Abstract:
A micropump configured to control flow of an insulation fluid includes: a rectangular channel  370  configured to have a rectangular shape in which a movement passage of the insulation fluid; a planar electrode forming section  310  configured to be formed inside the rectangular channel and have a planar shape for applying an electric field; an inflow section  320  configured such that the insulation fluid flows in; and an outflow section  330  configured such that the insulation fluid flows out. Since an insulation fluid with low conductivity in a range of 10 −10  to 10 −12  S/m is transported with a simple technical structure without using a complicated component, it is possible to obtain the advantage of cost saving and application to various minute dynamics devices.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a micropump, and more particularly, to a micropump configured to include a planar electrode or a cylinder electrode installed so that a direct-current or alternating-current electric field is applied to a rectangular channel or a cylinder channel and to be capable of transporting an insulation fluid with low conductivity in the range of 10 −10  to 10 −12  S/m. 
     Description of the Related Art 
     In recent years, interest and development of microfluidic systems have increased internationally. Such microfluidic systems are systems using micro-electromechanical systems (MEMS) technologies and are very important systems applied to fields such as clinical diagnoses, bio-medicine studies such as DNA and peptide, chemical analyses for new medicine development, ink jet printing, small cooling systems, small fuel cell fields. 
     Micropump and microvalves are core components configured to enable a fluid to flow in such a microfluidic system and have fluid control functions of adjusting an amount of fluid and a rate of the fluid and blocking the flow. 
     Here, micropumps are devices, such as small mechanical devices, minute fluid dynamics devices, microrobots, and electromechanical devices, configured to transport a fluid in a variety of fields and are evaluated as very important technologies in the near future. 
     In the related art, since pump devices configured to realize mechanical pressure transduction mainly used to transmit a fluid have very large sizes, there are technical limitations in manufacturing the pump devices with very small sizes. Therefore, there is a problem that it is difficult to apply the pump devices to micropumps required to have very small sizes. 
     In order to overcome the foregoing problems, in the related art, technologies for transporting a fluid by electrohydraulic flow occurring at the time of application of an electric field to the fluid to transport the fluid with a simple structure without using many components have been used to manufacture micropumps. 
     As representative examples, there are an ion-drag pump and an electro-sensitive fluid micropump usable for an insulation fluid. 
     However, the ion-drag pump and the electro-sensitive fluid micropump of the related art have the following technical problems. 
     First, the technologies of the related art have the problems that a target fluid usable in a pump is specified and it is difficult to apply the technologies to a general-purpose insulation fluid with electric conductivity in the range of 10 −10  to 10 −12  S/m. 
     Second, in the technologies of the related art, a micropump is operated only by a direct-current (DC) electric field and a flow rate of an insulation fluid is adjusted only by a voltage. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a micropump capable of transporting an insulation fluid with low conductivity in the range of 10 −10  to 10 −12  S/m. 
     In order to achieve the above object, according to one aspect of the present invention, there is provided a micropump configured to control flow of an insulation fluid include: a rectangular channel ( 370 ) configured to have a rectangular shape in which a movement passage of the insulation fluid; a planar electrode forming section ( 310 ) configured to be formed inside the rectangular channel and have a planar shape for applying an electric field; an inflow section ( 320 ) configured such that the insulation fluid flows in; and an outflow section ( 330 ) configured such that the insulation fluid flows out. 
