Liquid control device and its use

Abstract

To provide a liquid control device for more efficiently controlling movement of a liquid, and its use.SOLUTION: A liquid control device includes a substrate 4, and a plurality of projections 10 that are inclined in a first direction X on a reference surface 6 of the substrate 4 and are arranged in the first direction X, in which the plurality of projections 10 each include an inclined surface 14 that is a surface inclined to the reference surface 6 at an obtuse angle and is directed to a second direction Y that is approximately opposite to the first direction X, and a back surface 16 directed to the first direction X on the back face side of the inclined surface 14, and have a shape extending in a third direction Z crossing the first direction X. The plurality of projections 10 are configured so as to impart anisotropy to a dynamic wet behavior of a liquid when the liquid to be controlled is brought into contact with the plurality of projections 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification relates to a liquid control device capable of controlling the movement of a liquid, such as maintaining and moving the liquid to any part, and its use.

Background Art

[0002] For example, a superhydrophilic coating can guide the movement direction of an aqueous liquid within the range where the aqueous liquid is in contact with the coating. However, when an excessive amount of liquid is in contact with the coating surface, it becomes impossible to control the movement direction. Also, for a superhydrophobic coating, by actively suppressing contact with an aqueous liquid, the aqueous liquid etc. will separate from the coating surface due to its own weight, making it impossible to control the movement direction.

[0003] Also, a flow path having protrusions mimicking the fine protrusions present on the legs of Ligia exotica has been reported as a device capable of controlling the flow rate of a fluid (Patent Document 1). In this device, a plurality of fine protrusions (10 μm to 100 μm long in the fluid flow direction) are erected along the fluid flow direction. And when a fluid comes into contact with these fine protrusions, a fluid flow is generated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the device of Patent Document 1, the protrusion size is small, there is a limit to the amount of liquid to be controlled, and its processing is also difficult. In its flow path structure, it is difficult to assume and process a specific structure for controlling the maintenance of liquid at an arbitrary part and the movement in an arbitrary direction, etc.

[0006] This specification provides a liquid control device capable of more efficiently controlling the movement of a liquid and its use.

Means for Solving the Problems

[0007] The inventor focused on the cuticles such as animal hair and body hair. The cuticle has a structure in which, for example, scale-like protrusions with a height of about 1 μm are erected in large numbers at intervals of about 20 μm and inclined toward the hair tip, covering the outer peripheral surface of the shaft portion from the hair root to the hair tip. As a result of the inventor's study, it was found that on such a cuticle surface, the vector of the surface tension of the liquid created by the anisotropic-shaped structure can be controlled to control the movement ability and movement direction of the liquid. This specification provides the following means based on such findings.

[0008] [1] A device for controlling the movement of a liquid, comprising: a substrate; a plurality of convex portions that are inclined in a first direction on a reference plane of the substrate and arranged along the first direction; the plurality of convex portions each include an inclined surface that is inclined at an obtuse angle with respect to the reference plane and points in a second direction that is substantially opposite to the first direction, and a back surface that points in the first direction on the back side of the inclined surface, and has a shape extending in a third direction intersecting the first direction; the plurality of convex portions are configured to impart anisotropy to the dynamic wetting behavior of the liquid when the liquid to be controlled comes into contact with the plurality of convex portions. [2] The device according to [1], wherein the plurality of convex portions are configured to direct the receding angle of the liquid in the first direction or the second direction when the liquid comes into contact with the plurality of convex portions. [3] The liquid is a liquid having a static contact angle of 70 degrees or less on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid comes into contact with the plurality of convex portions, the receding angle of the liquid is directed in the second direction, the device according to [1] or [2]. [4] The liquid is a liquid having a static contact angle of more than 70 degrees on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid comes into contact with the plurality of convex portions, the receding angle of the liquid is directed in the first direction, the device according to [1] or [2]. [5] The liquid is a liquid having a static contact angle of 70 degrees or less on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid to be controlled comes into contact with the plurality of convex portions, the falling angle of the liquid in the second direction is larger than the falling angle of the liquid in the first direction, the device according to [1] or [2]. [6] The liquid is a liquid having a static contact angle of more than 70 degrees on the surface of the substrate, and when it comes into contact with the plurality of convex portions, the falling angle of the liquid in the first direction is larger than the falling angle of the liquid in the second direction, the device according to [1] or [2]. [7] The plurality of convex portions are configured such that the falling angle of the liquid to be controlled increases in order in the third direction, the second direction, and the first direction, the device according to [1] or [2]. [8] The plurality of convex portions are configured to suppress the movement of the liquid to be controlled in the first direction, the device according to any one of [1] to [7]. [9] The plurality of convex portions are arranged substantially parallel along the first direction, and are a flaky body having a predetermined length extending in the third direction, a predetermined height, and an inclined surface inclined at the predetermined obtuse angle, the device according to any one of [1] to [8].

[10] The plurality of convex portions are arranged at substantially equal intervals along the first direction, the device according to [9].

[11] The height of the plurality of convex portions is 10 μm or more and 200 μm or less, and the interval of the plurality of convex portions along the first direction is 50 μm or more and 1000 μm or less. The device according to any one of [1] to

[10] .

[12] A method for treating a liquid, a substrate, and a plurality of convex portions arranged along the first direction while being inclined in the first direction on a reference surface of the substrate, the inclined surface being a surface that is inclined at an obtuse angle with respect to the reference surface and that faces a second direction which is substantially opposite to the first direction, and a back surface facing the first direction on the back side of the inclined surface, and using the plurality of convex portions having a shape extending in a third direction intersecting the first direction, by bringing a liquid to be controlled into contact with the plurality of convex portions to impart anisotropy to the dynamic wetting behavior of the liquid, a method for controlling the movement of the liquid.

