JP2016116248A - Solvent control method, and solvent for use in solvent control method - Google Patents

Abstract

In general, it has been shown that a polar solvent containing water is used for droplet operation by electrowetting, but water has a problem that it easily evaporates and its volume changes. A solvent control method for controlling a position of a solvent using a solvent control device according to an aspect of the present invention includes: a substrate; a plurality of electrodes disposed on the substrate; A dielectric disposed to cover the substrate and the plurality of electrodes; and a water-repellent film disposed on the dielectric and having water repellency, and applies a voltage to the plurality of electrodes. By controlling the position of the solvent on the water repellent film, the solvent contains at least one of amide, glycol, glycerin, amino alcohol, hydroxyamine, polyhydric alcohol, and 3.1 ( mN / m) to 28.8 (mN / m) of polar force component. [Selection] Figure 1

Description

  The present invention relates to a solvent control method and a solvent used in the solvent control method.

  There is droplet movement control using “electrowetting (EW)”. EW is a technique for controlling the wetting of droplets on a solid surface by applying a voltage.

  An example of a control device using EW includes a substrate, a plurality of electrodes disposed on the substrate, and a water repellent film disposed on the plurality of electrodes. A droplet is dropped on the water repellent film, the application of a voltage to each electrode is controlled, and the droplet is moved to move the position of the droplet.

  It is disclosed that the polar force component of the water repellent coating layer is one of the factors that determine the force acting on the interface between water and the water repellent material (for example, Patent Document 1).

  Various organic solvents and ionic liquids are disclosed as polar solvents used for electrowetting other than water. The conditions for the polar solvent indicate viscosity, surface tension of the droplet, and conductivity (Patent Documents 2 and 3).

Japanese Patent No. 4370687 Special table 2012-520485 gazette Special table 2013-501259 gazette

  In the apparatus according to the patent document, whether or not the solvent is operated has not been sufficiently examined even after a predetermined time since the solvent was dropped.

  In the solvent control method for controlling the position of the solvent using the solvent control device according to one aspect of the present invention, the solvent control device includes a substrate, a plurality of electrodes disposed on the substrate, the substrate, and the substrate. A dielectric disposed so as to cover the plurality of electrodes, a water repellent film disposed on the dielectric and having water repellency, and applying a voltage to the plurality of electrodes, The position of the solvent on the water-repellent film is controlled, and the solvent includes at least one of amide, glycol, glycerin, amino alcohol, hydroxyamine, polyhydric alcohol, and 3.1 (mN / m) It has a polar force component of 28.8 (mN / m) or less.

  The solvent control method according to the present disclosure can operate the solvent even after a predetermined time since the solvent is dropped.

It is the figure which looked at an example of the solvent control apparatus 100 from the upper surface. It is the figure which looked at an example of solvent control device 100 from the side. 5 is a diagram illustrating an example of a method for controlling the position of a solvent 203. FIG. 5 is a diagram illustrating an example of a method for controlling the position of a solvent 203. FIG. 5 is a diagram illustrating an example of a method for controlling the position of a solvent 203. FIG. 5 is a diagram illustrating an example of a method for controlling the position of a solvent 203. FIG. It is a figure which shows the relationship between the polar force component of a solvent, and the minimum drive voltage.

  Prior to describing the embodiments, the knowledge on which the present invention is based will be described.

  The inventors conducted experiments to control the position of the solvent based on the polar force component of the solvent. As a result of the experiment, it was found that there is a difference in whether or not the solvent can be operated according to the time after dropping.

  Furthermore, the present inventors have obtained new knowledge as to whether or not the solvent operates depending not only on the polar force component of the solvent but also on the material and volume of the solvent. Specific contents will be described with reference to embodiments and examples.

(Embodiment 1)
Hereinafter, embodiments will be described with reference to the drawings.

  “Electrowetting (EW)” means a method of controlling the wetting of a droplet by applying a voltage to a droplet having a polarity.

  FIG. 1 shows a view of an example of the solvent control device 100 as viewed from above. FIG. 2 shows a side sectional view of an example of the solvent control device 100.

