CN109100485B - A kind of micron capillary column gas-liquid dynamic phase interface test macro - Google Patents
A kind of micron capillary column gas-liquid dynamic phase interface test macro Download PDFInfo
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- CN109100485B CN109100485B CN201810875914.0A CN201810875914A CN109100485B CN 109100485 B CN109100485 B CN 109100485B CN 201810875914 A CN201810875914 A CN 201810875914A CN 109100485 B CN109100485 B CN 109100485B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
Abstract
The present invention provides a kind of micron capillary column gas-liquid dynamic phase interface test macros, the present invention determines the movement speed of phase interface using dynamic checkout unit by image processing algorithm, and then the speed of Mobile base is adjusted by motor using the speed, microfluidic chip is set to do corresponding movement always with the phase interface direction of motion, to make phase interface accordingly be maintained in the field of view of camera unit, to realize that the dynamic contact angular measurement under low capillary number, low Bond's number state provides Fundamentals of Measurement, the efficiency and measurement accuracy of data processing are greatly improved.
Description
Technical field
The present invention relates to petroleum enhanced recovery fields, more particularly to for measuring gas-liquid dynamic displacement in micron capillary column
Phase interface can be made to be automatically positioned within the scope of field of view by controlling movement speed and the direction of microfluidic chip in the process
Micron capillary column gas-liquid dynamic phase interface test macro.
Background technique
Two-phase driving mechanism in the capillary of single micro-meter scale is the two-phase displacement in natural environment porous media
Basis, the two-phase displacement in porous media occur in numerous industry or natural process, such as the water drive gas, molten of compact oil reservoir
The processes such as gas drive, water drive oil are solved, obtain the dynamic Contact angle information under above-mentioned industrial condition for assessing in entire porous media
Two-phase displacement process is most important.
Having many realize in diameter in the prior art is that dynamic contact angle is measured in millimetre-sized capillary
Scheme.Wherein in order to observe contact angle, needs to obtain the image of amplification using the microscope of high magnification numbe, also mean that observation
The visual field it is small.However dynamic displacement process means phase interface and can move a certain distance, therefore the microscope of high magnification numbe without
Method observes the motion process of phase interface.
If observed using the microscope of low power number, it can be observed that the variation of phase interface position, can not but observe
To phase interface, contact angle also just can not be directly measured.
In conclusion needing one kind that the motion process of phase interface not only can be observed, but also it can accurately observe phase phase interface
The dynamic test system of details.
Summary of the invention
The invention aims to provide a kind of survey that can facilitate observation to gas-liquid dynamic phase interface in micron capillary column
Test system.
Particularly, the present invention provides a kind of micron capillary column gas-liquid dynamic phase interface test macro, comprising:
Microfluidic chip is provided with micron capillary tube passage for passing through for test liquid;
Pressure control conduit is equipped on pipeline including the syringe pump being connect by pipeline with the microfluidic chip
Detect the pressure sensor of pressure;
Mobile platform, including the pedestal as support, and the lead screw of installation on the base, by thread bush on lead screw edge
The Mobile base of linear movement, the motor of driving lead screw rotation, the microfluidic chip are mounted on Mobile base;
The top of the microfluidic chip is arranged in camera unit, for obtaining the test phase interface image of liquid and defeated
Out;
Control system, the injection process of the syringe pump is controlled according to the information of the pressure sensor, while controlling institute
Stating motor keeps the horizontal movement velocity of the microfluidic chip identical as the test liquid movement speed in the microfluidic chip
And it is contrary, the step of controlling the motor, is as follows:
If the speed of the Mobile base is v, according to:
N=f/k
Wherein, n is the revolving speed of motor, and f is the pulse signal frequency that control system issues, and k is to turn frequency ratio;Then:
V=Lpn
LpFor the screw pitch of known lead screw;Judged after obtaining the direction of motion and speed of phase interface according to real-time micro-image,
The microfluidic chip synchronization can control to move on the contrary after releasing motor speed by the way that obtained Mobile base speed v is counter, so that
The phase interface that test fluid body is formed remains at the camera unit within sweep of the eye.
In an embodiment of the invention, further include the process of the anti-displacement for pushing away phase interface and speed, process is as follows:
If displacement of the Mobile base from 0 moment to t moment is s, according to displacement formula:
Control is since the moment 0, every the speed v of the time interval record Mobile base of Δ ti, i=1,2,3 ... m, then
M speed data is had recorded in total when carving t, then the formula can be separated into:
Wherein, velocity variations of the value of Δ t dependent on Mobile base described in actual mechanical process;It is calculated by image recognition
Method obtains on any time phase interface two contact points to the distance d of image left endAAnd dB, then the displacement x of any time phase interface
Are as follows:
The displacement x of opposite phase interface, the speed V of phase interface is the first derivative of displacement xTo displacement x with centered difference
Format carries out derivation to displacement data, wherein assuming that including m data in x, the footmark of i and x indicate the number of displacement data:
Thus the speed of phase interface is obtained.
