JP4005297B2 - Microvalves and micropumps - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microvalve and a micropump that are used in the medical field and analysis field and perform fluid control with a small size and high accuracy.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a pump that performs small and highly accurate fluid control, for example, there is a pump described in Japanese Patent Laid-Open No. 4-66784 in FIG. According to the positional relationship between the two valves 15 and the fluid inlet / outlet 4, each of them functions as a one-way valve. Therefore, one-way liquid feeding is realized by applying a voltage to the central piezoelectric element 6 to generate a volume change inside the pump. Moreover, the glass substrate 13 and the silicon substrate 14 are joined by anodic bonding.
[0003]
In the case of the micropump described in Japanese Patent Laid-Open No. 5-1669 in FIG. 3, a thin film of metal or polysilicon 16 is formed on the sacrificial layer of the oxide film on the silicon substrate 14, and the sacrificial layer is further formed by etching. By removing it, a metal or polysilicon check valve is formed, and the piezoelectric element 6 provided on the glass substrate 13 forms a pump.
[0004]
[Problems to be solved by the invention]
Conventional microvalves and micropumps have some problems. In the case of the micropump shown in FIGS. 2 and 3, since the layers are firmly bonded by a technique such as anodic bonding, both cannot be removed. For this reason, when a malfunction occurs, the whole has to be replaced, and there is a problem that the cost becomes high. In addition, when foreign matter is mixed inside, there is a problem that it is very difficult to remove the foreign matter. It is also difficult to change performance such as the internal volume and the shutoff force of the valve.
[0005]
[Means for Solving the Problems]
The microvalve and the micropump of the present invention have a structure in which an actuator substrate for deforming a diaphragm by an actuator and a cover substrate having a valve portion, a pumping portion, a flow path portion, and the like are fixed by pressure bonding. Therefore, these substrates can be freely attached and detached, and the inside can be cleaned by removing the actuator substrate and the cover substrate when foreign matter is mixed. Further, when changing the volume and shape of the valve portion and the pumping portion, it is only necessary to replace the cover substrate, and the actuator substrate can be used in common.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[Embodiment 1]
In this embodiment, an example of a microvalve in which a silicon substrate is used as the actuator substrate and a silicone resin is used as the cover substrate will be described.
[0007]
FIG. 4 is an exploded view of the microvalve. The microvalve is composed of an actuator substrate 1 made of a silicon substrate and a cover substrate 2 made of a silicone resin, and these two substrates are fixed in close contact with each other.
[0008]
First, the cover substrate 2 will be described. The cover substrate 2 has a recess, and the recess is separated by a separator 3. Each of the recesses divided into two by the separator 3 is formed with a through hole so as to penetrate the cover substrate 2, and this through hole serves as a fluid inlet / outlet 4 connecting the inside and the outside of the microvalve. In addition, there is no limitation in particular about the shape of a recessed part, You may use a circular recessed part like FIG. Further, the position of the fluid inlet / outlet is not particularly limited, and it is possible to use a structure in which the flow path 7 is directly used as the fluid inlet / outlet as shown in FIG. The cover substrate 2 can be formed in any shape by creating a mold using a photolithographic technique, pouring an uncured silicone resin into the mold, and then curing the mold.
[0009]
Next, the actuator substrate 1 will be described. In this embodiment, first, anisotropic etching with KOH is performed on a silicon substrate. This etching is performed from the back surface of the silicon substrate, and the etching is continued until a diaphragm 5 having a desired thickness is formed. However, the surface of the silicon substrate is left flat without being etched. However, the size of the diaphragm 5 is set to be the same as or smaller than the concave portion (including the separator) in the cover substrate 2. The reason why both sizes are set in this way will be described later. When silicon anisotropic etching is used, the shape of the diaphragm is quadrangular. However, if isotropic etching such as reactive ion etching is used, it is possible to form a diaphragm having a shape other than the quadrangular shape. . A piezoelectric element 6 is bonded to the diaphragm 5 formed by etching from the back surface, and a unimorph structure of the diaphragm 5 and the piezoelectric element 6 is formed. The diaphragm 5 can be deformed by applying a voltage to the piezoelectric element 6. The deformation of the diaphragm can be realized by various actuators using electrostatic force, magnetic force, air pressure, shape memory alloy, and the like, and is not limited to the piezoelectric element. Further, the method for forming the diaphragm is not limited, and the material for the actuator substrate is not limited to silicon.