  The solvent control apparatus 100 shown in FIGS. 1 and 2 includes a substrate 204, a plurality of electrodes 201, a dielectric 205, and a water repellent film 206. In FIG. 1, the dielectric 205 and the water repellent film 206 are omitted. Actually, the dielectric 205 and the water repellent film 206 are disposed on at least the plurality of electrodes 201.

  The solvent control apparatus 100 controls the position of the solvent 203 disposed on the water repellent film 206 by applying a voltage to the plurality of electrodes 201. Each configuration will be described below.

<Substrate 204>
A known insulating material is used for the substrate 204. Examples of the insulating material include glass and sapphire.

As the substrate 204, a substrate in which an insulating material such as SiO ₂ , Al ₂ O ₃ , or a polymer material is coated on a conductive material or a semiconductor material containing silicon or metal may be used.

<Electrode 201>
The plurality of electrodes 201 are disposed inside a dielectric 205 described later. Alternatively, the plurality of electrodes 201 are disposed on the substrate 204 and are disposed so that the dielectric 205 covers the top.

  As shown in FIG. 2, each of the plurality of electrodes 201 is disposed at a position separated from each other. The distance between the two electrodes 201 is smaller than the width of the electrode 201. An example of the distance between the two electrodes 201 is desirably 1 mm or less. Each electrode in the plurality of electrodes 201 is also referred to as an electrode 201a, an electrode 201b, an electrode 201c, an electrode 201d, and an electrode 201e. The electrode 201a, the electrode 201b, the electrode 201c, the electrode 201d, and the electrode 201e are also collectively referred to as the electrode 201.

  A voltage is applied to the plurality of electrodes 201. As shown in FIGS. 1 and 2, for example, an electrode wiring 202 is electrically connected to each of the plurality of electrodes 201. For example, the electrode wiring 202a, the electrode wiring 202b, the electrode wiring 202c, the electrode wiring 202d, and the electrode wiring 202e are electrically connected to the electrode 201a, the electrode 201b, the electrode 201c, the electrode 201d, and the electrode 201e, respectively.

  The power source (voltage application unit) 207 controls the position of the solvent 203 by applying a voltage to at least one of the plurality of electrodes 201 via the electrode wiring 202. Details will be described later.

  For the electrode 201, a known material having electrical conductivity can be used. An example of the material of the electrode 201 is at least one metal selected from Au, Pt, Cu, Al, and Ag.

  When the solvent control device 100 is used for a display device or the like and an electrode having optical transparency is required, a transparent conductive material containing ITO (Indium Tin Oxide) or ZnO is used as the electrode 201. desirable.

  In addition, by using Cr or Ti as the material of the electrode 201, adhesion between the electrode 201 and the substrate 204 or the dielectric 205 can be improved.

  The electrode 201 can be formed by using a known film formation method such as an evaporation method or a sputtering method.

  The electrode 201 desirably has a thickness of 0.01 μm to 2 μm.

  For example, when the electrode 201 having a thickness larger than 2 μm is formed on the substrate 204, the height of the region where the electrode 201 is formed on the surface of the substrate 204 and the height of the region where the electrode 201 is not formed are formed. There is a big difference. As a result, when the dielectric 205 and the water repellent film 206 are formed, regions having different heights may be formed in the dielectric 205 and the water repellent film 206. May have an impact.

  The electrode 201 having a thickness smaller than 0.01 μm has high electric resistance, and the electric resistance of the electrode 201 and the electrode wiring 202 is high. That is, since the electric resistance of the portion to which the voltage is applied (the electrode 201 and the electrode wiring 202) is increased, the voltage applied from the voltage applying unit 207 is lost, so that it is difficult to apply a desired voltage to the electrode 201. .

<Dielectric 205>
The dielectric 205 is disposed on the electrode 201. The dielectric 205 may also be disposed on the substrate 204. As the dielectric 205, a known insulating material can be used. An example of the dielectric 205 is an insulating material such as a polymer compound, various oxides of an inorganic compound, a composite oxide, or a nitride.

  When a voltage is applied to the electrode 201, the dielectric 205 desirably has a large capacitance. Therefore, the dielectric 205 can be a dielectric material capable of forming a film having a thickness of 1 μm or less, or a material having a high relative dielectric constant.

