JP2007303410A - Structure of micropump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micropump with a small size and a simple configuration. <P>SOLUTION: The micropump is provided with (a) a diaphragm 25 formed on an inner side of a peripheral part of an insulating film having rubber elasticity by supporting the peripheral part of the insulating film, (b) a pair of electrodes 26 and 28 abutted to both surfaces of the diaphragm 25 without restricting the surfaces in a surface direction, and (c) a flow passage 12d arranged adjacently to a diaphragm 23 and varying its capacity interlocked with the deformation of the diaphragm 23. An area of the diaphragm 25 is varied and capacity of the flow passage 12d is varied when a voltage is applied between the electrodes 26 and 28, and thereby, the fluid in the flow passage 12d is carried by the micropump. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure of a micropump.

  Development of a microchip that causes a chemical reaction in a minute region and realizes functional devices such as transport, separation, and detection on the chip is underway.

  The microchip can be used not only in the fields of chemistry such as gene analysis, clinical diagnosis and drug screening, biochemistry, pharmacy, medicine and veterinary medicine but also in a wide range of applications such as chemical industry and environmental measurement. The microchannel and reaction vessel in the microchip handle fluids, mainly liquids such as chemicals and samples. For this purpose, a fluid control element that controls the flow and transfer of the fluid, that is, a micropump is required.

  Conventionally, many types of micropumps have been developed, and are divided into non-mechanical pumps and mechanical pumps. In general, the latter mechanical pump is considered to be more versatile because it does not affect the electrical properties of the fluid.

  Some mechanical pumps are driven by an actuator using a piezoelectric material capable of obtaining a high generated stress. This type can be driven at a low voltage and has high frequency response.

Patent Document 1 discloses a diaphragm pump for increasing the discharge pressure for the purpose of using a micropump or the like. This micro pump uses a piezoelectric material to drive a diaphragm.
JP 2005-188355 A

  Piezoelectric materials are usually ceramics and difficult to miniaturize, and since they are inorganic materials, they are not suitable for large deformations. Therefore, micropumps using piezoelectric materials are difficult to miniaturize and improve performance. Further, the diaphragm pump of Patent Document 1 has a complicated structure.

  In view of such circumstances, the present invention intends to provide a micro pump having a small size and a simple configuration.

  In order to solve the above problems, the present invention provides a micropump configured as follows.

  The micropump (a) supports the peripheral part of the insulating film having rubber elasticity, thereby restraining the diaphragm part formed inside the peripheral part, and (b) restraining both surfaces of the diaphragm part in the surface direction. A pair of electrodes that are in contact with each of the both surfaces, and (c) a channel that is disposed adjacent to the diaphragm portion and whose volume changes in conjunction with deformation of the diaphragm portion. When a voltage is applied between the electrodes, the micropump changes the area of the diaphragm and changes the volume of the flow path, thereby transporting the fluid in the flow path.

  According to the above configuration, when a diaphragm portion formed by an insulating film having rubber elasticity (for example, an insulating elastomer film) is applied with a voltage between the electrodes and an attractive force acts between the electrodes, In the diaphragm portion, both surfaces of the diaphragm portion in contact with the electrode are not constrained in the surface direction, so that the compressed portion between the electrodes extends in a direction perpendicular to the compression direction and the area of the diaphragm portion changes. For example, the diaphragm part or a part that deforms integrally with the diaphragm is configured to be a part of the wall surface of the flow path, and the volume of the flow path changes following the change in the area of the diaphragm part. The micropump can convey the fluid in the flow path by utilizing such a change in volume of the flow path.

  According to the above configuration, a micro pump having a small size and a simple configuration can be realized.

  Preferably, a second diaphragm portion formed inside the peripheral portion is provided between the diaphragm portion and the flow path by supporting the peripheral portion of the second film having rubber elasticity. A conductive fluid serving as one of the pair of electrodes is sealed between the diaphragm portion and the second diaphragm portion. A conductive fluid serving as the other of the pair of electrodes is adhered to the surface of the diaphragm portion opposite to the flow path.