[13] A flow path device, at least a part of a flow path includes a plurality of convex portions arranged along the first direction while being inclined in the first direction on a reference surface of a substrate, the plurality of convex portions each include an inclined surface that is inclined at an obtuse angle with respect to the reference surface and that faces a second direction which is substantially opposite to the first direction, and a back surface facing the first direction on the back side of the inclined surface, and have a shape extending in a third direction intersecting the first direction, the plurality of convex portions are configured to impart anisotropy to the dynamic wetting behavior of a liquid when the liquid supplied to the flow path comes into contact with the plurality of convex portions. A device.

[14] An evaluation device for the movement of a liquid, includes a plurality of convex portions arranged along the first direction while being inclined in the first direction on a reference surface of a substrate, the plurality of convex portions each include an inclined surface that is inclined at an obtuse angle with respect to the reference surface and that faces a second direction which is substantially opposite to the first direction, and a back surface facing the first direction on the back side of the inclined surface, and have a shape extending in a third direction intersecting the first direction, The device is configured such that when the liquid to be evaluated comes into contact with the plurality of convex portions, anisotropy is imparted to the dynamic wetting behavior of the liquid.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0010] The disclosure of this specification relates to a liquid control device capable of controlling the movement of a liquid and its use. According to the liquid control device disclosed in this specification (hereinafter, also simply referred to as "this device"), an anisotropy can be imparted to the dynamic wetting behavior of the liquid in contact with the convex portions by the arrangement structure of a plurality of convex portions having inclined surfaces inclined in a certain direction. In other words, such a plurality of convex portions can effectively impart a vector of surface tension with directionality to the liquid. Therefore, by appropriately adjusting the shape, size, and surface characteristics of these plurality of convex portions, it is possible to impart the type and amount of the liquid to be controlled and the vector of the surface tension to be imparted to the liquid, and to control the movement of the liquid.

[0011] In addition, by using this device, a liquid control method capable of controlling the movement of a liquid is also provided. Furthermore, this device can be used as a flow path device and also as an evaluation device for the movement of a liquid.

[0012] Hereinafter, this device and its use will be described in detail with reference to the drawings as appropriate.

[0013] (Device for Controlling the Movement of a Liquid) The device can include a plurality of convex portions that are inclined in a first direction on a reference plane and arranged along the first direction. An example of the device is shown in Fig. 1(a). Note that the example shown in Fig. 1(a) is just an example and does not limit the scope of the device. In Fig. 1, X means the first direction in which the plurality of convex portions are inclined, Y means the second direction that is substantially opposite to the first direction, and Z means the third direction in which the convex portions extend. The first direction X and the second direction Y are generally opposite directions, and the first direction X or the second direction Y and the third direction Z intersect and are generally perpendicular, but are not limited thereto.

[0014] As illustrated in Fig. 1(a), the device includes a plurality of convex portions 10 that are inclined in the first direction X on the reference plane 6 of the base body 4 and arranged along the first direction X. The convex portions 10 include an inclined surface 14 that forms an obtuse angle with the reference plane 6 and inclines in the first direction X and points in the second direction Y that is substantially opposite to the first direction X, and a back surface 16 that points in the first direction X on the back side of the inclined surface 14. By including the plurality of convex portions 10 having a shape extending in the third direction Z that intersects the first direction X, the movement of liquid in these three directions X, Y, and Z can be controlled. In particular, the mobility in the first direction X or the second direction Y can be controlled, and the mobility in the third direction Z can also be controlled. That is, anisotropy can be imparted to the dynamic wetting behavior of the liquid.

[0015] As shown in Fig. 1(a), the device 2 includes a plurality of convex portions 10. The device 2 is provided with each convex portion 10 standing on the reference plane 6 of the base body 4. The shape of the base body 4 is not particularly limited and can adopt any shape. For example, it can be a plate-like body, a sheet-like body, or a film-like body having an arbitrary planar shape, or for example, a plate-like body processed to have a curved surface, or for example, a columnar body or a rod-like body having an arbitrary cross-sectional shape, or for example, a hemispherical body, a spherical body, or a cylindrical body having an arbitrary curved surface, or for example, a three-dimensional shaped body having an arbitrary cavity and using the cavity surface as the reference plane 6.

[0016] At least a part of the base body 4 is the reference surface 6, and the reference surface itself may be not only an arbitrary plane but also a curved surface, and in addition to the outer surface, in the case of a hollow body, it may be its inner surface. Further, the reference surface 6 may be substantially the whole of a part of the base body 4, or may be provided with an arbitrary pattern. Further, the reference surface 6 may be configured to be inclined with respect to any one or two or more of the first direction X, the second direction Y, and the third direction Z.

[0017] The material of the base body 4 is not particularly limited and is appropriately selected according to the liquid to be controlled, the type (maintenance, movement) and amount of its movement, etc. Generally, as the material of the base body 4, a known water-repellent material or super water-repellent material such as polydimethylsilicone is used in order to improve the mobility of the liquid. These materials are well known to those skilled in the art, and those skilled in the art can appropriately select them as necessary.

[0018] Further, the base body 4 may be surface-treated on its reference surface 6 or convex portions 10. The surface treatment may be a coating layer or a treatment such as roughening. It is appropriately selected as necessary.