  In the case where the dielectric 205 is made of a polymer compound, the dielectric 205 can be formed using a known method such as a dipping method, a spray coating method, or a spin coating method. In the case where the dielectric 205 is made of an inorganic compound, the dielectric 205 can be formed using a known method such as a sputtering method, a spray coating method, or a spin coating method.

<Water repellent film 206>
It is disposed on the dielectric 205. An example of the material of the water-repellent film is a compound having a fluoroalkyl chain such as polytetrafluoroethylene (PTFE) or AF1600 (manufactured by DuPont).

  In general, the water repellent film 206 has a high water repellency by having a fluoroalkyl chain.

  Among compounds having a fluoroalkyl chain, a compound having a silane coupling agent is desirable because it can be covalently bonded by a coupling reaction with the dielectric 205, thus preventing peeling of the dielectric 205 and the water repellent film 206. .

  Examples of the compound having a fluoroalkyl chain capable of silane coupling with dielectric 205 are trifluoropropyltrimethoxysilane, perfluorooctyltrimethoxysilane, perfluorodecyltrimethoxysilane, perfluorooctyltrichlorosilane, perfluorodecyl. It is trichlorosilane, Cytop (registered trademark) (manufactured by Asahi Glass), or OPTOOL (manufactured by Daikin Industries).

  Since the water repellent film 206 operates the solvent on its surface, it is desirable that the water repellent film 206 has a weak adhesion to the solvent. As a more specific example, the sliding angle is 30 ° or less with respect to the solvent 203.

<Solvent 203>
An example of the solvent 203 is a material including at least one selected from amide, glycol, glycerin, aminoalcohol, hydroxyamine, and polyhydric alcohol.

  Specific examples of the solvent 203 include at least one selected from formamide, ethylene glycol monoethyl ether, and tetrabromoethane.

  The solvent 203 has a polar force component of 3.1 (mN / m) or more and 28.8 (mN / m) or less.

  More desirably, it contains at least one selected from formamide and ethylene glycol monoethyl ether, and the polar force component is 3.1 (mN / m) or more and 28.8 (mN / m) or less.

  More preferably, it contains at least one selected from formamide and ethylene glycol monoethyl ether, and the polar force component is 3.1 (mN / m) or more and 22.0 (mN / m) or less.

  In the embodiment, the specific contents described above will be described in detail.

  Formamide can be used particularly preferably because it has a polar force component higher than a predetermined value and a high boiling point, so that droplet operation by electrowetting occurs stably.

  In addition, ethylene glycol monoethyl ether has a polar force component of a predetermined value or more and has a low melting point and a high boiling point. Therefore, ethylene glycol monoethyl ether can be preferably used in a droplet operation by electrowetting that requires a low temperature operation.

<Solvent control method>
Next, a droplet control method in the solvent control apparatus 100 will be described with reference to FIGS. 3A to 3D.

  3A to 3D, the dielectric 205 and the water repellent film 206 are omitted as in FIG. 1, but the dielectric 205 and the water repellent film 206 are actually disposed on the electrode 201.

<FIG. 3A>
As shown in FIG. 3A, a solvent 203 is disposed on the water repellent film 206. The solvent 203 is located on the at least two electrodes 201. In FIG. 3A, the solvent 203 is located on the electrode 201a and the electrode 201b.

<FIG. 3B>
A voltage is applied so that a voltage is applied only to the electrode 201b from the state of FIG. 3A. For example, when the electrode 201b is electrically connected to the electrode wiring 202b and the voltage application unit 207 (not shown), the voltage application unit 207 applies a voltage to the electrode 201b via the electrode wiring 202b. A portion of the solvent 203 located on the electrode 201b has a small contact angle due to a change in wettability, and a contact area with the water repellent film 206 is increased. As a result, the solvent 203 moves from the current position toward the upper side of the electrode 201b.

  Specifically, as shown in FIG. 3B, the solvent 203 moves in the direction of arrow A.

<FIG. 3C>
A voltage is applied so that a voltage is applied only to the electrode 201c from the state of FIG. 3B. As a result, the solvent 203 moves in the direction of arrow A as shown in FIG. 3C.