  In this case, by sealing or adhering a conductive fluid (for example, conductive grease), it is possible to easily configure an electrode that is in contact with both surfaces of the diaphragm without constraining both surfaces of the diaphragm portion in the surface direction. it can.

  Note that the second film constituting the second diaphragm portion may have conductivity. However, if the same film (insulator film) as the diaphragm portion is used, the constituent elements may be shared. Since it can do, it is preferable that the 2nd diaphragm part and a diaphragm part are the same films | membranes.

  Preferably, the diaphragm portion is formed inside the peripheral portion by supporting the peripheral portion of the insulating elastomer film in a state in which a tensile strain is applied in advance. The thickness of the diaphragm portion is 100 μm or less. The diaphragm portion has an electric field of 50 V / μm or more between the electrodes due to a voltage applied to the pair of electrodes.

  Elastomers have rubber elasticity, but the rigidity is weak as it is, so reducing the thickness by applying tensile strain beforehand improves the rigidity and increases the effective electric field, so the driving force of the diaphragm part must be increased. Can do. When the thickness of the diaphragm portion is 100 μm or less and the electric field is 50 V / μm or more, good Maxwell stress necessary for driving the pump can be obtained, and the fluid can be conveyed.

  Preferably, the diaphragm portion has a diameter of 3 mm or less. The elastomer constituting the diaphragm part is preliminarily applied with a tensile strain of 150% or more and less than 500%.

  If the diameter of the diaphragm part is too large, or if the tensile strain of the elastomer is too small, the rigidity of the diaphragm part will be reduced and the generated force will be reduced, but in the above case, the area change and tension of the diaphragm part will increase, A driving force capable of transporting fluid can be obtained.

  Preferably, a relative dielectric constant of the elastomer constituting the diaphragm portion is 4 or more.

  In this case, the force generated in the diaphragm portion is proportional to the relative dielectric constant, and by using a material having a relative dielectric constant of 4 or more, a good Maxwell stress necessary for driving the pump can be obtained.

  Preferably, two valves are provided in the flow path. In the flow path, the diaphragm portion is disposed adjacent to the valve. The valve is formed by molding integrally with the flow path using PDMS (Polydimethylsiloxane).

  In this case, a micropump or a valve can be easily produced by pouring PDMS, which is a photocurable resin, into a mold and curing it. PDMS retains the shape of the wall surface of the flow path, and has such rigidity that a portion that becomes a valve is elastically deformed. Since PDMS is transparent, the fluid flowing through the channel can be observed from the outside using light.

  Preferably, the valve is formed with a gap of 1 μm or more and 10 μm or less from the wall surface of the flow path in the vicinity of a boundary between portions where the widths of the flow paths are different.

  In this case, since the flow path and the valve are made of the same material, friction and adsorption force due to contact increases, but by providing a gap between the wall surface of the flow path and the valve, the micropump can operate stably. It becomes. If the gap between the wall surface of the flow path and the valve is 1 μm or more, the valve can be manufactured so as not to contact the wall surface of the flow path even if the processing accuracy varies. On the other hand, if the gap between the wall surface of the flow path and the valve is 10 μm or less, fluid leakage from the gap does not cause a problem in practice.

  The present invention also provides an actuator configured as follows.

  The actuator supports (a) a peripheral portion of an insulating film having rubber elasticity, thereby restraining a diaphragm portion formed inside the peripheral portion and (b) both surfaces of the diaphragm portion in a surface direction. And a pair of electrodes that are in contact with both surfaces. The actuator uses the deflection of the diaphragm when a voltage is applied between the electrodes for driving.

  In the above structure, the diaphragm portion formed of an insulating film having rubber elasticity deforms and bends when a voltage is applied between the electrodes. The displacement due to the deflection of the diaphragm portion is not limited to the driving of the diaphragm of the micropump, and can be used for, for example, driving such as opening and closing of a flow path and contact and separation of a switch.