[0010]
The cover substrate 2 and the actuator substrate 1 are pressure-bonded so that the surface of the cover substrate 2 where the concave portion exists and the surface of the actuator substrate 1 that is not etched are in contact with each other (FIG. 7). . At this time, the two substrates are positioned such that the center of the recess in the cover substrate 1 and the diaphragm 5 of the actuator substrate 1 coincide. If a highly adhesive silicone resin such as PDMS (polydimethylsiloxane) is used for the cover substrate 2 and a silicon substrate having a high flatness is used for the actuator substrate 1, there is no need to perform physical fixing. Sufficient adhesion can be obtained. In this case, even if a pressure of about several kilopascals is applied from the fluid inlet / outlet 4, no fluid leaks from between the actuator substrate 1 and the cover substrate 2.
[0011]
Further, as shown in FIG. 8, there is a method of fixing by sandwiching the actuator substrate 1 and the cover substrate 2 using the holder 8. The holder 8 is fixed by a screw 10 through a spacer 9. The pressure-bonding force between the actuator side substrate 1 and the cover substrate 2 can be adjusted by the thickness of the spacer 9. In this case, no leakage occurs between the two substrates even under a high pressure as compared with the case where the substrates are simply brought into close contact with each other. Furthermore, it is also possible to form a pipe line integrally with the holder on the cover substrate 2 side. Since high adhesion can be obtained also between the holder 8 and the cover substrate, a leak-free conduit can be realized between the microvalve body.
[0012]
In any case, the actuator substrate 1 and the cover substrate 2 are not particularly bonded to each other, and thus can be freely attached and detached. The material of the cover substrate 2 is not limited to silicone resin, and any material may be used as long as it has good adhesion to the actuator substrate 1 and is detachable.
[0013]
In addition, even when the cover substrate and the actuator substrate are both made of a material having no adhesion, an adhesive thin film is formed on at least one of the contact surfaces of the cover substrate 1 and the actuator substrate 2. By forming, it can also be set as the structure which can detach | desorb both and has high adhesiveness. Further, a thermoplastic adhesive layer can be used between the two substrates, and the two substrates can be attached and detached by heating / cooling.
[0014]
In order to repeat the positioning of both substrates and perform with high accuracy, alignment marks are installed on both substrates. Moreover, highly accurate positioning can be repeatedly performed by forming a guide on at least one of the substrates or the holder.
[0015]
Next, the operation of this microvalve will be described. As already shown in FIG. 7, in this microvalve, the actuator substrate 1 and the cover substrate 2 are in close contact with each other, so that the separator 3 and the diaphragm 5 are also in close contact with each other. For this reason, if no voltage is applied to the piezoelectric element, the two fluid inlets / outlets 4 are blocked by the separator 3, so that no flow occurs even if pressure is applied from one fluid inlet / outlet. The closed state is maintained.
[0016]
On the other hand, when a voltage is applied to the piezoelectric element 6, the diaphragm 5 bends due to the unimorph structure of the piezoelectric element 6 and the diaphragm 5, and a gap is generated between the diaphragm 5 and the separator 3. As the fluid moves through the gap, the valve is opened (FIG. 9). That is, the separator 3 functions as a kind of packing.
[0017]
In this way, this valve operates by opening by applying voltage and opening by stopping applying voltage. Further, by reversing the direction of the voltage applied to the piezoelectric element, an operation of pressing the diaphragm against the separator and closing the microvalve more firmly is possible.
[0018]
Finally, the relationship between the diaphragm and the size of the recessed portion will be described. As described above, the size of the diaphragm is the same as or smaller than the concave portion (including the separator) in the cover substrate. That is, the concave portion (including the separator) in the cover substrate covers the etched portion of the diaphragm. In this case, even if the diaphragm is deformed downward as already shown in FIG. 9, the peripheral edge of the recess is not peeled off from the actuator substrate 1. Therefore, the fluid inside the microvalve does not leak to the outside from between the actuator substrate and the cover substrate.
[0019]
Conversely, when the area of the diaphragm 5 is larger than the concave portion of the cover substrate 2 as shown in FIG. 10, if the diaphragm 5 is displaced downward, peeling occurs between the diaphragm 5 and the cover substrate 2 at the periphery of the concave portion. . When pressure is applied from the fluid inlet / outlet 4 in this state, the pressure is applied in a direction in which the actuator substrate 1 and the cover substrate 2 are peeled off, and therefore, there is a problem that fluid easily leaks between the two substrates. For this reason, the microvalve in the present invention is designed so that the concave portion in the cover substrate 2 is larger than the diaphragm 5.
