JPH05187974A - Liquid transporting method - Google Patents

Abstract

PURPOSE:To transport liquid with a simple constitution by way of a free path without forming a flow channel and without using a valve. CONSTITUTION:By scooping liquid 4 with a transporting member 11 having a poor wetness to the transported objective liquid, the liquid 5 forming a sphere due to its surface tension is put on the ring 11a of the transporting member 11 and the sphere liquid 5 is transported by moving the transporting member 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a mechanism for moving a liquid, and more particularly to a liquid used in a device for handling a small amount of liquid such as liquid chromatography, a blood analyzer, a microsynthesis device and the like. Regarding transfer method. Also,
The transfer method of the present invention can also be used when a mechanism for moving a liquid on a Si substrate or the like at a very short distance is realized by micromachining.

[0002]

2. Description of the Related Art Generally, in order to move a liquid, it is necessary to form a flow path with a pipe or a groove or to provide a valve.

[0003]

However, when the flow path is formed by pipes, grooves, etc., the transfer path is influenced by the formed flow path, which is inconvenient because the transfer path has less flexibility than solid transfer. .. Further, when it is desired to transfer a liquid at a very short distance, for example, when two pools of liquid existing at a distance of about 100 μm to 1 mm are prepared by micromachining, and when it is desired to transfer the liquid between them, a pipe or Although a valve is required, it is not easy to make a pipe or valve for such a short distance transfer. Therefore, for such a transfer at a close range, a method for transferring a liquid with a simple structure without using pipes or valves is desired.

Therefore, an object of the present invention is to provide a method capable of transferring a liquid through a free path with a simple structure without forming a flow path and thus without using a pipe or a valve.

[0005]

The liquid transfer method according to the present invention, which is made to solve the above-mentioned problems, makes the liquid to be transferred into a spherical shape having a predetermined size or less by the surface tension of the liquid. The spherical liquid is moved while being in contact with a member having a surface having poor wettability with respect to the liquid.

[0006]

With this structure, the liquid that has become spherical due to surface tension remains spherical even when it comes into contact with a member having a surface with poor wettability, so that the liquid to be transferred is spherical. You can move it as it is. For example, the spherical liquid is placed on a transfer member having a surface with poor wettability, or the spherical liquid is attached to the transfer member and moved together with the transfer member, or the spherical liquid has poor wettability. It can be moved by rolling on a member having a surface.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a transfer method according to a first embodiment of the present invention. In this embodiment, the transfer member 11 having a surface having poor wettability with respect to the liquid to be transferred is used.
As shown in FIG. 1 (a), the transfer member 11 is provided with a ring-shaped portion 11a. By scooping (scooping) the liquid 4 with such a transfer member 11, the surface tension of the liquid is increased. The spherical liquid 5 is transferred onto the ring 11a of the transfer member 11 by moving the transfer member 11 and the spherical liquid 5 is transferred.

To transfer the liquid to be transferred in a spherical shape,
As described above, it is necessary to use a transfer member having a surface that has poor wettability with respect to the liquid. As such a transfer member, when the transfer target is water, a transfer member made of, for example, Teflon (trademark) or a metal coated with paraffin can be considered. Here, “poor wettability” means that the contact angle with respect to the liquid to be transferred is 90 degrees or more. Further, the “contact angle” is an angle formed by the liquid surface and the solid surface at a place where the free surface of the liquid contacts the solid wall, and as shown in FIG.
Say. For example, at room temperature, the contact angle between water and paraffin is about 107 degrees, and the contact angle between mercury and glass is about 140 degrees.
The contact angle between water and glass is about 7 to 8 degrees.

Further, if the transfer member is too large, the liquid cannot be placed on it, so the size of the transfer member is limited. For example, the transfer member 1 shown in FIG.
In the case of 1, it is necessary to make the radius r of the ring smaller than a predetermined value. That is, since the weight of the spherical liquid on the transfer member is supported via the surface tension of the liquid, if the spherical liquid becomes large and the weight exceeds the limit that can be supported by the surface tension of the liquid, the spherical liquid It becomes impossible to transfer the liquid in the form of liquid on the transfer member. There is a certain limit to the size of the transfer member corresponding to the limit of the size of the spherical liquid, and the size cannot be increased beyond a certain value. The estimation of the size limit of the transfer member (the size limit of the spherical liquid that can be transferred) will be described below.