  According to the present invention, it is possible to provide a micro pump having a small size and a simple configuration.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  <Example 1> A microchip 10 including a micropump will be described with reference to FIGS.

  As shown in the cross-sectional view of FIG. 1, in the microchip 10, the liquid supplied from one opening 12x flows through the microchannels (flow channels) 12a to 12g and is discharged from the other opening 12y. Yes.

  A diaphragm 21 that moves up and down in the drawing is provided on the bottom surface of the intermediate portion 12d of the microchannel, and valves 12s and 12t are provided on the front and back of the diaphragm 21 so that the liquid flows in one direction (from left to right in the drawing). It has become.

  A pair of two substrates 14 and 16 having through holes 15 and 17 having a circular cross section are formed below the flow path substrate 12 in which the microchannels 12a to 12g and the openings 12x and 12y are formed. , 17 are arranged to face each other so as to communicate with each other. Between the substrates 14 and 16, two sheets 22 and 24 of an adhesive elastomer are sandwiched while being pulled in the surface direction. The two sheets 22 and 24 are formed with substantially hemispherical diaphragm portions 23 and 25 in the through holes 15 and 17 of the adjacent substrates 14 and 16, respectively, and the substantially spherical shape is formed between the diaphragm portions 23 and 25. In this space, conductive grease 26 having conductivity is filled and sealed. The conductive grease 26 is made by adhering a freely-deformable grease to a conductive material such as carbon, and has conductivity.

  A thin plate 30 having a conductive film 32 formed on one side is sandwiched between the two sheets 22 and 24. The thin plate 30 and the conductive film 32 protrude outward from the substrates 14 and 16, and the conductive film 32 is connected to one terminal of the external power supply 40. The thin plate 30 and the conductive film 32 are formed with through holes 31 and 33 smaller than the through holes 15 and 17 of the substrates 14 and 16, and the thin plate 30 and the conductive film 32 are inside the through holes 15 and 17 of the substrates 14 and 16. The conductive grease 26 that enters and is filled between the sheets 22 and 24 is in contact with the conductive film 32 and is electrically connected to one terminal of the external power supply 40.

  Of the pair of substrates 14 and 16, the substrate 14 facing the microchannels 12a to 12g has a resin cover layer 20 formed on the surface facing the microchannels 12a to 12g. The cover layer 20 is also formed in the through hole 15 of the substrate 14, and a portion formed in the through hole 15 of the substrate 14 is joined to the diaphragm portion 23, and moves together with the diaphragm portion 23 to form the diaphragm 21.

  Of the pair of substrates 14 and 16, a thin plate 34 having a conductive film 36 formed on one side is attached to the substrate 16 opposite to the microchannels 12 a to 12 g on the surface opposite to the microchannels 12 a to 12 g. It is attached. The thin plate 34 and the conductive film 36 protrude outward from the substrate 16, and the other terminal of the external power supply 40 is connected to the conductive film 36.

  Both ends of the through hole 17 of the substrate 16 are closed by the diaphragm portion 25 and the conductive film 36 of the sheet 24, and the conductive grease 28 is disposed in the through hole 17 to the extent that a gap 29 is formed. The conductive grease 29 contacts the diaphragm part 25 as a whole, contacts the conductive film 36, and is electrically connected to the other terminal of the external power supply 40. The conductive grease 29 is a mixture of carbon powder mixed with grease that is sticky and freely deformed, and has conductivity.

  As shown in FIG. 2, which is a cross-sectional view taken along line II-II in FIG. 1, valves 12 s and 12 t are formed on the substrate 12 integrally with the microchannels 12 a to 12 g. The valves 12s and 12t are formed so as to cover the openings communicating with the narrow microchannels 12b and 12e in the vicinity of the boundary between the wide microchannels 12c and 12f and the narrow microchannels 12b and 12e. The valves 12s and 12t are formed with a gap between the microchannels 12c and 12f so as not to adhere to the wall surfaces of the microchannels 12c and 12f.