[0019] The plurality of convex portions 10 are provided with respect to the reference surface 6. The convex portions 10 may be made of the same material as the base body 4 or may be made of a different material. For example, the convex portions 10 may be formed by molding the material of the base body 4, or by subjecting the base body 4 to cutting, chemical treatment, corrosion processing such as various etching, etc., or may be separately provided on the base body 4.

[0020] The convex portion 10 can include an inclined surface 14 that forms an obtuse angle with respect to the reference surface 6 and points in the second direction Y that is substantially opposite to the first direction X, and a back surface 16 that points in the first direction X on the back side of the inclined surface 14. Further, the convex portion 10 can have a shape extending in the third direction Z that intersects the first direction X.

[0021] The convex portion 10 only needs to have an inclined surface 14 and a back surface 16, and have a shape extending in the Z direction respectively. Therefore, the convex portion 10 can be a flaky body as shown in Fig. 1(a), or can also be a columnar body or the like that forms a triangular cross-section with the inclined surface 14, the back surface 16, and the interface where the convex portion 10 contacts the base body 4.

[0022] The inclined surface 14 is inclined at an obtuse angle a with respect to the reference surface 6. The angular range of the obtuse angle a formed by the inclined surface 14 and the reference surface 6 is appropriately set according to the type and amount of the liquid to be controlled, the movement to be controlled, etc. For example, it is 100° or more, and for example, it is 110° or more, and for example, it is 120° or more, and for example, it is 130° or more, and for example, it is 135° or more, and for example, it is 140° or more. Also, the obtuse angle is, for example, 170° or less, and for example, it is 160° or less, and for example, it is 150° or less, and for example, it is 145° or less. Also, the suitable range of the obtuse angle a can be set by appropriately combining these various lower and upper limits. For example, it is 110° or more and 170° or less, and for example, it is 120° or more and 160° or less, and for example, it is 130° or more and 150° or less.

[0023] The back surface 16 can be provided at an arbitrary angle b with respect to the reference surface 6. The angle b can be any angle, but is set according to the type of liquid to be controlled, the movement of the liquid to be obtained, etc. For example, when the convex portion 10 is in the form of a thin sheet or the like, it is generally an acute angle, and for example, when the convex portion 10 is a columnar body, it is a right angle or an obtuse angle. The angle b is configured such that, for example, the sum with the above-mentioned obtuse angle a is 180°. For example, when the convex portion 10 is a flat plate-like body having substantially the same thickness, its inclination angle may be described by the angle b. The inclination angle is, for example, 20° or more, and for example, 25° or more, and for example, 30° or more, and for example, 35° or more, and for example, 40° or more, and for example, 45° or more, and for example, 50° or more, and for example, 55° or more, and for example, 60° or more, and for example, 70° or more, and for example, 75° or more, and for example, 80° or more. Also, the inclination angle is, for example, 90° or less, and for example, 85° or less, and for example, 75° or less, and for example, 70° or less, and for example, 65° or less, and for example, 60° or less, and for example, 45° or less, etc. The range of the inclination angle can be appropriately selected and set from these lower and upper limits, but typically it is 20° or more and 80° or less, and for example, 25° or more and 60° or less, and for example, 30° or more and 60° or less, and for example, 30° or more and 45° or less.

[0024] The larger the inclination angle of the convex portion 10 (here, assuming that angle a + angle b is about 180°, it is described by angle b), the more likely the liquid repellency of the liquid is to improve, and the more likely the anisotropy of the movement of the liquid is to decrease. By appropriately setting the inclination angle of the convex portion 10, it is possible to maintain the liquid to be controlled at a specific site, or to design it to move in a specific direction.

[0025] The height of the convex portion 10 is not particularly limited and is set according to, for example, the surface composition of the base material 4, the magnitude of the surface tension of the base material 4, the type of liquid to be controlled, the movement and amount of the liquid to be obtained, etc. For example, the height of the convex portion 10 is 50 μm or more and 500 μm or less, and for example, 10 μm or more and 300 μm or less, and for example, 10 μm or more and 200 μm or less, and for example, 10 μm or more and 100 μm or less, and for example, 20 μm or more and 100 μm or less, and for example, 20 μm or more and 60 μm or less, and for example, 20 μm or more and 40 μm or less, and for example, 25 μm or more and 40 μm or less, etc.

[0026] The greater the height of the convex portion 10 and the smaller the surface tension of the base material 4, the more likely the liquid repellency is to improve, and also the more likely the anisotropy of the liquid movement is to decrease. By appropriately setting the height of the convex portion 10, it is possible to maintain the liquid to be controlled at a specific site, or to design it to move in a specific direction.

[0027] Also, the length of the convex portion 10 along the third direction Z does not necessarily need to be the longest compared to, for example, the length of the inclined surface 16 or the length of the back surface 16 in the convex portion 10, and is appropriately set according to the type of control of the movement required for the liquid, etc. For example, the length of the convex portion 10 along the third direction Z is 50 μm or more and 500 μm or less, and for example, 10 μm or more and 200 μm or less, and for example, 10 μm or more and 200 μm or less. Also, it may be continuous for 500 μm or more in the direction Z.

[0028] The convex portion 10 can include at least the inclined surface 14 and the back surface 16, and further can include a top surface defined by the upper edge of these two surfaces. Such a top surface is also formed incidentally, but may be actively formed as needed in contact with the liquid. The width of the top surface along the first direction X is not particularly limited and is appropriately set according to the purpose.

[0029] The shapes and sizes of the plurality of convex portions 10 do not have to be all the same and may be different. From the viewpoint of controlling the movement of the liquid, in a certain range, it may be preferable that the shapes and sizes of the plurality of convex portions 10 are the same.

