JP4625959B2 - Liquid feeding system - Google Patents

Description

  The present invention relates to a liquid delivery system, and more particularly to a liquid delivery system suitable for application to a micromachine.

  Stimulus-responsive polymer gels have properties that swell and shrink in response to the application of minute external stimuli such as temperature change, electric field application, light irradiation, pH change, addition of chemical substances, etc., and their shape and physical properties change significantly. . Attempts have been made to apply such characteristics to various uses related to material separation and energy conversion.

  Also in relation to the liquid feeding system, Patent Document 1 discloses that an electrically responsive or thermally responsive polymer gel is provided in a volume part having an elastic film as one wall, and the elastic film is elastically deformed by the deformation to directly or needle The flow rate control device is characterized in that the area of the fluid flow path is adjusted via the.

  Patent Document 2 describes a pressure-functional chemical valve in which a substance is selectively permeated or the amount of water permeation is controlled through a polymer gel whose mesh pore size changes with pressure.

JP 7-27239 A JP 2002-147628 A

  However, as in the apparatus described in Patent Document 1, in the case where the elastic membrane is elastically deformed by deformation of the polymer gel and the area of the flow path is adjusted, the area of the flow path is adjusted by adjusting the physical gap. Therefore, it is accompanied by mechanical deformation of the polymer gel depending on the flow rate, so that it cannot be applied to precise control of a minute flow rate of 1 microliter / minute or less in principle. On the other hand, as in the valve described in Patent Document 2, there has been an attempt to directly apply the change in the mesh size of the polymer gel to the adjustment of the water permeation amount. It was not applicable to precise control of

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid feeding system that does not require a mechanical control member and at the same time allows precise control of a minute flow rate and is suitable for application to a micromachine.

  In order to solve the above-described problems, the present invention provides a liquid delivery system having a pressurizing unit, a flow rate control unit, and a flow rate detection unit, wherein the flow rate control unit is in close contact with a tube wall of the flow channel. A main body and an external stimulus comprising a polymer gel layer provided, the polymer gel constituting this layer has stimulus responsiveness, and the thickness of the layer is not less than 0.5 times the equivalent diameter of the flow path It is characterized by comprising a giving means.

  In the present invention, the external stimulus is preferably a temperature change, and the polymer gel is preferably a crosslinked N-alkylacrylamide polymer hydrogel.

  The present invention is also characterized in that the stimulation response of the polymer gel layer of the main body of the flow rate control means provided at each end of the branching point is reversed.

  According to the present invention, a mechanical control member is not required, and at the same time, a target substance (liquid) is controlled at an arbitrarily controlled speed for a long period of time in a micro flow rate range of 10 −1 to −6 microliters / minute. A liquid delivery system that can be injected and is suitable for micromachine applications is provided. Since the pore size of the gel is determined by the network structure formed during gel synthesis, by controlling the external environment during synthesis, the average pore size can be changed using the non-uniformity of the network, and the absolute value of the flow rate is It is possible to control within the range.

  Moreover, in the aspect in which the stimulus responsiveness of the polymer gel layer of the flow rate control means main body provided at each end of the branch point is reversed, the same external stimulus is applied to both flow rate control means main bodies. The function of reversing the main flow path is also exhibited.

  In the present invention, the main body of the flow rate control means is composed of a polymer gel layer provided in close contact with the tube wall of the flow channel in a part of the flow channel, and the polymer gel constituting this layer exhibits stimulus responsiveness. And the thickness of the layer is equal to or more than the equivalent diameter of the flow path, specifically 0.5 times or more, preferably 1 to 50 times, particularly preferably 3 to 30 times the equivalent diameter. is important.

  In this way, even if the external environment is changed and the gel is stimulated, the gel is constrained by the flow path and hardly changes in volume, and it operates under conditions where the network density of the polymer matrix hardly changes. become. Since the flow rate is proportional to the applied pressure and inversely proportional to the layer thickness at the time of gel synthesis, the mechanical deformation of the polymer gel depending on the flow rate and the layer thickness does not affect the flow rate. Since the macroscopic volume change of the gel is suppressed, when the attractive force applied to the polymer matrix by an external stimulus increases, the area where the pores of the mesh become larger (domain) and the area where the pore becomes smaller (domain) are compatible. Separate (phase separation effect). At this time, if the large pore diameter domain is percolated in the thickness direction of the layer, the flow velocity increases (percolation effect). Otherwise, the flow velocity is reduced by the rate of passage through the small pore diameter domain. This balance of the phase separation effect / percolate effect determines the effective average pore size of the flow velocity due to changes in the external environment, and increases or decreases the macroscopic flow velocity.

