CN117412813A - Liquid storage cavity - Google Patents

Abstract

Embodiments described herein relate to a liquid storage chamber, comprising: a base; one or more walls extending from the base, wherein the reservoir has a volume defined by the base and the one or more walls; and a perimeter at which the one or more walls are joined to the base, wherein at least a portion of the perimeter includes a perimeter recess defined by the base and at least one of the one or more walls, wherein the perimeter recess is configured to hold a volume of liquid.

Description

Liquid storage cavity

Technical Field

The present disclosure relates to a reservoir, such as a reservoir capsule or chamber.

Background

Point-of-care diagnostic devices may include chambers, such as chambers and/or capsules, for storing liquids used in diagnostic tests. For example, capsules may be used to store reagents used in certain diagnostic tests. As another example, a mixing chamber may be implemented to allow mixing of solutions (e.g., dilution of a sample). Such chambers and/or capsules typically comprise an outlet, allowing liquid to be transferred to different parts of the device. For example, the solution may be transferred to a flow cell where electrochemical measurements are performed.

Inevitably, the chambers and/or capsules used in the diagnostic device contain a certain amount of air. Thus, there is a risk that the liquid flowing through the outlet of the chamber/capsule may contain one or more bubbles. Bubbles are undesirable in an instant diagnostic device because they can interfere with measurements performed on the solution in the flow cell. For example, if a bubble is located on one of the electrodes within the flow cell, the electrochemical measurement may provide an incorrect reading.

Accordingly, there is a need for an improved reservoir that reduces or prevents bubbles in the liquid exiting the chamber.

By preventing bubbles in the liquid flow or reducing bubbles in the liquid flow, a greater proportion of the liquid in the cavity can be removed before the bubbles are formed. This means that smaller reservoirs (chambers, capsules, etc.) can be implemented when a given amount of liquid is required. This is beneficial because the actual footprint of the point-of-care diagnostic device is often limited.

Disclosure of Invention

This summary introduces concepts that are described in more detail in the detailed description. It should not be used to determine the essential features of the claimed subject matter, nor should it be used to limit the scope of the claimed subject matter.

According to one aspect of the present disclosure, there is provided a liquid storage chamber comprising: a base; one or more walls extending from the base, wherein the reservoir has a volume defined by the base and the one or more walls; and a perimeter at which the one or more walls are joined to the base, wherein at least a portion of the perimeter includes a perimeter recess defined by the base and at least one of the one or more walls. Wherein the peripheral recess is configured to accommodate a liquid volume.

The volume of liquid contained within the elongate peripheral recess provides a continuous fluid path around the periphery of the cavity (or a portion thereof). This means that liquid can be pumped from the elongated peripheral recess to the outlet of the chamber as long as a liquid bridge can be established between the outlet and the elongated peripheral recess. This allows the liquid to continuously flow out of the outlet of the chamber without introducing bubbles in the liquid stream.

At least one of the one or more walls may extend outwardly from the interior of the reservoir to define a peripheral recess. At least one of the one or more walls may comprise: a first wall portion and a second wall portion, wherein the first wall portion extends between the base portion and the second wall portion around the portion of the perimeter, wherein the second wall portion extends from the first wall portion in a direction away from the base portion.

The first wall portion may define a rounded corner between the second wall portion and the base portion. The radius of the fillet defined by the first wall portion may be between 0.15mm and 1 mm. The radius of the fillet is suitable for certain liquids, maintaining a continuous supply of liquid in the peripheral recess (without breaking the liquid in the peripheral recess) and without retaining too much liquid in the peripheral recess after the reservoir is emptied. Preferably, the radius of the fillet defined by the first wall portion may be between 0.2mm and 0.6 mm.

The first wall portion may extend at an acute angle between the base portion and the second wall portion such that the peripheral recess has a triangular cross-section. The acute angle between the first wall portion and the base portion may be less than or equal to 45 degrees. The first wall portion may extend laterally beyond the junction between the first wall portion and the second wall portion by a distance of less than or equal to 0.5mm. These limitations on the angle and distance of the first wall portion apply to certain liquids, maintaining a continuous supply of liquid within the peripheral recess (without breaking the liquid within the peripheral recess) while not retaining too much liquid within the peripheral recess after the reservoir is emptied.

The first wall portion may include a first portion and a second portion. Wherein the first portion of the first wall portion is joined to the second wall portion and extends outwardly from the interior of the reservoir in a direction generally parallel to the base. The second portion of the first wall portion extends between the first portion and the base such that the elongated recess has a quadrilateral cross section. The first portion of the first wall portion may have a width of less than or equal to 0.5mm. The second portion of the second wall portion may have a height of less than or equal to 0.5mm. These limitations on the angle and distance of the first wall portion apply to certain liquids, maintaining a continuous supply of liquid within the peripheral recess (without breaking the liquid within the peripheral recess) while not retaining too much liquid within the peripheral recess after the reservoir is emptied.

The reservoir may be a capsule. The height of the liquid storage cavity can be less than or equal to 5mm. The height of the chamber is such that a column of liquid is formed between the upper and lower inner surfaces of the chamber, which increases the volume of bubble-free liquid that can be evacuated from the chamber when the chamber is inverted (i.e. its outlet is located at the top surface of the chamber). Preferably, the height of the reservoir may be less than or equal to 3.5mm.

The angle between the second wall portion and the base portion may be less than 55 degrees. This reduces pooling of liquid and droplet formation within the chamber when the chamber is evacuated in an inverted orientation. The second wall portion may define an upper surface of the cavity that is non-parallel to the base. This further reduces the tendency for liquid pooling or droplet formation during inverted drain. The width of the cavity may not exceed 2.5 times the height of the cavity.

