JP2003024753A - Microextractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microextractor having simple constitution increasing the tolerance width of the differential pressure ΔP between two kinds of fluids respectively guided to two microchannels and usable under simple control. SOLUTION: The microextractor is equipped with two microchannels 1 and 2 demarcated by a partition wall 3 having a plurality of fine holes 4 to be provided in parallel to each other and the partition wall is especially realized as a membrane deformed corresponding to the pressure difference between the fluids flowing through the respective microchannels to change the cross-sectional areas of the microchannels. Preferably, the partition wall has a wavy deformable part 5 formed along the fluid passing direction of the microchannels.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microextractor suitable for separating and extracting a product synthesized by a chemical reaction in a micro space using a microreactor.

[0002]

2. Related Background Art Separation and extraction of products synthesized by using a microreactor are provided in parallel by being partitioned by partition walls 4 having a plurality of pores 3 as shown in the schematic configuration of FIG. Two micro channels 1, 2
Is performed using a microextractor equipped with. By the way, the microreactor introduces two kinds of reactive fluids into a microchannel in which a fluid communication channel having a minute channel cross-sectional area is formed, and these fluids are brought into contact with each other to cause a microchemical reaction. Separation of substances produced by such a microreactor using a microextractor
By extracting, for example, detection of a specific substance accompanied by a biochemical reaction or analysis of a chemical reaction mechanism in a micro area is performed.

The flow channel cross-sectional area of each microchannel in the above microreactor or microextractor is generally about 10 to 500 μm square, and such a microchannel having a minute flow channel cross-sectional area is made of silicon. It is formed using a micromachining technique such as etching.

[0004]

By the way, the micro-extractor basically consists of two micro-channels 1 and 2.
And the second immiscible fluids A and B, respectively,
The specific solute C contained in the fluid B is diffused and moved to the microchannel 1 (fluid A) side through the pores 4 provided in the partition wall 3 to separate only the specific solute C from the fluid B.・ It is to be extracted.

In this case, two micro channels 1, 2
The differential pressure ΔP allowed between the immiscible fluids A and B, which are made to flow through, respectively, is such that the interfacial tension of the immiscible fluids A and B is γ, the contact angle to the pores 4 is θ, and the diameter of the pores 4 is Is generally expressed as ΔP 2 = (4γ cos θ) / d 2. Therefore, in order to set the allowable differential pressure ΔP large and relax the usage conditions of the microextractor, the interfacial tension γ is uniquely determined by the types of immiscible fluids A and B. It is necessary to adjust to increase the component of (cos θ) or to reduce the diameter d of the pores 4.

However, even if the contact angle θ is adjusted, the above component (cos θ) can only be maximized to [1],
Further, the contact angle θ itself is likely to change due to the dirt on the surface of the partition wall 3. On the other hand, when the diameter d of the pores 4 is reduced, the processing becomes difficult as the diameter d is reduced,
Moreover, it becomes difficult to secure the entire opening area by the plurality of pores 4. Moreover, as the diameter d of the pores 4 decreases, the diffusion rate in the microchannel decreases. Therefore, there is a limit in reducing the diameter d of the pores 4.
Therefore, the differential pressure ΔP allowed between the two types of immiscible fluids A and B in the micro-extractor is naturally limited, and the pressure (flow rate) of the fluids A and B introduced to the micro-extractor is adjusted respectively. Therefore, there is a problem that precise process control is required.

The present invention has been made in consideration of such circumstances, and its purpose is to widen the allowable range of the differential pressure ΔP between two kinds of fluids respectively guided to two microchannels, and to reduce the cost. An object of the present invention is to provide a micro-extractor having a simple structure that enables use under simple control.

[0008]

In order to achieve the above-mentioned object, a micro-extractor according to the present invention comprises two micro-channels which are defined in parallel by partition walls having a plurality of pores and which are provided in parallel. In particular, it is characterized in that the partition wall is realized as a membrane that deforms according to the pressure difference of the fluids flowing through the respective microchannels to change the channel cross-sectional area of the respective microchannels.