  That is, as shown in the enlarged view of the main part of FIG. 3, the step surfaces of the wide microchannels 12c and 12f are communicated with the narrow microchannels 12b and 12e, which reduce the contact area with the valves 12s and 12t. A protrusion extending in a streak shape along the opening, that is, a protrusion 12k is formed.

  For example, in FIG. 2 and FIG. 3, the width of the wide microchannels 12c and 12f (the vertical dimension in the figure) is 100 μ, the width of the narrow microchannels 12b and 12e is 50 μm, and the thickness of the valves 12s and 12t. The dimension (the dimension in the left-right direction in the figure) is 10 μm.

  A gap S1 is formed between the protrusion 12k and the valves 12s and 12t, and a gap S2 is provided between the valves 12s and 12t and the wall surfaces of the microchannels 12c and 12f. Further, as shown in FIG. 4 which is an enlarged cross-sectional view taken along line IV-IV in FIG. 3, between the bottom surface 20a of the microchannels 12c and 12f and the lower ends 12p and 12q of the valves 12s and 12t. Is provided with a gap S3.

  The sizes of these gaps S1, S2, S3 are preferably 1 μm or more and 10 μm or less, respectively. Since the wall surfaces of the microchannels 12c and 12f and the valves 12s and 12t are made of the same material, friction and adsorption force due to contact increase, but the gaps S1 and S1 between the wall surfaces of the microchannels 12c and 12f and the valves 12s and 12t are increased. By providing S2 and S3, the micropump can operate stably. If the sizes of the gaps S1, S2, and S3 are 1 μm, the valves 12s and 12t can be manufactured so as not to contact the wall surfaces of the microchannels 12c and 12f even if the processing accuracy varies. If the sizes of the gaps S1, S2, and S3 are 10 μm or less, fluid leakage from the gaps S1, S2, and S3 is not a problem in practice.

  Next, the operation of the micropump will be described with reference to FIGS.

  As shown in FIG. 5 (a), the electrodes 54 and 56 are arranged so as to be in contact with both surfaces of the sheet 52, and as shown in FIG. 5 (b), the electrodes 54 and 56 are connected to the power source 50 to apply a voltage. Then, an attractive force acts on the electric charges of the electrodes 54 and 56. By this force, the portion of the sheet 54 sandwiched between the electrodes 54 and 56 is compressed. At this time, if the electrodes 54 and 56 are freely deformed while being in contact with the surface of the sheet 54 like conductive grease having conductivity, the sheet 54 is not restrained from being deformed in the surface direction by the electrodes 54 and 56. Therefore, the thickness is reduced by the compression by the electrodes 54 and 56 and extends in the surface direction as indicated by an arrow 58.

  As shown in FIG. 6A, when a voltage is applied between the conductive greases 26 and 28, the diaphragm 25 sandwiched between the conductive greases 26 and 28 extends. At this time, the other diaphragm portion 23 is in a state where a tension is applied, and the conductive grease 26 is sealed between the diaphragm portions 23 and 25, so that the upper diaphragm 23 contracts. As a result, as indicated by the arrow 50, the diaphragm 21 constituting a part of the wall surface of the microchannel 12d is lowered, the volume of the microchannel 12d is increased, and the fluid is sucked into the microchannel 12d. Due to this suction, the valves 12s and 12t bend toward the microchannel 12d, so that the upstream valve 12s provided near the boundary between the relatively wide microchannel 12c and the relatively narrow microchannel 12b The downstream valve 12t provided near the boundary between the microchannel 12e having a relatively narrow width and the microchannel 12f having a relatively wide width is closed. As indicated by an arrow 52, the microchannel 12d from the upstream side is closed. Fluid flows into the inside.

  The conductive grease 28 is filled to such an extent that a gap 29 is formed in the through hole 17 of the substrate 16, so that the gap 29 is formed even when the diaphragm portion 25 is extended so that the diaphragm portion 25 can be freely deformed.