The second wall portion may extend away from the base portion in a direction substantially perpendicular to the base portion. This maximizes the volume of the cavity for a given space occupation of the cavity.

The peripheral recess may extend around the entire periphery of the reservoir. This allows liquid to be pumped into the peripheral recess around any part of the periphery of the cavity.

The reservoir may further comprise an outlet in the base. The outlet coincides with the portion of the perimeter. Providing an outlet coincident with the perimeter means that no liquid bridge is required between the outlet and the perimeter to withdraw liquid from the chamber.

According to another aspect of the present disclosure, there is provided a method of removing liquid from a liquid storage chamber, the method comprising: providing a reservoir according to the first aspect; an inlet of the liquid storage cavity and an outlet of the liquid storage cavity are arranged in the base part of the liquid storage cavity; orienting the reservoir such that the outlet is positioned on a top side of the reservoir; and supplying gas via the inlet to expel liquid from the outlet.

The peripheral recess of the reservoir allows the reservoir to be emptied even when the reservoir is in an inverted configuration (i.e., when the outlet is positioned on the top side of the reservoir).

Providing an outlet in the base of the reservoir may include providing a reservoir comprising an outlet in the base. Alternatively, providing the outlet in the base of the reservoir may comprise forming the outlet in the base of the reservoir.

Drawings

The specific embodiments are described below, by way of example only, with reference to the accompanying drawings, in which:

fig. 1A is a schematic cross-sectional view of a reservoir having a peripheral recess, wherein the reservoir is in the process of being emptied.

Fig. 1B is a schematic cross-sectional view along the reservoir of fig. 1A after being emptied.

Fig. 2A is an isometric view of a reservoir capsule.

Fig. 2B is a top view of the reservoir capsule shown in fig. 2A.

Fig. 2C is a side view of the reservoir capsule shown in fig. 2A.

Fig. 2D is a simulation showing the liquid within the liquid storage capsule shown in fig. 2A.

Fig. 3A is a simulation showing an isometric view of the liquid remaining in the liquid storage capsule after a first period of time.

Fig. 3B is a top view of the simulation shown in fig. 3A.

Fig. 4A is a simulation showing an isometric view of the liquid remaining in the liquid storage capsule after a second period of time, simulated in fig. 3A.

Fig. 4B is a top view of the simulation shown in fig. 4A.

Fig. 4C is a cross-sectional view taken along line A-A in fig. 4B.

Fig. 4D is a cross-sectional view taken along line B-B in fig. 4B.

Fig. 5A is a simulation showing an isometric view of the liquid remaining in the liquid storage capsule after a third period of time, simulated in fig. 3A.

Fig. 5B is a cross-sectional view taken along line A-A in fig. 4B after a third period of time.

Fig. 5C is a cross-sectional view taken along line B-B in fig. 4B after a third period of time.

Fig. 6A is a simulation showing an isometric view of the volume of liquid within the chamber after a first period of time.

Fig. 6B is a top view of the simulation shown in fig. 6A.

Fig. 6C is a cross-sectional view taken along line A-A in fig. 6B.

Fig. 7A is a simulation showing an isometric view of the liquid volume within the chamber after a second period of time, simulated in fig. 6A.

Fig. 7B is a cross-sectional view taken along line A-A in fig. 6B after the second period of time.

Fig. 8A to 8C each show a simulation result of the cross-sectional area of the liquid in the peripheral recess of the liquid storage chamber, wherein the peripheral recess is defined by rounded corners.

Fig. 9 is a cross-sectional view along a reservoir having a peripheral recess defined by a chamfer.

Fig. 10A to 10E each show a simulation result of the cross-sectional area of the liquid in the peripheral recess of the liquid storage chamber, wherein the peripheral recess is defined by a chamfer.

Fig. 11 is a cross-sectional view along a reservoir having a peripheral recess defined by a step.

Fig. 12A to 12F each show a simulation result of the cross-sectional area of the liquid in the peripheral recess of the liquid storage chamber, wherein the peripheral recess is defined by a step.

Fig. 13A is a cross-sectional view of a reservoir with an outlet at the top of the reservoir.

Fig. 13B is a cross-sectional view of another reservoir with an outlet at the top of the reservoir.

Fig. 14A to 14C each show the simulation result of the cross-sectional area of the liquid in the peripheral recess of the liquid storage chamber having the outlet at the top of the liquid storage chamber.

Fig. 15A is a side view of a tool for deforming a reservoir capsule.

Fig. 15B is a cross-sectional view taken along line A-A in fig. 15A.

Fig. 16 is a flow chart of a method of removing liquid from a liquid storage chamber.

Detailed Description

Embodiments of the present disclosure are explained below with specific reference to liquid storage cavities such as capsules and chambers. However, it should be appreciated that the embodiments described herein are applicable to other types of cavities having a base and one or more walls. While the following examples are described as being particularly useful in point-of-care diagnostic devices, such as microfluidic devices, it should be appreciated that such examples are not limited to implementation in point-of-care diagnostic devices, and may be implemented in other applications in which liquid is stored in a chamber having an outlet.

Fig. 1A shows a reservoir 10 according to the present disclosure. In general, the reservoir 10 has a base 12 and one or more walls 20 (e.g., one wall for a cylindrical cavity, four walls for a cavity with a quadrilateral area, etc.). One or more walls 20 extend from the base 12. The reservoir 10 has a volume defined by a base 12 and one or more walls 20. The reservoir 10 also has a perimeter 30, the perimeter 30 being defined as the junction between one or more walls 20 and the bottom 12. At least a portion of the perimeter 30 (in some examples, the entire perimeter) includes a perimeter recess 32 defined by at least one of the one or more walls 20 and the base 12. The peripheral recess 32 is configured to accommodate a liquid volume 34 (e.g., as shown in fig. 1B).

