. 28. A liquid container as defined in any one of claims 1 to 17 comprising means operatively associated with said container and operable in response to contact by liquid therewith within the container for causing the liquid to 4 4' 4 32 form a concave meniscus within the container, said meniscus formation means comprising means for forming a capillary pathway for liquid flow thereinto by capillary action. 29. A liquid container as in claim 28, said means for forming a capillary pathway comprising means for forming a sharp-cornered surface juncture with the surface of said container. A liquid container as in claim 28, said means for forming a capillary pathway comprising means for forming a plurality of separate and distinct capillary pathways. 31. A liquid container as in claim 28, further comprising means operatively associated with said container for disposing a predetermined volume of an immescible isolation liquid on said concave meniscus for retention thereon generally centrally of said concave liquid meniscus. 32. A method for the containment of a liquid in a container as defined in any one of claims 18 to 27 comprising the steps of flowing a liquid into a container to contact a capillary pathway therewithin, and flowing liquid into said capillary pathway by capillary action to cause the liquid to form a concave meniscus within the container. 33. A method as in claim 32, further comprising the steps of concomitantly flowing liquid into a plurality of said capillary pathways to form said concave liquid meniscus. 34. A method as in claim 32, further comprising the steps of disposing a predetermined volume of an immiscible isolation liquid on said concave liquid meniscus for support thereon generally centrally of said concave liquid meniscus. A liquid container comprising self-levelling means operatively associated with said container substantially as herein described with reference to the accompanying Figures. ?,AL Z leN 33 36. A method for the containment of a liquid in a container substantially as herein described with reference to the accompanying Figures. DATED this 18th day of NOVEMBER 1993 MILES INC. Attorney: PETER HEATHCOTE Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS *a *e