     Since an insulation fluid with low conductivity in the range of 10 −10  to 10 −12  S/m is transported merely with a simple technical structure without using a complicated component, it is possible to obtain the advantage of cost saving and application to various minute dynamics devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description taken in conjunction with the drawings, in which: 
         FIG. 1  is a diagram for describing a first principle of a cylinder electrode type insulation fluid micropump according to a first embodiment of the present invention; 
         FIG. 2  is a perspective view illustrating a cylinder electrode-rectangular channel type micropump according to the first embodiment of the preset invention; 
         FIG. 3  is a diagram illustrating an inner electrode arrangement of the cylinder electrode-rectangular channel type micropump according to the first embodiment of the present invention; 
         FIG. 4  is a diagram for describing a second principle of a planar electrode type insulation fluid micropump according to second to fourth embodiments of the present invention; 
         FIG. 5  is a plan view illustrating a planar electrode-rectangular channel type micropump according to the second embodiment of the present invention; 
         FIG. 6  is a plan view illustrating an inner arrangement of the planar electrode-rectangular channel type micropump according to the second embodiment of the present invention; 
         FIG. 7  is a plan view illustrating arrangement of inner electrodes of the planar electrode-rectangular channel type micropump according to the second embodiment of the present invention; 
         FIG. 8  is a perspective view illustrating a planar electrode-cylinder channel type micropump according to a third embodiment of the present invention; 
         FIG. 9  is a perspective view illustrating arrangement of inner electrodes of the planar electrode-cylinder channel type micropump according to a third embodiment of the present invention; 
         FIG. 10  is a perspective view illustrating a planar electrode-cylinder type electrohydraulic motor according to a fourth embodiment of the present invention; 
         FIG. 11  is a perspective view illustrating arrangement of inner electrodes of the planar electrode-cylinder type electrohydraulic motor according to the fourth embodiment of the present invention; and 
         FIG. 12  is a perspective view illustrating an inner rotor of the planar electrode-cylinder type electrohydraulic motor according to the fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
     Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. 
       FIG. 1  is a diagram for describing a first principle of a cylinder electrode type insulation fluid micropump according to a first embodiment of the present invention. 
     Referring to  FIG. 1 , the cylinder electrode type insulation fluid micropump include a first cylinder electrode  110 , a second cylinder electrode  111   a , and a third cylinder electrode  111   b  installed to form a triangle shape in a vertical direction perpendicular to rectangular channels  114  and  115 . 
     The first cylinder electrode  110  includes a (−) pole or a (+) pole. A direct-current (DC) or alternating-current (AC) voltage is applied to the first cylinder electrode  110 . A ground (GND) voltage is applied to the second cylinder electrode  111   a  and the third cylinder electrode  111   b.    
     Hereinafter, an operation principle of the cylinder electrode type insulation fluid micropump according to the present invention will be described in brief. 
     When the insides of the rectangular channels  114  and  115  are filled with an insulation fluid and a direct-current (DC) or alternating-current (AC) voltage is subsequently applied to the first cylinder electrode  110 , irregular electrode fields  112  are formed between the first cylinder electrode  110  and the second cylinder electrode  111   a  and between the first cylinder electrode  110  and the third cylinder electrode  111   b.    
     In the formed irregular electric fields  112 , a gradient of electric conductivity of the insulation fluid is formed due to the Onsager effect. The formed gradient of the electric conductivity forms free charges in the insulation fluid due to the Maxwell-Wagner polarization phenomenon. 
     The formed free charges transfer a momentum to the peripheral insulation fluid while moving due to the influence of an electric force, so that the insulation fluid moves in one direction along an illustrated path  113 . Thus, the cylinder electrode type insulation fluid micropump according to the present invention functions as a pump. 
     As the insulation fluid according to the present invention, a solution is used in which an ionic or non-ionic surfactant or an alcoholic additive is a little added to an organic or inorganic insulation fluid with very low electric conductivity in the range of 10 −10  to 10 −12  S/m. Preferably, an additive of 0.001 wt % to 10 wt % is contained. In an example of the present invention, a silicon oil, dodecane, or toluene is used as the insulation fluid. Sorbitane trioleate (Span 85) may be used as the ionic surfactant. Sodium di-2-ethylhexyl sulfosuccinate (AOT) may be used as the non-ionic surfactant. Tetrabutylammonium tetrabutylborate may be used an oil soluble salt and methanol may be used as the alcohol. 
     In the present invention, metal substances with a property which is not solved in the insulation fluid are used for all of the first cylinder electrode  110 , the second cylinder electrode  111   a , and the third cylinder electrode  111   b . An insulation substance such as glass, plastic, or rubber is used for the rectangular channels  114  and  115 . For example, iron, copper, tungsten, aluminum, gold, silver, or the like is used as the metal substance. 