In the example shown in fig. 1A, the wall 20 defining the peripheral recess 32 extends outwardly from the interior 14 of the reservoir 10, thereby defining a wedge-shaped or groove-shaped peripheral recess 32 extending laterally from the chamber 10.

To define the peripheral recess 32, the wall 20 of the reservoir 10 shown in fig. 1A includes a first wall portion 22 and a second wall portion 24. The dashed line in fig. 1A shows the interface between the first wall portion 22 and the second wall portion 24. Specifically, in the example shown in fig. 1A, the first wall portion 22 has a different curvature than the second wall portion 24. The first wall portion 22 extends between the base 12 and the second wall portion 24 around a portion of the perimeter 30 that includes a perimeter recess 32. In the example shown in fig. 1A, the first wall portion 22 defines a rounded corner 36 between the second wall portion 24 and the base portion 12. The second wall portion 24 extends from the first wall portion 22 in a direction away from the base portion 12.

The liquid volume 34 contained within the peripheral recess 32 provides a continuous fluid path around the periphery 30 (or a portion of the periphery 30) of the chamber 10. This means that liquid can be drawn from the peripheral recess 32 to the outlet 16 of the chamber 10 as long as a liquid bridge can be established between the outlet 16 and the peripheral recess 32 (unless the outlet 16 coincides with the periphery 30, in which case no liquid bridge is required). Drawing liquid from the peripheral recess 32 to the outlet 16 allows the liquid to continuously flow out of the outlet 16 of the chamber without introducing bubbles into the liquid flow.

Due to the surface tension effect of the solution and the wetting contact angle of the solution with the cavity wall 20 and the base 12, a continuous fluid path within the peripheral recess 32 is formed. This liquid volume 34 is drawn into the peripheral recess 32 by capillary action so that the free surface energy of the liquid within the chamber 10 is minimized. In particular, the geometry and dimensions of the peripheral recess 32 provide an energetically favorable condition for balancing liquid-solid surface energy and liquid-gas surface energy, and result in the formation of a continuous liquid "wedge" within the peripheral recess 32 (e.g., as shown in fig. 1B). This effect is observed whether the base of the chamber 10 is oriented downward (e.g., fig. 1A) or the base of the chamber 10 is oriented upside down such that the outlet is at the top of the chamber (e.g., fig. 13A).

Importantly, even when the cavity 10 is only partially filled, the continuous liquid volume 34 within the peripheral recess 32 is not interrupted during liquid flow out of the cavity 10. This means that the volume of liquid 34 retained within the peripheral recess 32 provides a continuous guide for liquid out of the chamber 10 during evacuation of the chamber 10. An advantageous surface energy balance may be utilized by pressurizing the chamber 10 to allow the liquid to continuously flow out of the chamber 10. For example, air may be injected into the cavity 10 through an inlet (not shown in FIG. 1A) to the cavity 10. In such examples, air cannot escape through the outlet 16 until the outlet 16 becomes unobstructed by the liquid. Thus, by injecting a corresponding volume of air into the chamber 10, the volume of liquid can be continuously evacuated from the chamber 10.

When pumping liquid from an almost empty chamber 10, the flow rate should be controlled to minimize the shearing effect on the liquid. If the shear force on the liquid is too high, the liquid volume 34 within the peripheral recess 32 will break, which means that the pressurization of the chamber 10 needs to be stopped to re-form the liquid bridge by capillary action. This is only a problem when the chamber 10 is almost empty, because for example a liquid bridge is present when the chamber is half full.

The peripheral recess 32 may take the following form: (i) rounded corners 36 (e.g., as shown in fig. 1A); (ii) A chamfer (e.g., as shown in fig. 9) providing a peripheral recess having a triangular cross-section; (iii) A step (e.g., as shown in fig. 11) that provides a peripheral recess having a quadrangular cross section; or (iv) combinations of the above.

Parameters for optimizing the dimensions of the peripheral recess 32 are described in more detail below. In general, it is preferred that the peripheral recess 32 be sized such that the steady state cross-sectional profile of the liquid volume 34 within the peripheral recess 32: (i) Large enough so that liquid can be pumped from any point along the peripheral recess 32 while maintaining a continuous supply of liquid from the other liquid volume within the cavity 10 into the peripheral recess 32; and (ii) small enough so that the volume of liquid 34 remaining in the peripheral recess 32 after the cavity 10 is emptied is not too large to minimize wastage of liquid. Waste of some volume of liquid is unavoidable because the liquid volume 34 will remain trapped in the peripheral recess 32 after the cavity is emptied. This is illustrated in fig. 1B, which shows the reservoir 10 in an empty state.

Fig. 2A to 2C show a reservoir in the form of a reservoir capsule 100, to which the peripheral recess shown in fig. 1A is applied. The reservoir capsule 100 may be implemented in a point-of-care diagnostic device such as a microfluidic cartridge that may be housed in an analyzer device.

The reservoir capsule 100 includes three parts: an inlet chamber 102, a reservoir chamber 104, and an outlet chamber 106. These portions of the reservoir capsule 100 are defined by the base 112 (shown in fig. 2C) of the reservoir capsule 120 and the continuous wall 120. The junction between wall 120 and base 112 defines a perimeter 130 (also shown in fig. 2C) of reservoir capsule 100.

