JP3974531B2 - Microchannel mixing method and microchannel apparatus - Google Patents

Abstract

This invention relates to a microchannel device comprising a microchannel and a liquid introduction means for introducing at least two liquids into the microchannel; characterised in that the introduction means comprises a pulse means for introducing each liquid into the microchannel in the form of a plurality of pulses, and for staggering the pulses of each liquid relative to the pulses of the other liquids. The device may be used to mix liquids for microfluidic applications.

Description

  The present invention relates to a novel macro channel apparatus. More specifically, the present invention relates to a novel microchannel device that facilitates mixing two or more liquids in a microchannel. The present invention also relates to a novel method for mixing two or more liquids together in a microchannel.

  A microchannel device is a device having one or more microchannels through which liquid can flow, each microchannel or each microchannel having a dimension between 100 nm and 1 mm perpendicular to the channel. . In addition to microchannels, the device can include other components such as chambers, filters, electrodes, pumps, valves, or mixing systems. Microchannels can be formed from PTFE, plastic, glass, quartz, or can be formed by micromachining a silicon wafer.

  Microchannel devices are used in analytical and synthetic applications involving very small quantities of material. For example, reagents used in the analytical process can be expensive. By carrying out the process in a microchannel device, the amount of chemical required is small and therefore the cost is minimized.

  Some chemical combinations may be possible only on a small scale due to their high reactivity.

  Since microchannel devices can be mass-produced at a relatively low cost, the reaction can be scaled up simply by performing the reactions simultaneously in the required number of microchannel devices.

  However, carrying out reactions and other processes on such a small scale can present several serious problems. A specific area of concern is the combination of two or more liquids that are necessary as a first step in causing a chemical reaction. Due to the laminar flow, it is generally not easy enough to flow the two liquids together. Because of the adjacent flow, the liquid only remains almost unmixed. This laminar flow is a result of the small dimensions of the channel and the flow rates typically used in microfluidics. Such mixing that occurs is the result of diffusion across the interface of the two liquids.

  One way that this problem can be addressed is to divide the flow of each liquid to be mixed into multiple flows, each flow having a reduced cross-sectional area, as shown in FIG. . FIG. 1 is a schematic diagram of a portion of a prior art apparatus capable of generating multiple streams. A plurality of microchannels 11, 12, 13, 14, 15, and 16 are fabricated on the silicon chip 17. The microchannels 11 to 16 include a first microchannel 11, a second microchannel 12, a third microchannel 13, a fourth microchannel 14, a fifth microchannel 15, and a sixth microchannel 16. . The first microchannel 11 includes a first liquid, and the second microchannel 12 includes a second liquid. Arrow 18 indicates the direction in which both liquids flow. The first microchannel 11 flows into the third microchannel 13 and the fourth microchannel 14, both of which have reduced dimensions that are perpendicular to the flow. The second microchannel 12 flows into the fifth microchannel 15 and the sixth microchannel 16, both of which have a reduced cross-sectional dimension perpendicular to the flow. The fourth microchannel 14 and the fifth microchannel 15 are manufactured so as to intersect but not intersect.

  As a result of the intersection of the fourth microchannel 14 and the fifth microchannel 15, a liquid spatial alternation order is obtained. The order of the liquids at the bottom of FIG. 1 is from the right to the left, the first liquid, the second liquid, the first liquid, and the second liquid. The four flows contained in the third microchannel 13, the fourth microchannel 14, the fifth microchannel 15, and the sixth microchannel 16 are such that the alternating order and the reduced cross-sectional area are maintained. In addition, it can be combined into a single microchannel (not shown in FIG. 1). In this way, interaction by diffusion and thus mixing is improved.

  The device of FIG. 1 shows inferior to the ideal solution because the device is relatively complex and difficult to manufacture. Specifically, it is difficult to machine channels that intersect but do not intersect. Another problem associated with the apparatus of FIG. 1 is that it is difficult to change the ratio of the first liquid to the second liquid in the resulting mixture. The ratio is largely determined by the relative cross-sectional area of the microchannel.