  Note that a voltage may be applied to the electrode 201b and the electrode 201c. By applying a voltage only to the electrode 201c after applying a voltage to both the electrode 201b and the electrode 201c, the solvent 203 can be moved above the electrode 201c as shown in FIG. 3C.

<FIG. 3D>
A voltage is applied so that a voltage is applied only to the electrode 201c from the state of FIG. 3C. As a result, as shown in FIG. 3D, the solvent 203 moves in the direction of arrow A.

  As described above, when a voltage is applied to the electrode 201 in which at least a part of the solvent 203 is located above, the wettability of the solvent 203 located above the electrode 201 changes. As a result, the position of the solvent 203 moves on the water repellent film 206.

  The position of the solvent 203 can be moved (controlled) not only in the direction of the arrow A shown in FIGS. 3A to 3D but also in the opposite direction of the arrow A by controlling the position of the electrode with the voltage.

  The following examples teach the present disclosure in more detail.

Example 1
A glass substrate was prepared as the substrate 204.

  An electrode 201 and an electrode wiring 202 made of chromium and gold were formed on a glass substrate by photolithography.

  Specifically, it will be described. Chromium and gold were deposited on the entire top surface of the glass substrate. A resist was applied to the upper surface of chrome and gold. After applying the resist, exposure was performed using a photomask. After exposure, the resist was removed and etched to form chromium and gold in desired shapes.

  As shown in FIG. 1, the shape of the electrode 201 and the electrode wiring 202 was formed. The electrode 201 was 0.5 mm in the width direction and 3 mm in the vertical direction. Here, the width direction is the left-right direction shown in FIG. 1, and is the direction in which the solvent 203 described later moves. The vertical direction is a direction perpendicular to the width direction. Forty electrodes 201 were formed to be aligned in the width direction. The space between the electrodes 201 was 50 μm. Forty electrodes 201 had a length of 41 mm in the width direction.

As the dielectric 205, SiO ₂ having a thickness of 150 nm was formed on the glass substrate, the electrode 201 and the electrode wiring 202 made of chromium and gold by a sputtering method.

As the water repellent film 206, an amorphous fluorinated polymer thin film (CYTOP (registered trademark) manufactured by Asahi Glass Co., Ltd.) was formed on SiO ₂ using a spin coating method. The film thickness of the water repellent film 206 was about 2 μm.

  As the solvent 203, formamide was used. The amount of the solvent 203 was three types: 3 μL, 5 μL, and 10 μL.

  After formamide was dropped on the water-repellent film 206, a voltage of 150 V was applied to the electrode 201 via the electrode wiring 202, and an experiment was conducted as to whether or not the solvent 203 moved.

  At the same time when formamide was dropped onto the water-repellent film 206, application of a voltage to the electrode 201 and switching of the electrode 201 to which the voltage was applied (hereinafter also referred to as switching of voltage application) were started. The voltage application to each electrode 201 was switched every 0.1 second. The voltage is applied from end to end of the 40 electrodes 201 in 4 seconds, and the direction of voltage application is reversed every 4 seconds, and the solvent 203 reciprocates left and right every 4 seconds. Condition. An experiment was conducted as to whether or not formamide operates immediately after the addition of the solvent 203, 5 minutes after the addition, and 10 minutes after the addition.

(Example 2)
The experiment was performed in the same manner as in Example 1 except that ethylene glycol monoethyl ether was used as the solvent 203. Table 1 shows the experimental results.

(Example 3)
The experiment was performed in the same manner as in Example 1 except that tetrabromoethane (TBE) was used as the solvent. Table 1 shows the experimental results.

(Comparative Example 1)
The experiment was performed in the same manner as in Example 1 except that water was used as the solvent. Table 1 shows the experimental results.

(Comparative Example 2)
The experiment was performed in the same manner as in Example 1 except that ethanol was used as the solvent. Table 1 shows the experimental results.

(Comparative Example 3)
The experiment was performed in the same manner as in Example 1 except that n-hexadecane, which is a nonpolar solvent, was used as the solvent. Table 1 shows the experimental results.