In an embodiment of the invention, phase interface is made to be automatically maintained at the visual field width of the camera unit always
Centre method it is as follows:
Wherein, V is the phase boundary face velocity acquired in real time, d be phase interface in the visual field width of camera unit From Left
The distance of edge, v are the speed of Mobile base, τvFor time constant, physical significance is from the view that phase interface is deviateed to camera unit
The distance d-W of Yezhong centres/ 2 drop to 0 required for the time, WsFor the visual field width of camera unit.
In an embodiment of the invention, the microfluidic chip is plate structure made of transparent material, on one side
On be provided with the groove of indent, the cover board for being bonded the groove upper surface is stamped on the groove, the micron capillary column is logical
Road setting is provided in the groove and with array manner multiple, and the both ends of each micron capillary tube passage are respectively set
There are feed liquor area and out liquid zone;The width of the micron capillary tube passage is 10~100 μm, the feed liquor area and it is described go out liquid zone
Width is at least 15~20 times of the micron capillary column channel width.
In an embodiment of the invention, the feed liquor area and the liquid zone out are the tip of water-drop-shaped and water-drop-shaped
Be connected to the micron capillary tube passage, the feed liquor area and it is described go out liquid zone in be equably provided with respectively more it is vertical
Prevent the column that micron collapses, the column in an annular fashion arrange by from coil to coil, and centre reserve the inlet opening and it is described go out
The installation space of fluid apertures;The centre in the feed liquor area is provided with the inlet opening of bottom opening, is set in the centre of the liquid zone out
It is equipped with the fluid hole of bottom opening.
In an embodiment of the invention, the upper surface of the Mobile base is installed there are two relative spacing and vertically
Support plate is separately installed with the fixed station of the fixed microfluidic chip on the opposite face of two support plates;Described
Be provided with multiple mounting holes on Mobile base, the support plate by L shape tabs using on the Mobile base mounting hole with it is described
Mobile base is fixed, and the sliding groove of the microfluidic chip after placing, the fixed station are provided perpendicular in the support plate
It is mounted in the support plate by the way that the sliding groove is adjustable.
In an embodiment of the invention, the fixed station is the support bar of strip, or to be provided with described in clamping
The clamping strip of the groove of microfluidic sides of chip installs the promising microfluidic chip illumination between two support plates
Light source.
In an embodiment of the invention, threeway is provided with by L shape tabs in the side of the Mobile base
Transparent connector, two of them through-hole is horizontal and what is be oppositely arranged leads directly to, another through-hole is perpendicular to two straight-through middle parts
It erects and leads to, the pressure sensor connecting with the control system is above equipped with by screw thread erecting to lead to, is led directly at two and passes through spiral shell
Line is connected with female Luer, and the syringe pump is connect by flexible hose with the female Luer, another straight-through female Luer
It is connect by flexible hose with the inlet opening in the feed liquor area, the fluid hole of the liquid zone out is connected by flexible hose and water receiver
It connects.
In an embodiment of the invention, it includes such as under type that the control system, which controls the syringe pump injection pressure:
If the pressure value of micron capillary pipeline entrance is Pd, the hope pressure value in micron capillary tube passage is Pt, syringe pump
Injection flow be Q, then:
One, manual control works as Pd<Pt, then increase Q, make PdRise to Pt;Work as Pd>Pt, then reduce Q, make PdIt is decreased to Pt;
Two, ratio controls, and control system given one has dimension Proportional coefficient KpIf system is linear response function, then:
Q=Kp(Pt-Pd);
Three, theoretical control, has according to Washburn formula:
V is phase boundary face velocity in formula, and x is the length for testing liquid in micron capillary tube passage, and θ is the contact of phase interface
Angle, μ are test liquid viscosity, and S is micron capillary column channel cross-section side length, and A is micron capillary hole path area of section, and R is micro-
The equivalent redius of rice capillary channel, γ is interfacial tension;
Due to Q=AV, above formula be can be rewritten as:
According to wishing pressure value Pt, contact angle measured value θ and length x of the test liquid in micron capillary tube passage are direct
Ideal injection flow Q is calculated, control system then can be with the flow of real-time control syringe pump according to Q.
