CN102961966A - Method for specific continuous separation of micro-scale particles - Google Patents
Method for specific continuous separation of micro-scale particles Download PDFInfo
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Abstract
The invention discloses a method for specific continuous separation of micro-scale particles. The method can be used for realizing continuous adjustable multi-path separation of three types of different-size polystyrene microsphere mixtures by using a dielectrophoresis (DEP) microfluidic chip for specific continuous separation of micro-scale particles, and by regulating the flow rate of a fluid, the electric field intensity and the pulse frequency under the condition of continuous sampling. The three types of particles can move to the different spanwise positions of a channel since the three types of particles bear different intensities of DEP force and Stokes force; and the type of the extracted particle can be controlled at will by regulating control parameters. When an electric field parameter and a flow field parameter are matched, the medium-size 5mum particles can move on a flow channel always in an electrode tilting direction; the 3mum particles can move forwards substantially along the main flow direction; and the 10mum particles are influenced remarkably by the electric field and the flow field, and can move to the other side of the channel, so that the three types of particles are discharged from different outlets to obtain the 3mum, 5mum, and 10mum polystyrene particles, respectively.
Description
Technical field
The invention belongs to enrichment and separation method and device in the chemical field, particularly a kind of minute yardstick particle specificity continuous separation method is specially adapted to the not specific isolation of charged neutrophil granule.
Background technology
In the overwhelming majority was used at present, employed dielectrophoresis (Dielectrophoresis, DEP) power only spatially changed, and does not change over time, is that a kind of field of force continuous in time is continuous type DEP.Utilize this technology to realize multiple particle being separated and individual particle/micro element that cell catches.The below will at first briefly introduce the research in this DEP field of force continuous in time, set forth subsequently another time upper discontinuous DEP field of force form, the present Research of impulse type DEP.Under the minute yardstick, similar with other separation means, usually can be divided into following two classes based on the particle separation in the continuous type DEP field of force: separating on the separation on the time domain and the space.
1) continuous type dielectrophoresis particle separation present situation
● the separation on the time domain
In this clastotype, sample generally is introduced into by buffer solution, and the particle in the sample is because the difference on the locomitivity is separated gradually at flow direction, and the detector of placing by the downstream successively flows out from outlet at last.For example, at DEP-FFF(Field-Flow Fractionation) method
[1,2]In, because variable grain bears different DEP power and gravity in vertical direction, cause the separately difference of equilbrium position, they will be in respectively the different layers of parabolic velocity throwing face, thus, particle has had different translational speeds and final formation separates, such as Fig. 1.
Fig. 1 is known a kind of moving separation method of DEP field flow that separates multiple granulate mixture, at F
DEPzInteract down with particle gravity and buoyancy, different particles will be in respectively the different layers of parabolic velocity profile, thereby forms different translational speeds, flows through to produce behind the segment distance to separate
[3]
● the separation on the space
In this clastotype, sample is introduced into from import in the situation of continuous sample introduction, and different particles presents the exhibition vertical with main flow to locational distribution after separation, can be collected by setting in advance different outlets.For example, by laying electrode on the microchannel sidewall, introduce in the horizontal direction the power vertical with main flow, just can utilize the difference of variable grain on the transverse movement ability to separate, these class methods are referred to as horizontal DEP and separate (Lateral Dielectrophoresis Separation)
[4-6], as shown in Figure 2.
Fig. 2 is a kind of horizontal DEP method of separating multiple granulate mixture, and particle has different positions under the effect of horizontal DEP power, is collected in different exits, and U is voltage, and f is frequency
[6]
In addition, by distributing in the inner gradient that produces electrical conductivity of solution of microchannel, the particle of different surfaces characteristic can obtain at the diverse location place zero DEP power, and the separation of carrying out on this basis such as is called at the dielectric separation (Iso-dielectric Separation)
[7], as shown in Figure 3.