  Next, when the application of voltage to the conductive greases 26 and 28 is stopped, as shown in FIG. 6B, the lower diaphragm portion 25 contracts from the extended state, and the upper diaphragm portion 23 contracts. As shown by the arrow 54, the diaphragm 12 rises and fluid is discharged from the microchannel 12d. At this time, the upstream valve 12s is closed, the downstream valve 12t is opened, and the fluid in the microchannel 12d flows downstream, as indicated by the arrow 56.

  Next, an example of manufacturing the microchip 10 will be described with reference to FIGS.

  As shown in FIG. 7A, both ends of the sheet 60 are sandwiched by jigs and pulled as indicated by arrows 64. At this time, after pulling in one direction (X direction), it is further pulled in a direction perpendicular to this direction (Y direction) and held in a state where tension is applied in the surface direction. As the sheet 60, an elastomer sheet, for example, “3M VHB adhesive film” is used, and is stretched by 500% in the X and Y directions from the original dimensions to a thickness of 25 μm. The 3M VHB adhesive film is an elastomer having a relative dielectric constant of 4.7.

  The sheet 60 is preferably made of an elastomer having a relative dielectric constant of 4 or more. The force generated in the diaphragm portion formed by the sheet 60 is proportional to the relative dielectric constant indicated by the material of the sheet 60, and by using a material having a relative dielectric constant of 4 or more, a good Maxwell necessary for driving the pump is obtained. Stress can be obtained.

  Next, as shown in FIG. 7B, the substrates 14 and 16 in which the through holes 15 and 17 are formed are attached to one side of the sheet 60, and the sheet 60 protruding from the substrates 14 and 16 is cut. For example, a transparent acrylic plate having a thickness of 0.5 mm is used for the substrate 14, and a transparent acrylic plate having a thickness of 1.0 mm is used for the substrate 16. Each substrate 14 and 16 is formed with through holes 15 and 17 having a diameter of 1.5 mm.

  Next, as shown in FIG. 7C, a suction jig 70 is attached to the surface of the substrates 14 and 16 where the sheet 60 is not attached so as to cover the through holes 15 and 17, and suction is performed as indicated by an arrow 72. Then, recesses 23x and 25x are formed in portions 23 and 25 where the sheet 60 covers the through holes 15 and 17 of the substrates 14 and 16, respectively. For example, the suction is performed so that the differential pressure from the atmospheric pressure is 0.1 Pa.

  Next, as shown in FIG. 7D, the conductive grease 26 is filled in the recesses 23x and 25x, and the conductive film 32 is provided on one side between the substrates 14 and 16 disposed so that the sheets 22 and 24 face each other. The positions of the through holes 31 and 33 of the thin plate 30 and the conductive film 32 and the positions of the recesses 23x and 25x are aligned and joined together. For example, an OHP sheet (polyester sheet) having a thickness of 100 μm is used as the thin plate 30, and Al is deposited as the conductive film 32 on one surface thereof.

  Next, as shown in FIG. 8 (e), a resin is applied to the upper surface of one substrate 14 and the through hole 15 to form a cover layer 20 and a diaphragm 21, and conductive to the through hole 17 of the other substrate 16. The functional grease 28 is filled. For example, a cover layer 20 having a thickness of 30 μm is formed on the substrate 14 by spin-coating PDMS (Polydimethylsiloxane) and heating to cure.

  Next, as shown in FIG. 8 (f), the lower surface of the other substrate 16 is overlapped and joined to the thin plate 34 having the conductive film 36 formed on the upper surface, and the other substrate 16 filled with the conductive grease 28 is joined. The through hole 17 is closed.

  Next, as shown in FIG. 8G, a substrate in which microchannels 12a to 12g, valves 12s and 12t, and openings 12x and 12y are formed in advance on a cover layer 20 formed on the upper surface of one substrate 14. 12 are stacked, and the substrate 12 is bonded to the cover layer 20. Thereby, the microchip is completed. For example, the substrate 12 is formed of the same material PDMS as that of the cover layer 20, so that the substrate 12 and the cover layer 20 can be bonded by simply contacting them. In addition, with the cover layer 20 and the board | substrate 12, the quantity according to each use is acquired by changing the quantity of the hardening | curing agent added to PDMS.