[0030] By standing the plurality of convex portions 10 on the reference surface 6, the device 2 can impart anisotropy to the dynamic wetting behavior of the liquid in contact therewith by the plurality of convex portions 10 or by the fine structure constituted by the plurality of convex portions 10 and the reference surface 6. The plurality of convex portions 10 are arranged along the first direction X, or in other words, along the second direction Y. By arranging the plurality of convex portions 10 in such an arrangement, it becomes possible to impart anisotropy in the first direction X to the liquid as shown in Fig. 1(b), or to control and impart mobility to the second direction Y and the third direction Z as shown in Fig. 2(c).

[0031] The arrangement form of the plurality of convex portions 10 is not particularly limited. For example, as shown in Fig. 1(a), they may be arranged substantially parallel along the first direction X, or in other words, also substantially parallel along the second direction Y. By providing such an arrangement, it becomes possible to efficiently control the movement of the liquid. Note that the plurality of convex portions 10 being arranged in parallel means that the inclined surfaces 14 of the convex portions 10 are arranged in parallel.

[0032] The arrangement interval of the plurality of convex portions 10 is set as appropriate. Depending on the type of liquid to be controlled, the movement of the liquid to be obtained, etc. and the purpose, it may be preferable that they are arranged at equal intervals. Also, when arranged at equal intervals, the distance is set according to the purpose, but in the direction along the first direction X, for example, it is 10 μm or more and 1000 μm or less, and also for example, 50 μm or more and 1000 μm or less, and also for example, 100 μm or more and 500 μm or less. Note that the interval between the plurality of convex portions 10 means the interval between the points where the inclined surfaces 14 of the respective convex portions 10 are in contact with the reference surface 6.

[0033] Note that the arrangement intervals of at least some of the plurality of convex portions 10 may be different from those of the remaining convex portions 10. This is because in some cases, different controls on the liquid may be intended by at least some of the convex portions 10.

[0034] Further, the convex portion 10 may be constituted by a single convex portion 10 in the direction along the third direction Z, or a plurality of convex portions 10 may be arranged coaxially with or without intervals therebetween.

[0035] Also, due to the sizes, cross-sectional shapes, and arrangement intervals of the plurality of convex portions 10, the areas where the reference plane 6 is exposed between the convex portions 10 vary greatly. However, due to the presence and amount of the reference plane 6, etc., it can contribute to the control of the movement of the liquid in the gaps between the plurality of convex portions 10. For example, in relation to the liquid, the plurality of convex portions 10 and the reference plane 6 can also be designed with the intention of forming a Wenzel state or a Cassie - Baxter state.

[0036] By having the above configuration, this device can impart anisotropy to the dynamic wetting behavior of the liquid in the following manner. Note that various dynamic wetting behaviors are schematically shown in FIG. 2.

[0037] (1) For example, for a liquid with relatively low surface tension, as shown in the upper part of FIG. 2A, the receding angle during liquid evaporation can be made to point in the second direction Y. That is, a liquid having a surface tension equal to or lower than that of water, for example, a droplet larger than the arrangement interval of the convex portions 10 (the device is designed according to the droplet diameter (amount) to be controlled. For example, about 10 nl).), the device is designed such that the static contact angle with the surface of the substrate 4 including the convex portions 10 is 70 degrees or less, so that this liquid can be given a dynamic wetting behavior (surface tension vector) that imparts mobility in the second direction Y as shown by the arrow in the lower part of FIG. 2A. Whether the device generates such a surface tension vector can be determined, for example, by placing the droplet on the device and measuring the receding angle accompanying the evaporation of the liquid, and evaluating whether the ratio of the directionality of the receding angle indicating the second direction Y is larger than the ratio indicating the first direction X. In this case, it can also be said that the mobility of the liquid in the first direction X is suppressed (the pinning effect of the receding angle is exhibited at the end of the liquid on the second direction Y side).

[0038] When the static contact angle on the surface of the substrate 4 is 70 degrees or less, it becomes difficult for air to be trapped between the substrate 4 and the liquid, and the tendency for the surface of the substrate 4 to be filled with the liquid increases. The tendency for the surface of the substrate 4 to be filled with the liquid imparts mobility in the second direction Y to the liquid droplet.

[0039] In addition, for such a liquid, the static contact angle is, for example, 65 degrees or less, and also, for example, 60 degrees or less, and also, for example, 55 degrees or less, and also, for example, 50 degrees or less, and also, for example, 45 degrees or less, and also, for example, 40 degrees or less, and also, for example, 35 degrees or less, and also, for example, 30 degrees or less, and also, for example, 25 degrees or less, and also, for example, 20 degrees or less.

[0040] In this specification, for the static contact angle, a droplet, for example, a micro-droplet of 2 to 10 μl, can be dropped onto the surface including the convex portion 10 of the substrate 4, an image thereof can be acquired, and the contact angle can be calculated by analyzing the contour shape of the droplet from the image using the droplet method. Depending on the size of the droplet, etc., the contact angle can be calculated by appropriately selecting from the Θ / 2 method, the perfect circle fitting method, and the ellipse fitting method. The measurement conditions for the static contact angle can be calculated by measuring 20 times by the Θ / 2 method 5 seconds after dropping with a droplet volume of 3 μl at 25°C.