       FIGS. 2 and 3  are a perspective view illustrating a cylinder electrode-rectangular channel type micropump according to the first embodiment of the preset invention and a diagram illustrating an inner electrode arrangement of the cylinder electrode-rectangular channel type micropump, respectively. 
     Referring to  FIG. 2 , a cylinder electrode-rectangular channel type micropump  200  according to the present invention includes a channel upper plate  270 , a rectangular channel  250  including the channel upper plate and having a rectangular parallelepiped shape, an electrode forming section  210 , an inflow section  230 , and an outflow section  240 . 
     The electrode forming section  210  is configured to include a ground electrode connecting portion  211 , an external power supply connecting portion  212 , a first cylinder electrode upper joining portion  213 , a second cylinder electrode upper joining portion  214 , and a third cylinder electrode upper joining portion  215 . 
     The ground electrode connecting portion  211  has a structure in which the second cylinder electrode upper joining portion  214  and the third cylinder electrode upper joining portion  215  are connected to each other and the ground voltage (GND) may be applied thereto. 
     The external power supply connecting portion  212  has a structure which is connected to the first cylinder electrode upper joining portion  213  and a direct current (DC) or alternating current (AC) voltage supplied from an external power supply may be applied to first cylinder electrodes  216  connected to the first cylinder electrode upper joining portion  213 . Here, the direct current is preferably in the range of 10 V to 10,000 V and the alternating current is preferably in the range of 10 V rms  to 10,000 V rms  at 0.1 kHz to 10 kHz. 
     The first cylinder electrode upper joining portion  213  has a structure in which a plurality of first cylinder electrodes  216   a  to  216   e  having a cylinder shape are connected. Here, the cylinder electrodes  216   a  to  216   e  are distant at constant intervals and are preferably distant by 5 to 10 times a cylinder diameter. Likewise, the second cylinder electrode upper joining portion  214  and the third cylinder electrode upper joining portion  215  have structures in which a plurality of second cylinder electrodes  217   a  to  217   e  and a plurality of third cylinder electrodes  218   a  to  218   e  having a cylinder shape are connected at constant intervals, respectively. 
     The first cylinder electrode  216   a , the second cylinder electrode  217   a , and third cylinder electrode  218   a  located at the first position are formed as one set to constitute a first electrode set S 1  with a triangle shape. 
     Likewise, the first cylinder electrode  216   b , the second cylinder electrode  217   b , and the third cylinder electrode  218   b  located at the second position to the first cylinder electrode  216   e , the second cylinder electrode  217   e , and the third cylinder electrode  218   e  located at the fifth position constitute a second electrode set S 2  to a fifth electrode set S 5 , respectively. 
     The plurality of electrode sets S 1  may be formed at constant intervals. As the number of electrode sets S 1  increases, a flow rate of the insulation fluid is higher. Therefore, the intensity of the pump increases. 
     In the case of the present invention, the flow rate of the insulation fluid may be adjusted not only by adjusting a voltage in a direct-current electric field but also by adjusting a voltage and an alternating-current frequency in a case of an alternating-current electric field. 
     In the case of the present invention, the five electrode sets S 1  to S 5  have been described, but the present invention is not limited thereto. Of course, various modifications may be made in consideration of the fact that the movement rate of the insulation substance is faster as the number of electrode sets increases. 
       FIG. 4  is a diagram for describing a second principle of a planar electrode type insulation fluid micropump according to second to fourth embodiments of the present invention. 
     Referring to  FIG. 4 , the channels  124  and  125  include a first planar electrode  120  and a second planar electrode  121  on one side surface of the inside. 
     The channels  124  and  125  may use a rectangular shape or a cylinder shape. 
     The first planar electrode  120  includes a (−) pole or a (+) pole. A direct-current (DC) or alternating-current (AC) voltage is applied to the first planar electrode  120 . The second planar electrode  121  includes an electrode with a wide width planar shape. A ground (GND) voltage is applied to the second planar electrode  121 . 