Preferably, the partition wall composed of the membrane is provided with a corrugated deformation portion formed along the fluid flow direction of the microchannel. Regarding the partition having the corrugated deformed portion, for example, a portion forming the partition of the silicon body forming each microchannel is selectively anisotropically etched or isotropically etched to form a corrugated groove, A film having a predetermined thickness forming a partition wall may be formed on the surface of the silicon body including the corrugated groove, and then the silicon body located under the film may be removed. Alternatively, it may be formed by making the surface of the silicon body including the corrugated groove porous over a predetermined thickness, and then removing the porous silicon body located under the surface layer (porous silicon layer). Good.

Another micro-extractor according to the present invention is
A wall surface facing the partition wall of each microchannel,
It is realized as a membrane that elastically deforms according to the pressure of a fluid flowing through each of the microchannels to change the flow passage cross-sectional area of each of the microchannels. That is, the wall surface other than the partition wall forming the wall surface of the micro channel may be configured to be elastically deformed according to the pressure of the fluid flowing in the micro channel, thereby changing the flow passage cross-sectional area. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A micro-extractor according to an embodiment of the present invention will be described below with reference to the drawings. Figure 2
FIG. 3 is a perspective view showing a schematic configuration of a micro-extractor according to this embodiment. This micro-extractor is configured to include first and second micro-channels 1 and 2 which are partitioned by a partition wall 3 and are provided in parallel in two stages above and below. The partition wall 3 has a plurality of pores 4, and in particular, a membrane (thin film body) having a corrugated deformable portion 5 formed along the fluid flow direction of the fluid in the microchannels 1 and 2 in the peripheral portion thereof. ) Consists of. The partition wall 3 made of this membrane deforms the deforming portion 5 according to the pressure difference (differential pressure) of the fluids flowing through the microchannels 1 and 2, respectively, and displaces the main surface position thereof. The flow channel cross-sectional areas of the microchannels 1 and 2 are variable within a predetermined range.

That is, the partition 3 in this micro-extractor
Is, for example, as schematically shown in its planar structure in FIG.
A plurality of pores 4 are bored all over the main surface 3a, and the main surface 3a can be displaced in the surface direction through a plurality of wavy deformation portions 5 formed along the peripheral portion. It has a structure supported by. The partition wall 3 divides the two microchannels 1 and 2 into a microextractor as shown in FIG. 4 as a cross-sectional view and shows the flow of the fluid flowing through the two microchannels 1 and 2, respectively. Pressure P1, P2
The main surface 3a is positionally displaced so that the pressures P1 and P2 are balanced in accordance with the difference ΔP between the two, and the flow channel cross-sectional areas of the microchannels 1 and 2 are changed.

Incidentally, a micro-extractor having a structure in which two micro-channels 1 and 2 are partitioned by a partition wall 3 having such a corrugated deformation portion 5 is manufactured as shown in FIGS. 5 (a) to 5 (f), for example. To be done. That is, as a material for forming the microchannel 1, for example, a Si substrate 11 having a (100) plane as a main surface is prepared. Then, a silicon nitride (SiN _x ) film 12 is grown on the surface of the Si (100) substrate 11, and the SiN _x film 12 is formed on the SiN _x film 12 by photolithography.
As shown in (a), a plurality of slit-like holes 13 are provided in parallel at a predetermined opening pitch.

After that, SiN_xKO using the film 12 as a mask
H or TMAH (trimethylammonium hydride
Anisotropically etching the Si substrate 11 using
As shown in FIG. 5B, the surface of the Si substrate 11 has a triangular cross section.
The concave portion 14 having a plurality of grooves having a shape is formed into the above-mentioned SiN._xfilm
It is formed in parallel according to the mask pattern shape formed by 12.
It Then, the above-mentioned SiN_xAfter removing the film 12 once,
The entire area of the surface of the Si substrate 11 on which the groove-shaped recess 14 is formed is
As shown in FIG. 5 (c), the partition wall 3 has a predetermined thickness of SiN. _xfilm
Form 15. Then, as shown in FIG.
iN_xThe corrugation changes formed along the recess 14 of the film 15.
Dry etching from the shape part 5 to the area inside.
A plurality of holes 16 (4) having a predetermined opening diameter d
It is formed at a predetermined pitch. After that, the above SiN_xMembrane 15
As a mask, and through the plurality of holes 16 (4) described above,
As shown in FIG. 5E, the SiN on the Si substrate 11 is_x
The lower region of the film 15 is isotropically etched to remove the SiN_xfilm
A space 17 is formed under 15 and the space 17 is
Channel.