  A second way in which two liquids flowing through the microchannel can be combined is simply to increase the flow rate through the microchannel until the Reynolds number is greater than about 2300. At such a large Reynolds number, turbulence exists and therefore the liquid is mixed. In pressure driven flows, pressures in excess of 1 million Pa may be required to obtain a sufficiently high flow rate for Reynolds numbers greater than 2300. This requires the use of a relatively robust microchannel device, which can be difficult to create in practice.

  The following prior art is considered relevant to the present invention. GB 2355414A describes a micromixer with opposed nozzles. DE 196 11 270A1 describes a micromixer for very small volumes of liquid. US Pat. No. 6,150,119 describes the continuous introduction of multiple different samples into a microfluidic channel network.

  Other related conventional techniques include: Desmukhh, Solid State Sensors and Actuator Workshop, June 4-8, 2000, Hilton Head, South California, USA, Crowne Plaza Research.

  It is an object of the present invention to provide a novel microchannel device and a novel method for mixing two or more liquids in a microchannel that alleviates the above mentioned problems.

  According to a first aspect, the present invention is a method for mixing at least two liquids in a microchannel, comprising: (a) introducing each liquid into the microchannel; and (b) each liquid along the microchannel. And (ii) introducing each liquid into the microchannel in the form of a plurality of pulses; and (ii) one or more other liquids. Each liquid is introduced into the microchannel through at least one inlet channel having an inlet opening in the wall of the microchannel, and the depth of the inlet channel at the point of entry into the microchannel is A method characterized by being smaller than the depth of the microchannel.

  As no doubt, the term “liquid” should be recognized to include solutions and suspensions.

  The pulses can be formed by repeatedly increasing or decreasing the rate at which each liquid is introduced into the microchannel. The pulse can be formed by repeatedly stopping or starting the flow of each liquid into the microchannel. For example, a pulse can be formed by repeatedly opening and closing a valve. Alternatively, the pulses can be formed by adjusting the introduction of each liquid with a controllable pump. The formation of the pulse need not involve completely stopping liquid flow into the microchannel for any of the components to be mixed.

  Alternation can be achieved by sequentially opening and closing a plurality of valves. By alternating the pulses, different liquids can be introduced at different times. For example, it is possible to introduce only one of the liquids at a given time by ensuring that one valve is open and at the same time one or more other valves are closed.

  By alternating pulses, the liquid is mixed more efficiently in the microchannel. The efficiency of the technology means that it is not necessary to utilize high pressures and complex structures. The reason for this improved mixing is due to some degree of spatial separation between different liquids along the length of the microchannel, perpendicular to the length of the microchannel. Another factor is the non-uniform flow profile across the width of the microchannel, where the flow is fastest at the center of the microchannel. The combination of these two factors increases the boundary area between adjacent pulses as adjacent pulses travel along the channel, and the average diffusion required for mixing between pulses due to thinning as the boundary area increases. The path is reduced.

  In contrast, prior art methods often tend to spatially separate different liquids across the width of the microchannel. In this case, the non-uniform flow profile will not promote mixing.

  In the present invention, the spatial separation along the length, as opposed to the width of the microchannel, can allow the flow along the microchannel to mix different liquids. Note that the spatial separation between components along the length of the microchannel is likely to be most noticeable in the region of the microchannel where the liquid is introduced. Such spatial separation tends to decrease as liquid flows along the microchannel due to non-uniform flow across the microchannel.

  Each pulse can be introduced into the microchannel such that it contacts the opposite side of the microchannel.

  The time required between any one of the valves being opened and then closed can be less than 5 seconds. The time required between closing and then opening any one of the valves can be less than 0.1 seconds. A delay may be introduced while opening one valve and closing the other, and such a delay may be less than 0.1 seconds.

  Each liquid can be introduced into the microchannel at approximately the same position in the microchannel as the other liquid.