[0041] (2) For example, for a liquid with relatively high surface tension, as shown in the upper part of FIG. 2B, the receding angle of liquid evaporation can be made to point in the first direction X. That is, when the liquid is water or a liquid having a surface tension equal to or less than that of water, for example, by designing the device such that the static contact angle with the surface 6 of the substrate 4 is more than 70 degrees for a relatively large droplet (for example, about 10 nl), a dynamic wetting behavior that imparts mobility in the first direction X as indicated by the arrow in the lower part of FIG. 2B can be imparted to this liquid. Whether this device generates such a surface tension vector can be determined, for example, by placing the droplet on this device and evaluating whether the ratio of the receding angle directionality indicating the first direction X is greater than the ratio indicating the second direction Y when measuring the receding angle accompanying the evaporation of the liquid. In this case, it can also be said that the mobility in the second direction Y is suppressed (the pinning effect of the receding angle is exhibited at the end of the liquid on the first direction X side).

[0042] Note that for such a liquid, the static contact angle is, for example, 75 degrees or more, and for example, 80 degrees or more, and for example, 85 degrees or more, and for example, 90 degrees or more, and for example, 95 degrees or more, and for example, 100 degrees or more, and for example, 105 degrees or more, and for example, 110 degrees or more, and for example, 115 degrees or more, and for example, 120 degrees or more, etc.

[0043] (3) For example, as shown in the upper part of FIG. 2C, for a liquid having a static contact angle with the surface of the substrate 4 of 70 degrees or less, the falling angle of the liquid in the second direction Y can be made smaller than the falling angle of the liquid in the first direction X. By doing so, as shown by the arrow in the lower part of FIG. 2C, it is possible to impart a dynamic wetting behavior that facilitates mobility in the second direction Y. When this device exhibits such behavior, for example, when the liquid is a liquid having a surface tension equal to or less than that of water (for example, when it has a contact angle of 70 degrees or less to 60 degrees or less at the static contact angle with the substrate 4). Whether this device generates such a surface tension vector can be determined by placing a droplet of the liquid on the device and measuring its falling angle, i.e., whether the falling angle in the second direction Y is smaller than that in the first direction X. In this case, it can also be said that the mobility in the first direction X is suppressed (the pinning effect of the receding angle is exerted at the end of the liquid on the second direction Y side).

[0044] (4) For example, as shown in the upper part of FIG. 2D, for a liquid having a static contact angle with the surface of the substrate 4 of more than 70 degrees, the falling angle of the liquid in the first direction X can be made smaller than the falling angle of the liquid in the second direction Y. By doing so, as shown by the arrow in the lower part of FIG. 2D, it is possible to impart a dynamic wetting behavior that facilitates mobility in the first direction X. When this device exhibits such behavior, the liquid has a surface tension equal to or less than that of water, for example, when it has a contact angle of more than 60 degrees to more than 70 degrees at the static contact angle with the substrate 4. Whether this device exhibits such a surface tension vector can be determined by placing a droplet of the above liquid on the device and measuring its falling angle, i.e., whether the falling angle in the first direction X is smaller than that in the second direction Y. In this case, it can also be said that the mobility in the second direction Y is suppressed (the pinning effect of the receding angle is exerted on the first direction X side of the liquid).

[0045] (5) It has been found that the falling angle in the third direction Z is smaller than the falling angles in the first and second directions. Therefore, for example, by adopting the form of FIG. 2C, the falling angle of the liquid can be made to increase in order in the third direction Z, the second direction Y, and the first direction X. By doing so, it is possible to impart a dynamic wetting behavior that facilitates mobility in the second direction Y. Whether or not this device generates such a surface tension vector can be determined, for example, when the liquid is water or a liquid having a surface tension equal to or less than that of water, by placing a droplet of the liquid on this device and measuring its falling angle to see if it follows the above order. In this case, it can also be said that the mobility in the first direction X is suppressed (the pinning effect of the receding angle is exhibited at the end of the liquid on the second direction Y side).

[0046] In addition, since this device handles a relatively small amount of liquid, the reference plane may be a horizontal plane, or may be a vertical plane from the horizontal plane. Also, in some cases, in addition to the fine structure composed of a plurality of convex portions 10 and the reference plane 6, etc., it may be possible to impart the effect of gravity, etc., such as by inclining or curving the reference plane of this device itself.

[0047] Also, this device can appropriately change the size, shape, arrangement pattern, exposed amount of the reference plane, etc. of the plurality of convex portions, and further, by providing a side wall that regulates the direction of the liquid so as to partition the surface structure, etc., it is also possible to impart a surface tension vector in a direction other than the first direction X, the second direction Y, and the third direction Z.

[0048] In addition, the above various dynamic wetting behaviors of this device can be evaluated using the methods described in the examples.

[0049] The device described above can be manufactured by various methods and is not particularly limited. For example, the material of the substrate can be formed by a molding method or a casting method capable of forming a microstructure such as nanoimprinting to obtain a structure having convex portions on the reference surface, or the substrate can be partially removed by cutting, chemical treatment, etching, lithography, etc. to obtain a structure having convex portions on the reference surface, or further, convex portions can be bonded to the surface serving as the reference surface of the substrate.

[0050] (Use of this device) Since this device can be used as a device for controlling the movement of a liquid, it can be used as a device for various applications or a part thereof. For example, it can be used as a flow path device having a flow path through which a liquid passes, which is a device for various reactions, separations, extractions, mixings, detections, diagnoses, cultures, etc. That is, by utilizing the surface structure of this device, a liquid can be freely maintained or moved to a predetermined position.

