JP7585606B2 - Dispersion Solvent Replacement Device - Google Patents

Description

The present invention relates to a dispersion solvent replacement device.

Microchannel devices with capillary channels can be used in microanalysis devices such as DNA analysis devices, and can also be used as a method for processing suspensions containing particles such as cells (e.g., Patent Documents 1 and 2). When the particles contained in the suspension are rare or expensive, or when it is desired to quantitatively evaluate the particles contained in the suspension, it is necessary to process the entire suspension using a microchannel device. However, if air gets mixed into the device, this can cause problems with the delivery of the suspension or poor evaluation of the particles contained in the suspension, so it is necessary to accurately stop the gas-liquid interface between the suspension and the air just before the inlet of the device.

JP 2007-021465 A Special Publication No. 2007-175684

Miyuki Matsuda et al., Journal of the Institute of Electrical Engineers of Japan, 128(10), 396-401 (2008)

The objective of the present invention is to provide an apparatus that can deliver the entire amount of a suspension containing particles to a microchannel device while suppressing the inclusion of air, etc., when the suspension is introduced into the microchannel device.

In order to solve the above problems, the inventors conducted extensive research and arrived at the present invention.

That is, one aspect of the present invention is
A container 1 for containing a suspension containing particles;
an inlet 1 of a microchannel device connected to the container 1 by a pipe 1;
A measuring instrument for measuring the physical properties or flow rate of the liquid flowing through the pipe 1;
a pump 1 capable of pumping the suspension from the container 1 to the inlet 1;
A control unit that controls the operation of the pump 1 based on the measurement results of the measuring instrument;
A container 2 for containing a sheath liquid;
an inlet 2 of a microchannel device connected to the container 2 by a pipe 2;
a pump 2 capable of pumping the sheath liquid from the container 2 to the inlet 2;
a confluence flow path for confluence of the suspension introduced from the inlet 1 and the sheath liquid introduced from the inlet 2;
a separation channel connected to the confluence channel for separating particles contained in the suspension using a hydrodynamic filtration method;
an outlet connected to an end of the separation channel;
A container 3 connected to the outlet by a pipe 3;
The device is equipped with:

Another aspect of the present invention is
A method for delivering a suspension containing particles contained in a container to an inlet of a microfluidic device using a pump, comprising the steps of:
a sealing liquid having a specific gravity smaller than that of the suspension, a viscosity larger than that of the suspension, and immiscible with the suspension is layered on the suspension contained in the container;
The liquid transfer by the pump is performed under pressure conditions that allow the suspension to be transferred but that do not allow the sealing liquid to be transferred.

The present invention is described in detail below.

Regarding the suspension containing particles, the particles are not particularly limited, and examples thereof include inorganic particles such as metals and their oxides, organic particles such as polymers and lipids, and biological particles such as cells and endoplasmic reticulum secreted from cells. When the particles are the above-mentioned biological particles, specific examples of the suspension containing particles include biological samples such as blood, diluted blood, serum, plasma, cerebrospinal fluid, umbilical cord blood, blood component collection, urine, saliva, semen, feces, phlegm, amniotic fluid, and ascites, tissue suspensions in which pieces of tissue such as liver, lung, spleen, kidney, skin, tumor, and lymph node are suspended, fractions containing cells derived from the biological sample or the tissue obtained by separating from the biological sample or the tissue suspension, culture fluid of previously isolated cells, and suspensions containing extracellular vesicles such as exosomes and apoptotic vesicles secreted from cells. In this specification, the suspension containing particles may be simply referred to as a "suspension".

The size of the container 1 is smaller than that of the pressure vessel described later, and may be selected appropriately according to the amount of the suspension liquid. If the container is too large for the amount of the suspension liquid, the area of contact between the suspension and the container increases, and the amount of particles contained in the suspension adsorbed to the container surface increases. Therefore, the size of the container is preferably 50 times or less than the suspension, more preferably 10 times or less, and even more preferably 2 times or less. There is no restriction on the material of the container 1, but it is preferable that the container surface can suppress the adsorption of particles to the container. When the particles are biological particles, it is preferable to use a container made of a hydrophilic material or a container coated with a hydrophilic substance, since this can suppress the adsorption of biological particles. Examples of hydrophilic substances to be coated on the container include silicone, hydrophilic polymers such as polyethylene glycol and polyvinylpyrrolidone, and proteins such as albumin and casein. The shape of the container may be any shape that allows all of the suspension to be sucked in by the piping, and is preferably a structure that tapers from the top to the bottom of the container. The container 2 is not particularly limited as long as it is smaller than the pressure vessel and is large enough to fill with sheath liquid. There are no particular limitations on the container 3, so long as the container surface can suppress particle adsorption, similar to that of container 1.

