Abstract:
In order to solve the problem of the generation of the interspace between layers, the present invention provides an actuator including: a conductive polymer layer; an ambient temperature molten salt layer; and an opposite electrode layer; wherein the ambient temperature molten salt layer is interposed between the conductive polymer layer and the opposite electrode layer, the ambient temperature molten salt layer includes an adhesive layer in the inside thereof; one surface of the adhesive layer adheres to the conductive polymer layer; and the other surface of the adhesive layer adheres to the opposite electrode layer.

Description:
TECHNICAL FIELD  
       [0001]    The present invention relates to an actuator. 
       BACKGROUND ART  
       [0002]    Patent Literature 1 discloses an actuator comprising a conductive polymer layer, an ambient temperature molten salt layer, and an electrode layer. More particularly, see  FIG. 13B  included in Patent Literature 1. 
         [0003]      FIG. 1  shows a schematic cross-sectional view of the actuator  1  shown in Non Patent Literature 1. The actuator  1  comprises a laminate  21 . The actuator  1  shown in  FIG. 1  comprises two laminates  21   a - 21   b.    
         [0004]    The laminate  21   a  comprises a conductive polymer layer  31 , an opposite electrode layer  34 , and an ambient temperature molten salt layer  35 . The laminate  21   a  shown in  FIG. 1  comprises a first conductive polymer layer  31   a , a first ambient temperature molten salt layer  35   a , an opposite electrode layer  34 , a second ambient temperature molten salt layer  35   b , and a second conductive polymer layer  31   b.    
         [0005]    Support layers  32  are formed on the obverse and reverse surfaces of the laminate  21   a . In more detail, a first support layer  32   a  and a second support layer  32   b  are formed on the obverse and reverse surfaces of the laminate  21   a , respectively. 
         [0006]    The laminate  21   a  (hereinafter, referred to as “first laminate  21   a ”) is stacked on the laminated on the laminate  21   b  (hereinafter, referred to as “second laminate  21   b ”). An adhesive film  36  is interposed between two laminates  21   a - 21   b . The adhesive film  36  is interposed between the second support layer  32   b  included in the first laminate  21   a  and the first support layer  32   a  included in the second laminate  21   b  so as to adhere these layers to each other. 
         [0007]    Each conductive polymer layer  31  is electrically connected to a first electrode  26  provided on the one side of the actuator  1 . Each opposite electrode layer  34  is electrically connected to the second electrode  27  provided on the other side of the actuator  1 . 
       CITATION LIST  
     Patent Literature 
       [0008]    [Patent Literature 1] U.S. Pat. No. 7,679,268 (corresponding to Japanese Patent No. 3959104) 
       Non Patent Literature  
       [0009]    [Non Patent Literature 1] M. Hiraoka et al. “HIGH PRESSURE PUMP AS LAB ON CHIP COMPONENT FOR MICRO-FLUIDIC INTEGRATED SYSTEM”, IEEE MEMS 2011 Technical Journal, 1139-1142 
       SUMMARY OF THE INVENTION 
     Technical Problem  
       [0010]    Through the first electrode  26  and the second electrode  27 , a negative voltage and a positive voltage are applied to the conductive polymer layers  31  and the opposite electrode layers  34 , respectively. When this voltage difference is applied, the thickness of the conductive polymer layer  31  is increased. This is because cations are moved from the ambient temperature molten salt layer  35  to the conductive polymer layer  31 . 
         [0011]    Then, a positive voltage and a negative voltage are applied to the conductive polymer layers  31  and the opposite electrode layers  34 , respectively. When this voltage difference is applied, the thickness of the conductive polymer layer  31  is decreased so as to return the actuator  1  to its original state. This is because the canions are moved from the conductive polymer layer  31  to the ambient temperature molten salt layer  35 . In this way, the actuator  1  serves. 
         [0012]    However, as shown in  FIG. 2 , when the increase and the decrease of the thickness of the conductive polymer layer  31  are repeated, an interspace is generated between these layers. Due to this interspace, it becomes difficult for the canions are moved between the conductive polymer layer  31  and the ambient temperature molten salt layer  35 . As a result, the actuator  1  fails to serve. 
         [0013]    The purpose of the present invention is to provide an actuator solving this problem. 
       Solution to Problem  
       [0014]    The present invention directed to the following items 1-6 solves the above-mentioned problem. 
         [0015]    1. An actuator comprising:
       a conductive polymer layer  31 ;   an ambient temperature molten salt layer  35 ; and   an opposite electrode layer  34 ; wherein   the ambient temperature molten salt layer  35  is interposed between the conductive polymer layer  31  and the opposite electrode layer  34 ,   the ambient temperature molten salt layer  35  comprises an adhesive layer  33  in the inside thereof;   one surface of the adhesive layer  33  adheres to the conductive polymer layer  31 ; and   the other surface of the adhesive layer  33  adheres to the opposite electrode layer  34 .       
 