<Experimental results in Table 1>
Table 1 shows the experimental results of Examples 1 to 3 and Comparative Examples 1 to 3.

  As shown in Table 1, when the solvents of Example 1 and Example 2 were used, the solvent operated regardless of the volume and time of the solvent. In this embodiment, whether or not the solvent has operated is determined by determining whether or not the solvent 203 has operated for 20 mm or more after 4 seconds have elapsed since the time when the operation direction was switched first after that time. When the operation is less than 20 mm, it was determined that “does not work”. It is considered that the same result can be obtained by using a known method as a method for determining whether or not the solvent has been operated.

  The TBE of Example 3 was 3 μL, and the droplets operated immediately after dropping, 5 minutes after dropping, and 10 minutes after dropping. The TBE of Example 3 was 5 μL, and the droplet operated immediately after dropping, 5 minutes after dropping, and 10 minutes after dropping.

  However, when TBE is 5 μL and immediately after dropping, 5 minutes after dropping, and 10 minutes after dropping, and when TBE is 10 μL, immediately after dropping, 5 minutes after dropping, and 10 minutes after dropping. TBE did not work. TBEs with 5 μL and 10 μL were observed to change wettability when voltage was applied, but did not move.

  In Comparative Example 1, water operated immediately after dropping in any volume. However, water started to evaporate immediately after dropping, and the volume of water decreased. Five minutes after the dropping, the water having a volume of 3 μL and 5 μL was evaporated, and it was judged that it did not operate because almost all of the water was lost. In the case of water having a volume of 10 μL, the volume became less than several μL after 5 minutes, and the device became inoperative. The reason why the device did not operate at several μL despite the same volume is thought to be that dirt (or scale) adhered to the water-repellent film 206 after the water evaporated. It was judged that the water of Comparative Example 1 did not operate because water disappeared after 10 minutes in any volume.

  The ethanol of Comparative Example 2 did not work at any volume and time. When voltage was applied, it was confirmed that ethanol wettability changed on the electrode, but it did not move. This is probably because ethanol has a small polar force component. In addition, ethanol having any volume was evaporated after 5 minutes or 10 minutes from dropping.

  The n-hexadecane of Comparative Example 3 did not operate at any volume and time. Even when a voltage was applied, it was not possible to confirm a change in the wettability of n-hexadecane, and n-hexadecane did not operate.

  From the above results, in Examples 1 to 3, the solvent operates even after a predetermined time from the dropping of the solvent, whereas in Comparative Examples 1 to 3, the solvent operates after the predetermined time from the dropping of the solvent. There wasn't. In other words, by using formamide, ethylene glycol monoethyl ether, or TBE as a solvent, it was found that the solvent operates even after a predetermined time from the dropping of the solvent.

  Furthermore, in Examples 1 and 2, the solvent operated even when the volume of the solvent was large. In other words, it has been found that by using formamide or ethylene glycol monoethyl ether as a solvent, the solvent operates even when the volume of the solvent is large.

  Next, according to Examples 4 and 5, an experiment was conducted to determine whether or not the same effect can be obtained even when formamide and ethylene glycol monoethyl ether are mixed.

Example 4
ITO was used as the material of the electrode 201 and the electrode wiring 202.

  An electrode 201 and an electrode wiring 202 were formed on the substrate.

As the dielectric 205, SiO ₂ having a thickness of 150 nm was formed on the glass substrate, the electrode 201 and the electrode wiring 202 made of ITO by a sputtering method.

As the water repellent film 206, CYTOP (registered trademark) manufactured by Asahi Glass Co., Ltd. having a thickness of about 2 μm was applied on SiO ₂ by spin coating.

  As the solvent 203 of Example 3, a solvent in which formamide and ethylene glycol monoethyl ether were mixed was used. As shown in Table 2, the specific ratio was 36.5% for formamide and 63.5% for ethylene glycol monoethyl ether. The mixing ratio indicates the volume fraction.

  An experiment was conducted to determine whether or not the solvent operates immediately after dropping 10 μL of the solvent 203 on the water-repellent film 206 and at each time 30 minutes after the dropping. The experimental environment was in the atmosphere. Table 3 shows the experimental results.