     Hereinafter, an operation principle of the planar electrode type insulation fluid micropump according to the present invention will be described in brief. 
     When the insides of the channels  124  and  125  are filled with an insulation fluid and a direct-current (DC) or alternating-current (AC) voltage is subsequently applied to the first planar electrode  120 , an irregular electrode field  122  is formed between the first planar electrode  120  and the second planar electrode  121 . 
     In the formed irregular electric field  122 , a gradient of electric conductivity of the insulation fluid is formed due to the Onsager effect. The formed gradient of the electric conductivity forms free charges in the insulation fluid due to the Maxwell-Wagner polarization phenomenon. 
     The formed free charges transfer a momentum to the peripheral insulation fluid while moving due to the influence of an electric force, so that the insulation fluid moves in one direction along an illustrated path  123 . Thus, the planar electrode type insulation fluid micropump according to the present invention functions as a pump. 
     As the insulation fluid according to the present invention, a solution is used in which an ionic or non-ionic surfactant or an alcoholic additive is a little added to an organic or inorganic insulation fluid with very low electric conductivity in the range of 10 −10  to 10 −12  S/M. Preferably, an additive of 0.001 wt % to 10 wt % is contained. 
     In the present invention, metal substances with a property which is not solved in the insulation fluid are used for all of the first planar electrode  120  and the second planar electrode  121 . An insulation substance such as glass, plastic, or rubber is used for the channels  124  and  125 . 
       FIGS. 5, 6, 7  are a plan view illustrating a planar electrode-rectangular channel type micropump according to the second embodiment of the present invention, a plan view illustrating an inner arrangement of the planar electrode-rectangular channel type micropump, and a plan view illustrating arrangement of inner electrodes of the planar electrode-rectangular channel type micropump, respectively. 
     Referring to  FIG. 5 , a planar electrode-rectangular channel type micropump  300  according to the present invention is configured to include an electrode forming section  310 , an inflow section  320 , an outflow section  330 , and a rectangular channel  370  including a channel bottom section  340 , a vertical division wall  350 , and an upper cover  360 . 
     In the electrode forming section  310 , the channel bottom section  340  is subjected to patterning with a metal substance. A channel in which the insulation fluid may move from the inflow section  320  to the outflow section  330  is formed by the vertical division wall  350 . The upper portion of the vertical division wall  350  is sealed by the upper cover  360 . 
     Hereinafter, the shape, disposition, and the like of the electrode forming section  310  will be described in detail with reference to  FIG. 7 . 
     The electrode forming section  310  is configured to include a ground electrode connecting portion  311 , a second planar electrode upper joining portion  312 , an external power supply connecting portion  313 , and a first planar electrode upper joining portion  314 . 
     The ground electrode connecting portion  311  is connected to the second planar electrode upper joining portion  312  and has a structure in which a ground voltage (GND) may be applied to the plurality of second planar electrodes  312   a  to  312   e  connected via the second planar electrode upper joining portion  312 . 
     Likewise, the external power supply connecting portion  313  is connected to the first planar electrode upper joining portion  314  and has a structure in which a direct-current (DC) or alternating-current (AC) voltage supplied from an external power supply may be applied to a plurality of first planar electrodes  314   a  to  314   e  connected via the first planar electrode upper joining portion  314 . 
     The first planar electrodes  314   a  to  314   e  have the same planar shape, width, and length. The second planar electrodes  312   a  to  312   e  also have the same planar shape, width, and length. The first planar electrodes  314   a  to  314   e  preferably have a width of 10 μm to 10 mm, a length of 50 μm to 100 mm. The second planar electrodes  312   a  to  312   e  have the same length of the first planar electrodes  314   a  to  314   e , but the width of the second planar electrodes is 2 to 5 times of the width of the first planar electrodes. 