         [0023]    2. The actuator according to the item 1, wherein
       the ambient temperature molten salt layer  35  comprises a plurality of adhesive layers  33  in the inside thereof; and   the plurality of adhesive layers  33  are, dispersed in the ambient temperature molten salt layer  35  when viewed in the perspective top view.       
 
         [0026]    3. A method for driving an actuator, the method comprising:
       (a) preparing the actuator comprising:   a conductive polymer layer  31 ;   an ambient temperature molten salt layer  35 ; and   an, opposite electrode layer  34 ; wherein   the ambient temperature molten salt layer  35  is interposed between the conductive polymer layer  31  and the opposite electrode layer  34 ,   the ambient temperature molten salt layer  35  comprises an adhesive layer  33  in the inside thereof;   one surface of the adhesive layer  33  adheres to the conductive polymer layer  31 ; and   the other surface of the adhesive layer  33  adheres to the opposite electrode layer  34 ;   (b) applying a negative voltage and a positive voltage to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to increase the thickness of the conductive polymer layer  31 ; and   (c) applying a positive voltage and a negative voltage to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to decrease the thickness of the conductive polymer layer  31 .       
 
         [0037]    4. The method according to the item 3, wherein
       the ambient temperature molten salt layer  35  comprises a plurality of adhesive layers  33  in the inside thereof; and   the plurality of adhesive layers  33  are dispersed in the ambient temperature molten salt layer  35  when viewed in the perspective top view.       
 
         [0040]    5. A method for controlling a flow of an fluid flowing through a flow path  8 , the method comprising;
       (a) preparing the actuator comprising:   a conductive polymer layer  31 ;   an ambient temperature molten salt layer  35 ; and   an opposite electrode layer  34 ; wherein   the ambient temperature molten salt layer  35  is interposed between the conductive polymer layer  31  and the opposite electrode layer  34 ,   the ambient temperature molten salt layer  35  comprises an adhesive layer  33  in the inside thereof;   one surface of the adhesive layer  33  adheres to the conductive polymer layer  31 ; and   the other surface of the adhesive layer  33  adheres to the opposite electrode layer  34 ;   (b) applying a positive voltage and a negative voltage to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to stop the flow of the fluid flowing through the flow path  8  by increasing the thickness of the conductive polymer layer  31 ; and   (c) applying a negative voltage and a positive voltage to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to flow the fluid through the flow path  8  by decreasing the thickness of the conductive polymer layer  31 .       
 
         [0051]    6. The method according to the item 5, wherein
       the ambient temperature molten salt layer  35  comprises a plurality of adhesive layers  33  in the inside thereof; and   the plurality of adhesive layers  33  are dispersed in the ambient temperature molten salt layer  35  when viewed in the perspective top view.       
 
         [0054]    7. The method according to the item 5, wherein
       the actuator  1  is provided on a substrate  9 ;   in the step (b), a bottom surface of the actuator  1  is brought into contact with the actuator  1 ; and   in the step (c), the bottom surface of the actuator  1  is left from the actuator  1 .       
 