Container 1 is connected by pipe 1, and container 2 is connected by pipe 2 to inlets 1 and 2 of a microchannel device described later. There are no particular limitations on the shape or size of pipe 2 as long as it can connect container 2 and inlet 2 in a liquid-tight manner, but pipe 1 must have an inner diameter that allows the particles contained in the suspension to pass through. In addition, pipe 1 is preferably made of a material that can suppress particle adsorption in order to suppress clogging by particles.

Examples of measuring instruments that measure the physical properties or flow rate of the liquid flowing through the pipe 1 include a flow meter, an optical measuring instrument, and an electrical conductivity meter. The measuring instrument may be interposed between the pipes 1, and may be located inside or outside the pipe 1.

Pump 1 and pump 2 may be of the same type or different types. There are no particular limitations on the type of pump, and examples include an air pump, a syringe pump, and a peristaltic pump, but an air pump is preferable for pump 1. The operation of pump 1 is controlled by the control unit based on the measurement results of the aforementioned measuring instruments. For example, the control unit may send a signal to pump 1 to adjust the time for which pressure is applied.

In addition, if container 1 and a part of piping 1, and container 2 and a part of piping 2 are contained airtight in one pressure vessel, there is no need to provide pumps 1 and 2, and it is possible to pump liquid from containers 1 and 2 with one pump. There are no particular limitations on the pressure vessel, so long as it is large enough to contain containers 1 and 2 and is sealable so that it does not expand significantly when pressurized. The expansion rate of the volume inside the pressure vessel due to pressurization should be 10% or less. Note that a portion of the piping means that the tip of the piping is immersed in the solution introduced into the vessel, and there is no limitation on the length of the piping contained in the pressure vessel.

The microchannel device includes at least the inlets 1 and 2, a confluence channel for confluence of the suspension and the sheath liquid, a separation channel for separating particles contained in the suspension using hydrodynamic filtration, and an outlet. The inlets 1 and 2 are each connected to an end of the confluence channel, and the other end of the confluence channel is connected to a separation channel. The end of the separation channel has one or more outlets, one of which is connected to a container 3 via a pipe 3. There is no particular restriction on the separation channel as long as it has a structure using hydrodynamic filtration (see Non-Patent Document 1), and there is no problem if any one or more of the number of branch channels, the length, width, depth, diameter, etc. of the channel are appropriately adjusted according to the size of the particles to be separated. The microchannel device may be fabricated by patterning a microchannel having a predetermined shape on a resin substrate such as polydimethylsiloxane (PDMS) or a glass substrate, and then covering the substrate with a lid.

In container 1, a sealing liquid is layered on top of the suspension, and pumping is performed under pressure conditions that allow the suspension to be pumped but not the sealing liquid, which is preferable because it allows the suspension to be pumped while suppressing evaporation of the suspension and air from entering the microchannel device. The sealing liquid is selected to have a specific gravity lower than that of the suspension, a viscosity higher than that of the suspension, and is immiscible with the suspension. Since the sealing liquid has a specific gravity lower than that of the suspension, it is preferable to position the tip of pipe 1 at the bottom of container 1.

The specific gravity of the sealing liquid is preferably at least 0.1% smaller than the specific gravity of the suspension, and more preferably at least 1% smaller.

If the viscosity of the sealing liquid is greater than that of the suspension, the pressure loss in the pipe 1 increases when the liquid is fed into the microchannel device, and the flow rate becomes slower than that of the suspension when fed under a constant pressure. Therefore, by setting the liquid feeding pressure constant, it is possible to set conditions under which the suspension can be fed into the microchannel device but the sealing liquid cannot be fed. Specifically, if the feeding rate of the sealing liquid is 1/5 or less of the feeding rate of the suspension into the microchannel device, it can be said that the sealing liquid cannot be fed, and it is preferable that the viscosity of the sealing liquid is 5 times or more greater than the viscosity of the suspension.