  The substrate 12 on which the microchannels 12a to 12g, the valves 12s and 12t, and the openings 12x and 12y are formed is manufactured as shown in FIG.

  That is, as shown in FIG. 9A, the bottom upper portion 82 is formed on the base 80 corresponding to the gap S3 between the lower ends 12p, 12q of the valves 12s, 12t and the microchannel bottom surface 20a shown in FIG. The valves 12s and 12t are formed at positions corresponding to the lower ends 12p and 12q and the vicinity thereof. For example, SU-8 (manufactured by Microchem), which is a photo-curing resin, is applied to the bottom upper portion 82, and the portion that becomes the bottom upper portion 82 is exposed to parallel light and then heated to cure the transmission portion of the parallel light. Then, the non-transparent portion is removed using a developer. Thereby, for example, a bottom upper portion 82 having a height of 3 μm is formed.

  Next, as shown in FIG. 9B, a flow path portion 84 corresponding to the space of the microchannels 12a to 12g is produced. The flow path portion 84 is formed, for example, using SU-8, exposed to parallel light and then heated and developed to have a height of 50 μm.

  Next, as shown in FIG. 9C, the resin 88 is poured onto the base 80, and the shapes of the bottom upper part 82 and the flow path part 84 are transferred to the resin 88. Before or after pouring the resin 88, the columnar member 86 is inserted into a position corresponding to the openings 12x and 12y, and the resin 88 is cured with the columnar member 86 still inserted.

  For example, PDMS is used for the resin 88. Since PDMS is a transparent photocurable resin, a micropump can be easily produced by pouring into a mold and curing. The PDMS retains the shape of the microchannels 12a to 12g and has rigidity sufficient to elastically deform the valves 12s and 12t. Since PDMS is transparent, the fluid flowing through the microchannel can be observed from the outside using light.

  Next, by removing only the resin 88, the substrate 12 is completed as shown in FIG.

  Next, the characteristics of the micropump fabricated on the microchip 10 will be described with reference to the graphs of FIGS.

  FIG. 10A shows the relationship between the voltage (Voltage) applied between the conductive greases 26 and 28 and the displacement of the diaphragm 23 (Displacement). The displacement of the diaphragm 23 was measured by reflected light from the conductive grease 26 by mixing Ag particles into the conductive grease 26 and using a laser displacement meter from the substrate 12 side. Even when the Ag particles were mixed with the conductive grease 26, no change was seen in the pump characteristics. Gray triangle indicates an elastomer sheet 60 that has been given a tensile strain of 200% in each of the X and Y directions, and gray square indicates an elastomer sheet that has previously been provided with a 300% of the tensile strain in the X and Y directions. When 60 is used, black ♦ indicates a case where an elastomer sheet 60 is used in which tensile strains of 400% are applied in the X and Y directions in advance. It can be seen that if the tensile strain applied in advance is 150% or more, the displacement changes according to the voltage, and the micropump can be driven. When the tensile strain applied in advance is 500% or more, even if the tensile strain is increased, the relationship between the voltage and the displacement does not change, and the effect obtained by applying the tensile strain in advance is saturated.

  FIG. 10B shows the relationship between the frequency (Frequency) of the voltage (Voltage) applied between the conductive greases 26 and 28 and the displacement (Displacement) of the diaphragm 23. The gray triangle indicates that when a voltage of 2.4 kV is applied using an elastomer sheet 60 preliminarily applied with tensile strains of 200% in the X and Y directions, the gray square indicates 300% in advance in the X and Y directions. 2. When a 2.7 kV voltage is applied using a tensile strained elastomer sheet 60, the black ♦ uses an elastomer sheet 60 that has been previously given 400% tensile strain in the X and Y directions. The case where a voltage of 3 kV is applied is shown.