       Advantageous Effects of Invention  
       [0058]    In the actuator according to the present invention, the adhesive layer  33  prevents from generating the interspace between the layers, which causes the failure of the actuator. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0059]      FIG. 1  shows a cross-sectional view of the conventional actuator. 
           [0060]      FIG. 2  shows a cross-sectional view of the conventional actuator. 
           [0061]      FIG. 3  shows a cross-sectional view of the actuator according to the embodiment. 
           [0062]      FIG. 4  shows a cross-sectional view of the actuator according to the embodiment. 
           [0063]      FIG. 5  shows a cross-sectional view of the valve according to the embodiment. 
           [0064]      FIG. 6A  shows the cross-sectional view in one step of the method for fabricating the actuator according to the embodiment. 
           [0065]      FIG. 6B  shows a cross-sectional view in the step subsequent to  FIG. 6A . 
           [0066]      FIG. 6C  shows a cross-sectional view in the step subsequent to  FIG. 6B . 
           [0067]      FIG. 6D  shows a cross-sectional view in the step subsequent to  FIG. 6C . 
           [0068]      FIG. 7A  shows a cross-sectional view in one step of the method for fabricating the actuator according to the embodiment. 
           [0069]      FIG. 7B  shows a cross-sectional view in the step subsequent to  FIG. 6D . 
           [0070]      FIG. 7C  shows a cross-sectional view in the step subsequent to  FIG. 7A . 
           [0071]      FIG. 7D  shows a cross-sectional view in the step subsequent to  FIG. 7B  and  FIG. 7C . 
           [0072]      FIG. 8A  shows a cross-sectional view in the step subsequent to  FIG. 7D . 
           [0073]      FIG. 8B  shows a cross-sectional view in the step subsequent to  FIG. 8A . 
           [0074]      FIG. 8C  shows a cross-sectional view in the step subsequent to  FIG. 8B . 
           [0075]      FIG. 8D  shows a cross-sectional view in the step subsequent to  FIG. 8C . 
           [0076]      FIG. 9  shows a perspective top view of the inside of the ambient temperature molten salt layer  35 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS  
       [0077]    Hereinafter, an embodiment of the present invention will be-described. In the following description, the same components are designated by the same reference numerals, and hence repetitive description is omitted. 
         [0078]    As shown in  FIG. 3 . an adhesive layer  33  is added to the ambient temperature molten salt layer  35  included in the actuator  1 . In other words, the ambient temperature molten salt layer  35  comprises the adhesive layer  33  in the inside thereof. The adhesive layer  33  may have electrical insulation property. 
         [0079]    The one surface of the adhesive layer  33  adheres to the conductive polymer layer  31 . The other surface of the adhesive layer  33  adheres to the opposite electrode layer  34 . The number of the adhesive layer  33  may be one or more. 
         [0080]    Through the first electrode  26  and the second electrode  27 , a negative voltage and a positive voltage are applied to the conductive polymer layers  31  and to the opposite electrode layers  34 , respectively. As shown in  FIG. 4 , when this voltage difference is applied, the thickness of the conductive polymer layer  31  increases in a normal direction of the conductive polymer layer  31 . Then, when a positive voltage and a negative voltage are applied to the conductive polymer layers  31  and to the opposite electrode layers  34 , respectively, the thickness of the conductive polymer layer  31  decreases so as to returns the actuator  1  to the original state shown in  FIG. 3 . 
         [0081]    Unlike the case shown in  FIG. 2 , the interspace is not generated due to the adhesive layer  33 . 
         [0082]    As shown in  FIG. 4 , it is preferred that the conductive polymer layer  31 , the support layer  32 , and the adhesive film  36  each have flexibility to follow the increase and the decrease of the conductive polymer layer  31 . 
         [0083]    As shown in  FIG. 9 , when the ambient temperature molten salt layer  35  viewed in the perspective top-view, it is preferable that a plurality of the adhesive layers  33  are disposed to be dispersed in the inside of the ambient temperature molten salt layer  35 . 