The upper surfaces of both the inlet chamber 102 and the outlet chamber 106 may be deformed by an applied downward force (e.g., by an actuator of an analysis device in which a microfluidic cartridge comprising the reservoir capsule 100 is housed). The downward force applied to the inlet chamber 102 and the outlet chamber 106 deforms the material of the inlet chamber 102 and the outlet chamber 106 such that the material is forced into contact with the base 112. Continued application of downward force ruptures the base 112 below the inlet and outlet chambers 102, 106, forming the inlet and outlet ports 118, 116 (as shown in fig. 2D). It will be appreciated that the inlet 118 and outlet 116 may be formed in other ways, such as by actuating a piercing element disposed below the inlet chamber 102 and outlet chamber 106.

The wall 120 of the reservoir capsule 100 includes a first wall portion 122 and a second wall portion 124. First wall portion 122 extends around a perimeter 130 of reservoir capsule 100 between base 112 and second wall portion 124. The second wall portion 124 extends from the first wall portion 122 away from the base 112. In this example, the second wall portion 124 extends away from the first wall portion 122 to define an upper surface of the reservoir capsule 100.

The first wall portion 122 provides a rounded corner 136 between the base 112 and the second wall portion 124. Thus, rounded corners 136 define a peripheral recess 132 (best shown in fig. 2C) extending around periphery 130 of reservoir capsule 100 such that the peripheral recess is disposed at the bottom of inlet chamber 102, reservoir 104, and outlet chamber 106.

Liquid is drawn into the peripheral recess by capillary action, forming an annular liquid volume 134 around the edges of the outlet chamber 106 and the inlet chamber 102, as shown in fig. 2D. For example, as long as a liquid bridge is provided between the liquid volume 134 within the peripheral recess and the outlet 116, the liquid volume 134 provides a continuous path for liquid exiting the reservoir capsule 100 through the outlet 116 of the capsule when air is supplied via the inlet 118 of the capsule.

Fig. 3A and 3B are isometric and top views of a simulation of the volume of liquid remaining within a liquid storage capsule having a geometry similar to liquid storage capsule 100 shown in fig. 2A-2C. Although there are minor differences in the geometry of the reservoir capsule shown in fig. 2A-2C and fig. 3A and 3B (e.g., dimples in the inlet and outlet chambers), the same reference numerals will be used for convenience. The simulations in fig. 3A and 3B show the remaining liquid volume after a first period of time during the emptying of the reservoir capsule 100. Fig. 3A and 3B show a liquid bridge 140 extending between the liquid volume 134 in the peripheral recess 132 and the inlet 118 and outlet 116 of the capsule (centered within the inlet chamber 102 and outlet chamber 106, respectively).

Fig. 4A-4D show the remaining liquid volume after the second period of time (i.e., later during the draining operation). As shown in fig. 4A-4D, a majority of the liquid has been emptied from the reservoir 104. However, peripheral recess 132 still contains liquid volume 134, and liquid bridge 140 between liquid volume 134 and inlet 118 and outlet 116 remains (as best shown in fig. 4C and 4D), allowing continuous extraction of liquid from reservoir capsule 100.

Fig. 5A-5C show the remaining liquid volume after a third period of time (i.e., further later during the draining operation). As shown in fig. 5A-5C, a majority of the liquid has been emptied from the entire reservoir capsule 100. The liquid volume 134 within the peripheral recess 132 has been disconnected from the liquid bridge 140 between the inlet 118 and the outlet 116, which means that the continuous outflow of liquid from the reservoir capsule 100 has ended. That is, if no air bubbles are introduced between the extracted liquid and the remaining liquid, no more liquid can be extracted. Fig. 5A-5C illustrate the volume 134 of liquid remaining in the peripheral recess 132 after the purging operation has ended.

Fig. 6A-6C show simulations of the volume of liquid remaining in an alternative liquid storage chamber. In particular, the reservoir chamber simulated in fig. 6A-6C is a cylindrical chamber 200 (shown only in outline), which cylindrical chamber 200 may be implemented, for example, as a mixing chamber. The chamber 200 includes a base 212 and a continuous sidewall 220 joined at a perimeter 230 of the chamber 200. The second wall portion 224 of the continuous side wall 220 extends perpendicular to the base 212 such that the chamber 200 has a vertical wall. A peripheral groove 232 extends around the periphery 230 and is configured to receive a liquid volume 234.

The chamber 200 includes an outlet 216, the outlet 216 providing an opening in a perimeter 230 of the chamber 200. This means that unlike the examples shown in fig. 2A-2D, the outlet 216 coincides with the perimeter 230. The coincidence of the outlet 216 with the perimeter 230 means that no liquid bridge is required between the outlet and the perimeter to draw liquid from the chamber 200. The outlet 216 is connected to the channel 242. The chamber 200 also includes an inlet (not shown) which may be disposed, for example, at an upper extent of the sidewall 220.

Fig. 6A-6C illustrate the remaining liquid volume after a first period of time during which the chamber 200 is evacuated. The liquid volume 234 within the peripheral recess 232 can be clearly seen. This liquid volume is connected to liquid drawn through outlet 216.

Fig. 7A and 7B show the remaining liquid volume after the second period of time (i.e., later in the draining operation). As shown in fig. 7A-7B, most of the liquid has been emptied from the chamber 200. A volume of air is shown in the channel 242 connected to the outlet 216, which means that no more liquid can be extracted if no air bubbles are introduced between the already extracted liquid and the remaining liquid. Fig. 7A and 7B illustrate the volume 234 of liquid remaining in the peripheral recess 232 after the evacuation operation is completed.