On the other hand, a chip in which a concave portion 19 forming a predetermined space is formed on one surface of another Si substrate 18 is prepared. Then, as shown in FIG. 5F, the recess 19 of the Si substrate 18 is formed.
Is aligned with the partition wall 3 made of the SiN _x film 15 formed on the Si substrate 11, and these are joined to form the recess 19 as the other microchannel surrounded by the SiN _x film 15. As a result, the two microchannels 1 and 2 are formed by the space 17 formed in the Si substrate 11 and the recess 19 formed in the Si substrate 18, which are partitioned by the partition wall 3 made of the SiN _x film 15. become. The partition wall 3 made of the SiN _x film 15 is elastically supported by the corrugated deformation portion 5 formed around the partition wall 2.
The two microchannels 1 and 2 are displaceably provided.

Incidentally, when the micro-extractor is formed by using the SOI wafer provided with the oxide film, it may be performed as shown in FIGS. 6 (a) to 6 (f). That is, in this case, on the Si substrate 21 on the oxide film (SiO ₂ film) 22 Si layer 23 formed through which the base is grown silicon nitride (SiN _x) film 12, the SiN _x As shown in FIG. 6A, the film 12 is provided with slit-shaped holes 13 in parallel. And this S
The Si layer 23 is anisotropically etched using the iN _x film 12 as a mask to form a recess 14 having a plurality of grooves having a triangular cross section on the surface of the Si layer 23 as shown in FIG. 5B.

Then, after the SiN _x film 12 is once removed, S having a predetermined thickness as the partition 3 is formed on the entire surface of the Si layer 23 having the plurality of recesses 14 as shown in FIG. 6C.
forming a iN _x layer 15, the recess 14 of the the SiN _x film 15
A plurality of holes 16 (4) having a predetermined opening diameter d are formed at a predetermined pitch by dry etching or the like from the corrugated deformation portion 5 formed along the inner side of the corrugated deformation portion 5.

Thereafter, using the SiN _x film 15 as a mask, the Si layer 23 and the oxide film (SiO ₂ film) 22 are formed through the plurality of holes 16 (4) described above as shown in FIG. 5D. To form a vertical groove (hole) 24. Then, the Si layer 2 is formed through these grooves (holes) 24.
3 is anisotropically etched, and as shown in FIG.
The space 25 is formed in the lower region of the iN _x film 15 and the space 25 is formed.
Is a micro channel.

After that, as in the case of the above-described manufacturing example, a chip is prepared in which a concave portion 19 forming a predetermined space is formed on one surface of another Si substrate 18. Then, as shown in FIG.
The recess 19 of the substrate 18 is aligned with the partition wall 3 made of the SiN _x film 15 formed on the Si layer 23 described above, and these are joined to form the recess 19 in the SiN _x film 15.
If the other microchannel is surrounded by, the microextractor in which the two microchannels 1 and 2 are partitioned by the partition wall 3 is completed.

By the way, in the micro-extractor according to the above-mentioned embodiment, the SiN _x film 15 formed on the Si substrate 11 or the Si layer 23 is used as the partition wall 3. However, the surface layer itself of the Si substrate 11 is used as the partition wall 3. You can also In this case,
As shown in (a), a silicon nitride (SiN _x ) film 12 is grown on the surface of the Si substrate 11, and slit holes 13 composed of a plurality of grooves are made parallel to the SiN _x film 12 at a predetermined opening pitch. Set up. Then, the Si substrate 11 is anisotropically etched by using the SiN _x film 12 as a mask, and as shown in FIG. 5B, the concave portion 14 formed of a plurality of grooves having a triangular cross section is parallel to the surface of the Si substrate 11. To form. Then, after the SiN _x film 12 is once removed, a SiN _x film 31 as a new mask is formed around the surface of the Si substrate 11 having the plurality of recesses 14 as shown in FIG. 5C. To do.