         [0084]    An example of a suitable material of the conductive polymer layer  31  is polypyrrole/bis(trifluoromethanesulfonyl)imide. 
         [0085]    An example of a suitable adhesive layer  33  is an epoxide-based adhesive. 
         [0086]    An example of a suitable material of the ambient temperature molten salt layer  35  is 1-ethyl-3-methylimidazolium/bis(trifluoromethanesulfonyl)imide. 
         [0087]    An example of a suitable material of the opposite electrode layer  34  is polypyrrole/dodecyl benzene sulfonic acid. 
         [0088]    Then, a method for controlling a flow of a fluid using the actuator  1  will be described. 
         [0089]    As shown in  FIG. 5 , two walls  4  are disposed on the substrate  9 . The actuator  1  is fixed between these two walls  4 . A flow path  8  is formed between the substrate  9  and the bottom surface of the actuator  1 . Instead of the example shown in  FIG. 5 , a groove may be formed on the surface of the substrate to provide a flow path on the substrate. Note that  FIG. 5  does not show the details of the actuator  1 , such as the conductive polymer layer  31 . 
         [0090]    A negative voltage and a positive voltage are applied to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to increase the thickness of the conductive polymer layer  31 . Since the bottom surface of the actuator  1  is brought into contact with the substrate  9 , the flow of the fluid flowing flow through the flow path  8  is stopped. 
         [0091]    Then, a positive voltage and a negative voltage are applied to the conductive polymer layer  31  and the opposite electrode layer  34 , respectively, to decrease the thickness of the conductive polymer layer  31 . Since the bottom surface of the conductive polymer layer  31  is left from the substrate, the fluid flows through the flow path  8 . 
       EXAMPLE 
       [0092]    The following examples describe the present invention in more detail. 
       Example 1 
       [0093]    As shown in  FIG. 6A , the conductive polymer layer  31  was prepared. This conductive polymer layer  31  was fabricated in accordance with the method disclosed in Non Patent Literature 1 using a ionic liquid composed of 1-ethyl-3-methylimidazolium/bis(trifluoromethanesulfonyl)imide (hereinafter, referred to as “EMI/TFSI”) as a solvent. The chemical reagents for the fabrication of the conductive polymer layer  31  were purchased from Sigma Aldrich Corporation. 
         [0094]    The conductive polymer layer  31  was formed of polypyrrole/bis(trifluoromethanesulfonyl)imide (hereinafter, referred to as “PPy/TFSI”). The conductive polymer layer  31  had a length of 20 millimeters, a width of 20 millimeters, and a thickness of 70 micrometers. 
         [0095]    Then, as shown in  FIG. 6B , the support layer  32  was formed on the conductive polymer layer  31 . More specifically, an alloy layer (thickness: 20 nanometers) consisting of tungsten and titanium was formed on the conductive polymer layer  31  by sputtering. Subsequently, a gold layer having a thickness of 150 nanometers was stacked by sputtering. In this way, the support layer  32  was formed. 
         [0096]    As shown in  FIG. 6C , the two conductive polymer layer  31  each having the support layer  32  were adhered using an epoxide-based adhesive (purchased from Namics Company) in such a manner that the two support layers  32  face to each other. This adhesive corresponds to the adhesive film  36 . Subsequently, both side ends of the conductive polymer layer  31  were cut using a YAG laser device, as shown in  FIG. 6D . 
         [0097]    Meanwhile, the opposite electrode layer  34  was prepared as shown in  FIG. 7A . This opposite electrode layer  34  was fabricated by the method similar to that of the conductive polymer layer  31 . 
         [0098]    The opposite electrode layer  34  was formed of polypyrrole/dodecyl benzene sulfonic acid (hereinafter, referred to as “PPy/DBS”). 
         [0099]    Then, as shown in  FIG. 7B , the adhesive layers  33  were formed on the conductive polymer layer  31 . Similarly to the case of  FIG. 7B , the adhesive layers  33  were also formed on the opposite electrode layer  34  as shown in  FIG. 7C . The detail of the formation of the adhesive layer  33  will be described below. 