[0051] Also, for example, it can be used as a device for evaluating the movement of liquids used in various applications (for example, liquids for hair care, pharmaceuticals, various industrial products, foods, etc.). By detecting and evaluating the dynamic wetting behavior of a liquid with respect to this device having a surface structure for a certain evaluation, it becomes possible to identify the characteristics of the liquid, screen a liquid suitable for a predetermined application, and improve the characteristics of the liquid according to the application.

[0052] (Method for treating liquid) The liquid treatment method disclosed in this specification (hereinafter, also simply referred to as "this method") uses a plurality of convex portions that are inclined in a first direction on a reference plane and arranged along the first direction, and are inclined surfaces that form an obtuse angle with the reference plane and point in a second direction that is substantially opposite to the first direction, and a back surface that points in the first direction on the back side of the inclined surface. The method can be a method of controlling the movement of a liquid by bringing the liquid to be controlled into contact with the plurality of convex portions having a shape extending in a third direction intersecting the first direction, thereby imparting anisotropy to the dynamic wetting behavior of the liquid.

[0053] According to this method, an intended movement (maintenance at an arbitrary site, movement to an arbitrary method) can be imparted to the liquid, which can contribute to a desired treatment. Although this method is a liquid treatment method, it can also be implemented simply as a method for controlling the movement of a liquid, such as the movement, stop, and passage of the liquid.

Example

[0054] Hereinafter, examples will be described as specific examples to more specifically explain the disclosure of this specification. The following examples are for explaining the disclosure of this specification and do not limit its scope.

Example

[0055] (Evaluation of the dynamic wettability of water on the cuticle) In this example, as shown in FIG. 3, for the winter hair of a horse (diameter: about 30 to 60 μm), 3 to 40 pL of water was placed as a droplet with a diameter of 10 to 40 μm from a needle (tip thickness: 5 μm) on the cuticle. Using a minimum contact angle meter (automatic minimum contact angle meter MCA-3 TypeI), the evaporation process of the droplet was observed from the side and above, the receding angle associated with evaporation was measured, and the dynamic wetting behavior was observed. The measurement temperature was 25°C. The results are shown in FIG. 4.

[0056] As shown in Fig. 4, the larger the droplet volume, the higher the ratio of the receding angle that points to the root side of the cuticle (the second direction Y in this specification). On the other hand, when the droplet volume is small, at about 5 pl or less, the receding angle has a high ratio of not showing directivity. And it was found that when the droplet volume is between 5 and 10 pl, the ratio of pointing to the root is dominant.

[0057] From the above, it was found that the cuticle structure and its mimicking structure have a receding angle that points to the root side as the droplet volume in the contacted liquid increases. This is considered to be because the larger the droplet, the more it is affected by the cuticle structure. As a result, it is considered that the droplet is more likely to point to the root side. Also, when the droplet is small, the adhesion area to the cuticle structure is small, and as a result, it is considered that the receding angle does not show directivity. From the above, according to the cuticle structure and its mimicking structure, it was found that the moving direction of the droplet can be controlled by designing the cuticle structure according to the surface tension characteristics of the liquid to be controlled and its droplet volume (the size of the droplet).

Example

[0058] (Fabrication of an anisotropic surface structure mimicking the cuticle structure and evaluation of wetting behavior on the structure) In this example, using polytetrafluoroethylene, a mold with a cavity having the shape of a reference surface with convex portions was fabricated with a precision desktop 3-axis robot. The cavity of this mold was filled with polydimethylsilicone and heated and cured at 100 °C for 1 hour. After cooling, it was demolded to obtain a structure with a plurality of inclined convex portions. As shown in Figs. 5(a) to (c), this structure is one in which convex portions of a substantially plate-like body with a height of about 30 μm and inclined at 45° are arranged in parallel at intervals of 200 μm.

[0059] Using this anisotropic surface structure, a 2-μl water droplet was placed and the static contact angle was measured. As a control, a water droplet was similarly placed on a plate made of the same material (PDMS) as the anisotropic surface structure, and the static contact angle was measured (using a contact angle meter (automatic contact angle meter DCM-500 Type I)). The measurement temperature was 25°C. The results are shown in Fig. 6.

[0060] As shown in Fig. 6, the contact angle of the water droplet on the anisotropic surface structure was 144°. In contrast, the contact angle of the water droplet on the PDMS flat plate was 114°. Based on Wenzel's equation (cosΘ = R·cosΘ E、 where Θ is the contact angle on the structured surface, Θ E is the contact angle on the smooth surface, and R is the surface area ratio (roughness factor), when Rm was calculated from the measured contact angle, Rm was approximately 2.0, which was larger than R (1.5) calculated from the structure. From this, it was speculated that on the anisotropic surface structure, water repellency due to the anisotropic structure was imparted, and this water repellency was due to the presence of air on the anisotropic surface.

Example

[0061] (Measurement of the dynamic contact angle of a liquid on an anisotropic surface structure 1) In this example, as shown in Fig. 7, using the sliding method, while changing the liquid volume of water (10, 20, 30, 40, and 50 μl) using the anisotropic surface structure fabricated in Example 3, the falling angles in the tip (hair tip) direction, base (root) direction, and the direction along the base of the convex part of the structure were measured. In measuring the falling angle, a contact angle meter (automatic contact angle meter DCM-500 Type I) was used as the device, and the measurement was carried out under the conditions of a measurement temperature of 25 degrees and a tilt speed of 1 degree / second. The results are shown in Fig. 8.