The parameters defining the geometry of the fillet 36 will now be described with reference to fig. 8A-8C. Preferably, the geometry of the fillet 36 is optimized such that the cross-sectional profile of the liquid volume 34 within the peripheral recess 32 is not below the threshold cross-sectional area. A threshold is implemented to ensure that the liquid volume 34 within the peripheral recess 32 does not break. Disconnection of the liquid volume 34 will result in insufficient liquid volume 34 to draw liquid into the peripheral recess 32. Thus, the threshold ensures that liquid can be pumped from any point along the peripheral recess 32 while maintaining a continuous supply of liquid from other liquid volumes within the chamber 10. The threshold cross-sectional area may be determined based on properties of the liquid such as viscosity, surface tension, and contact angle.

As an example of a suitable liquid having a viscosity of between 0.005 pa.s and 0.015 pa.s, a surface tension of between 0.01N/m and 0.06N/m, and a wetting contact angle with the cavity wall/base of between 5 degrees and 40 degrees, the threshold cross-sectional area is 0.06mm ² . To achieve 0.06mm ² A corner radius of at least 0.15mm is required.

It is also desirable to keep the liquid volume 34 retained within the peripheral recess 32 below an upper limit. This is because after the cavity 10 is emptied, the liquid volume 34 remains within the peripheral recess 32, which means that the remaining liquid volume 34 cannot be extracted from the cavity 10. The upper limit will depend on the threshold cross-sectional area for a particular liquid.

Continuing with the example of certain liquids having viscosities between 0.005 Pa-s and 0.015 Pa-s, surface tensions between 0.01N/m and 0.06N/m, and wetting contact angles with the cavity wall/base between 5 degrees and 40 degrees, the fillet radius is preferably no greater than 1mm. The preferred range of corner radii for such liquids is between 0.2mm and 0.6 mm.

Fig. 8A-8C are simulations of the volume of liquid remaining in a peripheral recess having a different fillet radius. Simulations were performed using the following properties of the liquid: the viscosity was 0.005 Pa.s, the surface tension was 0.018175N/m, and the wetting contact angle was 20 degrees. Fig. 8A is a simulation of a cavity with a corner radius of 0.6 mm. When the fillet radius is 0.6mm, the cross-sectional area of the liquid in the peripheral concave portion is 0.11mm ² . Fig. 8B is a simulation of a cavity with a corner radius of 0.4 mm. When the fillet radius is 0.4mm, the cross-sectional area of the liquid in the peripheral concave portion is 0.082mm ² . Fig. 8C is a simulation of a cavity with a corner radius of 0.2 mm. With a fillet radius of 0.2mm, the cross-sectional area of the liquid in the peripheral recess is 0.063mm ² 。

The table in appendix 1 shows the cross-sectional area of liquid volume 34 within peripheral recess 32 for other combinations of liquid properties. These liquid properties include the direction of gravity. This feature is considered because the peripheral recess 32 may facilitate evacuation of the "inverted" cavity (i.e., the outlet 16 is located at the top of the cavity 10). The bubble free liquid volume emptied from the liquid storage chamber 10 is maximized if the chamber has a sufficiently shallow depth (e.g. no more than 5 mm) such that a vertical column of liquid is provided between the upper and lower inner surfaces of the liquid storage chamber 10 due to the surface tension of the liquid overcoming the gravitational force to which the liquid is subjected. In the table of appendix 1, the direction of gravity "1" indicates that outlet 16 is located at the bottom of chamber 10, while the direction of gravity "-1" indicates that outlet 16 is located at the top of chamber 10.

Fig. 9 shows an alternative reservoir 300 in which a first wall portion 322 extends at an acute angle between a base portion 312 and a second wall portion 324. This means that the first wall portion 322 provides a chamfer 344 between the base 312 and the second wall portion 324. Thus, the peripheral recess 332 has a triangular cross-section.

The geometry of chamfer 344 may be defined by two properties: the chamfer depth and chamfer angle, both of which are schematically shown in fig. 9. The chamfer depth is the lateral distance between the junction between the first wall portion 322 and the second wall portion 324 and the maximum laterally outward extension of the chamfer 344 (in other words, how far the chamfer 344 extends laterally from the junction with the second wall portion 324). The chamfer angle is the angle between the first wall portion 322 and the base 312.

Chamfer 344 retains liquid in the same manner as fillet 36 described above. If chamfer 344 is too large, a large volume of liquid is retained in peripheral recess 332, meaning that a proportion of the liquid within chamber 300 is lost. However, as with fillet 36, the cross-sectional area of liquid volume 334 within peripheral recess 332 is preferably at least a threshold.

For example, as in the example given above, the threshold cross-sectional area may be 0.06mm ² . To achieve this threshold, the chamfer depth should be at least 0.2mm and the chamfer angle should be at least 20 degrees. To prevent a large liquid volume from remaining in the elongated peripheral recess 332 after evacuation, the chamfer depth should be no greater than 0.5mm and/or the chamfer angle should be no greater than 45 degrees.

Fig. 10A-10E are simulations of the volume of liquid remaining in a peripheral recess having a different chamfer geometry. Simulation was performed using the following properties: the dynamic viscosity was 0.01 Pa.s, the surface tension was 0.054N/m, the wetting contact angle was 15 degrees, and the specific gravity was 1.02. Gravity is in the direction of the arrow shown in fig. 10A to 10E. Another parameter that varies in these simulations is the angle of the second wall portion 322 relative to the base portion 312. The second wall portion having an angle of 90 degrees (fig. 10A and 10B), the second wall portion having an angle of 60 degrees (fig. 10C and 10D), and the second wall portion having an angle of 30 degrees (fig. 10E) are simulated.