         [0100]    Each adhesive layer  33  was formed by a stencil printing method. In the stencil method, a nickel mask (thickness: 20 micrometers) corresponding to  FIG. 9  was used. This mask had a plurality of circular through-holes. Each circular through-hole had a radius of 40 micrometers. The distance interposed between the centers of the two adjacent through-holes was 260 micrometers. 
         [0101]    A liquid adhesive was applied on the conductive polymer layer  31  and on the opposite electrode layer  34  by a stencil printing method. Subsequently, the adhesive was provisionally cured in an oven kept at 120 degrees Celsius for one minute. At this stage, the adhesive layer  33  had a radius of 45-50 micrometers and a height of approximately 16 micrometers. 
         [0102]    Then, a plurality of the conductive polymer layers  31  shown in  FIG. 7B  and a plurality of the opposite electrode layers  34  shown in  FIG. 7C  were stacked alternately to form a laminated structure shown in  FIG. 7D . 
         [0103]    A weight of 250 grams was put on the top surface of the laminated structure. Then, the laminated structure was held in an oven maintained at 120 degrees Celsius for nine minutes to cure the adhesive completely. Afterwards, the weight was removed from the top surface. 
         [0104]    A silver paste was applied to both sides of the laminated structure thus obtained to form the first electrode  26  and second electrode  27 , as shown in  FIG. 8A . The first electrode  26  was connected to the conductive polymer layer  31  electrically. The second electrode  27  was connected to the opposite electrode layer  34  electrically. 
         [0105]    Then, as shown in  FIG. 8B , the laminated structure was disposed in a case  20 . Subsequently, a plate  22  and a rubber sheet  23  were fixed on the bottom surface of the laminated structure, using an adhesive (purchased from Namics Company). The plate  22  was formed of a quartz glass plate having a thickness of 0.5 millimeters. The rubber sheet  23  was formed of a silicone rubber sheet having a thickness of 0.1 millimeter. 
         [0106]    As shown in  FIG. 8C , a lid  24  was fixed to the case  20  using an adhesive (purchased from Huntsman Advanced Materials, trade name: Araldite Standard). The lid  24  consisted of quartz glass. The laminated structure was fixed to the lid  24  using an adhesive (purchased from Namics Company). 
         [0107]    Finally, as shown in  FIG. 8D , an EMI/TFSI ambient temperature molten salt (purchased from Sigma Aldrich Corporation) was injected to the case  20  through a through-hole  25  formed in the lid  24 . The case  20  was filled with this EMI/TFSI ambient temperature molten salt. In this way, the ambient temperature molten salt layer  35  was formed. 
         [0108]    Through the first electrode  26  and the second electrode  27 , a voltage difference was applied between the conductive polymer layer  31  and the counter electrode  34 . In more detail, cyclic bias voltages of −3.0 volts (for 100 seconds) and +3.7 volts (for 120 seconds) were applied alternately between the conductive polymer layer  31  and the counter electrode  34  for 10 hours. Ten hours later, the interspace, was not observed between the layers. 
       Comparative Example 
       [0109]    An actuator was formed similarly to the case of the example except that the adhesive layers  33  were not formed. Subsequently, the pulsed wave was applied to this actuator similarly to that of the example. However, the interspaces were observed between the layers after the application of the pulse wave. 
       INDUSTRIAL APPLICABILITY  
       [0110]    An actuator according to the present invention can be used in a biosensor. 
       Reference Signs List  
       [0000]    
       
           1 : actuator 
           21 : laminate 
           21   a : first laminate 
           21   b : second laminate 
           26 : first electrode 
           27 : second electrode 
           31 : conductive polymer layer 
           31   a : first conductive polymer layer 
           31   b : second conductive polymer layer 
           32 : support layer 
           32   a : first support layer 
           32   b : second support layer 
           33 : adhesive layer 
           34 : opposite electrode layer 
           35 : ambient temperature molten salt layer 
           36 : adhesive film 
           4 : wall 
           8 : flow path 
           9 : substrate 
           11 : valve 
           20 : case 
           22 : plate 
           23 : rubber sheet 
           24 : lid 
           25 : through hole