  Each of the liquids can be introduced into a portion of the microchannel having a width w. The portion preferably has a length of less than 5 w as measured along the direction of liquid flow in the microchannel. More preferably, each of the liquids can be introduced into a portion of the microchannel having a length of less than 2w.

  Step (a) is advantageously performed such that each flow of liquid is substantially perpendicular to the length of the microchannel as it enters the microchannel.

  The microchannel can be attached to or formed on the substrate. For the purposes of this specification, the term “microchannel depth” should be defined as the cross-sectional dimension of the microchannel approximately perpendicular to the plane of the substrate. The term “entrance channel depth” should be defined as the cross-sectional dimension of the inlet channel approximately perpendicular to the plane of the substrate at the point where the inlet channel enters the microchannel.

  The depth of the inlet channel or at least one inlet channel can be less than half the depth of the microchannel.

  The depth of the inlet channel or at least one inlet channel can be less than one tenth of the depth of the microchannel.

  The cross-sectional area of the inlet channel or at least one inlet channel can be smaller than the cross-sectional area of the microchannel.

  The cross-sectional area of the inlet channel or at least one inlet channel can be less than one half of the cross-sectional area of the microchannel.

  The cross-sectional area of the inlet channel or the at least one inlet channel can be less than one tenth of the cross-sectional area of the microchannel.

  The volume of the microchannel is preferably less than 20 μl. More preferably, the volume of the microchannel is less than 5 μl.

  Step (a) is advantageously performed such that at least one of the pulses of one liquid comes into contact with the other liquid pulses when entering the microchannel.

  The location, pressure, and time at which each liquid is introduced can cause a vortex to be established in the microchannel as a result of the fluid or the interaction of at least two liquids.

  The formation of vortices by introducing liquid into the microchannel can help to mix the liquid together.

The microchannel can have at least one cross-sectional dimension of less than 100 μm. The microchannel can have a cross-sectional area of less than 10,000 μm ² .

  Introducing at least two of the fluids or liquids into the microchannel is such that the flow of liquid at the end of the microchannel away from the region where the liquid is introduced is substantially continuous for a period longer than 100 seconds. Can be implemented.

  Many synthesis and analysis techniques require a relatively constant flow of reactants or products, which is a criterion that can be met by the present invention. For example, by continuously operating a valve for introducing a liquid, it is possible to continuously output from the microchannel.

  The composition of the resulting mixture can be altered by changing the relative duration of the pulses. For example, when mixing the first liquid with the second liquid, the proportion of the first liquid can be increased by increasing the pulse length of the first liquid relative to the pulse length of the second liquid.

  Again, this is an important feature for many synthetic and analytical applications that require changing the proportion of reactants for a given mixture.

  When mixing two fluids, for example, high mixing ratios of 10: 1, 100: 1, and 1000: 1 can be achieved.

  Pulse formation and alternation is preferably performed such that only one liquid is introduced into the microchannel at any given time. More preferably, the pulse shape and alternation are implemented to repeatedly change the liquid introduced into the microchannel.

  The method advantageously includes other steps of using electronic components to control the duration of each pulse. More preferably, the electronic component comprises a computer.

  The dimensions of the microchannel and the rate at which liquid is introduced into the microchannel are advantageously such that the flow of liquid through the microchannel is non-uniform across the width of the microchannel. More advantageously, the flow of liquid through the microchannel is approximately parabolic. That is, the velocity distribution over at least one line of the cross section is substantially parabolic. Because of this parabolic flow, as the pulse flows along the microchannel, the interaction between the different components being mixed is greater, the area of interaction is larger, the spatial separation is smaller, and therefore the mixing is performed. It is thought that the distance required for diffusion is shortened.

  Each flow of liquid flowing through the microchannel preferably occurs only by introducing each of the liquid into the microchannel. That is, each flow of liquid flowing through the microchannel does not occur by introducing gas into the microchannel. The gas can be used to apply pressure to the liquid to be mixed, provided that no gas-liquid contact occurs inside the microchannel. Alternatively, the flow can be induced by a microfluidic pump or electrokinetic phenomenon.

