CN104511258B - Temperature bias field-applied AC electrothermal microfluidic mixer and AC electrothermal microfluidic mixing method - Google Patents
Temperature bias field-applied AC electrothermal microfluidic mixer and AC electrothermal microfluidic mixing method Download PDFInfo
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- CN104511258B CN104511258B CN201410801857.3A CN201410801857A CN104511258B CN 104511258 B CN104511258 B CN 104511258B CN 201410801857 A CN201410801857 A CN 201410801857A CN 104511258 B CN104511258 B CN 104511258B
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Abstract
The invention provides an AC electrothermal microfluidic mixing method. The AC electrothermal microfluidic mixing method comprises the following specific step of applying a temperature difference to the outer wall of an AC electrothermal microfluidic mixing chamber to generate a temperature gradient inside the AC electrothermal microfluidic mixing chamber so as to promote mixing of a solution in the mixing chamber. The invention further provides an AC electrothermal microfluidic mixer. The AC electrothermal microfluidic mixer comprises at least two liquid inlet microchannels, a liquid outlet microchannel and an electrode pair, wherein the liquid inlet microchannels and the liquid outlet microchannel converge at the same place to form the AC electrothermal microfluidic mixing chamber; the electrode pair is arranged inside the AC electrothermal microfluidic mixing chamber; two liquid channels or a heater is/are arranged on the outer wall of the AC electrothermal microfluidic mixing chamber. Through additional application of the external temperature difference, the temperature gradient is generated inside the AC electrothermal microfluidic mixing chamber so as to promote mixing of liquid in the mixing chamber, so that the effect of mixing the liquid to be mixed by an electrothermal flow is improved, and the requirements on the conductivity, the voltage and the frequency of the solution are lowered.
Description
Technical field
The present invention relates to micromixing technology field and in particular to a kind of by apply the inclined field of temperature improve mixed effect friendship
Stream electric heating micro-mixer and method.
Background technology
In biochip system, micro-mixer has become as one of important component part in micro-fluidic system chip.One
Require rapid-action biological solution process, as DNA hybridization, cell-stimulating, enzyme reaction, protein folding etc. inevitably
It is related to the mixing of reactant.
Electrocaloric effect phenomenon gradually develops into common active in micro fluidic device and biochip system and declines in recent years
Hybrid technology.Electrocaloric effect phenomenon can produce chaotic advection effect, thus increasing the contact surface of different liquids, effectively improves liquid
The mixing efficiency of body.Therefore AC Electric Heater micro-mixer has a good application prospect.
Electrocaloric effect phenomenon is mainly caused by temperature gradient, produces thermograde meeting longitudinally and radially in microchannel
Lead to the change of fluid properties, such as the dielectric constant of electrolyte and electrical conductivity etc..The change of these physical propertys can be led in turn
The interaction crossing them with electric field is thus affect the motion of fluid, and then produces electric heating flowing.Electrocaloric effect intensity and solution
Electrical conductivity, voltage and its liquid internal thermograde related.The micro-mixer of general AC Electric Heater phenomenon includes
Article one, for the passage mixing and the bottom-side electrodes being connected with the two poles of the earth of alternating current power supply for a pair it is characterised in that the structure of electrode can
To be designed to different shape.But the micro-mixer currently with AC Electric Heater phenomena principles, though all mixed effect can be produced,
Be the electrical conductivity to solution, voltage requirement more harsh.Too high voltage can make to produce bubble in microchannel or lead to
In passage, biofluid loses activity, and too low voltage mixed effect is unable to reach.Too high electrical conductivity can lead to microring array
In device, temperature drastically raises and leads to channel wall deformation or the activity reduction of biofluid, and electric heating during too low electrical conductivity
Micro-mixer mixed effect is not good.
Content of the invention
Disadvantages described above for prior art or Improvement requirement, the invention provides a kind of AC Electric Heater micro-mixer and side
Method, it is intended that making to produce the inclined field of temperature in electric heating stream blender microchannel by additional temperature difference, improves electric heating stream pair
The mixed effect of liquid to be mixed, thus relaxing the requirement to electrical conductivity of solution, voltage swing and frequency, solves relatively low
The not good technical problem of electric heating micro-mixer mixed effect under voltage.
The invention provides a kind of alternating current hot-fluid microring array method, the outer wall in alternating current hot-fluid microring array chamber applies warm
Degree difference is so that alternating current hot-fluid microring array intracavity produces thermograde, thus promoting to mix the solution mixing of intracavity.