For simplicity, the ring 11 of the transfer member 11
It is assumed that a is a thin plate, and that the plate faces the direction of the center O of the spherical liquid 5 placed on the ring 11a, as shown in the sectional view of FIG. 1 (b). At this time,
Gravity acts on the spherical liquid 5 as a downward force, and force that the ring 11a lifts the spherical liquid 5 acts as an upward force, and both are balanced. When the ring 11a lifts the spherical liquid 5 in detail, as shown in FIG. 1B, this lifting force depends on the surface tension T of the liquid at the portion where the spherical liquid 5 contacts the plate of the ring 11a. It is a thing. The spherical liquid 5 is in contact with both sides of the plate of the ring 11a, and the value of the contact angle θ (see FIG. 3) at these contacts is the liquid 5 and the ring 11a.
Since it is a unique value determined by both substances on the surface of, the resultant force of the surface tensions T on both sides of this plate faces the center O of the spherical liquid 5, and its size is 2 · T · cos (180−θ). is there. Ring 1
The force Fu by which 1a lifts the spherical liquid 5 can be obtained by integrating the component force of the resultant force of the surface tensions in the upward vertical direction over the entire circumference of the ring 11a. That is, Fu = {2 · T · cos (180−θ)} × cosφ × (2 · π · r) where φ: a straight line connecting the center O of the spherical liquid 5 and the ring 11a and a vertical line It is a corner. This force Fu is equal to the gravitational force W acting on the spherical liquid 5, W = (4/3) · π · R ³ · ρ · g where ρ: mass density of the liquid g: gravitational acceleration, so {2 · T · cos (180-θ) } × cosφ × (2 · π · r) = (4/3) · π · R 3 · ρ · g ... become. Since the radius R of the spherical liquid 5 and the radius r of the ring have a relationship of r = R · sinφ…, this equation is substituted into the equation and rearranged, R = {3 · T · cos (180 −θ) · cosφ · sinφ / (ρ · g)} ^1/2 ... In this formula, T, ρ, g, and θ are known values, so if the angle φ is determined, the ring 11a with the radius r is
It is possible to determine the radius R of the spherical liquid 5 that can ride on. Here, considering that the spherical liquid 5 is transferred while being placed on the ring 11a, it is considered appropriate that the angle φ is about 30 ° to 45 °. Now
If φ = 30 ° (R = 2r), the liquid to be transferred is water, and the surface of the transfer member 11 is coated with paraffin, θ = 107 [°], T =
0.072 [N / m] and ρ = 1000 [kg / m ³ ]. Substituting these numerical values into the formula, R = {3 × 0.072 × cos73 ° cos30 ° sin30 ° / (1000 × 9.8)} ^1/2 = 0.00164 [m], and r = R · sinφ = 0.00164 × sin30 ° = It is 0.00082 [m]. Therefore, in this case, if the radius of the ring 11a of the transfer member 11 is set to about 0.8 mm or less, the water to be transferred can be transferred in a spherical shape.

FIG. 2 shows an example in which the above embodiment is slightly modified. In this modification, a transfer member provided with a ring is used instead of the transfer member provided with a ring, as shown in FIG. 2A. When using such a fork 12, as shown in FIG.
As shown in (b), between the two rod-shaped members of one fork 12 on which the spherical liquid 5 is placed, the other fork 13 is provided.
The spherical liquid 5 can be easily transferred between the transfer members by inserting the rod-shaped member and lifting the other fork 13.

In the above-described embodiment, the transfer member 11 provided with the ring 11a is taken as an example, and a force in the upward vertical direction based on the surface tension T at the portion where the spherical liquid 5 contacts the plate of the ring 11a is applied along the ring. By integrating
Although the limit of the size of the transfer member 11 (radius r of the ring 11a) was estimated, the spherical liquid in the transfer member should be placed on the transfer member such as a fork shown in FIG. 2 (a). Even when the portion is not ring-shaped, the size limit of the transfer member can be estimated in the same manner. That is, by integrating the force on the vertical line based on the surface tension T at the portion where the spherical liquid is in contact with the transfer member, the gap a in the fork 12 in FIG.
You can estimate the limits such as.