  Step (b) can include electrokinetically pumping at least some of the liquid in the microchannel. Step (b) may comprise electrokinetically pumping at least some liquid in the microchannel so that a parabolic flow is induced.

  Without the use of gas in the microchannel, each flow of liquid flowing through the microchannel minimizes the risk of contamination by dissolving the gas in the liquid or forming bubbles.

  Step (a) advantageously includes the step of introducing each liquid into the microchannel by means of an electrokinetic pump.

  Step (a) is preferably performed such that each pulse contacts a portion of the microchannel wall generally opposite the inlet channel through which each pulse was introduced.

  By performing step (a) in this way, it is possible to form a pulse in contact with the region of the inlet channel and with the region of the microchannel wall opposite the inlet channel. The flow along the channel of the pulse at the opposing contact point is constrained relative to the flow along the channel at a point along the line joining the opposing contact points. The difference in flow rate between the midpoint of the pulse and the end of the pulse is considered beneficial for the mixing process.

  Step (a) can include each pulse contacting two points of the microchannel such that the line between the contact points is substantially perpendicular to the direction of fluid flow through the microchannel. is there.

  Each pulse is advantageously introduced through at least two inlet channels. More advantageously, the two inlet channels or two of the inlet channels through which each pulse is introduced are arranged substantially opposite each other.

  Liquids from two or more inlet channels flow through the microchannel together to form each pulse. By forming each pulse with a flow of liquid flowing through two or more inlet channels, each pulse is introduced into the microchannel at the point of the region of the inlet channel through which the pulses are introduced and spaced from each other. It becomes possible to contact. The flow of each pulse is constrained at the point of contact to assist the mixing process.

  Step (b) can include applying gas pressure to the liquid in the microchannel with a hydrophobic membrane.

  According to a second aspect, the present invention provides a microchannel apparatus comprising a microchannel and a liquid introducing means for introducing at least two liquids into the microchannel through at least one inlet channel having an inlet opening in the wall of the microchannel. Wherein the liquid introduction means comprises pulse means for introducing each liquid into the microchannel in the form of a plurality of pulses and alternating the pulses of each liquid with the pulses of the other liquid at a point entering the microchannel. A microchannel device is provided wherein the depth of each inlet channel is less than the depth of the microchannel.

  The inlet channel or each inlet channel can be substantially perpendicular to the microchannel.

  The liquid introduction means may comprise a valve associated with one of the liquids. The valve, microchannel, and liquid are configured such that a liquid pulse is released into the microchannel by opening and then closing the valve.

  The liquid introduction means preferably includes a plurality of valves. More preferably, the control means includes means for sequentially opening and closing each of the plurality of valves. Even more preferably, the control means comprises means for opening only one valve at any given time to ensure that the other valve or valves are closed. Even more preferably, the control means comprises means for repeatedly changing which of the plurality of valves is opened at any given time.

  The control means may comprise means for forming the plurality of pulses by repeatedly stopping and starting the flow of liquid into the microchannel.

  The liquid introduction means can comprise an electrokinetic pump associated with one of the liquids. The electrokinetic pump, the microchannel, and the liquid are configured such that a liquid pulse is released into the microchannel upon actuation of the electrokinetic pump. The electrokinetic pump can be configured and operated such that a non-uniform velocity profile is generated across the microchannel. The electrokinetic pump can be configured and operated such that a parabolic velocity profile is generated across the microchannel.

  The liquid introduction means preferably includes a plurality of electrodynamic pumps. More preferably, the control means includes means for sequentially operating and stopping the electrodynamic pump. Even more preferably, the control means comprises means for activating only one electrokinetic pump at any given time to ensure that the other one or more electrokinetic pumps are stopped. . Even more preferably, the control means comprises means for repeatedly changing which of the plurality of electrodynamic pumps is activated at any given time.