  In contrast, when the volume of the gel is released by releasing the constraint of the gel, if the attractive force applied to the polymer matrix is also increased by external stimulation, all pore diameters are reduced and the flow velocity is reduced in the equilibrium state due to phase separation. Therefore, it becomes impossible to arbitrarily control the flow rate.

  In the present invention, the form of the pressurizing means is not particularly limited, and various types can be used. However, a method of adjusting the water level of the liquid supply storage tank from the viewpoint of the number of parts and the like can be preferably employed. Further, as the flow rate detecting means, a method of optically detecting the position of the front end surface of the flow rate control means passing liquid and measuring its moving speed is exemplified.

  Although the glass circular tube is exemplified as the constituent material of the flow path, a metal tube or a plastic tube can be adopted as the material, and the cross-sectional shape may be elliptical or rectangular. The equivalent diameter of the flow path is not particularly limited, but is usually set to about 0.1 to 10 mm from the aspect of the required flow rate.

  There are various forms of external stimuli such as temperature change, electric field application, light irradiation, pH change, chemical substance addition, etc., but temperature change in terms of the influence on the composition of the liquid to be delivered, the simplicity of the configuration of the applying means, etc. Is preferably employed. Examples of the temperature change providing means include a configuration in which a temperature-controlled heating medium is circulated in a tank that encloses the entire flow rate control means.

In the present invention, the composition of the polymer gel is appropriately selected according to the type of external stimulus to be applied, the required flow rate, etc., but when adopting a temperature change as the external stimulus and achieving precise control of a minute flow rate, the phase transition From the viewpoint of temperature range, availability, etc. , a crosslinked N-alkylacrylamide polymer hydrogel is preferably employed. By selecting the type of the alkyl moiety, the phase transition temperature can be changed, and the operating temperature can be selected in the range of 5 to 50 ° C.

  As a method for bringing the polymer gel into close contact with the tube wall of the flow path, as a method applicable when the constituent material is transparent, a predetermined portion on the inner surface of the flow path is treated with a silane coupling agent and the like, An example is a method in which a monomer mixture and a photopolymerization initiator solution (in the case of hydrogel, an aqueous solution) are partially filled and predetermined light irradiation is performed from the outside.

  In the present invention, the flow rate is controlled by controlling the gel network structure during the synthesis of the gel, setting the external environment appropriately, and changing the average flow diameter of the network corresponding to the nature of the solvent. is there.

  A configuration example of the present invention is shown in FIG. As the pressurizing means 1, in this example, a method of adjusting the water level of the liquid supply storage tank 11 and applying the water supply pressure Δp is adopted. The flow rate control means 2 includes a main body made of a thermoresponsive polymer gel layer 21 formed in close contact with the inner wall of the flow path, and an external stimulus applying means made of a thermostatic chamber 22 installed so as to cover this portion. Have. The constant temperature bath 22 is provided with an inlet 23 and an outlet 24 for the heat medium whose temperature is controlled. In the flow rate detection unit 3, a method of optically detecting the position of the tip surface 31 of the flow rate control means passage liquid and measuring the moving speed thereof is shown, but the detection means is not shown.

  An embodiment in the case where there is a branch in the flow path will be described with reference to FIG. A polymer gel layer 211 whose flow rate decreases with increasing temperature is provided on one of the flow paths ahead of the branch point 4, and a polymer gel layer 212 whose flow rate increases with increasing temperature is provided on the other side so as to cover both of them. When a low-temperature heating medium is supplied to the thermostatic chamber 221 installed in the tank, the main flow path is the 211 side, but when the heating medium temperature is raised to a predetermined value, the main flow path is cut to the 212 side. Change. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

  N-isopropylacrylamide (NIPA) 700 mM, N, N′-methylenebisacrylamide (BIS) is placed in the middle of a glass tube having an inner diameter of 1.35 mm which is internally treated with a silane coupling agent (γ-methacryloxypropyltrimethoxysilane). ) 8.6 mM, photopolymerization initiator (VA-086: 2,2′-azobis [2-methyl-N (2-hydroxyethyl) propionamide]) 1 mM aqueous solution was injected to a length of 1.5 mm. Then, at 0 ° C., gelation was performed by irradiating light for 30 minutes at a distance of 10 cm from an ultraviolet ray source (wavelength 365 nm, intensity 275 W / square m).

  The polymer gel layer thus obtained was used as the main body of the flow rate control means, and the liquid supply system shown in FIG. 1 was assembled and tested at a temperature of 30 ° C. and a water supply pressure (Δp) water column of 80 cm. The steady flow rate calculated from the position of the meniscus in the glass tube measured accurately using a microscope was 1 × 10 −6 ml / min. When a temperature change was applied to the polymer gel layer and the temperature was raised to 40 ° C., the steady flow rate was reduced by 3 orders of magnitude to 8 × 10 −10 ml / min.