The sealing liquid must also be immiscible with the suspension. "Immiscible" means that there is a ratio at which the mixture of the suspension and sealing liquid does not form a homogeneous solution. For example, if the solvent for the suspension is water, examples of immiscible sealing liquids include oils such as mineral oil and silicone oil.

In addition, when the sealing liquid is layered on top of the suspension and pumped under pressure conditions that allow the suspension to be pumped but not the sealing liquid, the structure of the microchannel device is not limited to the above-mentioned structure, and for example, a microchannel device that does not introduce sheath liquid may also be used.

The present invention allows the entire amount of suspension containing particles to be introduced into a microchannel device, making it possible to measure the particles contained in the suspension with high accuracy, which is effective in making quantitative evaluations. In addition, because the entire amount of the suspension can be introduced, loss of suspension is minimized.

FIG. 1 is a diagram illustrating a dispersion solvent replacement apparatus according to one embodiment of the present invention, and a method for replacing a dispersion solvent in a suspension using the apparatus. FIG. 2 is a diagram showing an example of a microfluidic device provided in the apparatus shown in FIG. 1 .

The following provides a more detailed explanation using a device that is one aspect of the present invention.

The dispersion solvent replacement apparatus 100 shown in FIG.
a microchannel device 30 including an inlet 31 for a sheath fluid 11, an inlet 32 for a suspension 12, outlets 33 (33a and 33b) for the introduced liquid, and a flow channel capable of liquid-tightly connecting the inlets 31 and 32 and the outlet 33;
a container 21 for containing a sheath liquid 11, a pipe 41 capable of liquid-tightly connecting the container 21 and an inlet 31, a container 22 for containing a suspension 12 and a sealing liquid 13, a pipe 42 capable of liquid-tightly connecting the container 22 and an inlet 32, a measuring instrument 70 for measuring a change in a physical property or a flow rate of the liquid in the pipe 42, and a pipe 43 capable of liquid-tightly connecting the collection container 23 and an outlet 33,
a pressure vessel 50 that airtightly houses the vessels 21 and 22 and a portion of the pipes 41 and 42; an air pump 60 that pressurizes the space inside the pressure vessel 50 through a pressurizing pipe 61; and a control unit 80 that is connected to the air pump 60 and a measuring instrument 70 via a lead 90.
It is equipped with:

The microchannel device 30 (FIG. 2) is composed of a main body 30a having a microchannel pattern formed on a substrate, and a cover 30b fixed to the main body 30a so as to cover the microchannel.
The microchannel formed in the main body portion 30a is
an inlet 31 for introducing a sheath liquid 11;
An inlet 32 for introducing the suspension 12;
Discharge ports 33a and 33b,
a joining flow path 34 for joining the sheath liquid 11 and the suspension 12;
a discharge flow path 35 extending linearly from the junction flow path 34 to the discharge port 33 a;
A plurality of branch flow paths 36 branching off from the discharge flow path 35 and extending linearly;
all of the branch flow paths 36 join together to form a discharge flow path 37 that extends linearly to the discharge port 33b;
It is composed of:

The discharge flow path 35, the multiple branch flow paths 36, and the discharge flow path 37 together correspond to a separation flow path for separating particles contained in the suspension using a hydrodynamic filtration method.

The outlet 33a is an outlet for discharging the remaining components that were not separated in the branch flow channel 36. In the microchannel device 30 shown in FIG. 2, the particles and sheath liquid mainly contained in the suspension are discharged from the outlet 33a. The outlet 33b is an outlet for discharging the components that flowed into the branch flow channel 36. The solution and sheath liquid excluding the particles mainly contained in the suspension 12 are discharged from the outlet 33b. The microchannel device 30 should be designed so that components smaller than the particles contained in the suspension can be removed. For example, it is preferable to make the dimensions of the branch flow channel 36 relatively narrow on the upstream side and relatively wide on the downstream side.

The following describes in detail a method for replacing the dispersion solvent in a suspension using the device 100 shown in Figure 1.