  The means for introducing each liquid into the microchannel in the form of a plurality of pulses can have a configuration such that each pulse contacts the opposite side of the microchannel.

  Each valve can be connected to a microchannel by an inlet channel.

  Each said inlet opening can preferably be formed inside a part of the microchannel having a length of less than 10 mm. More preferably, the inlet opening or each inlet opening can be formed inside a portion of a microchannel having a length of less than 5 mm.

  The pulsing means is advantageously constructed such that each flow of liquid into the microchannel is approximately perpendicular to the length of the microchannel.

  The depth of the inlet channel or each inlet channel at the location entering the microchannel can be less than half the depth of the microchannel.

  The depth of the inlet channel or each inlet channel at the location that enters the microchannel can be less than one tenth of the depth of the microchannel.

  The cross-sectional area of the inlet channel or each inlet channel can be smaller than the cross-sectional area of the microchannel.

  The cross-sectional area of the inlet channel or each inlet channel can be less than half the cross-sectional area of the microchannel.

  The cross-sectional area of the inlet channel or each inlet channel can be less than one tenth of the cross-sectional area of the microchannel.

  At least a portion of the liquid associated with each valve can be contained in the reservoir so that liquid can flow from the reservoir to the valve.

  The microchannel preferably has a minimum cross-sectional dimension between 500 μm and 100 nm. More preferably, the microchannel has a minimum cross-sectional dimension between 100 μm and 1 μm.

  The microchannel comprises at least two subchannels, each subchannel being substantially parallel to the microchannel, the cross-sectional area of each subchannel being smaller than the cross-sectional area of the microchannel, each subchannel being an interior of the microchannel It is possible to arrange in

  It is possible to establish a flow in each subchannel, provided that each subchannel is sufficiently long parabolic. Establishing a parabolic flow in each subchannel aids the mixing process.

  Advantageously, the control means comprises means that allow only one of the liquids to be introduced into the microchannel at any given time. More advantageously, the control means comprises means for repeatedly changing which liquid is introduced into the microchannel.

  The control means preferably comprises an electronic component. More advantageously, the control means comprises a computer. Even more advantageously, the control means comprises a computer programmed to operate in real time.

  The liquid introducing means is configured such that each pulse is introduced through one inlet channel and each pulse contacts a portion of the microchannel wall that is generally opposite the inlet channel through which each pulse is introduced. Can have.

  The liquid introduction means preferably has a configuration such that each pulse is introduced through at least two inlet channels. The fluid introduction means may have a configuration such that each pulse is introduced through two inlet channels arranged on opposite sides of the microchannel.

  The microchannel is advantageously closed at one end. More preferably, the microchannel is closed at the end of the microchannel substantially adjacent to the inlet channel or at least one of the inlet channels.

  The present invention will now be described by way of example only with reference to FIGS.

  FIG. 2 is a schematic diagram of a microchannel device according to the present invention, generally indicated by 21. The first reservoir 22 and the second reservoir 23 are connected to the microchannel 24 via the first valve 25 and the second valve 26 and the flow restrictors 27, 28, 31 and 32. The first reservoir 22 contains a first liquid, and the second reservoir 23 contains a second liquid. For the purposes of this example, the first liquid is an aqueous solution of a first water-soluble dye and the second liquid is an aqueous solution of a second water-soluble dye.

  The mixed macrochannel 24 has a cross-sectional dimension of 1 mm × 100 microns. That is, the microchannel 24 has a width of 1 mm and a depth of 100 microns. The total length of the microchannel 24 is 19 cm, and is configured in a serpentine structure so as to save space. The microchannel 24 is fabricated by bonding two thin layers of polymethyl methacrylate (PMMA) together by applying pressure at 120C. A microchannel structure is formed in one of the PMMA layers by micromilling. A connecting conduit is formed through another PMMA layer to allow connection to the buried microchannel structure. A metal tube is glued to the connecting conduit to allow easy connection of plastic piping.