The inventive method passes through the heater of the extra external temperature applying difference or setting so that alternating current hot-fluid
Microring array intracavity portion produces thermograde, promotes the liquid mixing of mixing intracavity, improves the mixing that electric heating stream treats mixing liquid
Effect, relaxes the requirement to electrical conductivity of solution, voltage swing and frequency.
In order to realize said method, the invention provides a kind of alternating current hot-fluid micro-mixer, including at least two liquid
Inlet microchannel, a liquid outlet microchannel and electrode pair, liquid inlet microchannel and liquid outlet microchannel converge at same
Form alternating current hot-fluid microring array chamber, electrode pair is arranged on alternating current hot-fluid microring array intracavity it is characterised in that also including at one
Article two, fluid passage, is symmetricly set on alternating current hot-fluid microring array cavity outer wall both sides, for be passed through the liquid with temperature difference with
Produce temperature difference in the both sides external of hybrid chamber, external temperature difference is ordered about alternating current hot-fluid microring array intracavity portion and produced temperature ladder
Degree, thus promote to mix the solution mixing of intracavity.
Described microchannel material adopts PDMS, PMMA, silicon or glass.Described conductive material is using metals such as gold, platinum and copper.
Described liquid adopts water, oil or organic solution.
The implementation of above-mentioned alternating current hot-fluid micro-mixer has that difficulty of processing is low, temperature control is simple and mixed effect is obvious
Advantageous Effects.
In order to realize said method, present invention also offers a kind of alternating current hot-fluid micro-mixer, including at least two liquid
Body inlet microchannel, a liquid outlet microchannel and electrode pair, liquid inlet microchannel and liquid outlet microchannel converge at
Same place forms alternating current hot-fluid microring array chamber, and electrode pair is arranged on alternating current hot-fluid microring array bottom of chamber portion it is characterised in that going back
Including heater, it is symmetricly set on alternating current hot-fluid microring array cavity outer wall, make alternating current hot-fluid micro- mixed by heater heat production
Close intracavity portion and produce non-uniform temperature field, thus promoting to mix the liquid mixing of intracavity.
The position of described heater is unrestricted, can be flow cavity bottom or the side of top or flow cavity
Wall.Described heater adopts the conductive oxide film such as tin indium oxide (ITO) or the larger conductive material of other resistance, outside two ends
Connect unidirectional current or alternating current power supply.
The implementation of above-mentioned alternating current hot-fluid micro-mixer has temperature control easily and and the significantly beneficial skill of mixed effect
Art effect.
Brief description
Fig. 1 is the top view of the electric heating stream micro-mixer of fluid passage relying on both sides to be each provided with different temperatures；
Fig. 2 is section A-A structural representation；
Fig. 3 is electrode shape schematic diagram；
Fig. 4 is provided with resistance heater to improve the top view of the alternating current hot-fluid micro-mixer of mixing efficiency；
Fig. 5 is section B-B structural representation；
Fig. 6 is section C-C structural representation；
Fig. 7 is the geometric model figure of emulation experiment；
Fig. 8 is concentration distribution result schematic diagram on each section of micro-mixer of emulation experiment, and Fig. 8 (a) is not apply temperature
The concentration schematic diagram of degree gradient, Fig. 8 (b) is the concentration schematic diagram applying thermograde.
Specific embodiment
In order that the objects, technical solutions and advantages of the present invention become more apparent, below in conjunction with drawings and Examples, right
The present invention is further elaborated.It should be appreciated that specific embodiment described herein is only in order to explain the present invention, and
It is not used in the restriction present invention.As long as additionally, involved technical characteristic in each embodiment of invention described below
The conflict of not constituting each other just can be mutually combined.
Embodiment one：Improve the AC Electric Heater micro-mixer of mixed effect by external temperature difference
As shown in Figure 1, both sides are each provided with the micro-mixer of isothermal liquid passage and include 1 Y type for mixed solution
Flow cavity and 2 U-shaped fluid passages being connected with constant temperature fluid, four walls of flow cavity adopt common microchannel material, material
Select unrestricted.Three microchannel connectivity parts of Y type flow cavity form alternating current hot-fluid microring array chamber, mixing chamber's basis rest
Have an electrode, electrode position be Fig. 1 shown in, positioned at two solution cross after after position, electrode material be conductive material, electrode
Shape unrestricted, be connected to the first alternating voltage between this two electrode.Y type flow cavity both sides are respectively provided with a generic continuous stream
The U-shaped passage A of dynamic isothermal liquid and passage B.