(1) Preparation for sending suspension 12 The suspension 12 is stored in the container 22, and the sheath fluid 11 is stored in the container 21, and the inlet 31 and the container 11 are liquid-tightly connected by a pipe 41, and the inlet 32 and the container 12 by a pipe 42. The pipes 41 and 42 are arranged so that their tips are at the bottom of each container.
It is preferable that the amount of sheath fluid 11 is sufficiently larger than that of suspension 12 to prevent a liquid shortage that may occur when the inside of microchannel device 30 is washed with sheath fluid 11 after feeding suspension 12. In addition, a pipe 43 is also liquid-tightly connected to outlet 33a of microchannel device 30, so that solution 14 after processing in microchannel device 30 (i.e., particle suspension with solvent replaced by sheath fluid) flowing out from pipe 43 can be collected in collection container 23, and solution 14 discharged from outlet 33a can be collected without any waste.
Mineral oil is layered as the sealing liquid 13 on the container 22 containing the suspension 12. By measuring the physical properties or flow rate of the liquid in the pipe 42 with a measuring instrument 70, the changeover of the liquid supply from the suspension 12 to the sealing liquid 13 can be detected.

(2) Delivery of Suspension 12 An air pump 60 is used to introduce the suspension 12. The containers 21 and 22 and a portion of the pipes 41 and 42 are airtightly housed in a pressure container 50, and the sheath fluid 11 and suspension 12 housed in the containers 21 and 22 are delivered to the microchannel device 30 by pressurizing the space inside the pressure container 50 through the pressurized pipe 61 with the air pump 60. Since the containers 21 and 22 are housed in the same pressure container 50, the sheath fluid 11 and the suspension 12 can be delivered at the same pressure. Note that it is preferable to discharge air from the pipes 41 and 42 before the delivery operation, since this allows delivery without air being mixed into the microchannel device 30.

(3) Completion of sending of suspension 12 When the sending of suspension 12 is completed, the inside of the pipe 42 is filled with sealing liquid 13. However, the pump 60 provided in the apparatus 100 shown in Fig. 1 applies a pressure to the pressure vessel 50 that can send the suspension 12 to the microchannel device 30 (inlet 32) but cannot send the sealing liquid 13. Therefore, the sealing liquid 13 is not sent to the microchannel device 30, and there is no risk of air entering through the inlet 32 due to the sealing liquid 13.
The liquid sending speed is significantly reduced by not introducing the sealing liquid 13 into the microchannel device 30. A change in the flow rate or a change in the physical properties of the sealing liquid in the pipe 42 is measured by the measuring instrument 70, and based on the change, a signal for adjusting the time for which pressure is applied by the air pump 60 is sent from the control unit 80 via the lead wire 90, thereby controlling the sending time of the sheath liquid 11 and automatically determining the processing completion time.

(4) Discharge of the Solvent-Substituted Solution 14 After the feeding of the sealing liquid 13 to the container 22 side is stopped, only the sheath liquid 11 is fed, and the particles remaining in the microchannel device 30 are discharged from the outlet 33a and collected in the container 23 through the piping 43. It is preferable to set the time for feeding only the sheath liquid to the time for the particles contained in the piping 43 connected to the collection container 23 from the outlet 33a to be discharged, because this allows the particles contained in the suspension 12 to be collected without any omissions. The particles contained in the solution 14 collected in the collection container 23 can be subjected to various analysis methods.

The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to these examples.

Example 1
Dispersion solvent replacement in a cell suspension was attempted using the dispersion solvent replacement device 100 shown in Fig. 1. The dimensions of the microchannel device shown in Fig. 2 used in this embodiment are all 50 μm high and have a rectangular cross-sectional shape, the cross-sectional shape other than the branch flow channel 36 and the discharge flow channel 37 is 32 μm wide, the length from the inlet 32 to the outlet 33a is 14 mm, the length from the inlet 31 to the end of the merging flow channel 34 is 4 mm, the narrow part on the upstream side of the branch flow channel 36 is 20 μm wide, the wide part on the downstream side is 42 μm wide, the entire length of the branch flow channel 36 is 11 mm, and the width and length of the discharge flow channel 37 are 250 μm and 10 mm, respectively.
(1) Human lung cancer cells (PC9 cells) were cultured in RPMI-1640 medium containing 10% (w/v) FBS (fetal bovine serum) in a 5% CO2 environment at 37°C for 24 to 96 hours, and then the cells were detached from the medium using 0.25% trypsin/1 mM EDTA, the solution was replaced with PBS (phosphate buffered saline), and the cells were suspended in 1 mL of PBS containing 0.04% (w/v) trypan blue to obtain suspension 12. The addition of trypan blue makes it easier to recognize the presence of cells in the suspension in piping and microchannel devices.
(2) The suspension 12 was placed in a container 22, and 0.5 mL of mineral oil (manufactured by Nacalai Tesque, Inc.) was layered on top as a sealing liquid 13.
(3) 5 mL of an aqueous solution containing 280 mM sucrose was prepared as the sheath liquid 11, and then placed in a container 21, which was then combined with a container 22 containing a suspension 12, and placed in a pressure vessel 50 connected to an air pump 60.
(4) The container 21 and the sheath liquid inlet 31 provided in the microchannel device 30 were connected by a tube (piping 41) having an inner diameter of φ0.5 mm and a length of 20 cm, and the container 22 and the suspension inlet 32 provided in the device were connected by two tubes (piping 42) having an inner diameter of φ0.5 mm and a length of 10 cm via a flow meter (manufactured by Blacktrace) as the measuring instrument 70. In addition, the outlet 33a provided in the microchannel device 30 and the collection container 23 were connected by a tube (piping 43) having an inner diameter of φ0.5 mm and a length of 6 cm.
(5) The liquid was pumped at 400 mbar for 40 minutes using the air pump 60.
(6) (5) The state of delivery of each liquid was confirmed by visually observing the change in color of the trypan blue added to the suspension 12 in the piping and microchannel device 30 when the liquid was delivered, and by measuring the fluctuation in the value of the flow meter 70.