  FIG. 11A shows the relationship between the frequency of the voltage applied between the conductive greases 26, 28, the flow rate (black rate), and the back pressure (blocked pressure; gray square). It can be seen that it can be driven well when the frequency of the voltage applied between the conductive greases 26 and 28 is in the range of about 10 Hz to 100 Hz.

  FIG. 11B shows the relationship between the magnitude of the voltage applied between the conductive greases 26 and 28, the flow rate (black rate), and the back pressure (blocked pressure; gray square). It can be seen that the driving force increases as the voltage is increased.

  FIG. 12A shows the relationship between the frequency of the voltage applied between the conductive greases 26 and 28, the output (Power; black ◆), and the efficiency (Efficiency; gray square). The output is energy when transporting the fluid. The efficiency is the ratio of the transport energy of the fluid obtained as an output with respect to the electric energy input by voltage application. It can be seen that the drive can be efficiently performed within the frequency range of about 10 Hz to 100 Hz.

  FIG. 12B shows the relationship between the frequency of the voltage applied between the conductive greases 26 and 28 and the displacement of the diaphragm 23. Black indicates no back pressure, and gray indicates a back pressure of 3.5 kPa. In either case, the fluid conveyed by the micropump is water.

  From FIG. 10A and FIG. 11B, if the voltage applied between the conductive greases 26 and 28 is 1 kV or more, the fluid can be conveyed. At this time, since the thickness of the diaphragm portion 25 is about 20 μm, the fluid can be conveyed if the electric field applied to the diaphragm portion 25 is 50 V / μm or more.

<Example 2> The micropump of Example 2 will be described with reference to a cross-sectional view of the main part of FIG.

  The micropump of the second embodiment is configured in substantially the same manner as the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the differences will be mainly described below.

In the micro pump of the second embodiment, conductive grease 27 is filled between the cover layer 20 x and the diaphragm portion 23. The conductive grease 27 in contact with the diaphragm portion 23 is electrically connected to the power source portion by wiring (not shown). The power supply unit is also electrically connected to the conductive grease 28 in contact with the diaphragm unit 25 through the conductive film 36. The conductive grease 26 filled between the diaphragm portions 23 and 25 is grounded through the conductive film 32. The power supply unit applies an AC voltage of ± V ₀ , but a negative voltage of −V _{0 to} 0 is applied only to the conductive grease 27 in contact with the diaphragm unit 23, and a positive voltage of 0 to + V ₀ is applied to the diaphragm unit 25 includes a circuit that is applied to the conductive grease 28 in contact with 25. Accordingly, the diaphragm portions 23 and 25 alternately expand and contract every half cycle of the AC voltage of ± V _0. Therefore, when the same AC voltage is applied, the displacement amount of the diaphragm 21x is such that only the diaphragm portion 25 expands and contracts. The driving frequency of the diaphragm 21x is half that of the first embodiment in which only the diaphragm portion 25 expands and contracts.

  <Summary> As described above, the micropump uses expansion and contraction of an elastomer material as a drive source. In general, commercially available elastomers have low rigidity, but by reducing the thickness by applying tensile strain in advance, the rigidity is improved and the effective electric field is increased, so that the driving force of the micropump can be increased. Since the elastomer has high insulation, a high voltage can be applied, and the output of the micropump can be increased.

  By using conductive grease for the electrodes, the elastomer can be greatly deformed in the surface direction because deformation in the surface direction is not constrained. In addition, since the elastomer has a two-layer structure, the conductive grease can be stably contained.

  Although the micropump of the present invention requires a high voltage, the structure of the pump itself can be reduced in size.

  In order to function as a pump, it is necessary to provide a valve function of the flow path. However, by transferring the mold to PDMS and integrating the microchannels 12a to 12g and the valves 12s and 12t, It is possible to manufacture a highly reliable microvalve.

  The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

  An electrode other than conductive grease may be used. For example, a fluid having conductivity other than the conductive grease may be sealed between the diaphragm portions 23 and 25.