Solution A is passed through syringe pump and is entered passage 4 from entrance 1, and solution B enters flow cavity 5, flow cavity 4 and flowing from entrance 2
Chamber 5 crosses and is merged into flow cavity 6, and solution A and solution B are mixed and from outlet 3 outflow in flow cavity 6.Liquid C passes through compacted
Dynamic pump enters flow cavity 9 from entrance 7, and from outlet 8 outflow.Liquid D is passed through peristaltic pump and is entered flow cavity 12 from entrance 10, and from
Outlet 11 outflow.Liquid C and liquid D temperature differ.Electrode 13 and 14 provides the alternating voltage needed for electrocaloric effect.
Fig. 2 is the schematic diagram of A-A cross section in Fig. 1 of passage.The material of cover plate 15 is PDMS, and the material of substrate 16 is glass
Glass.Microchannel full of solution to be mixed in channel cross-section 6, constant temperature fluid A (20 of generic continuous flowing in 9 and 12 difference
DEG C) and constant temperature fluid B (30 DEG C), the temperature that both temperature can control respectively and both are interior is unequal.Fig. 3 is passage bottom
It is machined with microelectrode figure.
By changing the temperature difference between channel cross-section 9 and 12 so that producing degree of heating in width in cross section 6
Gradient, thus strengthening electric heating flowing, reaches the purpose strengthening solution mixed effect in microchannel.
Embodiment two：It is provided with resistance heater to improve the alternating current hot-fluid micro-mixer of mixing efficiency
As shown in figure 4, solution A passes through syringe pump enters passage 4 from entrance 1, solution B enters flow cavity 5, stream from entrance 2
Dynamic chamber 4 and flow cavity 5 cross and are merged into flow cavity 6, and solution A and solution B are mixed and from outlet 3 outflow in flow cavity 6.
Fig. 5 is B-B cross-sectional view in Fig. 4, and electrode 13 and 14 provides the alternating voltage needed for electrocaloric effect.Fig. 5 is that in Fig. 4, C-C is vertical to be cut
Face figure, resistance heater 17 provides extra thermograde, have between electrode 13 and electrode 14 and resistance heater 17 one layer 1 micro-
The thick silicon dioxide insulating layer of rice, as electric field isolation layer, prevents electric jamming electrode 13 and and the electrode of resistance heater generation
The electric field of 14 generations.Resistance heater 17 two ends are loaded with DC voltage, by controlling the voltage at resistance heater 17 two ends, make
Obtaining resistance heater to be generated heat so that producing extra thermograde in passage, to reach the purpose improving electrocaloric effect, carrying
High mixed effect.
Thermal source is not limited to aforesaid way, by applying various forms of thermals source outside hybrid chamber so as to mix intracavity
Portion produces non-uniform temperature gradiance and temperature field.
Example：
Micro- to the AC Electric Heater improving mixed effect by external temperature difference using COMSOL Multiphysics 4.3a
Blender carries out numerical simulation, and the governing equation of flow field, electric field and thermograde and its boundary condition are encoded in software
Row calculates, and sets up using the triangular unit discrete 3D model with Lagrangian Quadratic Function Optimization, the passage length 600 in computational fields
μm, high 50 μm, wide 100 μm, as shown in Figure 7.Fig. 4 is the design drawing of bottom surface ac electrode.As Fig. 5, altogether produce on 3D model
Give birth to 355460 tetrahedron unstrctured grid, coupled and numerical solution with Finite Element Method.Convergence analysis show this
When solution not with mesh refinement change.Using software Solving Algebraic Equation group and repeat iterative process until two continuous iteration steps
Till absolute tolerance between rapid is less than specified value (taking 0.001 in this emulation).It is 10 that alternating voltage adopts frequency7Hz,
Rms voltage is 7V, and electrical conductivity is the condition of 0.1S/m.The situation having the temperature difference on the internal channel width of microchannel is discussed,
Being respectively provided with fixed temperature on channel side wall is 293K and 303K.A small amount of joule can be produced due to after ac electrode energising itself
Heat is it is assumed that bottom ac electrode surface-boundary is fixed temperature 298K.In feeder connection, concentration boundary conditions, entrance boundary are set
Left-half local arranges concentration C1in=1, entrance boundary right half part local arranges concentration boundary conditions C2in=0.Passage enters
Mouth is velocity boundary conditions, and entrance velocity is 200 μm/s.