Fig. 3 be separate multiple granulate mixture etc. the dielectric separation method
[7]Among the figure, (a) figure is experimental layout: set up electrode and two outlets that diffusion mixer, split tunnel, the one-tenth diagonal of electrical conductivity gradient arrange by two imports, one and form.(b) figure is experimentation: the cell of different electrical conductivity enters the microchannel of inclined electrode with fluid, DEP power interacts with fluid force and makes cell movement arrive different exhibitions to the position, with the dielectric points such as the direction arrival of successively decreasing of electrical conductivity, right figure is that the fluorescence granules of polystyrene is offset the dielectric points such as arrival under electrode.
● domestic research at present
For the research based on the micro-fluidic chip of DEP, domesticly also carried out a large amount of research work.In recent years, along with country to the input of association area and the improvement of hardware condition, a collection of good achievement in research of appearance.Domestic research institution mainly comprises Tsing-Hua University, Southeast China University, Chinese Academy of Sciences electron institute, Zhejiang University, University Of Chongqing and HUST etc.Related main research mainly comprises the DEP control method of Development of Novel
[8], the design novel DEP electrode
[9], the basic theories that relates in using of research DEP
[10-12]And seek concrete application
[13,14]Deng.
● the problem of existence
Based on the particle separation of continuous type DEP technology and the research accumulation of existing long duration of seizure research, accumulated abundant achievement in research, but also had certain problem; The effect that existing method generally can generation be sequentially separated, the stalling characteristic that namely relies on is monotone increasing or minimizing after separation, perhaps produces the effect that binary is separated (Fig. 4), and namely sample is divided into two according to the critical value of the stalling characteristic that relies on
[15]Finish if utilize continuous type DEP technology to realize that extraction to the specific objective particle, whole process need to leave away through twice minute at least, still lack ability and means that required target particles thing is extracted under continuous sample introduction condition single step.
Among Fig. 4, binary is separated
[15], the black and white ball represents two types particle; When electric field is opened black particle under positive dielectrophoresis force, be attracted to electrode edge and white particle with flow publish picture (A); When white particle flows out fully, turn off electric field, this moment, black particle was also with flow publish picture (B).
Secondly, ignored intergranular interaction and caused separating effect relatively poor.When the above particle of two classes appears in separated region simultaneously, the way of relative intensity between fluid viscous force and the DEP power is regulated in existing employing, mostly ignored the particle Interaction Force, these interaction forces are followed the existence in electric field and flow field and existed, and are inevitable.The particle that is flushed away will exert an influence to another kind of particle by this interaction force, cause particle adhesion, the purity that final impact separates.
2) based on the particle separation present Research of impulse type DEP
Except the continuous field of force, the time-varying force field also can be controlled particle.For example, in heat/Brownian movement ratchet (Thermal/Brownian Ratchet)
[16,17], by the attraction of repeatedly " opening ", " pass " one group of asymmetric electrode can produce interruption, just can realize movement to nano particle by the combination with warm-up movement.Yet for micron or slightly large particle, because molecular thermalmotion is not very remarkable, heat/Brownian movement ratchet method will be no longer applicable.In macrosystem, Brazil nut effect (Brazil Nut Effect, BNE) or vibrated fluidized bed are to use the typical method that particle separation and enrichment are carried out in the time-varying force field, are one of study hotspots of soft material and engineering field
[18-20]By regulating relative intensity and the frequency of vibration external force; the layering enrichment of different size granulate mixture in container be can realize, common BNE effect (macroparticle occupy the superiors), Reversed BNE effect (macroparticle occupy orlop) and marginal Sandwich structure (macroparticle occupy the centre position) formed.Passable from above-mentioned two examples, the application of time-varying force field can bring beyond thought effect, and it is introduced in the control of minute yardstick particle, can help more flexibly control mode of development.Therefore, using for reference the thought of above-mentioned time-varying force field, is that impulse type DEP is applied in the separation of micron particles with switch DEP method
[21]
● based on the particle separation present Research of impulse type DEP
By the microchannel be positioned at the runner bottom vertical on the micro-fluidic chip that the strip-type electrode of main flow consists of, utilize the runner top to be the nDEP field of force and the parabolical fluid velocity profile of periodic distribution, and with lower frequency (＜10Hz) " open ", " pass " DEP field of force realized specific particle separation i.e. impulse type dielectrophoresis particle separation technology.At present, realized in single step any one extracts in 3 μ m, 5 μ m and the 10 μ m polystyrene microspheres
[21]Can find out that by the simplified model of having set up the method is by based on the clastotype of intensity with based on the coefficient result of speed clastotype, can control neatly fluid and intergranular interaction by this extra parameter of frequency, the end-state of particle then depends on the degree of " receipts " and " putting ".