  A pressure of 40 kPa is applied to the first liquid and the second liquid by compressed air. The input of the first liquid and the second liquid to the macro channel 24 is controlled by two valves 25 and 26. Thus, the gas pressure is used to introduce the first and second liquids into the microchannel 24, but the gas pressure itself does not enter the microchannel 24.

  The first valve 25 and the second valve 26 are connected to control means (not shown in FIG. 2) for controlling whether the first valve 25 and the second valve 26 are open or closed. The control means can be programmed so that only one of the first valve 25 and the second valve 26 is open at any given time. The control means can also change which of the two valves 25, 26 is open so that alternating pulses of the first solution and the second solution are released into the microchannel 24. In this way, the introduction of the first liquid and the second liquid alternates so that the first liquid is not introduced at the same time as the second liquid.

  The duration of each pulse of the first liquid or the second liquid is about 0.8 seconds. 1.2 pulses per second are emitted into the microchannel 24. By alternating the pulses, some spatial separation occurs between the first liquid and the second liquid along the length of the microchannel 24. This spatial separation is greatest in the region of the microchannel 24 where the two liquids are introduced. The two liquids are mixed as they move along the microchannel 24.

  Valves 25 and 26 are commercially available solenoid valves. Each valve 25 and 26, when closed, displaces the fluid and performs the pumping action. The pumping action can be minimized by placing the flow restrictors 27, 28, 31, and 32 on both sides of each valve. Each flow restrictor has a length of 5 mm, a depth of 40 microns, and a width of 100 microns.

  By arranging the flow restrictors 27, 28, 31, and 32 on both sides of each valve, the influence of the operation of closing the first valve 25 and the second valve 26 by the liquid flow in the microchannel is minimized. . By closing the first valve 25 and the second valve 26, the pressure in the region of the valves 25, 26 tends to increase. The flow restrictor configuration protects the microchannel from the effects of pumping of the solenoid valves 25,26.

  In the embodiment of FIG. 2 of the present invention, the flow restrictors 27 and 28 form an inlet channel, whereby the first and second liquids are introduced into the microchannel. That is, the dimensions of the inlet channel are 40 microns (depth), 100 microns (width), and 5 mm (length) in the embodiment of FIG.

  After the mixture of the first liquid and the second liquid is delivered to the microchannel 24, the liquid contained in the microchannel 24 can be delivered by applying gas pressure to the fluid. The pressure is applied via the gas line 30 and is advantageously a pressure of 10 kPa. The gas line is connected via a hydrophobic membrane 29 that allows gas to pass but does not allow liquid based aqueous solutions to pass through. Thus, when liquid is delivered to the microchannel 24 via valves 25 and 26, the flow is stopped by the hydrophobic membrane 29. In this way, delivery of liquid along the microchannel 24 also results in a mixing operation.

  In other embodiments, although not shown in the figure, the microchannel device according to the present invention can have the same structure as the device of FIG. 2, but has a microchannel depth of 200 microns. Different.

  FIG. 3 is a microchannel device comprising a microchannel 32 and inlet channels 35, 36, indicated generally by 31. The microchannel comprises three subchannels 33 formed by baffles 34. The liquid flows down the length of the microchannel 31 and is mixed. If the subchannel is long enough, a parabolic flow through the subchannel can occur. Thus, the presence of the baffle 34 increases the mixing interaction between the liquids as compared to the case without the baffle 34.