In an embodiment of the invention, the Proportional coefficient K in the ratio controlpEvaluation method it is as follows:
It is injected with test liquid in the micron capillary tube passage, in the syringe pump to the micron capillary tube passage
Between pipeline in be injected with sealing liquid, and there are airspaces between the sealing liquid and the test liquid, wherein
Avoid the junction of pipeline in airspace position;
If volume of air present in pipeline is Va, sealing liquid is Δ V, goal pressure Pt, for adiabatic compression process
Perfect gas have:
(Pa+Pd)Va=(Pa+Pt)(V1-ΔV)
P in formulaaFor atmospheric pressure, the time for causing the above variation to need is τp, make pipeline pressure from PdChange to PtInjection
Flow Q is then are as follows:
Above formula can be according to PtAnd PdThe flow Q needed is calculated, then syringe pump is controlled by control system, and then obtain ratio
COEFFICIENT KpEstimated value:
V in formula1For the volume of air in pipeline, the total volume of inlet pipeline can be used;τpIt, can basis for time constant
Requirement of experiment specifically adjusts;PaFor atmospheric pressure, PtFor goal pressure, the driving pressure P needed due to Micro-flowstIt can be remote small
In atmospheric pressure, P can be ignoredt。
The present invention determines the movement speed of phase interface by image processing algorithm, so using the speed by motor come
The speed for adjusting Mobile base, makes microfluidic chip do corresponding movement always with the phase interface direction of motion, to keep phase interface corresponding
It is maintained in the field of view of camera unit, to realize that the dynamic contact angular measurement under low capillary number, low Bond's number state provides
Fundamentals of Measurement, greatly improves the efficiency and measurement accuracy of data processing.
Detailed description of the invention
Fig. 1 is the test system structure schematic diagram of one embodiment of the present invention;
Fig. 2 is the overall structure diagram of microfluidic chip;
Fig. 3 is the feed liquor plot structure schematic diagram of micron capillary column;
Fig. 4 is the mobile translation structural schematic diagram of one embodiment of the present invention;
Fig. 5 is the structural schematic diagram of Fig. 5 center tap.
Specific embodiment
As shown in Figure 1, 2, 3, one embodiment of the invention provides a kind of micron capillary column gas-liquid dynamic phase interface test system
System, generally comprises microfluidic chip 20, pressure control conduit 40, mobile platform 30, camera unit 50 and control system 10.
The microfluidic chip 20 is used to pass through for test liquid, is provided with micron capillary tube passage 21;Specific microfluidic
Chip 20 can be the slab structure of the production such as glass, organic material.Micron capillary tube passage 21 is gas-liquid dynamic two-phase displacement
The place of generation needs to have enough intensity, machining accuracy and operability.Needs according to the present embodiment, micron
The characteristic size of capillary channel 21 in 10~100 μ ms, as present embodiment use be 20,40 and 80 μm respectively into
Row test.
Specific microfluidic chip 20 can use dimethyl silicone polymer (PDMS) material, and micron capillary tube passage 21
It can then be made of Soft lithograph technique, the processing section of micron capillary tube passage 21 can be rectangle or circle.This embodiment party
Formula is using square, in experiment condition are as follows: 1. etching depths are 20 microns (i.e. height is 20 microns), and length is to meet phase boundary
Enough moving distances in face;2. test liquid is crosslinking agent, concentration 10%;3. key and temperature are 100 degrees Celsius;4. hard
Changing the time is 120 minutes.Technique requirement 2,3 and 4 can guarantee that the elasticity modulus of structure is 2000KPa, can meet less than 20KPa
Requirement of experiment (elastic strain is less than 1%).
Pressure control conduit 40 includes the syringe pump 41 being connect by pipeline with microfluidic chip 20, is equipped on pipeline
Detect the pressure sensor 42 of pressure.Pressure sensor 42 is tested for measuring the pressure that syringe pump 41 is applied in pipeline
The real-time pressure of 41 injected current amount of syringe pump generation simultaneously passes to control system 10.Syringe pump is high-precision syringe pump, Er Qie
The adjustment of injection rate is realized under the control of control system.
The mobile platform 30 includes the pedestal 32 as support, and the lead screw 34 being mounted on pedestal 32, passes through thread bush
The Mobile base 33 moved along a straight line on lead screw 34, the motor 31 that driving lead screw 34 rotates, microfluidic chip 20 are mounted on movement
On seat 33.Entire mobile platform 30 is the equal of a screw structure, drives the rotation of lead screw 34 to make to move by motor 31
Seat 33 moves horizontally, and then moves horizontally the realization of microfluidic chip 20.
The top of microfluidic chip 20 is arranged in camera unit 50, for obtaining test liquid in micron capillary tube passage 21
In phase interface image, then export to control system 10 and carry out the data analysis such as contact angle.Camera unit 50 can be using height
The digital camera of precision.
Control system 10 can be the computer with control program, be controlled according to the information of pressure sensor 37
The injection process of syringe pump 41, to adjust pressure;Make the horizontal movement velocity of microfluidic chip 20 by controlling motor 31 simultaneously
It is identical and contrary as the test liquid movement speed in micron capillary tube passage 21, so that the phase interface that test fluid body is formed
It remains at camera unit 50 within sweep of the eye, has both realized that high-precision is observed, but also with enough field of view.Control electricity
The step of machine, is as follows:
If the speed of Mobile base is v, according to:
N=f/k
Wherein, n is the revolving speed of motor, and f is the pulse signal frequency that control system issues, and k is to turn frequency ratio;Then:
V=Lpn
LpFor the screw pitch of known lead screw;Judged after obtaining the direction of motion and speed of phase interface according to real-time micro-image,
The microfluidic chip synchronization can control to move on the contrary after releasing motor speed by the way that obtained Mobile base speed v is counter, so that
The phase interface that test fluid body is formed remains at the camera unit within sweep of the eye.