● the problem of existence
Can find out, impulse type DEP technology has embodied the Some features that is different from or is better than continuous type DEP, but the research to it also rests on initial stage, still there are some problem demanding prompt solutions, such as, only carried out for polystyrene microsphere or saccharomycetic research work, need to test to the reliability of the method by more grain type; Not yet be implemented in the space multi-way separation problem of particle under the continuous sample introduction condition; In ongoing experiment of extracting for the target particles thing, employed strip-type electrode is vertical with main flow direction, the particle that extracts rests on the upstream of electrode, unwanted particle is then rushed to the downstream, be subject to the width of electrode, if in a single day the particle that extracts has taken whole electrode or assembled agglomerating
[22], the method will lose efficacy, such as Fig. 5.This only can carry out to very micro-sample the extraction of required particle with regard to meaning the method, and the approach that addresses this problem is exactly to set up a kind of method of extracting for the arbitrary target particle under the continuous sample introduction condition, and the method that satisfies this condition must be a kind of adjustable multi-channel separation method simultaneously.
Fig. 5 is the particle aggregation under electric field and the flow field effect
[22]Wherein figure (a) is microchannel and interdigitation electrode experimental provision.The left figure of figure (b) is illustrated in that particle is in the experimentation " Y ", and font is assembled, and the right figure of figure (b) is that numerical simulation discloses the gathering of particle under electrostatic field and fluid effect.
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[8] Ni Zhonghua, Yi Hong, Zhu Shucun, Song Chunfeng; Micro-nano biomone manoeuvring platform key technology [J] based on light-induction dielectrophoresis. Chinese science: E collects .2009. (010): 1635-1642.
[9] Liu Yonghong, Zhao Zhan; Based on the dielectrophoresis chip of NEMS technology and the research [J] of critical process problem thereof. sensing technology journal, 2006.19 (05B): 1978-1982.
[10] Shen Xiaozhong, Chen Zhenqian, Shi Mingheng, the Joule heat analysis [J] in the dielectrophoresis particle flow of microchannel; The Engineering Thermophysics journal, 2008.29 (003): 476-478.
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[14] Xu Yi, Cao Qiang once avenged Wu Yongjie, Zhang Wenpin; Array is to electrode dielectrophoresis chip and be used for cell separation and enrichment research [J]. SCI, 2009. (005): 876-881.
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【16】Ajdari?A，Prost?J.Drift?induced?by?a?spatially?periodic?potential?oflow?symmetry:pulsed?dielectrophoresis【J】.CR?Acad.Sci.II(Paris).1992.315:1635。
【17】Gorre-Talini?L，Jeanjean?S，Silberzan?P.Sorting?of?Brownianparticles?by?the?pulsed?application?of?an?asymmetric?potential【J】.PhysicalReview?E.1997.56(2):2025。
【18】Ciamarra?MP，Vizia?M，Fierro?A，Tarzia?M，Coniglio?A，NicodemiM.Granular?species?segregation?under?vertical?tapping:Effects?of?size,density,friction,and?shaking?amplitude【J】.Phys?Rev?Lett.2006.96(5):58001。
【19】Rosato?A，Strandburg?KJ，Prinz?F，Swendsen?RH.Why?the?Brazilnuts?are?on?top:Size?segregation?of?particulate?matter?by?shaking【J】.PhysicalReview?Letters.1987.58(10):1038-1040。
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Summary of the invention
The object of the invention is to, a kind of minute yardstick particle specific isolation method is provided, to solve the agglomerate problem of particle, realize that the continuous adjustable multi-channel of particle separates.