  FIG. 4 is a microchannel device having first inlet channels 42, 43 and second inlet channels 44, 45, indicated generally by 41. Inlet channels 42, 43, 44 and 45 form inlet openings 42 a, 43 a, 44 a and 45 a in the walls of microchannel 46. A first liquid is introduced through the first inlet channels 42 and 43 and a second liquid is introduced through the second inlet channels 44 and 45. The first liquid and the second liquid are introduced in the form of a plurality of pulses. Each pulse of the first liquid is formed by a substantially simultaneous flow of liquid flowing through both first inlet channels 42, 43. Each pulse of the second liquid is formed by a substantially simultaneous flow of liquid flowing through both the second inlet channels 44, 45. Two first inlet channels 42, 43 are configured on opposite sides of the microchannel, and two second inlet channels 44, 45 are also configured on opposite sides of the microchannel with respect to each other. This configuration of inlet channels 42, 43, 44, and 45 causes a greater interaction of the two liquids as they flow along the microchannel. FIG. 5 is a schematic diagram of another microchannel device according to the present invention, indicated generally by 51. The microchannel device is the same as that shown in FIG. 3 except that it does not include a subchannel. The cross-sectional dimension of the microchannel 52 is 1 mm (width) × 200 microns (depth). The inlet channel 53 has a cross-sectional dimension of 100 microns (width) x 40 microns (depth). The inlet channel 53 is configured to be perpendicular to the microchannel 52 and the end of the microchannel 52 adjacent to the inlet channel 53 is closed. The walls of the microchannel 52 of FIG. 5 are constructed from a transparent material.

  FIG. 6 shows the results of an experiment performed using the apparatus of FIG. A pulse of water and an aqueous solution of a red dye is introduced into the microchannel of FIG. 5 by the method according to the invention. The plot in FIG. 6 shows the concentration at the center of the channel of the red dye in the microchannel against the distance along the microchannel. The concentration of red dye in the microchannel is determined by measuring the absorption of light by the liquid in the channel. The concentration is determined by the Beer Lambert law. FIG. 6 illustrates the effectiveness of the mixing of the method and apparatus of the present invention.

  The mixing of the two liquids was investigated by the method according to the invention using CFD (Flume CAD (RTM) (Conventor)). The result of the 2D calculation is shown in FIG. FIG. 7 (a) shows the injection of a pulse through one of the inlet channels 71. As can be seen from the result of FIG. 7A, the pulse does not reach the opposing wall of the microchannel 72.

  FIG. 7 (b) shows the results for the same microchannel device as in FIG. 7 (a). However, the calculation of FIG. 7B was performed for a 3D simulation. The difference between the results of FIGS. 7A and 7B is that the calculation of FIG. 7B takes into account the difference in depth between the inlet channel 71 and the microchannel 72. Since the results of FIG. 7 (a) are for 2D calculations, the depth of the injection channel is treated in these results as virtually the same as the depth of the microchannel. Accordingly, the results of FIG. 7 show that it is advantageous that the depth of each of the inlet channels should be less than the depth of the microchannel.

1 is a schematic view of a part of a conventional microchannel device. 1 is a schematic view of a microchannel device according to the present invention. 1 is a schematic diagram of a microchannel device according to the present invention comprising at least two subchannels. 1 is a schematic view of a microchannel device according to the present invention in which each pulse of liquid is introduced through two inlet channels. FIG. 1 is a schematic view of a microchannel device according to the present invention, wherein each inlet channel is perpendicular to the microchannel. FIG. 4 shows the absorption of light by a microchannel device according to the invention containing two liquids as a function of distance along the microchannel. FIG. 6 shows the modeling results for injecting pulses into a microchannel by the method according to the invention. FIG. 6 shows the modeling results for injecting pulses into a microchannel by the method according to the invention.

Claims (13)