Thereafter, as shown in FIG. 7 (c), the chip is soaked in hydrofluoric acid (HF) water with its front and back surfaces liquid-tightly divided, and a predetermined density between the anode 32 and the cathode 33. Energize the current. Then, as shown in FIG. 5C, the Si substrate 1
The surface layer of No. 1 is anodized over a predetermined thickness to make it porous to form a porous silicon layer 34. By making the Si substrate 11 porous, fine pores 4 are uniformly formed on the surface of the Si substrate 11.

Next, the Si substrate 11 under the porous silicon layer 34 is etched by increasing the current density flowing between the anode 32 and the cathode 33 to form a space 35 forming a microchannel. That is, by changing the anodizing current density of the Si substrate 11, a porous silicon layer 34 having a predetermined thickness is first formed on the surface layer of the Si substrate 11, and then the anodizing current density is increased. , Si substrate 11 is etched. As a result, FIG.
As shown in (e), the porous silicon layer 3 forming the partition wall 3
A space 35 forming a microchannel is formed below 4.

After that, as in the case of each of the above production examples, another S
A chip in which a concave portion 19 forming a predetermined space is formed on one surface of the i substrate 18 is prepared. Then, as shown in FIG. 7 (f), the recess 19 of the Si substrate 18 is aligned with the partition wall 3 made of the porous silicon layer 34 formed on the Si substrate 11, and these are joined to form the recess. When the other microchannel 19 is surrounded by the porous silicon layer 34, the microextractor in which the two microchannels 1 and 2 are partitioned by the partition wall 3 is completed.

According to the partition wall 3 thus manufactured, the pores 4 are formed by making the silicon porous, so that the fine pores 4 can be uniformly provided over the entire area of the partition wall 3. However, there is an advantage that the manufacturing itself is very easy. Further, the partition wall 4 is formed by etching silicon.
Since the thickness of the partition wall 4 can be adjusted, the partition wall 4
There are advantages such as easy adjustment to the physical characteristics required for

Thus, according to the microextractor having the structure in which the two microchannels 1 and 2 are partitioned by the partition wall 3 which is manufactured as described above and has the structure in which the corrugated deformation portion 5 is provided in the peripheral portion, the partition wall 3 is formed. Each pressure P of the fluids A and B flowing through the two microchannels 1 and 2, respectively
When there is a difference between 1 and P2, the partition wall 3 is pushed from the channel side having a high pressure to the channel side having a low pressure to change the position of its main surface 3a. Then, the channel cross-sectional area of the channel on the high pressure side is expanded, and the channel cross-sectional area of the channel on the low pressure side is narrowed. The flow path resistance of each channel changes in accordance with the change of the flow path cross-sectional area, and the partition wall 3 is reached when the pressures P1 and P2 of the fluids A and B flowing through the two microchannels 1 and 2 are balanced. The position of is stabilized.

As a result, the two microchannels 1, 2
The differential pressure ΔP between the fluids A and B flowing through the
Thus, the specific substance is satisfactorily diffused and moved through the pores 4 between the microchannels 1 and 2, and the specific substance is effectively separated and extracted. Particularly in this case, the flow pressure P1,
Even if P2 is not strictly controlled, the function of the microextractor can be effectively operated to reliably separate and extract the specific substance. However, in this case, in reality, a minute pressure difference is generated by the elastic force corresponding to the deformation of the corrugated deforming portion 5.

Therefore, for example, as shown in FIG. 8, the operation of the pumps 41 and 42 is controlled by using the constant flow rate control unit 40, and 2
Fluid A supplied to each of the two microchannels 1 and 2,
If a specific substance is separated and extracted using a microextractor while controlling the constant flow rate of B, the fluid A,
Since the pressures P1 and P2 in the microchannels 1 and 2 are automatically balanced by the positional displacement of the partition wall 3 according to the differential pressure ΔP between B, the specific substance can be stably separated under certain conditions.
It can be extracted and its practical advantages are great.