In order to realize above-mentioned task, the present invention takes following technical solution:
A kind of minute yardstick particle specific isolation method, it is characterized in that, the method adopt minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip, under the continuous sample introduction condition, by commutating speed and pulse frequency, take the mixture of three kinds of different size polystyrene microspheres as example, can realize that continuously adjustable multichannel separates.The DEP power that is subject to owing to three kinds of particles is different with Stokes power, can move to the difference exhibition of passage to the position.Directly extracting the median size particle is the typical case of this method, at this moment, 5 μ m can move along the electrode incline direction all the time in the runner upstream, 3 μ m particles are because particle diameter is less substantially along with main flow travels forward, and 10 μ m particles are subject to electric field and the flow field disturbance is larger, the opposite side of pipeline be can move to, thereby so that three kinds of particles flow out from different outlets, 3 μ m, 5 μ m and 10 μ m granules of polystyrene obtained respectively.By regulating parameter, can obtain the extraction to other particles.Thereby avoid the traditional method for extracting medium grain to need at least the process of twice separation.
Described minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip comprise: buffer solution import and particle import, the electrode of angle of inclination between 45 degree are spent to 60,3 μ m particle outlets, 10 μ m particle outlets, 5 μ m particle outlet and microchannels, wherein, the microchannel upper surface has PDMS, and electrode is connected with the alternating signal that adds.
The minute yardstick particle specificity continuous separate that the present invention adopts from the dielectrophoresis micro-fluidic chip, inclined electrode can overcome the line clogging problem that vertical electrode produces effectively, can realize the continuous adjustable multi-channel particle separation of high flux, and the angle of inclination is best to separating effect between 60 degree between 45 degree.
Description of drawings
Fig. 1 is known a kind of moving separation method schematic diagram of DEP field flow that separates multiple granulate mixture.
Fig. 2 is known a kind of horizontal DEP method schematic diagram that separates multiple granulate mixture.
Fig. 3 be the known multiple granulate mixture of separation etc. dielectric separation method schematic diagram, among the figure, (a) figure is experimental layout.(b) figure is experimentation.
Fig. 4 is that binary is separated schematic diagram.Wherein figure (A) is that black particle is attracted to electrode edge and white particle flows out with fluid under positive dielectrophoresis force when electric field is opened, and figure (B) is when white particle flows out fully when, turns off electric field, and black particle also flows out with fluid at this moment.
Fig. 5 is the particle aggregation under electric field and the flow field effect
[22]Wherein figure (a) is microchannel and interdigitation electrode experimental provision.The left figure of figure (b) is illustrated in that particle is in the experimentation " Y ", and font is assembled, and the right figure of figure (b) is that numerical simulation discloses the gathering of particle under electrostatic field and fluid effect.
Fig. 6 is the velocity component at flow direction that the particle of diameter 5 μ m produces under electric field and flow field acting in conjunction.
Fig. 7 is when electrode incline 60 is spent, and the as a result picture of the particle separation that obtains wherein, is followed successively by (a) picture, t=5s from left to right; (b) picture, t=14s; (c) picture, t=24s.
Fig. 8 is that the electrode incline angle is for the impact of separating resulting.Wherein (a) figure is that exhibition is to spacing (top view) after the particle separation, and (b) figure opens up to spacing after 3 μ m and 10 μ m particle separation finish under the different angles.
Fig. 9 be minute yardstick particle specificity continuous separate from the model schematic diagram of dielectrophoresis micro-fluidic chip.
Figure 10 be minute yardstick particle specificity continuous separate from dielectrophoresis micro-fluidic chip preparation technology flow chart.
Figure 11 be the later minute yardstick particle specificity continuous separate of electrode and passage bonding from the picture of dielectrophoresis micro-fluidic chip.