In present embodiment, the movement speed of Mobile base can accurately be controlled by control system, and the controller of motor can
To receive the voltage signal in control direction, if comparison voltage is 2.5V, a high voltage (such as 5V) is inputted to controller, then motor
It will rotate forward, input a low-voltage (such as 1V) to controller, then motor will invert.Therefore Mobile base movement speed v and
Direction all can carry out real-time control and record by computer.Speed v is positive when specific Mobile base is mobile toward some direction
Number, on the contrary v is that negative then can be by artificially providing.
According to prior experiment or the test of limited times, it can determine the pressure size of syringe pump under current caliber
With the relationship between phase interface movement speed, and then the mobile speed of phase interface can be extrapolated by the data that pressure sensor measures
Degree realizes the control of Mobile base speed and direction then further according to the relationship between the motor speed of acquisition and Mobile base.
In an embodiment of the invention, it provides a kind of by the anti-process for pushing away phase boundary face velocity of motor speed, mistake
Journey is as follows: displacement of the Mobile base from 0 moment to t moment is set as s, according to displacement formula:
Control is since the moment 0, every the speed v of the time interval record Mobile base of Δ ti, i=1,2,3 ... m, then
M speed data is had recorded in total when carving t, then the formula can be separated into:
Wherein, whether the value of Δ t has quick variation dependent on the speed of Mobile base described in actual mechanical process.
As long as time interval Δ t acquirement is sufficiently small, such as 10ms~100ms, then high-precision displacement data can be obtained.The value of Δ t
Whether the speed dependent on Mobile base in actual mechanical process has quick variation.
Two contact points are obtained on any time phase interface to the distance d of image left end by image recognition algorithmAAnd dB,
The then displacement x of any time phase interface are as follows:
The displacement x of opposite phase interface, the speed V of phase interface is the first derivative of displacement xDisplacement x is one group of dispersion number
According to for discrete data processing, main use carries out derivation to displacement data with central difference schemes to displacement x, wherein assuming that
Include m data in x, the footmark of i and x indicate the number of displacement data:
Thus the speed of phase interface is obtained.It, can also be in reverse as control motor rotation after the speed for determining phase interface
Condition.
In an embodiment of the invention, one kind is provided while controlling phase interface position, and can make its beginning
It is automatically maintained among the width of the camera unit visual field eventually, the method is as follows:
Wherein, V is the phase boundary face velocity acquired in real time, d be phase interface in the visual field width of camera unit From Left
The distance of edge, v are the speed of Mobile base, τvFor time constant, physical significance is from the view that phase interface is deviateed to camera unit
The distance d-W of Yezhong centres/ 2 drop to 0 required for the time, WsFor the visual field width of camera unit.It include two on the right of equation, the
One is V, and Section 2 isWhen phase interface is located at visual field center, it is 0 that Section 2, which obtains calculated result, at this time speed
Control is v=-V, as long as that is, electric platforms are contrary for phase interface, the identical speed operation of size keeps phase boundary
The visual field is central again in face;When phase interface is more than the central and right end close to the visual field in the visual field, Section 2Illustrate v
>-V, the speed of electric platforms can be moved with the speed greater than phase interface toward opposite direction at this time, to reduce phase interface to the visual field
The distance in centerAnd in the process, withDiminution, electric platforms speed v can be becoming tight phase interface gradually
Opposite speed-V, untilI.e. phase interface returns to visual field center, and speed at this time is v=-V;Whole process is one
Dynamic Regulating Process.When phase interface does not arrive to visual field center and when being proximate to visual field left end, Section 2Illustrate v
<-V, the speed of electric platforms can be moved with the speed less than phase interface toward opposite direction at this time, to make phase interface close to the visual field
Center.And in the process, withDiminution, electric platforms speed v can be becoming tight the opposite speed-V of phase interface gradually,
UntilI.e. phase interface returns to visual field center, and speed at this time is v=-V.
At work, first the microfluidic chip 20 set is horizontally arranged on Mobile base 33, digital camera and calculating
It is mounted on the surface of microfluidic chip 20 after machine connection, adjusts shooting distance;Liquid injection microfluidic will be tested accordingly
In the micron capillary tube passage 21 of chip 20, is controlled by the course of work of the computer to syringe pump 41, make injection pressure
The predeterminated target pressure in micron capillary tube passage 21 that relative experimental requires reaches consistent;Simultaneous computer needs to control motor
41 rotation is mobile to make the drive microfluidic chip 20 of Mobile base 33, since the phase interface of test liquid can be with syringe pump 31
Pressure oscillation and move back and forth in micron capillary tube passage 21, influence the observation of digital camera;At this point it is possible to control microfluidic
Chip 20 relative to phase interface movement and synchronizing moving, but the moving direction of the direction moved every time and phase interface is on the contrary, make phase
Although interface is mobile but is dynamically limited in the field of view of digital camera, to guarantee existing enough field of view again
Clearly phase interface image can be obtained.