In Example 1, the entire amount of cell suspension containing trypan blue was delivered approximately 35 minutes after the start of delivery, and the state in which the inside of the piping 42 was subsequently replaced with mineral oil was confirmed from the color of the trypan blue. Furthermore, when the mineral oil reached the inlet 32, the flow rate changed from 30 μL/min to 0 μL/min, and the flow meter (measuring device 70) confirmed that the delivery of mineral oil had stopped. Meanwhile, by continuing to deliver the sheath liquid 11 while pressurizing with the air pump 60 (40 minutes), the cells remaining in the piping 43 connecting the microchannel device 30 (outlet 33a) and the collection container 23 could be discharged, and it was visually confirmed that bubbles and mineral oil were not mixed into the suspension in the collection container 23.

Example 2
Using the same dispersion solvent replacement apparatus and microchannel device as in Example 1, an attempt was made to replace the dispersion solvent in the cell suspension.
(1) After detaching PC9 cells, the solution was replaced with RPMI-1640 medium containing 10% (w/v) FBS, and the cells were suspended in 1 mL of the medium containing 0.04% (w/v) trypan blue and 1% (w/v) dextran and adjusted to a specific gravity of 1.077 using OptiPrep (Abbott Diagnostics Technologies), to give suspension 12. The number of cells contained in the suspension (measured using a cell counting plate; manufactured by Watson), electrical conductivity (measured using an electrical conductivity meter LAQUAtwin-EC-33B; manufactured by Horiba, Ltd.), and absorbance at 600 nm, which is the absorption wavelength of trypan blue (measured using a spectrophotometer NanoDrop; manufactured by ThermoFisher) were measured.
(2) The suspension 12 was placed in a container 22, and 0.5 mL of mineral oil (manufactured by Nacalai Tesque, Inc.) was layered on top as a sealing liquid 13.
(3) As sheath liquid 11, 5 mL of an aqueous solution containing 1% (w/v) dextran and 280 mM sucrose and having a specific gravity adjusted to 1.077 using OptiPrep was prepared, and the solution was pumped at 1,400 mbar for 30 minutes using the air pump 60. Except for this, the solution was pumped in the same manner as in Example 1 (3) to (5).
(4) After the liquid was delivered in (3), the number of cells contained in the solution 14 discharged from the outlet 33a and the amount of the recovered liquid were measured. The amount of the solution 14 was filled up to 1 mL with sheath liquid using a micropipette, and then the electrical conductivity and the absorbance at 600 nm, which is the absorption wavelength of trypan blue, were measured.

The cell suspension before the dispersion solvent replacement contained 1.34 x 10^6 cells, electrical conductivity 9.3 mS/cm, and absorbance 1.182, whereas after the dispersion solvent replacement the cell suspension contained 1.29 x 10^6 cells, the recovered liquid volume 109 μl, electrical conductivity 0.028 mS/cm, and absorbance 0.019. The cell recovery rate after the dispersion solvent replacement was 96.2%, indicating a high recovery rate. In addition, the electrical conductivity was 1/100 or less, and the absorbance was 1/50 or less, indicating that the solution replacement was highly efficient.