[0020]
As described above, the microvalve according to the present invention has a structure in which a closed state is maintained during non-driving when no voltage is applied. For this reason, even in a situation where there is a pressure difference between the fluid inlet side and the outlet side, the fluid can be held without any energy consumption. In addition, when the cover substrate and actuator substrate are fixed by a holder via a spacer, the pressure of the cover substrate and actuator substrate can be adjusted by the thickness of the spacer. By doing so, it becomes possible to arbitrarily set the fluid holding force when not driven.
[0021]
If the holder in which the pipe line is integrally formed is used, the pipe line creation in the microvalve can be realized at the same time, and the process can be simplified. Since the holder and the cover substrate are also pressure-bonded, it is possible to form a conduit without leakage.
[0022]
Further, since the cover substrate and the actuator substrate are not bonded together, they can be attached and detached freely. For this reason, it has an advantage that the cover substrate can be removed when the foreign matter enters the microvalve, and the inside can be easily cleaned. Furthermore, when the separator is deteriorated due to repeated opening and closing of the valve, it is possible to replace only the cover substrate, and the actuator substrate can be used as it is. Since partial replacement is possible in this way, the life of the entire microvalve can be extended.
[0023]
It is also possible to replace the cover substrate according to the characteristics required for the microvalve. When the microvalve is opened by voltage application, if the applied voltage is constant, the pressure-flow rate characteristic is determined by the width of the separator. By preparing a plurality of cover substrates with different separator widths and replacing them as necessary, it is possible to realize microvalves having different pressure-flow characteristics, and cost reduction is also realized. At the same time, since common actuator wiring and control systems can be used, versatility is enhanced.
[Embodiment 2]
In this embodiment, an example of a micro pump in which a silicon substrate is used as the actuator substrate and a silicone resin is used as the cover substrate will be described.
[0024]
FIG. 1 is an exploded view of the micropump. The micropump is composed of a cover substrate 2 made of silicone resin and an actuator substrate 1 made of silicon substrate, and these two substrates are fixed in close contact.
[0025]
First, the cover substrate 2 will be described. The cover substrate 2 is formed with two valve portions 11 that operate on the same principle as the microvalve already described in the first embodiment. One concave portion is formed in the middle of these valve portions 11 and functions as a pumping portion 12 for sucking and discharging fluid. The two valve parts 11 and the pump part 12 are connected by the flow path 7, and are arranged in series in the order of valve part-pumping part-valve part. Moreover, the fluid inlet / outlet 4 is provided in the valve part of both ends, respectively. Although FIG. 1 shows an example in which the width of the flow path 7 is narrower than the width of the valve portion 11 and the pumping portion 12, these may be the same width.
[0026]
Next, the actuator substrate 1 using a silicon substrate will be described. Three diaphragms 5 similar to those described in the first embodiment are formed on the silicon substrate, and a unimorph structure is formed by bonding the piezoelectric elements 6. These diaphragms are arranged so as to correspond to the valve portion 11 and the pumping portion 12 in the cover substrate 2.
[0027]
The actuator substrate 1 and the cover substrate 2 are brought into close contact with each other in the same manner as shown in the first embodiment. Further, the processing method, shape, size, and the like of each element are all the same as those described in the first embodiment.
[0028]
Subsequently, the operation of the micropump in the present embodiment will be described. The opening and closing of the two microvalves is as shown in the first embodiment. Regarding the pumping portion, the diaphragm is displaced by the unimorph structure of the diaphragm and the piezoelectric element, and fluid is discharged and sucked by the volume change. By driving these two microvalves and one pumping part in a certain sequence, liquid feeding from one fluid inlet / outlet to the other fluid inlet / outlet is realized. Since such a micro pump can arbitrarily open and close two valves and drive the pumping unit, the direction of liquid feeding can be changed by changing the driving order of the three actuators. In addition, since the micropump uses two microvalves shown in Embodiment 1, the micropump has a structure in which a closed state is maintained without applying a voltage to the piezoelectric element. For this reason, even in a situation where there is a pressure difference between the fluid inlet side and the outlet side, the fluid can be held without any energy consumption.
[0029]
Furthermore, since the micropump has a structure in which the cover substrate and the actuator substrate are not bonded to each other, they can be freely attached and detached. For this reason, it has an advantage that the cover substrate can be removed when the foreign matter is mixed inside the micropump and the inside can be easily cleaned. When the separator is deteriorated due to repeated opening and closing of the valve, it is possible to replace only the cover substrate, and the actuator substrate can be used as it is. Since partial replacement is possible in this way, the life of the entire micropump can be extended.