The control mode of specific motor 31 can be formed with the injection pressure of syringe pump 41 and is associated with.The movement speed of phase interface
With direction by the pressure influence in micron capillary tube passage 21, after getting the pressure size in micron capillary tube passage 21,
It can determine the moving direction and movement speed of current phase interface, control system 10 controls the positive and negative rotation of motor 31 according to the value
And revolving speed size, to make Mobile base 33, speed opposite with the moving direction of phase interface and the two reaches unanimity always, makes phase
Interface remains within the scope of digital camera or microscopical field of view or the middle part in the visual field, requires to meet observation.
Present embodiment can realize that gas liquid film is current by mutually independent mobile platform and pressure control conduit
The automatic control of stop place enables camera unit to be consistently observed most suitable phase interface image, improves practical operation
When flexibility to meet the needs of various operating conditions.
As shown in Figure 3,4, in an embodiment of the invention, for convenience of observing, which be can be
The plate structure being made of clear material, is arranged the groove 22 of indent in one plane, and the shape of groove 22 can be circle
Shape or rectangle are stamped the removable cover (being similarly transparent) of upper surface in fitting groove 22, for glass material on groove 22
Material, cover board and groove 22 are combined, bonding technology can be used by 22 knot of cover board and groove for PDMS material using sintering process
It closes;Micron capillary tube passage 21 is arranged in the plane in groove 22, and multiple, each micron capillary column can be arranged with array manner
Channel 21 is parallel between each other, as six micron capillary tube passages 21 are arranged in present embodiment on microfluidic chip 20;Each
The both ends of micron capillary tube passage 21 are respectively arranged with feed liquor area 211 and out liquid zone 212, and the width of micron capillary tube passage 21 can
It is arranged in 10~100 μm according to requirement of experiment, and feed liquor area 211 and the out width of liquid zone 212 are at least micron capillary column and lead to
15~20 times of 21 width of road;This is because the width of micron capillary tube passage 21 itself is micron order, if test liquid is straight
It taps into pressure not easy to control, liquid zone 212 can form one at the both ends of micron capillary tube passage 21 using feed liquor area 211 and out
The buffer channel of a test liquid inlet and outlet makes it in micron capillary tube passage 21 to guide the flowing of test liquid
The phase interface of formation can be in stable moving condition.
The shape of feed liquor area 211 and out liquid zone 212 is so that test fluid body can steadily enter in micron capillary tube passage 21
Subject to, it is such as round, oval;In an embodiment of the invention, the feed liquor area 211 and out liquid zone 212 use water-drop-shaped, water
The tip of drop shape is connected to micron capillary tube passage 21, and the angle that tip and 21 junction of micron capillary tube passage are formed can be 60
Degree left and right, so that test fluid body can steadily enter micron capillary tube passage 21 in a contracted state.
Equably it is provided with the more vertical columns for preventing micron from collapsing respectively in feed liquor area 211 and out liquid zone 212
213, it is spaced apart from each other between column 213 and column 213, while the diameter of column 213 can be with the width of micron capillary tube passage 21
Spend identical or for its 1~2 times, the spacing distance between column 213 can be the diameter of column 213.Be using column 213 because
PDMS material belongs to elastic-plastic material, is greater than 2 region in the width of microchannel structure and the ratio of depth, material can be because attaching most importance to
The effect of power and generate micron dimension " collapsing " deformation.Column 213 can avoid deformation to be influenced on caused by test liquid flowing.
And inlet opening and fluid hole for testing liquid inlet and outlet are separately positioned on feed liquor area 211 and the out interposition of liquid zone 212
It sets and is open in the bottom of groove 22.Inlet pipe and drain line can be connected directly with corresponding inlet opening and fluid hole.
The arrangement of column 213 can be according to feed liquor area 211 and the shape determination of liquid zone 212 out, such as present embodiment
Central post 213 in an annular fashion arrange by from coil to coil, and centre reserves the installation space of inlet opening and fluid hole.
It, can be with for convenience of mobile and adjustment microfluidic chip 20 as shown in Fig. 2, in an embodiment of the invention
Two relative spacings and vertical support plate 36 are installed in the upper surface of Mobile base 33, the spacing distance between support plate 36 with it is micro-
The width for flowing chip 20 is corresponding;Fixed or support microfluidic chip 20 is separately installed on the opposite face of two support plates 36
Fixed station 361;Multiple mounting holes 331 are provided on Mobile base 33, mounting hole 331 can make support plate 36 with respect to microfluidic
The width adjustment installation site of chip 20;Support plate 33 utilizes mounting hole 331 and movement on Mobile base 33 by L shape tabs 35
Seat 33 is fixed, is respectively arranged with fixation hole on two flangings of L shape tabs 35, by bolt respectively with Mobile base 33 and support plate
36 is fixed.