(Example 5)
The experiment was performed in the same manner as in Example 4 except that the mixing ratio of formamide and ethylene glycol monoethyl ether was different as the solvent. As shown in Table 2, the specific ratio was 90.7% for formamide and 9.3% for ethylene glycol monoethyl ether. The mixing ratio indicates the volume fraction.

  Next, an experiment was conducted on whether or not the effect was obtained in the same manner as in Example 6 even when formamide and water were mixed. Table 3 shows the experimental results.

(Example 6)
The experiment was performed in the same manner as in Example 3 except that the mixing ratio of water and formamide was used as the solvent. The specific ratio was 20% for water and 80% for formamide. The mixing ratio indicates the volume fraction.

  In addition, each material of the solvent used in Examples 4 to 6 corresponds to a material having a surface tension of 30 mN / m, 40 mN / m, 50 mN / m, or 60 mN / m as defined in JIS K6768. Table 3 shows the experimental results.

  Table 2 shows specific ratios of Examples 4 to 6.

<Experimental results in Table 3>
In addition to Examples 4 to 6, also in Example 2, whether or not the solvent operates immediately after dropping 10 μL of the solvent 203 on the water-repellent film 206 and at each time 30 minutes after the dropping. The experiment was conducted. Table 3 shows the experimental results.

  According to the experimental results for the solvents of Examples 2 and 4 to 6, it was found that the solvent was operated immediately after the dropping and at each time 30 minutes after the dropping. When the electrode 201 is made of ITO, the resistance of the electrode 201 is higher than that of the first embodiment. That is, it is a disadvantageous condition when applying a voltage, but there is no change in the operation of the solvent as in Example 1, and the solvent depends on the type of electrode 201 in Example 1 and Example 2 being different. It is considered that the influence on the operation 203 is small.

  In Example 6, it was observed that the volume of the solvent decreased at the time 30 minutes after the dropping. It is thought that water contained in the solvent has evaporated. The solvent of Example 6 worked even when the water contained in the solvent evaporated.

From the results of Examples 4 and 5, it was found that when a mixture of formamide and ethylene glycol monoethyl ether was used as the solvent, the solvent operated by applying a voltage.
From this result, it is considered that the solvent of the mixture of the materials of Examples 1 to 3 operates when a voltage is applied.

  From the results of Example 6, it was found that when a mixture of ethylene glycol monoethyl ether and water was used as a solvent, the solvent was operated by applying a voltage even 30 minutes after dropping. When the solvent is composed of water, the solvent does not operate by applying a voltage 30 minutes after dropping. That is, in the mixture of the materials of Examples 1 to 3 and a material that does not operate when used as a solvent, it is considered that the solvent operates by applying a voltage even after 30 minutes from dropping. It is considered desirable that the ratio of the material that does not operate when used as a solvent is not more than a predetermined ratio. This is because it is considered that it becomes difficult for the solvent to operate by mixing a material that does not operate when used as a solvent at a ratio higher than a predetermined ratio. From the result of Example 6, the example of the predetermined ratio is 20%.

Table 4 shows the surface tension (γ) and the polar force component (γ ^P ) for Examples 1 to 6 and Comparative Examples 1 to 3 described above. Table 4 shows whether the solvent was operated by applying a voltage immediately after dropping the solvent and 30 minutes after dropping.

  The solvent volume was 3 μL. For Examples 1 to 3 and Comparative Examples 1 to 3, the result of Table 1 adds the result of whether or not the solvent operates 30 minutes after dropping. The results 30 minutes after the dropping of Examples 1 to 3 and Comparative Examples 1 to 3 were the same as the results after 10 minutes from the dropping.

A method for calculating the polar force component will be described. (Expression 1) shows an extended Fowkes expression. The surface tension (γ) is expressed as the sum of the dispersion component (γ ^d ), the polar component (γ ^p ), and the hydrogen bond component (γ ^h ) shown in (Equation 2). The polar force component is represented by the sum of the polar component and the hydrogen bond component. Γ ^p was calculated using (Equation 1) and (Equation 2).