[0062] As shown in Fig. 8, when the volume of the dropped liquid was increased, the falling angles in all three directions decreased, but the falling angle in the convex part direction Z was the smallest, the falling angle in the hair tip direction X was the next smallest, and the falling angle in the root direction Y was the largest. From these results, it was found that the ease of movement of the water droplet was in the order of the convex part direction Z, the hair tip direction X, and the root direction Y.

[0063] From the above, it was found that on the anisotropic surface structure used in this example (a structure made of PDMS in which roughly plate-like convex portions with a height of approximately 30 μm and inclined at 45° are arranged in parallel at 200 μm intervals), a 10-50 μl water droplet acts as a droplet with high surface tension (for example, when the static contact angle with the substrate is greater than 60 to 70 degrees), and between the tip direction X and the base direction Y, it moves easily in the tip direction X, but moves less easily in the base direction Y due to the pinning effect of the sweepback angle at the end of the tip direction. The ease of movement in the tip direction is thought to be due to the movement in the tip direction acting to reduce the contact line at the interface between the convex portions and the droplet, making the liquid interface move more easily. Conversely, the difficulty of movement in the base direction is thought to be due to the fact that movement of the droplet in the base direction does not reduce the contact line at the interface between the liquid and the convex portions, making the liquid interface less mobile. [Example]

[0064] (Evaluation of wetting behavior of liquids with surface tensions lower than that of water on anisotropic surface structures) In this example, the anisotropic surface structure produced in Example 2 was formed so that the width along the base of the convex portion was 2 mm, and 1 μl of ethanol (which has a static contact angle of 30° on a flat PDMS substrate) was placed on the surface of this structure. The results are shown in Figure 9.

[0065] 9, after spreading along the convex direction Z, the ethanol spread in the root direction Y and did not move in the tip direction X. It was presumed that ethanol with high wettability (for example, when the static contact angle with the substrate is 60 degrees or less to 70 degrees or less) spread along the convex direction Z, and then the pinning effect of the receding angle occurred at the root side end of the liquid, but not at the tip side end of the liquid, and therefore moved preferentially in the root direction Y.

[0066] From the above, for a liquid with a small surface tension, it was considered that the adhesion area to the anisotropic surface structure was large, and as a result, the receding angle during evaporation pointed in the root direction Y, making it easier to move in the root direction Y.

Example

[0067] (Measurement of the dynamic contact angle of a liquid on an anisotropic surface structure 2) In this example, the inclination angles (45 degrees) of the convex portions of the anisotropic surface structure fabricated in Example 3 were set to 0 degrees, 30 degrees, 60 degrees, and 90 degrees, and an anisotropic surface structure was fabricated in the same manner except that the height of the convex portions was 40 μm. Using anisotropic structures with inclination angles of 0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees, with the liquid droplet volume of water being 20 μl, the static contact angle (automatic contact angle meter DCM - 500 TypeI) was measured according to Example 2. According to Example 3, the falling angles (using an automatic contact angle meter DCM - 500 TypeI, measurement temperature 25 degrees, inclination speed 1 degree / second) were measured for three directions: the tip direction, the root direction, and the convex portion direction. Furthermore, the hysteresis (using an automatic minimum contact angle meter MCA - 3 TypeI) was measured. The results are shown in Fig. 10. When it did not slide down, the falling angle was plotted as 90°.

[0068] As shown in Fig. 10, the static contact angle generally tended to increase as the inclination angle increased, indicating that the water repellency increased with a larger inclination angle. Also, when the inclination angles were 30 degrees and 45 degrees, the static contact angles in the tip direction and the root direction were generally equal and exceeded the static contact angle in the convex portion direction, but otherwise they were generally equal.

[0069] The falling angle tended to have a large difference between the falling angles in the root direction and the tip direction when the inclination angles were 30 degrees and 45 degrees, and otherwise they were generally equal in all three directions. That is, it was found that when the inclination angle was too large, the anisotropy of the rollability tended to decrease.

[0070] Moreover, the hysteresis increased in the order of the convex part direction, the tip direction, and the root direction when the tilt angles were 30 degrees and 45 degrees, and the difference also increased. At other tilt angles, they were generally equivalent. That is, it was found that when the tilt angle was too large, the anisotropy of the ease of rolling tended to decrease.

Example

[0071] (Measurement of the dynamic contact angle of a liquid on an anisotropic surface structure 3) In this example, an anisotropic surface structure was fabricated in the same manner as in Example 6, except that the height of the convex part (30 μm) of the anisotropic surface structure fabricated in Example 3 was set to 0 μm, 25 μm, 40 μm, and 100 μm. Using the anisotropic structures with tilt angles of 0 μm, 25 μm, 40 μm, and 100 μm, with the liquid droplet volume of water being 20 μl, the static contact angle was measured in the same manner as in Example 6, the falling angles were measured for three directions: the tip direction, the root direction, and the convex part direction, and furthermore, the hysteresis was measured. The results are shown in FIG. 11.

[0072] As shown in FIG. 11, it was found that the static contact angle tended to increase as the height of the convex part increased. Also, from the results of the falling angle and hysteresis, it was found that as the height of the convex part increased, the effect on the anisotropy of the ease of rolling of the liquid droplet due to anisotropy became smaller but was maintained.

[0073] According to the above examples, in the cuticle-mimicking structure, the contact area between the liquid and the structure changes depending on the tilt angle and height of the convex part, the surface tension of the liquid, the size of the liquid droplet, etc. By configuring the structure so that the receding angle in the cuticle-mimicking structure points in the root direction for the liquid to be controlled, it was found that the liquid can be made to move easily in the root direction and difficult to move in the tip direction. In particular, it was also found that such anisotropic movement control becomes possible when the liquid is a liquid with low surface tension, for example, when the static contact angle on the surface of the anisotropic structure shows 70 degrees or less to 60 degrees or less.