  A polymer gel was produced in the same manner as in Example 1, except that the composition and concentration of the monomer aqueous solution were NIPA 600 mM, acrylamide (AAm) 100 mM, BIS 8.6 mM, and the glass tube length was 2 mm. The steady flow rate measured in the same manner as in Example 1 in this case is 1 × 10 −6 ml / min at 30 ° C., and 6 × 10 −8 ml / min and 2 by raising the temperature to 65 ° C. Decreased by orders of magnitude.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the aqueous monomer solution were NIPA 619 mM, AAm 81 mM, BIS 8.6 mM, the glass tube length was 5 mm, and the polymerization gelation temperature was 40 ° C. It was. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column is 10 cm is 5 × 10 −7 ml / min at 30 ° C., and when the temperature is raised to 40 ° C., 9 × 10 − It increased by an order of magnitude to 6 6 ml / min.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the aqueous monomer solution were NIPA 620 mM, AAM 80 mM, BIS 8.6 mM, the glass tube length was 9 mm, and the polymerization gelation temperature was 40 ° C. It was. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column is 1 cm in this case is 8 × 10 −6 ml / min at 30 ° C., and 2 × when the temperature is raised to 40 ° C. This was also increased by an order of magnitude to 10 −4 ml / min.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the monomer aqueous solution were NIPA 1050 mM, BIS 12.9 mM, the glass tube length was 5 mm, and the polymerization gelation temperature was 40 ° C. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column is 5 cm in this case is 2 × 10 −4 ml / min at 30 ° C., the temperature is raised to 40 ° C. and the water column is 2 cm. The steady flow rate measured in was 8 × 10 −3 ml / min.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the monomer aqueous solution were NIPA 2100 mM, BIS 25.8 mM, the glass tube length was 6 mm, and the polymerization gelation temperature was 40 ° C. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column is 23 cm in this case is 2 × 10 −4 ml / min at 30 ° C., the temperature is raised to 40 ° C., and the water column is 9 cm. The steady flow rate measured in was 1 × 10 −4 ml / min.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the monomer aqueous solution were NIPA 525 mM, BIS 175 mM, the glass tube length was 5 mm, and the polymerization gelation temperature was 40 ° C. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column in this case was 78 cm was 4 × 10 −7 ml / min at 23 ° C., and when the temperature was raised to 40 ° C., 1 × It decreased to 1/4 to 10 −7 ml / min.

  A polymer gel was produced in the same manner as in Example 1 except that the composition and concentration of the aqueous monomer solution were NIPA 525 mM, BIS 175 mM, the glass tube length was 2 mm, and the polymerization gelation temperature was 40 ° C. The steady flow rate measured in the same manner as in Example 1 except that the height of the water column is 27 cm in this case is 5 × 10 −6 ml / min at 23 ° C., and 4 × when heated to 40 ° C. It increased by 10 digits to the fourth power ml / min.

  The liquid feeding system of the present invention does not require a mechanical control member, and at the same time, can arbitrarily control a target substance (liquid) for a long period of time in a minute flow rate range of 10 -1 to -6 microliters / minute. Since it can be injected at a speed, it is expected to be applied to micromachines, production processes, environmental management, and drug administration in the medical field.

Explanatory drawing which shows the structure of the liquid feeding system of this invention. The typical top view which shows the principal part of an aspect when there exists a branch in a flow path.

Explanation of symbols

1 Pressure means
2 Flow rate control means 3 Flow rate detection unit (detection means not shown)
4 Branching point 11 Supply liquid storage tank 21 Polymer gel layer (flow rate control means body)
22 Thermostatic chamber (External stimulus application means)
23, 231 Heat medium inlet 24, 241 Heat medium outlet 31, 311, 312 Front end surface 211 of flow rate control means passage liquid First polymer gel layer 212 Stimulus response characteristics opposite to those of first polymer gel layer Second polymer gel layer

Claims (4)

  In the liquid feeding system having the pressurizing means, the flow rate control means, and the flow rate detection means, the flow rate control means comprises a polymer gel layer provided in close contact with the pipe wall of the flow path in a part of the flow path. The polymer gel constituting the layer is characterized by comprising a main body having stimulus responsiveness, and the thickness of the layer being 0.5 or more times the equivalent diameter of the flow path, and an external stimulus applying means. Liquid delivery system.   The liquid feeding system according to claim 1, wherein the external stimulus is a temperature change.   The liquid feeding system according to claim 1 or 2, wherein the polymer gel is a hydrogel of a cross-linked N-alkylacrylamide polymer.   The liquid feeding system according to any one of claims 1 to 3, wherein the flow path has a branch and the stimulus responsiveness of the polymer gel layer of the flow rate control means main body provided at each of the ends of the branch points is reversed.

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