It is possible to further install a light source between the support plate 36 of the lower section of microfluidic chip 20 two, light source is used
In keeping microfluidic chip 20 brighter, to facilitate camera unit 50 to obtain clear phase interface image.Specific light source can be
LED light.
In addition, can be respectively set in every piece of support plate 36 perpendicular to placement for convenience of the height for adjusting fixed station 361
The twice interval sliding slot (not shown) of microfluidic chip 20 afterwards, fixed station 361 can using the bolt across sliding groove
What is adjusted is mounted in support plate 36.Given here is the method for adjusting microfluidic chip 20, in other embodiments
The height of digital camera can also be directly adjusted, and microfluidic chip 20 remains stationary.
In addition, support plate 36, fixed station 361 and L shape tabs 35 can use and microfluidic chip 20 for convenience of observing
Same transparent material production.
Specific fixed station 361 can be the support bar of strip, horizontally-supported to be formed to microfluidic chip 20;It can be with
For be provided with clamping 20 side of microfluidic chip groove clamping strip, microfluidic chip 20 during installation, opposite two sides
It can clampingly be mounted in the groove of clamping strip, which can be improved the stability of microfluidic chip 20 after installation.
As shown in figure 5, in an embodiment of the invention, it, can be in movement for convenience of pressure sensor 42 is installed
A transparent connector 37 with threeway is installed by L shape tabs 35 in the side of seat 33,37 two of them through-hole of connector be it is horizontal and
Straight-through 371 be oppositely arranged, another through-hole are perpendicular logical 372 perpendicular to two straight-through 371 middle parts, are passed through on perpendicular logical 372
Screw thread is equipped with the pressure sensor 42 connecting with control system 10, has been connected through a screw thread Rule on two straight-through 371 and has connect
First 373, syringe pump 41 can be connect by flexible hose with female Luer 373, and another straight-through 371 female Luer 373 then passes through
Flexible hose is connect with the inlet opening in feed liquor area 211, and the fluid hole of liquid zone 212 is connected by flexible hose and water receiver 43 out
It connects.
During the test, then the pressure that syringe pump 41 is released can directly be measured by pressure sensor 42 and send control to
System 10 processed, control system 10 are then compared according to the pressure size with scheduled target pressure value, and control system 10 is at this
The injection process of syringe pump 41 is persistently controlled during a according to the pressure value of pressure sensor 42, until micron capillary column pipeline
Pressure value in 21 reaches scheduled target pressure value.
In the present embodiment, to prevent joint from revealing, test liquid can be only injected in micron capillary tube passage 21,
Guarantee test liquid amount corresponding phase interface can be formed in micron capillary tube passage 21, behind then injected by syringe pump 41
For sealing liquid to form injection pressure in pipeline, sealing liquid is also possible to it either the test same liquid of liquid
Its class I liquid I, such as water;It will be pre-filled with liquid in pipeline before experiment, by liquid transfering pressure and occupies the seam of tie point
Gap.Since leakage rate and fluid viscosity are inversely proportional, air viscosity 0.01mPas, the viscosity of liquid is far longer than air (such as
The viscosity of water is about 1mPas in the case where marking condition), leakage rate can be allow to greatly reduce as pressure transmission medium using liquid.
Being sealed between liquid and test liquid under this structure has one section of space interval (air column), and air column, which does not contact, is related to pipeline
The region connecting with connector can play the role of isolation test liquid and sealing liquid.
In an embodiment of the invention, it includes following several that control system 10, which controls 41 pressure mode of syringe pump:
If the pressure value of micron capillary column feeder connection is Pd, it is desirable to reference pressure value be Pt, the injection flow of syringe pump
For Q, then:
One, manual control, when the pressure value P of micron capillary column feeder connectiond<Pt, then increase the injection flow Q of syringe pump,
Make pressure value PdRise to Pt;Work as Pd>Pt, then reduce injection flow Q, make pressure value PdIt is decreased to Pt;The process can completely by
Experimenter manually controls according to the variation of current pressure values.