Here, cos θ represents a contact angle. γ _S indicates the surface tension of the water repellent film. γ _S ^d represents a dispersed component of the water-repellent film. γ _S ^p represents a polar component of the water repellent film. γ _S ^h represents a hydrogen bond component of the water repellent film. γ _L indicates the surface tension of the solvent. γ _L ^d represents a dispersed component of the solvent. γ _L ^p represents the polar component of the solvent. γ _L ^h represents a hydrogen bond component of the solvent. The polar force component of the solvent in this example is represented by the sum of the polar component of the solvent and the hydrogen bonding component of the solvent.

  The contact angle of the solvent was measured using a contact angle meter (“DM500” manufactured by Kyowa Interface Chemical Co., Ltd.).

Two types of water-repellent films with known surface tension (γ _S ), dispersion component (γ _S ^d ), polar component (γ _S ^p) , and hydrogen bond component (γ _S ^h ) were prepared. A solvent having a known surface tension (γ _L ) was dropped onto the two types of water-repellent films to obtain contact angles cos θ (that is, two types of contact angles) for each of the two types of water-repellent films.

From the two (Formula 1) and (Formula 2) obtained by the two types of water-repellent films, the polar component (γ _L ^p ) of the solvent and the hydrogen bond component (γ _L ^h ) of the solvent were determined. Next, the polar force component of the solvent represented by the sum of the polar component (γ _L ^p ) and the hydrogen bond component (γ _L ^h ) was calculated.

<Experimental results of Table 1 and Table 4>
As shown in Table 4, Examples 1 to 6 are at least one selected from amide, glycol, glycerin, aminoalcohol, hydroxyamine, and polyhydric alcohol, and 3.1 (mN / m) It has a polar force component of 28.8 (mN / m) or less. More specifically, the materials of Examples 1 to 6 include at least one selected from formamide, ethylene glycol monoethyl ether, and tetrabromoethane. Thereby, the solvent can be operated even after a predetermined time since the solvent was dropped.

  In addition, as shown in Table 4, when the volume of tetrabromoethane according to Example 3 was 3 μL, the solvent operated. However, as shown in Table 1, the solvent did not work when the volume of tetrabromoethane was 5 μL and 10 μL. That is, it contains at least one selected from formamide, ethylene glycol monoethyl ether, and tetrabromoethane, and the polar force component is 3.1 (mN / m) or more and 28.8 (mN / m). However, depending on the volume of the solvent, the solvent could not be operated.

  The polar force component of Example 3 was 3.2 (mN / m). On the other hand, the polar component of Example 2 was 3.3 (mN / m) which is substantially the same as the polar force component of Example 3. However, as shown in Table 1, the solvent of Example 2 did not depend on the volume and the solvent operated, but in Example 3, there was a change in whether or not the solvent operated depending on the volume. . That is, the present inventors have found that there is a difference in whether or not the solvent operates depending on not only the polar force component but also the solvent material or the like.

As in Examples 1, 2, 4 to 6, it contains at least one selected from formamide and ethylene glycol monoethyl ether, and the polar force component is 3.1 (mN / m) or more and 28.8 (mN / M) In the following cases, the dependency of the volume of the solvent is reduced, and the solvent can be operated even after a predetermined time after the solvent is dropped. In Example 6, even after 30 minutes from the dropping, The solvent could be operated but the solvent volume was reduced. This result shows that the solvent has a polar component of a predetermined value or more by containing water, but causes a reduction in volume. By reducing the volume, it may be difficult to arrange on the plurality of electrodes. Therefore, it is desirable to suppress a reduction in the volume of the solvent after the solvent has been dropped.

  Therefore, as in Examples 1, 2, 4, and 5, it contains at least one selected from formamide and ethylene glycol monoethyl ether, and the polar force component is 3.1 (mN / m) or more and 22. More preferably, it is 0 (mN / m) or less. Thereby, the volume reduction of the solvent can be suppressed, the dependency on the volume of the solvent can be reduced, and the solvent can be operated even after a predetermined time by dropping the solvent. It was found that the same effects can be obtained when the volume of the solvent in Examples 1, 2, 4, and 5 is at least 3 μL or more and 10 μL or less.