     The first planar electrode  314   a  and the second planar electrode  312   a  located at the first position constitute a first electrode set S 1 . Likewise, the first and second planar electrodes located at the second to fifth positions constitute a second electrode set S 2  to a fifth electrode set S 5 , respectively. 
     In the case of the present invention, the five electrode sets have been described, but the present invention is not limited thereto. Of course, various modifications may be made in consideration of the fact that the movement rate of the insulation fluid is faster as the number of electrode sets increases. 
       FIGS. 8 and 9  are a perspective view illustrating a planar electrode-cylinder channel type micropump according to a third embodiment of the present invention and a perspective view illustrating arrangement of inner electrodes of the planar electrode-cylinder channel type micropump, respectively. 
     Referring to  FIG. 8 , a planar electrode-cylinder channel type micropump  400  according to the present invention is configured to include an electrode forming section  410 , an inflow section  420 , an outflow section  430 , and a cylinder channel  440 . 
     The electrode forming section  410  includes a ground electrode connecting portion  411 , an external power supply connecting portion  412 , a first planar electrode  413  having a cylindrical narrow planar surface, and a second planar electrode  414  having a cylindrical large planar surface. 
     On the other hand, an operation principle and a basic configuration of the planar electrode-cylinder channel type micropump  400  according to the third embodiment are basically the same as those of the planar electrode-rectangular channel type micropump  300  according to the second embodiment. There are differences in that the shape of the planar electrode is modified to the cylindrical shape and the rectangular shape depending on whether the shape of the channel is cylindrical or rectangular. 
     Accordingly, the repeated description of the details of the forgoing second embodiment will be omitted. 
       FIGS. 10, 11, and 12  are a perspective view illustrating a planar electrode-cylinder type electrohydraulic motor according to a fourth embodiment of the present invention, a perspective view illustrating arrangement of inner electrodes of the planar electrode-cylinder type electrohydraulic motor, and a perspective view illustrating an inner rotor of the planar electrode-cylinder type electrohydraulic motor, respectively. 
     Referring to  FIG. 10 , a planar electrode-cylinder type electrohydraulic motor  500  according to the present invention is configured to include a cylinder container  510 , an electrode forming section  520 , a rotor  530 , and an upper cover  540 . 
     The electrode forming section  520  is configured to include a ground electrode connecting portion  521 , and an external power connecting portion  523  and include first planar electrodes  524  with a narrow width and second planar electrodes  522  with a large width for which a plurality of planar electrodes are patterned in the vertical direction on the wall surface of the cylinder container  510 . 
     The electrode forming portion  520  of the fourth embodiment and the electrode forming portion  410  of the third embodiment are common in that the cylinder type channel has the planar electrode form, but differ in that the first and second planar electrodes of the electrode forming section are disposed in an intersection manner in a straight form in the vertical direction along the cylinder wall surface in the case of the fourth embodiment, but are arranged in an intersection manner in a circular form in the case of the third embodiment. 
     Due to this difference in the disposition of the electrodes, the insulation fluid is transported clockwise in the case of the fourth embodiment. In the case of the third embodiment, however, the insulation fluid is transported in a straight from in the direction from the inflow section  420  to the outflow section  430 . 
     The rotor  530  is located inside the cylinder container  510  moves rotor&#39;s wirings  532  and provides a momentum to the rotor&#39;s wirings using a force which is generated at the time of application of an external electric field to the electrode forming section  520  and by which the insulation fluid is transported clockwise along the wall surface of the cylinder container  510 . The rotor  530  dynamically works to the outside through a rotor shaft  531  connected to the dynamic body. 
     Accordingly, since a component configuration is simpler than the configuration of an electromagnetic motor of the related art, application to manufacturing of a small motor can be achieved. 
     Although the technical sprit of the present invention have been described for illustrative purposes with reference to the accompanying drawings, the preferred embodiments of the present invention are merely exemplified and do not limit the present invention. It should be apparent to those skilled in the art that various modifications, additions and substitutions are possible, without departing from the scope and the technical spirit of the present invention as disclosed in the accompanying claims.