Two, ratio controls, and control system given one has dimension Proportional coefficient KpIf system is linear response function,
Q=Kp(Pt-Pd);
Wherein, the Proportional coefficient K in ratio controlpEvaluation method it is as follows:
Assuming that injection process liquid or gas are flowed out not over micron capillary column, whole system is that closing insulation is
System, the water for serving as pressure transmission medium is incompressible liquid;Due to studying gas-liquid displacement process, there can be certain body in system
Product VaAir (about 40~50 μ L), initial pressure Pd;Syringe pump advances the water Δ V of certain volume into system, causes sky
The volume of gas reduces Δ V and pressure rises to Pt, have for the perfect gas of adiabatic compression process:
(Pa+Pd)Va=(Pa+Pt)(V1-ΔV)
P in formulaaFor atmospheric pressure, the time for causing the above variation to need is τp, make loine pressure from PdChange to PtInjection
Flow is then are as follows:
Above formula can be according to goal pressure Pt, real-time pressure PdThe flow Q needed is calculated, then is controlled and is injected by control system
Pump;From the available Proportional coefficient K of above formulapEstimated value:
V in formula1For the volume of air in pipeline, the total volume of inlet pipeline can be used;τpIt, can basis for time constant
Requirement of experiment specifically adjusts;PaFor atmospheric pressure, PtFor goal pressure, the driving pressure P needed due to Micro-flowstIt can be remote small
In atmospheric pressure, P can be ignoredt。
Three, theoretical control, since the pressure loss of whole system is the two-phase flow process in micron capillary column,
Flow Q and goal pressure can be obtained according to the fundamental equation Washburn derivation of equation of two-phase flow in description micron capillary column
PtBetween relationship.Had according to Washburn formula:
V is phase boundary face velocity in formula, and x is length of the liquid in micron capillary tube passage, and θ is the contact angle of phase interface, μ
For liquid viscosity, S is micron capillary column channel cross-section side length (needing exist for the Adjusting Shape corresponding coefficient according to section), and A is
Micron hollow billet cross sectional area, R are the equivalent redius of micron capillary tube passage, and γ is interfacial tension;
According to the relationship of volume flow Q and phase boundary face velocity V: Q=AV, therefore above formula can be rewritten as:
According to goal pressure Pt, the length x of contact angle measured value θ and liquid in micron capillary tube passage directly calculates
Ideal injection flow Q, control system then can be with the flow of real-time control syringe pump according to Q.
After obtaining injection flow Q, it can be contacted with the movement speed foundation of this and the revolving speed and Mobile base of motor, and then then may be used
Control the position of phase interface on microfluidic chip.
So far, although those skilled in the art will appreciate that present invention has been shown and described in detail herein multiple shows
Example property embodiment still without departing from the spirit and scope of the present invention, still can according to the present disclosure directly
Determine or deduce out many other variations or modifications consistent with the principles of the invention.Therefore, the scope of the present invention is understood that and recognizes
It is set to and covers all such other variations or modifications.
Claims (9)
1. a kind of micron capillary column gas-liquid dynamic phase interface test macro characterized by comprising
Microfluidic chip is provided with micron capillary tube passage for passing through for test liquid;
Pressure control conduit is equipped with detection including the syringe pump connecting by pipeline with the microfluidic chip on pipeline
The pressure sensor of pressure;
Mobile platform, including the pedestal as support, and the lead screw of installation on the base, by thread bush along straight line on lead screw
Mobile Mobile base, the motor of driving lead screw rotation, the microfluidic chip are mounted on Mobile base;
The top of the microfluidic chip is arranged in camera unit, for obtaining the phase interface image of test liquid and exporting;
Control system, the injection process of the syringe pump is controlled according to the information of the pressure sensor, while controlling the electricity
Machine keeps the horizontal movement velocity of the microfluidic chip and the test liquid movement speed in the microfluidic chip identical and square
To on the contrary, the step of controlling the motor is as follows:
If the speed of the Mobile base is v, according to:
N=f/k
Wherein, n is the revolving speed of motor, and f is the pulse signal frequency that control system issues, and k is to turn frequency ratio;Then:
V=Lpn
LpFor the screw pitch of known lead screw;Judged after obtaining the direction of motion and speed of phase interface according to real-time micro-image, by
To Mobile base speed v it is counter release motor speed after can control the microfluidic chip synchronization to move on the contrary so that test fluid
The phase interface that body is formed remains at the camera unit within sweep of the eye;
Further include the process of the anti-displacement for pushing away phase interface and speed, process is as follows: setting the Mobile base from 0 moment to t moment
Displacement is s, according to displacement formula:
Control is since the moment 0, every the speed v of the time interval record Mobile base of Δ ti, i=1,2,3 ... m, when to moment t
M speed data is had recorded in total, then the formula can be separated into:
Wherein, velocity variations of the value of Δ t dependent on Mobile base described in actual mechanical process;It is obtained by image recognition algorithm
Distance d of two contact points to image left end on to any time phase interfaceAAnd dB, then the displacement x of any time phase interface are as follows:
The displacement x of opposite phase interface, the speed V of phase interface is the first derivative of displacement xTo displacement x with central difference schemes
Derivation is carried out to displacement data, wherein assuming that including m data in x, the footmark of i and x indicate the number of displacement data:
Thus the speed of phase interface is obtained.
2. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 1, which is characterized in that
The method for making phase interface be automatically maintained at the centre of the visual field width of the camera unit always is as follows:
Wherein, V is the phase boundary face velocity acquired in real time, and d is phase interface edge From Left in the visual field width of camera unit
Distance, v are the speed of Mobile base, τvFor time constant, physical significance is from the visual field that phase interface is deviateed camera unit
The distance d-W of centres/ 2 drop to 0 required for the time, WsFor the visual field width of camera unit.
3. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 1, which is characterized in that
The microfluidic chip is plate structure made of transparent material, on one side on be provided with the groove of indent, in the groove
On be stamped the cover board for being bonded the groove upper surface, the micron capillary tube passage is arranged in the groove and with array manner
It is provided with multiple, the both ends of each micron capillary tube passage are respectively arranged with feed liquor area and out liquid zone;The micron capillary
The width of tube passage is 10~100 μm, and the width of the feed liquor area and the liquid zone out is at least the micron capillary tube passage
15~20 times of width.
4. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 3, which is characterized in that
The feed liquor area and it is described go out liquid zone be that water-drop-shaped and the tip of water-drop-shaped are connected to the micron capillary tube passage, in institute
State feed liquor area and it is described go out liquid zone in be equably provided with the more vertical columns for preventing micron from collapsing respectively, the column with
The mode from coil to coil arrangement of annular, and the intermediate installation space for reserving the inlet opening and the fluid hole;In the feed liquor area
Centre is provided with the inlet opening of bottom opening, and the centre of the liquid zone out is provided with the fluid hole of bottom opening.
5. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 3, which is characterized in that
The upper surface installation of the Mobile base is there are two relative spacing and vertical support plate, in the opposite of two support plates
The fixed station of the fixed microfluidic chip is separately installed on face;Multiple mounting holes are provided on the Mobile base, it is described
Support plate is fixed using the mounting hole on the Mobile base with the Mobile base by L shape tabs, is arranged in the support plate
There is the sliding groove perpendicular to microfluidic chip described after placement, the fixed station is mounted on institute by the way that the sliding groove is adjustable
It states in support plate.
6. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 5, which is characterized in that
The fixed station is the support bar of strip, or to be provided with the clamping strip for the groove for clamping the microfluidic sides of chip,
The light source of the promising microfluidic chip illumination is installed between two support plates.
7. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 5, which is characterized in that
Be provided with the transparent connector of threeway by L shape tabs in the side of the Mobile base, two of them through-hole be it is horizontal and
What is be oppositely arranged is straight-through, another through-hole be perpendicular to the perpendicular logical of two straight-through middle parts, it is perpendicular it is logical it is upper be equipped with by screw thread and
The pressure sensor of the control system connection, leads directly at two and has been connected through a screw thread female Luer, and the syringe pump is logical
It crosses flexible hose to connect with the female Luer, another straight-through female Luer passes through the feed liquor of flexible hose and the feed liquor area
The fluid hole of hole connection, the liquid zone out is connect by flexible hose with water receiver.
8. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 1, which is characterized in that
It includes such as under type that the control system, which controls the syringe pump injection pressure:
If the pressure value of micron capillary pipeline entrance is Pd, the hope pressure value in micron capillary tube passage is Pt, the note of syringe pump
Amount of jet is Q, then:
One, manual control works as Pd<Pt, then increase Q, make PdRise to Pt;Work as Pd>Pt, then reduce Q, make PdIt is decreased to Pt;
Two, ratio controls, and control system given one has dimension Proportional coefficient KpIf system is linear response function, then:
Q=Kp(Pt-Pd);
Three, theoretical control, has according to Washburn formula:
V is phase boundary face velocity in formula, and x is the length for testing liquid in micron capillary tube passage, and θ is the contact angle of phase interface, μ
To test liquid viscosity, S is micron capillary column channel cross-section side length, and A is micron capillary hole path area of section, and R is micron hair
The equivalent redius of capillary passages, γ are interfacial tension;
Due to Q=AV, above formula be can be rewritten as:
According to wishing pressure value Pt, length x in micron capillary tube passage of contact angle measured value θ and test liquid directly calculates
Flow Q is preferably injected out, and control system then can be with the flow of real-time control syringe pump according to Q.
9. a kind of micron capillary column gas-liquid dynamic phase interface test macro according to claim 8, which is characterized in that
Proportional coefficient K in the ratio controlpEvaluation method it is as follows:
It is injected with test liquid in the micron capillary tube passage, in the syringe pump between the micron capillary tube passage
Pipeline in be injected with sealing liquid, and there are airspace between the sealing liquid and the test liquid, wherein air
Avoid the junction of pipeline in interval position;
If volume of air present in pipeline is Va, sealing liquid is Δ V, goal pressure Pt, for the reason of adiabatic compression process
Think that gas has:
(Pa+Pd)Va=(Pa+Pt)(V1-ΔV)
P in formulaaFor atmospheric pressure, the time for causing the above variation to need is τp, make pipeline pressure from PdChange to PtInjection flow Q
Then are as follows:
Above formula can be according to PtAnd PdThe flow Q needed is calculated, then syringe pump is controlled by control system, and then obtain proportionality coefficient
KpEstimated value:
V in formula1For the volume of air in pipeline, the total volume of inlet pipeline can be used;τpIt, can be according to experiment for time constant
It is required that specific adjustment;PaFor atmospheric pressure, PtFor goal pressure, the driving pressure P needed due to Micro-flowstIt can be much smaller than big
Air pressure can ignore Pt。
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