<Results of drive voltage>
In FIG. 3, the result of having measured the minimum drive voltage which can operate | move a solvent in Examples 1-6 is shown. The vertical axis in FIG. 3 is the minimum driving voltage (V), and the horizontal axis is the polar force component (mN / m) of the solvent.

  After the solvent 203 was dropped on the water repellent film, the applied voltage was gradually increased, and the voltage at which the solvent 203 started to move was defined as the minimum driving voltage.

As shown in FIG. 2, the minimum drive voltage decreases as γ ^P decreases. Therefore, it is desirable that γ ^P is small because the solvent can be operated at a low voltage.

<Other physical properties>
The formamide of Example 1 had a specific gravity of 1.13 (g / cm 3), a boiling point of 210 ° C., a melting point of 2 ° C. to 3 ° C., and a vapor pressure of 0.11 hPa. The ethylene glycol monoethyl ether of Example 2 had a specific gravity of 0.93 (g / cm 3), a boiling point of 135 ° C., a melting point of −70 ° C., and a vapor pressure of 0.5 kPa.

  The specific gravity of water of Comparative Example 1 was 1, the boiling point was 100 ° C., the melting point was 0 ° C., and the vapor pressure was 23 hPa. Since the materials of Examples 1 and 2 have a boiling point higher than that of water and have a low vapor pressure, they are difficult to evaporate and have a small volume change. It is desirably used as a solvent used in the above.

  As described above, since the solvent according to this embodiment can be operated for a long time after the solvent is dropped, it is suitable for a solvent control method (for example, transportation of parts) used in an environment such as a biochip or outdoors. Used for.

  The solvent control method according to the present disclosure is useful for stably controlling the solvent, and can be used particularly in the field of solvent removal or component transportation in an outdoor environment.

201, 201a, 201b, 201c, 201d, 201e Electrode 202, 202a, 202b, 202c, 202d, 202e Electrode wiring 203 Solvent 204 Substrate 205 Dielectric 206 Water repellent film

Claims (10)

A solvent control method for controlling the position of a solvent using a solvent control device,
The solvent control device includes:
A substrate,
A plurality of electrodes disposed on the substrate;
A dielectric disposed to cover the substrate and the plurality of electrodes;
A water-repellent film disposed on the dielectric and having water repellency;
By applying a voltage to the plurality of electrodes, the position of the solvent on the water repellent film is controlled,
The solvent contains at least one of amide, glycol, glycerin, aminoalcohol, hydroxyamine, and polyhydric alcohol, and has a polar power of 3.1 (mN / m) or more and 28.8 (mN / m) or less. A solvent control method comprising a component. The solvent includes at least one selected from formamide, ethylene glycol monoethyl ether, and tetrabromoethane.
The solvent control method according to claim 1. The solvent includes at least one selected from formamide and ethylene glycol monoethyl ether.
The solvent control method according to claim 1. The solvent has a polar force component of 3.1 (mN / m) or more and 22.0 (mN / m) or less,
The solvent control method according to claim 3. The solvent has a volume of 3 μL or more and 10 μL or less;
The solvent control method according to claim 4. A solvent used in a solvent control method for controlling the position of a solvent by a solvent control device,
The solvent control device includes:
A substrate,
A plurality of electrodes disposed on the substrate;
A dielectric disposed to cover the substrate and the plurality of electrodes;
A water-repellent film disposed on the dielectric and having water repellency;
The solvent control method controls the position of the solvent on the water repellent film by applying a voltage to the plurality of electrodes,
The solvent contains at least one of amide, glycol, glycerin, aminoalcohol, hydroxyamine, and polyhydric alcohol, and has a polar power of 3.1 (mN / m) or more and 28.8 (mN / m) or less. A solvent having components. The solvent contains at least one selected from formamide, ethylene glycol monoethyl ether, and tetrabromoethane in a predetermined ratio or more.
The solvent according to claim 6. The solvent includes at least one selected from formamide and ethylene glycol monoethyl ether.
The solvent according to claim 6. The solvent has a polar force component of 3.1 (mN / m) or more and 22.0 (mN / m) or less,
The solvent according to claim 8. The solvent has a volume of 3 μL or more and 10 μL or less;
The solvent according to claim 9.

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