Figure 12 is 5 μ m particles and the motion picture of 3 μ m particles under inclined electrode, wherein, is followed successively by from left to right t=0s; T=8s; T=23s.
Figure 13 be minute yardstick particle specificity continuous separate from the concrete structure figure of dielectrophoresis micro-fluidic chip, wherein, figure A is top view, figure B is side view.
The present invention is described in further detail below in conjunction with drawings and Examples.
The specific embodiment
According to technical scheme of the present invention; minute yardstick particle specific isolation method of the present invention; adopt a kind of minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip; under the continuous sample introduction condition; by commutating speed and pulse frequency; three kinds of different size polystyrene microsphere mixtures are carried out continuous adjustable multi-channel to be separated; the DEP power that is subject to owing to three kinds of particles is different with Stokes power; can move to the difference exhibition of passage to the position; 5 μ m particles can move along the electrode incline direction all the time in the runner upstream; 3 μ m particles are because particle diameter is less substantially along with main flow travels forward; and 10 μ m particles are subject to electric field and the flow field disturbance is larger; can move to the opposite side of pipeline, thereby so that three kinds of particles flow out from different outlets, obtain respectively 3 μ m; 5 μ m and 10 μ m granules of polystyrene.
Minute yardstick particle specificity continuous separate from the structure of dielectrophoresis micro-fluidic chip referring to Figure 13, comprise: buffer solution import 1 and particle import 2, the electrode 5 of angle of inclination between 45 degree are spent to 60,3 μ m particle outlets, 3,10 μ m particle outlets, 4,5 μ m particle outlet 6 and microchannels 7, wherein, microchannel 7 upper surfaces have PDMS(8), electrode 5 is connected with the alternating signal that adds.
1) separation principle
Fig. 6 has provided the velocity component at flow direction that the particle of diameter 5 μ m produces under electric field and flow field acting in conjunction.Wherein, the part of flow field contribution is U in the particle speed
f, remaining unchanged, the speed that particle speed dielectric electrophoretic force is induced is U
DEP, streamwise is periodic distribution, and the final speed of particle is two parts sum, have periodically and to upper offset U
fIf U
DEPPeak value greater than U
f, will occur particle speed among Fig. 6 is zero point, means that this moment, DEP was enough to overcome Stokes power, keeps this particle, this is the situation that the application studies, if U
DEPPeak value less than U
f, this moment, particle speed all greater than zero, did not have intersection point, meaned that the flow field is leading, and particle will be by punching to the downstream.
In Fig. 6, U
DEP+ U
fWith speed be that zero line has two intersection points, be called point of safes and burble point according to the difference of direction.At point of safes, the speed of particle upstream and downstream is all pointed to this point, even exist in the situation of disturbance, particle is stable this position that is in still; At burble point, although this spot speed is zero, upstream and downstream speed is pointed to opposite, in the situation that has disturbance to exist, and particle meeting unstability, the upwards point of safes in downstream motion.
In the Dynamic Separation process, burble point has important effect.Consider that initial electric field is "On" state and DEP power when enough large, particle will rest on point of safes at this moment, study subsequently the motion of particle in the process of the switch DEP field of force.After the DEP field of force was closed, particle only was subject to the Stokes power effect in flow field, and beginning is motion downstream, opens the DEP field of force after a period of time again.Move at this moment the burble point upstream side such as fruit granule, it will be pushed back initial position under the effect of the DEP power of pointing to the left side so; If movement of particles is to the burble point downstream, when DEP opened so, particle was tried hard to recommend another point of safes to the downstream with the DEP on directed right side.Therefore, by adjusting the cycle of DEP switch, particle just might experience near vibration or the generation clean motion downstream point of safes.
It may be noted that in traditional continuous type DEP the particle that is retained is in point of safes all the time, DEP power continuous action is on target particles, and particle has no chance to move to burble point, therefore the research of this position is not related to usually.