[0030]
On the other hand, it is possible to replace the cover substrate according to the characteristics required for the micropump. For example, it is possible to change the characteristics of the microvalve by using the method shown in the first embodiment, and it is also possible to change the characteristics at the time of suction and discharge by changing the depth and area of the recess of the pumping part. It is. Since the micropump having different characteristics can be realized only by replacing the cover substrate, the cost can be reduced. At the same time, since it is possible to use common actuator wiring and control systems, versatility is enhanced.
[0031]
【The invention's effect】
Since the microvalve and the micropump of the present invention use a structure in which the actuator substrate and the cover substrate are detachable, when foreign matter is mixed inside, the cleaning can be performed by removing both of them. have. Also, by preparing a plurality of cover part substrates having different parameters and replacing them as necessary, microvalves or micropumps having different characteristics can be easily realized. In this case, it suffices to replace only the cover substrate, and the actuator substrate can be used in common. Therefore, there is an advantage that the cost can be reduced. In addition, since common actuator wiring and control systems can be used, versatility is enhanced.
[Brief description of the drawings]
FIG. 1 is an exploded view showing an example of a micropump of the present invention.
FIG. 2 is a cross-sectional view showing the structure of a conventional micropump.
FIG. 3 is an exploded view showing a structure of a conventional micropump.
FIG. 4 is an exploded view showing the structure of the microvalve of the present invention.
FIG. 5 shows an example of a cover substrate in the microvalve of the present invention.
FIG. 6 shows an example of a cover substrate in the microvalve of the present invention.
FIG. 7 is a cross-sectional view showing the structure of the microvalve of the present invention.
FIG. 8 is a cross-sectional view showing a state where a cover substrate and an actuator substrate are fixed by a holder.
FIG. 9 is a cross-sectional view showing a state in which the microvalve of the present invention is open.
FIG. 10 is a cross-sectional view showing a state in which the microvalve is opened when the diaphragm is larger than the recess in the cover substrate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Actuator substrate 2 Cover substrate 3 Separator 4 Fluid inlet / outlet 5 Diaphragm 6 Piezoelectric element 7 Flow path 8 Holder 9 Spacer 10 Screw 11 Valve portion 12 Pumping portion 13 Glass substrate 14 Silicon substrate 15 Valve 16 Polysilicon

Claims (4)

In a valve for controlling fluid, at least two fluid inlets and outlets;
A substrate A made of silicone resin , connected to the fluid inlet / outlet, and having a recess that is internally divided into at least two regions by a separator;
Diaphragm,
It is composed of a silicon substrate and is composed of a substrate B having an actuator for deforming the diaphragm,
Combining the substrate A and the substrate B to form a flow path divided by a separator; and
In a state where the substrate A and the substrate B are combined, a deformed portion of the diaphragm is disposed immediately above the separator,
The outer periphery of the deformed portion of the diaphragm is inside the outer periphery of the concave portion of the substrate A, and
Due to the deformation of the diaphragm accompanying the driving of the actuator, the non-contact / contact state between the diaphragm and the separator changes, and the flow path is opened and closed, and
A valve having a structure in which a contact surface of the substrate A at a bonding site with the substrate B has adhesiveness, and the substrate A and the substrate B can be easily combined and separated.   2. The adhesive force according to claim 1, wherein the adhesive adhesive force is maintained in a state larger than the pressure of the fluid from the fluid inlet / outlet even when the bonding and separation of the substrate A and the substrate B are repeated. valve. For pumps that transfer fluids,
At least two fluid ports;
A substrate A made of silicone resin , connected to the fluid inlet / outlet, and having a recess that is internally divided into at least three regions by a separator;
At least two valve diaphragms;
At least one pumping diaphragm;
It is composed of a silicon substrate, and is composed of a substrate B having an actuator for deforming the valve diaphragm and the pumping diaphragm,
Combining the substrate A and the substrate B to form a flow path divided by a separator; and
In a state where the substrate A and the substrate B are combined, a deformed portion of the valve diaphragm is disposed immediately above the separator,
The outer circumferences of the deformed portions of the valve diaphragm and the pumping diaphragm are all inside the outer circumference of the concave portion of the substrate A, and
Due to the deformation of the valve diaphragm accompanying the driving of the actuator, the non-contact / contact state of the valve diaphragm and the separator changes, and the flow path is opened and closed, and
A structure for discharging and sucking fluid by deformation of the pumping diaphragm accompanying the driving of the actuator; and
A pump having a structure in which a contact surface of the substrate A at a bonding site with the substrate B has adhesiveness, and the substrate A and the substrate B can be easily combined and separated. The adhesive of the adhesive strength, even after repeated splitting and combining of the substrate A the substrate B, according to claim 3, characterized in that it is maintained in a greater state than the pressure of the fluid from the fluid port pump.

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