  Moreover, you may support two or more places intermittently instead of supporting the periphery of a diaphragm part continuously. The planar shape of the diaphragm portion is not limited to a circle, and may be an arbitrary shape such as a triangle, a rectangle, a polygon, or an asymmetric shape.

  The raising / lowering of the diaphragm part can be used for driving other than the micropump. For example, the flow path may be opened and closed by raising and lowering the diaphragm part, or the switch may be contacted and separated.

It is sectional drawing of a microchip. Example 1 It is sectional drawing cut | disconnected along line II-II of FIG. Example 1 It is a principal part expanded sectional view of FIG. Example 1 FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. Example 1 It is explanatory drawing of the expansion-contraction of a sheet | seat. Example 1 It is explanatory drawing of operation | movement of a micropump. Example 1 It is explanatory drawing of the manufacturing process of a microchip. Example 1 It is explanatory drawing of the manufacturing process of a microchip. Example 1 It is explanatory drawing of the manufacturing process of a microchip. Example 1 It is a graph which shows the characteristic of a micropump. Example 1 It is a graph which shows the characteristic of a micropump. Example 1 It is a graph which shows the characteristic of a micropump. Example 1 It is a principal part expanded sectional view of a micropump. (Example 2)

Explanation of symbols

12a-12g Microchannel (flow path)
12s, 12t Valve 20 Cover layer 21 Diaphragm 22 Sheet (membrane)
23 Diaphragm part (second diaphragm part)
22 Sheet (membrane)
25 Diaphragm part 26 Conductive grease (electrode)
28 Conductive grease (electrode)

Claims (8)

By supporting the peripheral portion of the insulator film having rubber elasticity, a diaphragm portion formed inside the peripheral portion;
A pair of electrodes that are in contact with both surfaces of the diaphragm part without constraining both surfaces in the surface direction;
A flow path that is arranged adjacent to the diaphragm portion and whose volume changes in conjunction with deformation of the diaphragm portion;
With
When a voltage is applied between the electrodes, the area of the diaphragm changes to change the volume of the flow path, thereby transporting the fluid in the flow path. By supporting the peripheral part of the second film having rubber elasticity between the diaphragm part and the flow path, a second diaphragm part formed inside the peripheral part is provided,
Between the diaphragm portion and the second diaphragm portion, a conductive fluid that becomes one of the pair of electrodes is sealed,
2. The micropump according to claim 1, wherein a conductive fluid serving as the other of the pair of electrodes is adhered to a surface of the diaphragm portion opposite to the flow path. The diaphragm part is formed inside the peripheral part by supporting the peripheral part of the film in a state in which tensile strain is applied in advance to the elastomer film of the insulator,
The diaphragm portion has a thickness of 100 μm or less,
The micro pump according to claim 1, wherein the diaphragm portion has an electric field of 50 V / μm or more between the electrodes due to a voltage applied to the pair of electrodes. The diaphragm portion has a diameter of 3 mm or less,
4. The micropump according to claim 1, wherein a tensile strain of 150% or more and less than 500% is applied in advance to the elastomer constituting the diaphragm portion. 5.   The micropump according to claim 1, 2, or 3, wherein a relative dielectric constant of the elastomer constituting the diaphragm portion is 4 or more. Two valves are provided in the flow path,
In the flow path, the diaphragm portion is disposed adjacent to the valve,
The micro pump according to claim 1, wherein the valve is formed by molding integrally with the flow path using PDMS (Polydimethylsiloxane).   The micro valve according to claim 6, wherein the valve is formed with a gap of 1 μm or more and 10 μm or less from a wall surface of the flow channel in the vicinity of a boundary between portions having different widths of the flow channel. pump. By supporting the peripheral portion of the insulator film having rubber elasticity, a diaphragm portion formed inside the peripheral portion;
A pair of electrodes that are in contact with both surfaces of the diaphragm part without constraining both surfaces in the surface direction;
With
An actuator using the deflection of the diaphragm portion when a voltage is applied between the electrodes for driving.