Fig. 10A is a simulation of a cavity with a chamfer depth of 0.25mm, a chamfer angle of 45 degrees, and an angle of 90 degrees for the second wall portion (i.e., such that the second wall portion 324 extends substantially perpendicular to the base 312). In the case of this cavity and chamfer geometry, the cross-sectional area of the liquid in the peripheral recess is 0.220mm ² . Fig. 10B is a simulation of a cavity with a chamfer depth of 0.75mm, a chamfer angle of 45 degrees and an angle of 90 degrees for the second wall. In the case of this cavity and chamfer geometry, the cross-sectional area of the liquid in the peripheral recess is 0.268mm ² . Fig. 10C is a simulation of a cavity with a chamfer depth of 0.75mm, a chamfer angle of 30 degrees and an angle of 60 degrees for the second wall. In the case of this cavity and chamfer geometry, the cross-sectional area of the liquid in the peripheral recess is 0.249mm ² . Fig. 10D is a simulation of a cavity with a chamfer depth of 1.125mm, a chamfer angle of 30 degrees and an angle of 60 degrees for the second wall. In the case of this cavity and chamfer geometry, the cross-sectional area of the liquid in the peripheral recess is 0.276mm ² . Fig. 10E is a simulation of a cavity with a chamfer depth of 0.937mm, a chamfer angle of 27.5 degrees and an angle of 30 degrees for the second wall. In the case of this cavity and chamfer geometry, the cross-sectional area of the liquid in the peripheral recess is 0.253mm ² 。

Fig. 11 shows another alternative reservoir 400, wherein the first wall portion 422 defines a peripheral recess 432 in the form of a step 446. Specifically, the first wall portion 422 includes a first portion 426, the first portion 426 being joined to the second wall portion 424 and extending outwardly from the second wall portion 424 (i.e., outwardly from the interior 414 of the reservoir 400). The first wall portion 422 also includes a second portion 428 that extends between the first portion 426 and the base 412. This means that the first portion 426 and the second portion 428 of the first wall portion 422 define a quadrilateral (e.g., square, rectangular, trapezoidal) cross-section of the peripheral recess 432.

The geometry of the step 446 may be defined by two properties: the width of the step 446 (i.e., the length of the first portion 426 of the first wall portion 422), and the height of the step 446 (i.e., the length of the second portion 428 of the first wall portion 422). These two properties are schematically shown in fig. 11.

The step 446 retains liquid in the same manner as the fillet 36 and chamfer 334 described above. If the step 446 is too large, a large volume of liquid is retained in the peripheral recess 432, meaning that a proportion of the liquid within the cavity 400 is lost. However, as with fillet 36, the cross-sectional area of liquid volume 434 within peripheral recess 432 is preferably at least a threshold.

For example, the threshold cross-sectional area may be 0.06mm ² As in the example given above. To achieve this threshold, the width of the step should be at least 0.2mm and the height of the step should be at least 0.2mm. To prevent a large liquid volume from remaining in the elongated peripheral recess 332 after evacuation, the width of the step should not be greater than 0.5mm and/or the height of the step should not be greater than 0.5mm.

Fig. 12A to 12F are simulations of the liquid volume remaining in the peripheral recess of the step having a different geometry. Simulation was performed using the following properties: the dynamic viscosity was 0.01 Pa.s, the surface tension was 0.054N/m, the wetting contact angle was 15 degrees, and the specific gravity was 1.02. Gravity is in the direction of the arrow shown in fig. 12A to 12F. Another parameter that varies in these simulations is the angle of the second wall 422 relative to the base 412. The second wall portion having an angle of 60 degrees (fig. 12A to 12E) and the second wall portion having an angle of 30 degrees (fig. 12F) are simulated. Another parameter that varies in these simulations is the height of the cavity 400. Cavities with a height of 2.5mm (fig. 12A to 12D), 3mm (fig. 12E) and 2.75mm (fig. 12F) were simulated.

FIG. 12A is a view showing a step height of 0.25mm, a step width of 0.645mm, a cavity height of 2.5mm, and a second wall portionIs simulated for a cavity with an angle of 60 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.311mm ² . Fig. 12B is a simulation of a cavity with a step height of 0.375mm, a step width of 0.375mm, a cavity height of 2.5mm and a second wall angle of 60 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.228mm ² . Fig. 12C is a simulation of a cavity with a step height of 0.25mm, a step width of 0.39mm, a cavity height of 2.5mm, and a second wall angle of 60 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.250mm ² . Fig. 12D is a simulation of a cavity with a step height of 0.5mm, a step width of 0.785mm, a cavity height of 2.5mm, and a second wall angle of 60 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.238mm ² 。

Fig. 12E is a simulation of a cavity with a step height of 0.25mm, a step width of 0.39mm, and a second wall angle of 60 degrees (as in fig. 12C). However, the height of the cavity increases to 3mm. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.320mm ² . Fig. 12F is a simulation of a cavity having a step height of 0.25mm, a step width of 0.68mm, a cavity height of 2.75mm, and a second wall angle of 30 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.371mm ² 。

As described above, implementing the peripheral recess 32 allows the cavity to be emptied when the cavity (e.g., capsule) is "inverted" (i.e., the outlet 16 is located at the top of the cavity 10). The bubble free liquid volume emptied from the liquid storage chamber 10 is maximized if the chamber has a depth that is shallow enough (e.g., no more than 5 mm) such that a vertical column of liquid is provided between the upper and lower inner surfaces of the liquid storage chamber 10 due to the surface tension of the liquid overcoming the gravitational force to which the liquid is subjected.

Fig. 13A is an example of a reservoir 500, the top of the reservoir 500 having an outlet 516 (i.e., the base 512 is disposed upward, meaning that the reservoir 500 is inverted). To ensure that a liquid column is provided between the upper and lower surfaces, the height of the cavity (as shown in fig. 13B) should be less than 5mm, preferably less than 3.5mm, more preferably less than 3mm. Above 5mm, gravity will overcome the surface tension effect.