A method of mixing at least two liquids in a microchannel formed as a tube having a width and depth , comprising: (a) introducing each liquid into a microchannel (24, 32, 46, 52, 72); (B) causing each liquid to flow along the microchannel (24, 32, 46, 52, 72), wherein step (a) comprises: (i) each liquid in the form of a plurality of pulses. (24, 32, 46, 52, 72) and (ii) alternating the plurality of pulses of each liquid with pulses of one or more other liquids, , At least one inlet channel (27, 28, 35, 36, 42, 43, 44, 45, 5) having an inlet opening in the wall of the microchannel (24, 32, 46, 52, 72) 71) is introduced into the microchannel (24, 32, 46, 52, 72) and enters the microchannel (24, 32, 46, 52, 72) at the entry channel (27, 28, 35, 36). , 42, 43, 44, 45, 53, 71) is smaller than the depth of the microchannel (24, 32, 46, 52, 72).   Each liquid is in contact with the portion of the microchannel wall that generally faces the inlet channel (27, 28, 35, 36, 42, 43, 44, 45, 53, 71) through which each liquid is introduced. The method of claim 1, wherein step (a) is performed.   Step (a) is performed so that each liquid is introduced into the microchannel (24, 32, 52, 72) at approximately the same location as the other liquid in the microchannel (24, 32, 52, 72). The method according to claim 1 or 2.   Step (a) is performed so that the liquid flow at the end of the microchannel (24, 32, 46, 52, 72) away from the area where the liquid is introduced is substantially continuous for a period longer than 100 seconds. The method according to any one of claims 1 to 3.   The rate at which liquid is introduced into the microchannel (24, 32, 46, 52, 72) is approximately equal to the velocity distribution across at least one line of the cross-section of the liquid flowing through the microchannel (24, 32, 46, 52, 72). 5. A method according to any one of the preceding claims, wherein the method is selected with respect to the dimensions of the microchannel (24, 32, 46, 52, 72) so as to be parabolic. Microchannel (24, 32, 46, 52, 72) formed as a tube having a width and depth, and at least one inlet having an inlet opening in the wall of the microchannel (24, 32, 46, 52, 72) Liquid introduction means (22) for introducing at least two liquids into the microchannel (24, 32, 46, 52, 72) through the channels (27, 28, 35, 36, 42, 43, 44, 45, 53, 71). , 23, 25, 26), wherein the liquid introduction means (22, 23, 25, 26) feed each liquid in the form of a plurality of pulses into the microchannel (24, 32, 46, 52 , 72) and pulse means for alternating each liquid pulse with one or more other liquid pulses and comprising microchannels (24, 32, 46, 5 72) the depth of the inlet channel or each inlet channel (27, 28, 35, 36, 42, 43, 44, 45, 53, 71) at the point of entry into the microchannel (24, 32, 46, 52). 72), which is smaller than the depth of 72).   The micro of claim 6, wherein the inlet channel or each inlet channel (35, 36, 42, 43, 44, 45, 53, 71) is substantially perpendicular to the micro channel (32, 46, 52, 72). Channel device.   The liquid introducing means comprises a valve (25, 26) associated with one of the liquids, the valve (25, 26), the microchannel (24, 32, 46, 52, 72) and the liquid being a valve 8. The device according to claim 6, wherein the liquid pulse is configured to be released into the microchannel (24, 32, 46, 52, 72) by opening and then closing (25, 26). Microchannel device.   9. A device according to claim 8, wherein the liquid introduction means comprises a plurality of valves (25, 26).   10. The inlet opening or each inlet opening is formed within a portion of a microchannel (24, 32, 46, 52, 72) having a length of less than 10 mm. Microchannel device.   The microchannel device according to any one of claims 6 to 10, wherein the microchannel (24, 32, 46, 52, 72) has a minimum cross-sectional dimension between 1 mm and 100 nm.   The depth of the inlet channel or each inlet channel (27, 28, 35, 36, 42, 43, 44, 45, 53, 71) at the point of entry into the microchannel (24, 32, 46, 52, 72) is The microchannel device according to any one of claims 6 to 11, wherein the microchannel device is less than one half of the depth of the microchannel (24, 32, 46, 52, 72).   The microchannel (32) comprises at least two subchannels (33), each subchannel (33) being substantially parallel to the microchannel (32), and the cross-sectional area of each subchannel (33) being a microchannel 13. The microchannel device according to any one of claims 6 to 12, wherein each subchannel (33) is smaller than the cross sectional area of (32) and is arranged inside the microchannel (32).

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