The present invention is not limited to the above embodiment. For example, in the embodiment, the partition wall is formed using a silicon (Si) or silicon nitride (SiNx) film, but it may be formed using a metal plate (film). Further, as described above, not only the partition 3 is deformed, but also the flow channel cross-sectional area of each microchannel 1, 2 is changed according to the differential pressure ΔP between the fluids A, B flowing through the two microchannels 1, 2. Since the pressures P1 and P2 may be balanced, for example, the above-mentioned corrugated deformation portion is formed on the wall surface of the microchannels 1 and 2 facing the partition walls 3 as shown in FIG. However, it is also possible to displace each of these wall surfaces to change the flow passage cross-sectional area. In this case, the deformable portion may be provided with a predetermined spring constant, and the wall surface may be displaced in a direction in which the flow passage cross-sectional area expands with reference to a certain pressure Pref.

In addition, the shape of the corrugated portion that forms the deformable portion can be variously modified, and the point is that various modifications can be made without departing from the spirit of the invention.

[0030]

As described above, according to the present invention, the constraint on the difference in fluid pressure between the two microchannels allowed in the microextractor can be greatly relaxed, and the two microchannels can be provided. It is possible to automatically correct the pressure difference between the introduced fluids and stably generate the separation / extraction action of the specific substance. Moreover, since the micro-extractor itself can be realized as a simple structure, it is possible to obtain effects such as great practical advantages.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a schematic structure of a microextractor and its operation.

FIG. 2 is a perspective view showing a schematic configuration of a microextractor according to an embodiment of the present invention.

FIG. 3 is a plan view showing a schematic configuration of partition walls in the microextractor shown in FIG.

FIG. 4 is a diagram showing a sectional structure of the microextractor shown in FIG. 2 and a mode of positional displacement of partition walls.

FIG. 5 is an exploded view showing a first manufacturing example of a micro-extractor.

FIG. 6 is an exploded view showing a second manufacturing example of the micro-extractor.

FIG. 7 is an exploded view showing a second manufacturing example of the micro-extractor.

FIG. 8 is a diagram showing an example of use of a microextractor provided with a constant flow rate control system.

FIG. 9 is a schematic configuration diagram of a micro-extractor according to another embodiment of the present invention.

[Explanation of symbols]

1, 2 micro channels 3 partitions 4 pores 5 Waveform deformation part 11 Si substrate 14 Recessed portion with a triangular cross section (deformed portion) 20 Constant flow controller 21,22 pumps

Claims (5)

[Claims] 1. The apparatus includes two microchannels which are partitioned in parallel by partition walls having a plurality of pores and are provided in parallel, and the partition walls are deformed in accordance with a pressure difference between fluids flowing through the respective microchannels, and the microchannels are deformed according to the pressure difference. A micro-extractor comprising a membrane that changes the cross-sectional area of each micro-channel. 2. The micro-extractor according to claim 1, wherein the partition wall made of the membrane is provided with a corrugated deformation portion formed along a fluid flow direction of the micro-channel. 3. The partition having the corrugated deformed portion is formed after a corrugated groove is formed by selectively anisotropically or isotropically etching a surface of a silicon body forming one of the microchannels. One of the microchannels formed by forming a film forming the partition on the surface of the silicon body including the corrugated groove and then selectively etching a lower region of the film of the silicon body. The microextractor according to claim 2, which is provided as a wall surface. 4. The partition having the corrugated deformed portion is formed after the corrugated groove is formed by selectively anisotropically or isotropically etching the surface of the silicon body forming one of the microchannels. A microchannel formed by making the surface of the silicon body including the corrugated groove porous over a predetermined thickness, and then selectively etching a lower region of the porous silicon layer of the silicon body. The microextractor according to claim 2, which is provided as one wall surface of the. 5. A plurality of microchannels provided adjacent to each other with a partition wall having a plurality of pores interposed therebetween, wherein a wall surface of each of the microchannels facing the partition wall is formed.
A microextractor comprising a membrane that elastically deforms according to the pressure of a fluid flowing through each of the microchannels to change the flow passage cross-sectional area of each of the microchannels.