This orientation of the row of cavities 500 may result in the formation of droplets 548 at the bottom of the cavities 500, as shown in fig. 13A, which fig. 13A illustrates the cavities having second walls angled at 90 degrees. When the second wall is 60 degrees, the liquid also collects at the bottom of the chamber, as shown in fig. 13B. In order to minimize liquid pooling and drop formation, the angle of the second wall portion (schematically shown in fig. 13B) is preferably less than 55 degrees (e.g., as shown in fig. 14C).

Liquid pooling and droplet formation may also be minimized by ensuring that no flat surface is provided at the bottom of the cavity (e.g., as also shown in fig. 14C), or by providing a curved surface at the bottom of the cavity (e.g., as shown in fig. 2A-2D). In other words, liquid pooling and droplet formation is minimized when the second wall portion 524 defines an upper surface of the cavity 500 that is not parallel to the base.

If the outlet 516 is centrally located at the top of the chamber 500 (i.e., at the center of the perimeter 530 of the chamber 500), the width to height aspect ratio of the cross-section should not be greater than 5:2 (in other words, the width of the chamber should not be greater than 2.5 times the height of the chamber).

While fig. 13A and 13B illustrate an inverted evacuation of a cavity 500 having a stepped profile peripheral recess 532, it will be appreciated that a cavity having a peripheral recess defined by a chamfer and rounded corners may also be evacuated in this configuration, provided that the cavity is shallow enough so that a liquid column is formed between the upper and lower surfaces.

Fig. 14A-14E are simulations of the volume of liquid remaining in the peripheral recess when the chamber is evacuated using the outlet 516 at the top of the chamber 500. Simulation was performed using the following properties: dynamic viscosity of 0.01 Pa.s, surface tension of 0.054N/m, wetting contact angle of 15 degrees and specific gravity of 1.02. Gravity is in the direction of the arrow shown in fig. 14A to 14E. Another parameter that varies in these simulations is the angle of the second wall 522 with respect to the base 512. The second wall portion having an angle of 90 degrees (fig. 14A), the second wall portion having an angle of 60 degrees (fig. 14B), and the second wall portion having an angle of 30 degrees (fig. 14C) are simulated. Another parameter that varies in these simulations is the height of the cavity 500. Cavities with a height of 3mm (fig. 14A and 14B) and cavities with a height of 2.75mm (fig. 14C) were simulated.

Fig. 14A is a simulation of inverted evacuation of a cavity with a step height of 0.25mm, a step width of 0.25mm, a cavity height of 3mm and a second wall angle of 90 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.301mm ² . Fig. 14B is a simulation of inverted evacuation of a cavity with a step height of 0.25mm, a step width of 0.39mm, a cavity height of 3mm and a second wall angle of 60 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.314mm ² . Fig. 14C is a simulation of a cavity with a step height of 0.25mm, a step width of 0.68mm, a cavity height of 2.75mm, and a second wall angle of 30 degrees. In the case of the cavity and step geometry, the cross-sectional area of the liquid in the peripheral recess is 0.370mm ² 。

As described above, a liquid bridge is required between the peripheral recess 32 and the outlet 16 to ensure that liquid is drawn from the peripheral recess 32 during evacuation of the chamber 10. For centrally located outlets 16 (i.e., at the center of the perimeter 30), one way to provide a liquid bridge is to deform the cavity 10 such that a saddle 50 is provided between the perimeter 30 and the outlets 16 (as schematically shown in fig. 15A). The saddle 50 provides a path between the perimeter 30 and the outlet 16 along which the upper surface of the chamber 10 is recessed such that the distance between the upper and lower surfaces along the saddle 50 is less than in other areas of the chamber 10. This provides a path for liquid flow between the perimeter 30 and the outlet 16 because the surface tension of the liquid keeps the liquid along the path defined by the saddle 50.

To deform the cavity 10 to provide the saddle 50, an actuator 52 having a ridge 54 may be used when deforming the cavity 10 to form the inlet and outlet. The ridge 54 is visible from the cross-sectional view of the actuator 52 shown in fig. 15B. The actuator may be a component of an analysis device in which a microfluidic cartridge comprising the chamber 10 is housed.

Fig. 16 is a flow chart of a method 60 of removing liquid from a liquid storage chamber. It should be appreciated that the features of the method 60 do not have to be performed in the order depicted in fig. 16, and that certain steps may be performed in a different order. As one example, method feature 66 may be performed before method feature 64. Thus, the method 60 is not limited to the particular sequence depicted in FIG. 16 and described below.

At 62, a reservoir is provided. The reservoir may be any of the reservoirs described with reference to fig. 1A to 15A. For example, the reservoir may be a capsule (e.g., as shown in fig. 2A-2D), or a chamber (e.g., as shown in fig. 6A-6C). Other examples (e.g., tanks, channels, etc.) are also contemplated.

At 64, an inlet of the reservoir and an outlet of the reservoir are provided. Providing an outlet of the reservoir may include providing a reservoir with a permanent outlet (e.g., in the case of the chambers shown in fig. 6A-6C). Where the reservoir has a permanent outlet, providing the outlet may further comprise opening a valve in a liquid handling device in which the reservoir is implemented. Alternatively, providing the outlet of the reservoir may comprise forming the outlet of the reservoir. Forming the outlet may include deforming the reservoir cavity to cause the cavity material to rupture (e.g., as described with reference to fig. 2A-2D), or piercing the cavity using a piercing element.

Similarly, providing an inlet to a reservoir may include providing a reservoir with a permanent inlet, or forming an inlet to a reservoir (e.g., by rupturing, puncturing, or otherwise destroying the reservoir material).