As described above, if the material (surface material) of the transfer member is determined with respect to the liquid to be transferred, the size limit of the transfer member can be estimated accordingly, and this estimate When the transfer method of the present embodiment is applied based on the above, the liquid can be moved in a spherical shape. Thereby, the liquid to be transferred can be treated like a solid and transferred along a free path, and it is possible to use both the solid transfer tool and the liquid transfer tool. Further, in the conventional liquid transfer method, a valve is normally used to stop the transfer, but in this embodiment, the liquid transfer is stopped by stopping the movement of the transfer member carrying the spherical liquid. Therefore, a valve is unnecessary. Furthermore, since the liquid can be scooped by the transfer member used in the present example by a substantially constant amount, the method of the present example can be applied to the quantification of the liquid.

As a specific application example of the transfer method of the present embodiment, application to laboratory automation is considered, and as a part of laboratory automation, it is used for analysis / synthesis using liquid and exchange of a small amount of liquid in the field of biotechnology. be able to. For example, as shown in FIG. 4, the fork 1 described above is attached to the tip of the manipulator 20.
By attaching a fork 21 having the same configuration as that of No. 2 and placing a spherical liquid on the fork 21 and moving the fork, liquid can be exchanged between the containers A to D.

FIG. 5 is a diagram showing a transfer method according to the second embodiment of the present invention. In the present embodiment, the needle-like transfer member 31 is immersed in the liquid to be transferred and then pulled up to attach the droplets to the tip of the needle-like transfer member 31 and move the needle-like transfer member 31. To transfer the liquid.

Here, when a member having a surface having poor wettability with respect to the liquid to be transferred is used as the needle-shaped transfer member 31, the liquid to be transferred becomes spherical due to the surface tension, and the needle-shaped transfer member is formed. Attach to 31. However, as the wettability deteriorates, the spherical liquid becomes less likely to adhere, and the size of the spherical liquid 5 that adheres also decreases. Therefore, an appropriate wettability is selected as necessary. On the other hand, if the wettability is good, the droplets adhering to the needle-shaped transfer member 31 may not be spherical, and when the droplets are separated from the needle-shaped transfer member 31 at the target point of transfer, they may be separated. It ’s harder, but
In this case, the adhered droplets can be separated by shaking the needle-shaped transfer member 31 or applying vibration thereto. Therefore, in the transfer method of this embodiment, a member having good wettability may be used.

The transfer method of this embodiment is different from the transfer method of the first embodiment in that the spherical liquid is moved by being mounted on a ring or a fork in that droplets are attached to the needle-shaped transfer member and moved. Although it is different, it is the same as the first embodiment in terms of the obtained effects such that the liquid can be transferred through a free path and the valve is unnecessary. In addition, the same applies in that it can be used as a part of laboratory automation as a specific application example. In this case, for example, in the device shown in FIG. By attaching a member, attaching a droplet to the member, and moving the liquid, the container A to
Liquid will be exchanged between D.

FIG. 6 is a diagram showing a transfer method according to the third embodiment of the present invention. In this embodiment, the liquid is moved on a member having a surface having poor wettability with respect to the liquid to be transferred by rolling the liquid into a spherical shape by surface tension. As shown in FIG. 5, the force required to roll the spherical liquid 5 is such that the rod-shaped member 51 having poor wettability pushes the spherical liquid 5 or the surface on which the spherical liquid 5 is rolled (the planar member 41 This can be applied by inclining the surface) or by charging the spherical liquid 5 and applying an electric field. Further, in order that the liquid to be transferred becomes spherical due to the surface tension and easily rolls on the planar member 41, the poorer the wettability of the surface of the planar member 41, the better. In addition, a material having a contact angle of 90 degrees or more with respect to at least the liquid to be transferred is used (see FIG. 3).