Among Fig. 6, the pass between each speed is: U
DEPBe the simple speed of electric field action on particle; U
fSpeed for simple fluid; U
DEP+ U
fFor electric field and flow field act on the speed that particle obtains simultaneously.
2) obtained the particle separation result of continuous adjustable multi-channel by numerical simulation
When electrode incline 60 is spent, obtained the result (such as Fig. 7) of particle separation, exhibition after separating by definitions particles is to separation delta d, and weighs purity after particle separation with this parameter, proved electrode incline angle separation effect more satisfactory (such as Fig. 8) when 45 degree are spent to 60.
Among Fig. 7, particle is in the difference moment residing position (top view) under continuous sample introduction, the inclined electrode; Black stripe is electrode, and white is the insulated part between two electrodes, and three kinds of balls are respectively the granules of polystyrene that diameter is 3 μ m, 5 μ m and 10 μ m, mean flow rate 30 μ m/s, voltage 8V, cycle 2.4s.
Fig. 8 is that the electrode incline angle is for the impact of separating resulting.(a) scheme: open up to spacing (top view) after the particle separation, the grey strip is the electrode of the runner interdigital distribution in bottom, and β is the electrode incline angle, and Δ d is opening up to locational center distance for separating rear 3 μ m particles and 10 μ m particles; (b) figure: exhibition was to spacing after 3 μ m and 10 μ m particle separation finished under the different angles; Curve is got by a plurality of data point matches among the figure, and calculating parameter is: mean flow rate 30 μ m/s, width of flow path 100 μ m.
3) on the basis of numerical simulation, verified by experiment the feasibility of the method.
A. experimental provision schematic diagram:
Fig. 9 be minute yardstick particle specificity continuous separate from the model schematic diagram (top view) of dielectrophoresis micro-fluidic chip, mainly formed by buffer solution import, outlet, particle suspension liquid import (microchannel) and electrode, grey strip among the figure represents electrode, three kinds of beads represent the granules of polystyrene of 3 μ m, 5 μ m and 10 μ m, electrode incline 60 degree.In import department, because the buffer solution inlet velocity is greater than the particle suspension liquid inlet velocity, cause particle to be directed to passage one side, under the effect of nDEP power, because the difference of locomitivity and suffered nDEP power separately, 5 μ m particles are retained in the runner upstream, and 3 μ m enter different channel outlet with 10 μ m particles;
B. according to above minute yardstick particle specificity continuous separate from the structural representation of dielectrophoresis micro-fluidic chip, utilize technological process shown in Figure 10 to be prepared, mainly comprise two parts of preparation of electrode and runner, wherein:
The step that the electrode preparation comprises has: with traditional method ito glass is cleaned (deionized water, acetone), N
2Or compressed air dries up, gluing (NR9-1000p), all (800r/min accelerates 5s to glue, rotation 10s), 150 ℃ of front baking 6min, the exposure 40s(different light intensity time for exposure is different), dry by the fire 6min after 100 ℃, RD6 development 20s, etching 6-8min is with the RR41 liquid 1-2min that removes photoresist that removes photoresist, flushing (deionized water) N
2Or compressed air dries up, and obtains the ITO electrode.
The step that the runner preparation comprises has: silicon chip gluing (SU-8T2025) is glue all: the first order (800r/min accelerates 5s, rotation 10s); The second level (3000r/min accelerates 10s, rotation 30s); 65 ℃ of oven dry 1min are dried 6min for 95 ℃ more first; The exposure 80s(different light intensity time for exposure is different), SU-8 developer solution 4-5min, isopropyl alcohol, deionized water rinsing/N
2Or compressed air dries up; 65 ℃ of baking 30min-60min;
PDMS is mixed by 10:1 with curing agent, vacuumize 30min after the mixing, PDMS is poured on the silicon chip after the baking, place 24h or baking 1-2h.
Preparation technology according to Figure 10, at last with ITO electrode and silicon chip (passage) bonding, processing obtained minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip structure as shown in figure 11, in Figure 11, lead-in wire links together by conductive tape and ITO electrode.