Claims

1. A device for controlling the movement of a liquid, comprising: a substrate; a plurality of convex portions provided on a reference surface of the substrate, inclined in a first direction on the reference surface and arranged along the first direction; each of the plurality of convex portions includes an inclined surface that forms an obtuse angle with the reference surface and is inclined in a second direction that is substantially opposite to the first direction, and a back surface that faces the first direction on the back side of the inclined surface, and further includes a substantially rectangular thin plate extending in a third direction intersecting the first direction or a triangular prism having a substantially triangular cross section; when the plurality of convex portions are brought into contact with the liquid to be controlled, the device controls the movement of the liquid by imparting anisotropy to the dynamic wetting behavior of the liquid by one or more elements selected from the group consisting of the inclination angle, height, arrangement interval, cross-sectional shape, and size of the plurality of convex portions.

2. The device according to claim 1, wherein the plurality of convex portions are configured such that when the liquid contacts the plurality of convex portions, the receding angle of the liquid is directed in the first direction or the second direction.

3. The liquid is a liquid having a static contact angle of 70 degrees or less on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid contacts the plurality of convex portions, the receding angle of the liquid is directed in the second direction. The device according to claim 1 or 2.

4. The liquid is a liquid having a static contact angle of more than 70 degrees on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid contacts the plurality of convex portions, the receding angle of the liquid is directed in the first direction. The device according to claim 1 or 2.

5. The liquid is a liquid having a static contact angle of 70 degrees or less on the surface of the substrate, and the plurality of convex portions are configured such that when the liquid to be controlled contacts the plurality of convex portions, the falling angle of the liquid in the second direction is smaller than the falling angle of the liquid in the first direction. The device according to claim 1 or 2.

6. The liquid is a liquid having a static contact angle of more than 70 degrees on the surface of the substrate, and is configured such that when contacting the plurality of convex portions, the falling angle of the liquid in the first direction is smaller than the falling angle of the liquid in the second direction. The device according to claim 1 or 2.

7. The device according to claim 1 or 2, wherein the plurality of convex portions are configured such that the falling angle of the liquid to be controlled increases in order in the third direction, the second direction, and the first direction.

8. The device according to any one of claims 1, 2, 3, 5, and 7, wherein the plurality of convex portions are configured to suppress the movement of the liquid in the first direction to be controlled.

9. The device according to any one of claims 1 to 8, wherein the plurality of convex portions are arranged substantially parallel to each other along the first direction, and are a substantially rectangular thin plate or a triangular prism having a substantially triangular cross section, having a predetermined length extending in the third direction, a predetermined height, and an inclined surface inclined at the predetermined obtuse angle.

10. The device according to claim 9, wherein the plurality of convex portions are arranged at substantially equal intervals along the first direction.

11. The device according to any one of claims 1 to 10, wherein the height of the plurality of convex portions is 10 μm or more and 200 μm or less, and the interval of the plurality of convex portions along the first direction is 50 μm or more and 1000 μm or less.

12. A method for treating a liquid, using a substrate and a plurality of convex portions arranged along the first direction while being inclined in the first direction on a reference surface of the substrate, each having an inclined surface inclined at an obtuse angle with respect to the reference surface and pointing in a second direction that is substantially opposite to the first direction, and a back surface pointing in the first direction on the back side of the inclined surface, and the plurality of convex portions each comprising a substantially rectangular thin plate or a triangular prism having a substantially triangular cross section and extending in a third direction intersecting the first direction, wherein when the plurality of convex portions are brought into contact with the liquid, the movement of the liquid is controlled by imparting anisotropy to the dynamic wetting behavior of the liquid by one or more elements selected from the group consisting of the inclination angle, height, arrangement interval, cross-sectional shape, and size of the plurality of convex portions.

13. A flow path device, comprising a plurality of convex portions arranged along the first direction while being inclined in the first direction on a reference surface of a substrate at at least a part of the flow path. each of the plurality of protrusions includes an inclined surface that is inclined at an obtuse angle with respect to the reference plane and faces a second direction that is substantially opposite to the first direction, and a back surface that faces the first direction on the back side of the inclined surface; and the protrusions each include a substantially rectangular thin plate or a triangular prism with a substantially triangular cross section that extends in a third direction that intersects with the first direction; A device in which, when the plurality of convex portions come into contact with a liquid in the flow path, they impart anisotropy to the dynamic wetting behavior of the liquid by one or more elements selected from the group consisting of the inclination angle, height, arrangement spacing, cross-sectional shape, and size of the plurality of convex portions, thereby controlling the movement of the liquid in the flow path.

14. A liquid movement evaluation device, comprising: a plurality of protrusions arranged along a first direction and inclined toward the first direction on a reference surface of a base body; each of the plurality of protrusions includes an inclined surface that is inclined at an obtuse angle with respect to the reference plane and faces a second direction that is substantially opposite to the first direction, and a back surface that faces the first direction on the back side of the inclined surface; and the protrusions each include a substantially rectangular thin plate or a triangular prism with a substantially triangular cross section that extends in a third direction that intersects with the first direction; A device wherein the plurality of protrusions are configured to impart anisotropy to the dynamic wetting behavior of the liquid when the liquid to be evaluated comes into contact with the plurality of protrusions by one or more factors selected from the group consisting of the inclination angle, height, arrangement spacing, cross-sectional shape, and size of the plurality of protrusions.

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