At 66, the reservoir is oriented such that the outlet is positioned on a top side of the reservoir. As explained above, the reservoir may be oriented in this way before the inlet and outlet are provided in the reservoir. As one example, the reservoir may be implemented in the liquid handling device in this orientation. The liquid handling device may then be housed in an analysis device having an actuatable puncturing element. The cavity material may then be pierced by the piercing element of the analysis device.

At 68, gas is supplied via the inlet to expel liquid from the outlet. The gas may be supplied, for example, via a pneumatic actuator in fluid communication with the inlet. As one example, the inlet of the reservoir may be in fluid communication with a pneumatic port of a liquid handling device in which the reservoir is implemented. The liquid handling device may then be accommodated in an analysis device with a pneumatic supply system. Air may be supplied to the inlet by a pneumatic supply system of the analysis device via a pneumatic port of the liquid handling device.

The gas causes the liquid in the liquid storage chamber to leave. The liquid is drawn into the peripheral recess of the reservoir by capillary action. The liquid in the peripheral recess provides a continuous feed path from the other volume of the reservoir to the outlet, thereby maximising the volume of bubble free liquid discharged from the reservoir.

In some embodiments, the peripheral recess 32 may not extend around the entire periphery of the cavity 10. Further, a combination of stepped, chamfered, and rounded contours may be used to define the peripheral recess 32.

While the above discussion focuses on capsules and chambers as examples of cavities that may include peripheral recesses, peripheral recesses may also be included in other fluidic components (such as channels). When included in the channel, the peripheral recess facilitates liquid flow through the channel.

The singular terms "a," an, "and" the "are not to be construed as limiting the" one and only one. Rather, unless otherwise indicated, they should be construed as "at least one" or "one or more". The word "comprising" and its derivatives, including "comprising" and "contains", include each of the stated features, but do not exclude the inclusion of one or more further features.

The above embodiments have been described by way of example only, and the described embodiments are to be considered in all respects only as illustrative and not restrictive. It will be appreciated that variations may be made to the described embodiments without departing from the scope of the invention. It will also be apparent that there are many variations that have not been described yet, but which fall within the scope of the appended claims.

Accessory1: cross-sectional area of liquid retained in peripheral recess for different liquid properties and fillet radii

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Claims (22)

1. A reservoir, comprising:

a base;

one or more walls extending from the base, wherein the reservoir has a volume defined by the base and the one or more walls; and

a perimeter at which the one or more walls are joined to the base, wherein at least a portion of the perimeter comprises a perimeter recess defined by the base and at least one of the one or more walls, wherein the perimeter recess is configured to hold a liquid volume.

2. The reservoir of claim 1, wherein the at least one of the one or more walls extends outwardly from an interior of the reservoir to define the peripheral recess.

3. The reservoir of claim 1 or claim 2, wherein the at least one of the one or more walls comprises:

a first wall portion and a second wall portion, wherein the first wall portion extends between the base and the second wall portion around the portion of the perimeter;

wherein the second wall portion extends from the first wall portion in a direction away from the base portion.

4. A reservoir according to claim 3, wherein the first wall portion defines a rounded corner between the second wall portion and the base portion.

5. The reservoir of claim 4, wherein the radius of the rounded corner defined by the first wall portion is between 0.15mm and 1 mm.

6. A reservoir according to claim 5, wherein the radius of the fillet defined by the first wall portion is between 0.2mm and 0.6 mm.

7. A reservoir according to claim 3, wherein the first wall portion extends at an acute angle between the base portion and the second wall portion such that the peripheral recess has a triangular cross-section.

8. The reservoir of claim 7, wherein the acute angle between the first wall portion and the base portion is less than or equal to 45 degrees.

9. A reservoir according to claim 7 or claim 8, wherein the first wall portion extends laterally beyond the junction between the first and second wall portions by a distance of less than or equal to 0.5mm.

10. A reservoir according to claim 3, wherein the first wall portion comprises a first portion and a second portion,

wherein the first portion of the first wall portion is joined to the second wall portion and extends outwardly from the interior of the reservoir in a direction generally parallel to the base; and

the second portion of the first wall portion extends between the first portion and the base such that the elongate recess has a quadrilateral cross section.

11. The reservoir of claim 10, wherein the first portion of the first wall portion has a width of less than or equal to 0.5mm.

12. A reservoir according to claim 10 or claim 11, wherein the second portion of the second wall portion has a height of less than or equal to 0.5mm.

13. A reservoir according to any one of claims 3 to 12, wherein the reservoir is a capsule.

14. The reservoir of claim 13, wherein the height of the reservoir is less than or equal to 5mm.

15. The reservoir of claim 14, wherein the height of the reservoir is less than or equal to 3.5mm.

16. A reservoir according to any one of claims 3 to 15, wherein the second wall portion extends away from the base portion in a direction substantially perpendicular to the base portion.

17. A reservoir according to any one of claims 1 to 16, wherein the peripheral recess extends around the entire periphery of the reservoir.

18. The reservoir of any of claims 1-17, further comprising an outlet in the base.

19. A reservoir according to claim 18, wherein the outlet coincides with the portion of the perimeter.

20. A method of removing liquid from a liquid storage chamber, the method comprising:

providing a reservoir according to any one of claims 1 to 19;

an inlet of the liquid storage cavity and an outlet of the liquid storage cavity are arranged;

orienting the reservoir such that the outlet is positioned on a top side of the reservoir; and

a gas is supplied via the inlet to expel the liquid from the outlet.

21. The method of claim 20, wherein providing an outlet of the reservoir comprises providing a reservoir according to claim 18 or claim 19.

22. The method of claim 20, wherein providing an outlet of the reservoir comprises forming the outlet in the base of the reservoir.