Example 3
Using the same dispersion solvent replacement apparatus and microchannel device as in Example 1, an attempt was made to replace the dispersion solvent in the cell suspension.
(1) PC9 cells were detached, labeled with a fluorescent dye (CFSE, Dojindo Laboratories), and the solution was replaced with RPMI-1640 medium containing 10% (w/v) FBS. The cells were then suspended in 1 mL of the medium containing 0.04% (w/v) trypan blue and 1% (w/v) dextran, the specific gravity of which was adjusted to 1.077 using OptiPrep, so that the number of cells was about 200, to give suspension 12. The cell suspension was spread on a plate and visually counted using a fluorescent microscope, and the cell suspension added to the plate was collected and added to the suspension. The number of cells added to the suspension was measured by subtracting the number of cells remaining on the plate from the number of cells counted.
(2) The suspension 12 was placed in a container 22, and 0.5 mL of mineral oil (manufactured by Nacalai Tesque, Inc.) was layered on top as a sealing liquid 13.
(3) As sheath liquid 11, 5 mL of an aqueous solution containing 1% (w/v) dextran and 280 mM sucrose and having a specific gravity adjusted to 1.077 using OptiPrep was prepared, and the solution was pumped at 1,400 mbar for 30 minutes using the air pump 60. Except for this, the solution was pumped in the same manner as in Example 1 (3) to (5).
(4) After the liquid was delivered in (3), the number of fluorescently labeled cells contained in the solution 14 discharged from the outlet 33a was counted in the same manner as in (1).

The number of cells contained in the cell suspension before the dispersion solvent replacement was 153, whereas the number of cells contained in the cell suspension after the dispersion solvent replacement was 139. The cell recovery rate after the dispersion solvent replacement was 90.8%, indicating that even a small number of cells can be recovered with high efficiency.

100: Apparatus 11: Sheath liquid 12: Suspension 13: Sealing liquid 14: Suspension after treatment 21: Container (Container 2)
22: Container (Container 1)
23: Container (Container 3)
30: Microchannel device 30a: Main body 30b: Lid 31: Sheath fluid inlet (inlet 2)
32: Suspension inlet (inlet 1)
33: Exhaust port 34: Junction flow path 35: Exhaust flow path 36: Branch flow path 37: Exhaust flow path 41: Pipe (pipe 2)
42: Piping (Pipe 1)
43: Piping (Pipe 3)
50: Pressure vessel 60: Air pump 61: Pressurized piping 70: Measuring instrument 80: Control unit 90: Conducting wire

Claims (1)

A container 1 for containing a suspension containing particles;
an inlet 1 of a microchannel device connected to the container 1 by a pipe 1;
A measuring instrument for measuring the physical properties or flow rate of the liquid flowing through the pipe 1;
a pump 1 capable of pumping the suspension from the container 1 to the inlet 1;
A control unit that controls the operation of the pump 1 based on the measurement results of the measuring instrument;
A container 2 for containing a sheath liquid;
an inlet 2 of a microchannel device connected to the container 2 by a pipe 2;
a pump 2 capable of pumping the sheath liquid from the container 2 to the inlet 2;
a confluence flow path for confluence of the suspension introduced from the inlet 1 and the sheath liquid introduced from the inlet 2;
a separation channel connected to the confluence channel for separating particles contained in the suspension using a hydrodynamic filtration method;
an outlet connected to an end of the separation channel;
A container 3 connected to the outlet by a pipe 3;
Equipped with
The container 1 and a part of the pipe 1, and the container 2 and a part of the pipe 2 are hermetically accommodated in a pressure container, one pump is connected to the pressure container, and a liquid is pumped using the one pump connected to the pressure container as the pump 1 and the pump 2,
A method for feeding a suspension containing particles contained in the container 1 to an inlet of a microfluidic device using the pump, comprising the steps of:
A sealing liquid having a specific gravity smaller than that of the suspension, a viscosity larger than that of the suspension, and immiscible with the suspension is layered on the suspension contained in the container 1 ;
A method for pumping a suspension, characterized in that the pump is used to pump the suspension from the container 1 to the inlet 1 under pressure conditions that allow the suspension to be pumped into a microchannel device but prevent the sealing liquid from being pumped into the microchannel device.