Fig. 8 is concentration distribution on each section of micro-mixer, and a is to consider electric heating effect, no external temperature gradient；B is to examine
Consider electrocaloric effect, have external temperature gradient.The distribution that be can be seen that concentration by concentration distribution result is tight with the form of corresponding streamline
Close correlation.After additional thermograde, the contact surface of two kinds of solution increases, and the effect of solution mixing improves.External temp gradient
Afterwards, two liquid on channel cross-section produce asymmetric mixing due to the unsymmetry of flowing, and contact area increases,
In figure mixes more abundant after can be seen that applying external temp gradient.
The computing formula of mixing efficiency on assessment channel exit section is：
Wherein C is the concentration distribution on outlet, C∞For concentration when being mixed thoroughly, value is 0.5, C0For not
The concentration values of mixing are 0.In the case of no additional thermograde, mixing efficiency is 61.0%, and there are additional temperature gradient conditions both sides
Lower mixing efficiency is 99.4%, and result shows to be conducive to the raising of mixing efficiency in temperature difference.
As it will be easily appreciated by one skilled in the art that the foregoing is only presently preferred embodiments of the present invention, not in order to
Limit the present invention, the Y type micro-mixer that for example present example is selected, be not limited to this, the mixing containing multiple access roades
Device is all suitable for the present invention.All any modification, equivalent and improvement made within the spirit and principles in the present invention etc., all should
It is included within protection scope of the present invention.
Claims (5)
1. a kind of alternating current hot-fluid microring array method is it is characterised in that the method is specially：
One two internal electrode of electrode is arranged in the flow path both sides in alternating current hot-fluid microring array intracavity portion, electrode carries
Solution to be mixed is made to produce electrocaloric effect for alternating voltage, so that solution to be mixed produces electric heating flowing；
Outer wall in alternating current hot-fluid microring array chamber applies temperature difference so that alternating current hot-fluid microring array intracavity produces temperature ladder
Degree, thus promote to mix the solution mixing to be mixed of intracavity.
2. a kind of alternating current hot-fluid micro-mixer, including at least two liquid inlet microchannels, a liquid outlet microchannel and
Electrode pair, liquid inlet microchannel and liquid outlet microchannel converge at same place and form alternating current hot-fluid microring array chamber, electrode
To the flow path both sides being arranged on alternating current hot-fluid microring array intracavity portion, for providing alternating voltage so that solution to be mixed is produced
Electrocaloric effect, so that solution to be mixed produces electric heating and flows it is characterised in that also including two fluid passages, is symmetrical arranged
In alternating current hot-fluid microring array cavity outer wall both sides, for being passed through the liquid with temperature difference to produce in the outer wall both sides of hybrid chamber
Temperature difference, outside wall temperature difference is ordered about alternating current hot-fluid microring array intracavity portion and is produced the inclined field of temperature, thus promoting to mix treating of intracavity
Mixed solution mixes.
3. a kind of alternating current hot-fluid micro-mixer, including at least two liquid inlet microchannels, a liquid outlet microchannel and
Electrode pair, liquid inlet microchannel and liquid outlet microchannel converge at same place and form alternating current hot-fluid microring array chamber, electrode
To the flow path both sides being arranged on alternating current hot-fluid microring array bottom of chamber portion, for providing alternating voltage so that solution to be mixed is produced
Electrocaloric effect, so that solution to be mixed produces electric heating and flows it is characterised in that also including heater, is arranged on AC Electric Heater
The bottom of stream microring array cavity outer wall or side, make alternating current hot-fluid microring array intracavity portion produce temperature by heater heat production
Field partially, thus promote to mix the liquid mixing to be mixed of intracavity.
4. alternating current hot-fluid micro-mixer according to claim 3 is it is characterised in that also include being arranged on described electrode pair
Electric field isolation layer and heater between, the electric field that the electric jamming electrode pair for preventing heater from producing produces.
5. the alternating current hot-fluid micro-mixer according to claim 3 or 4 is it is characterised in that described heater is conductor
Part.
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| CN110716046B (en) * | 2018-07-11 | 2023-03-28 | 中国人民解放军军事科学院军事医学研究院 | Solid phase immune reaction accelerating technology based on temperature difference |
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| CN101059526B (en) * | 2007-05-24 | 2011-04-20 | 上海交通大学 | Method for driving fluid movement in micropassage using electric heat flow |
| US8206025B2 (en) * | 2007-08-07 | 2012-06-26 | International Business Machines Corporation | Microfluid mixer, methods of use and methods of manufacture thereof |
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