By adjust minute yardstick particle specificity continuous separate from flow velocity and the pulse frequency of dielectrophoresis micro-fluidic chip, 5 μ m particles and 3 motions of μ m particle under inclined electrode have been obtained, as as can be seen from Figure 12, the particle of 5 μ m moves along the electrode incline direction all the time, as shown in Figure 12, component and DEP power perpendicular to electrode direction in two components of Stokes power are cancelled out each other, and another component impels the particle of 5 μ m to move along inclined electrode.Under same voltage and flow velocity, 3 μ m particles are because particle diameter is less, and DEP power is very little than Stokes power, and electric field is fainter for the motion effects of 3 μ m particles, and it is to move along with the motion of main flow substantially.The result that this and numerical simulation obtain is basically identical.
Among Figure 12,5 μ m particles are retained, and 3 μ m particles are released (top view).Being 5 μ m granules of polystyrene in the white circle among the figure, is 3 μ m granules of polystyrene in the black circles, and the dash area of grey bar banding pattern namely is positioned at the runner bottom and is the electrode that interdigitation distributes, electrode incline 60 degree, the flow direction of main flow as shown in the figure, f=1.5Hz, V=17Vpp, V
Flow=20 μ L/h.
It below is the specific embodiment that the inventor provides.
By numerical simulation and experimental result, design and processed minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip, concrete structure is made (as shown in figure 13) according to the preparation technology of Figure 10, mainly comprises buffer solution import 1, particle import 2,3 μ m particle outlets, 3,10 μ m particle outlets 4, electrode 5,5 μ m particle outlets 6, microchannel 7, PDMS(8).During use; electrode 5 is connected with the alternating signal that adds; by buffer solution import 1 particle is directed at passage one side; under the acting in conjunction in impulse electric field and flow field; the DEP power that is subject to owing to three kinds of particles is different with Stokes power; can move to the difference exhibition of passage to the position; 5 μ m particles can move along electrode 5 incline directions all the time in the runner upstream; 3 μ m particles are because particle diameter is less substantially along with main flow travels forward; and 10 μ m particles are subject to electric field and the flow field disturbance is larger; can move to the opposite side of pipeline, thereby so that three kinds of particles flow out from different outlets.Wherein, electrode 5 angles of inclination are 60 degree, and microchannel 7 highly is 30 μ m.Microchannel 7 upper surfaces are PDMS(8) can affect Electric Field Distribution in the microchannel and the introducing of particle because the thickness of PDMS is too thin, obtaining its minimum thickness by numerical computations must be greater than 20 μ m.
Claims (2)
1. minute yardstick particle specific isolation method, it is characterized in that, the method adopt minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip, under the continuous sample introduction condition, by rectification body flow velocity, electric-field intensity and pulse frequency, three kinds of different size polystyrene microsphere mixtures are carried out continuous adjustable multi-channel separate, the DEP power that is subject to owing to three kinds of particles is different with Stokes power, can move to the difference exhibition of passage to the position; The grain type that extracts can change arbitrarily by the adjustment of control parameter; when electric field, flow field parameter coupling; 5 medium μ m particles can move along the electrode incline direction all the time in the runner upstream; 3 μ m particles are because particle diameter is less substantially along with main flow travels forward; and 10 μ m particles are subject to electric field and the flow field disturbance is larger; the opposite side of pipeline be can move to, thereby so that three kinds of particles flow out from different outlets, 3 μ m, 5 μ m and 10 μ m granules of polystyrene obtained respectively.
2. the method for claim 1, it is characterized in that, described minute yardstick particle specificity continuous separate from the dielectrophoresis micro-fluidic chip comprise: buffer solution import (1) and particle import (2), the electrode (5) of angle of inclination between 45 degree are spent to 60,3 μ m particle outlets (3), 10 μ m particle outlets (4), 5 μ m particle outlets (6) and microchannel (7), wherein, microchannel (7) upper surface has PDMS(8), electrode (5) is connected with the alternating signal that adds.
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