In this embodiment, as shown in FIG. 6, it is preferable to provide a groove 52 in the planar member 41 on which the spherical liquid 5 rolls. If the groove is provided, there is no freedom in the transfer path, but the spherical liquid 5 can be reliably transferred to the target point without precise control of the force for rolling.

Further, in this embodiment, as a method for bringing the liquid to be transferred into a spherical shape and bringing it into the planar member 41 (or the groove 52), the transfer method of the first and second embodiments is used. In addition to the method of bringing the liquid contained in the container or the like into a spherical shape by means of the method, a method of directly discharging the liquid to be transferred from the tube or the like to the planar member 41 (or the groove 52) in an appropriate amount is also possible. Conceivable.

As can be seen from the above description of each embodiment, the present invention is particularly effective for transporting a small amount of liquid, and can be applied to micromachining, which has recently received attention. That is, it has been considered to use a semiconductor microfabrication technique to handle a liquid on a Si substrate. In this case, the method of the present invention, for example, the first method described above, is used to transfer the liquid at a distance of about 100 μm to 1 mm. The method of three examples (FIG. 6) can be used. When the fluid needs to be separated, the fluid can be separated by applying an electric field while moving the fluid as the charged spherical liquid 5 by the method of the third embodiment. For example, as shown in FIG. 7, on a Si substrate (on the xy plane), a groove 52 that branches in the a direction and the b direction is provided midway, and the fluid to be separated is made into a spherical shape and is rolled and moved. Sometimes, the electrode 6 provided near the branch point of the groove 52
A voltage is applied between 1 and 62. As a result, an electric field is generated in a direction perpendicular to the moving direction of the spherical liquid 5, so that the charged spherical liquid 5 receives a force in a direction perpendicular to the moving direction. Then, the spherical liquid 5 moves in either the a direction or the b direction depending on the direction of the force received from the electric field (either the x direction or the −x direction in FIG. 7). Therefore, the fluid can be separated into the a direction and the b direction by operating the switches SW1 and SW2 to control the direction of the electric field (control which direction is the x direction or the −x direction). ..

The surface of Si is easily oxidized, and when the object to be transferred is water, the surface may be wetted by oxidation. In such a case, the surface may be changed by paraffin or Teflon (trademark). It can be dealt with by treating it to make it less wettable.

[0023]

As described above, according to the present invention, liquid can be freely formed by forming a simple member using a surface material having poor wettability without forming a flow path with pipes or grooves. It can be transferred by various routes. Further, since the liquid transfer can be stopped by a method such as stopping the movement of the transfer member on which the spherical liquid is placed, the valve is unnecessary. That is, since the liquid can be moved in a spherical shape, the liquid can be transferred with the same feeling as the transfer of the solid, and in some cases, the same transfer device can be used to transfer both the liquid and the solid. It is also possible to do so.

During the transfer of the liquid, the liquid agglomerates into droplets due to its own surface tension, so it is not necessary to consider a structure for preventing the liquid from scattering.

[Brief description of drawings]

FIG. 1 is a diagram showing a liquid transfer method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a modification of the transfer method of the first embodiment.

FIG. 3 is a diagram for explaining a contact angle when a liquid contacts a solid.

FIG. 4 is a diagram showing an example in which the liquid transfer method of the first embodiment is applied to the field of laboratory automation.

FIG. 5 is a diagram showing a liquid transfer method according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a liquid transfer method according to a third embodiment of the present invention.

FIG. 7 is a diagram showing an example in which the liquid transfer method of the third embodiment is used for fluid separation.

[Explanation of symbols]

5 ... Spherical liquid 11 ... Transfer member (member having poor wettability surface) 12, 13, 21 ... Fork (member having bad wettability surface) 31 ... Needle-like transfer member 41 ... Planar member ( Member having a surface with poor wettability) 52 ... Groove

Claims (1)

[Claims] 1. A method of transferring a liquid, wherein the liquid to be transferred is formed into a spherical shape having a predetermined size or less by the surface tension of the liquid, and the spherical liquid is wettable with respect to the liquid. A liquid transfer method characterized in that the liquid is moved while being brought into contact with a member having a bad surface.