CN102678526A - Travelling-wave valveless piezoelectric micropump of multistage diffusion micro-flow pipeline - Google Patents

Abstract

The invention provides a structure and a forming method of a travelling-wave valveless piezoelectric micropump of a multistage diffusion micro-flow pipeline. The structure of the travelling-wave valveless piezoelectric micropump comprises a micropump base, a micro-flow pipeline and a travelling-wave driving array, wherein the micropump base mainly comprises a driving array clamping groove, a micro-flow pipeline bonding area, a sample inlet and a sample outlet; the multistage diffusion micro-flow pipeline is made of a PDMS (Polydimethylsiloxane) material; a corresponding trapezoidal protrusion corresponding to each stage of diffusion structure is formed on the upper surface of the pipeline; the overall dimension of each corresponding trapezoidal protrusion is matched with the inside diameter of a diffusion pipe; the micro-flow pipeline and the micropump base are bonded together to form an integral pump body; the travelling-wave driving array is arranged in parallel by adopting dual piezoelectric bimorphs; one end of each piezoelectric bimorph is arranged on the corresponding trapezoidal protrusion on the surface of the micro-flow pipeline and is tightly contacted with the corresponding trapezoidal protrusion; and the other end of each piezoelectric bimorph is fixedly arranged on the micropump base. According to the travelling-wave valveless piezoelectric micropump disclosed by the invention, the multistage diffusion micro-flow pipeline is combined with the travelling-wave valveless piezoelectric micropump, so that the reverse reflow of the micro-flow pipeline is reduced and the output flow speed of the micropump is increased; and the travelling-wave valveless piezoelectric micropump has the characteristics of simple manufacturing process, small size, convenience and accuracy in flow control and the like and is suitable for manufacturing integrated micro-fluid chips.

Description

The travelling-wave-type Valveless piezoelectric Micropump of multistage diffusion miniflow pipeline

Technical field

The present invention relates to a kind of Valveless piezoelectric Micropump of multistage diffusion miniflow pipeline, its driving mode drives for the row ripple.

Background technique

Microfluid (chip lab) technology is one of the new and high technology that develops rapidly at present and field, multidisciplinary intersection science and technology forward position, is the important technological platform of life science, chemical science and information science input and Study on processing method.It can make biological sample and reagent consumption in the biomedical sector reduce greatly, and analysis speed significantly improves, and cost descends at double; At chemical field, it can use small amount of sample and reagent to accomplish a large amount of experiments simultaneously with the very short time on chip piece; In the analytical chemistry field, it makes big analytical instrument become square centimeter ANALYZER of size scale.The involved parts of micro-fluid chip comprise: dialysis, film, SPE, the purification relevant with sample introduction and Sample handling; The little valve (comprising aggressive valve and passive valve) that is used for fluid control, Micropump (comprising mechanical pump and on-mechanical pump); Micromixer, microreactor also has micro passage and little detector etc. certainly.

Micropump is the important symbol of its development level as the important power unit of micro-fluid chip fluid drives part.Micropump mainly is used to provide fluid drives power in whole system, be responsible for control pump feeding sample, control flow rate and flow velocity.The mode classification of Micropump has a variety of: according to having or not movable valve block, can being divided into valve Micropump and valve free pump are arranged; Different according to driving mode, can be divided into piezoelectricity type, electrostatic, pneumatic type, hot drive-type etc.

It generally is to utilize cycle of cavity volume to change with one-way cock work that the valve Micropump is arranged, and has the principle of valve Micropump simple, and preparation process is comparatively ripe and be easy to control, is the main flow of application at present.But owing to there is mechanical part such as valve block in the pump housing, the fatigue of valve block and life problems are puzzlement researcher's difficult problems always, greatly limitations its application area; And the processing technology of these mechanical movable members and machining precision have limited the further miniaturization that the valve Micropump is arranged, the technical need of the incompatible micro-fluid chip that develops rapidly in recent years.Compared the valve Micropump, valve free pump is because its principle is novel, structure is simple relatively, manufacture process requirement is not high, be suitable for microminiaturization, thereby has unique advantages for development and wide application prospect.

Be used in the capable ripple Driving technique in the valve free pump, be to use the piezo actuator array on elasticity miniflow pipeline, to evoke a row row ripple, drive the pump liquid mode of liquid directional flow.This Micropump comes controlling liquid to flow with the voltage signal that is added on the piezo actuator, realizes the liquid bidirectional conveying to change voltage-phase.Under this capable ripple driving mode, the movement locus of liquid particle is approximately elliptic motion in the miniflow pipeline, and after a capable period of wave, the liquid particle is compared the generation minute movement with initial position, this directed flow of fluid that moves final formation certain flow rate.

People such as Estemme had developed a kind of novel contraction/distension type valve free pump in 1993; Be to replace movable valve block with the difformity miniflow pipeline that shrinks and expand; Utilize the asymmetric pumping that realizes liquid of the asymmetric pressure loss that causes of miniflow pipeline configuration, but the reverse fluid stopping poor-performing of this type pump, liquid is from shrinking and the expansion pipeline flows into simultaneously and flows out pump chamber; Cause flow loss bigger, efficient is lower.The valve free pump of this contraction/distension type is simple in structure, and novelty is suitable for the Micropump of this structure is integrated in the micro-fluidic chip.

For the miniflow pipe resistance and raising Micropump output flow velocity that reduce row ripple Micropump, the present invention proposes a kind of multistage diffusion miniflow pipeline travelling-wave-type Valveless piezoelectric Micropump.Multistage diffusion miniflow pipeline is that a plurality of diffusing tube structures are laterally superposeed, and places the pump district part of capable ripple Micropump, and the piezo actuator array is installed in multistage diffusing tube structure upper surface, directly in the miniflow pipeline, evokes capable ripple.Utilize the nonsymmetry of multistage diffusing tube structure to cause the difference of convection cell resistance, reduce the resistance of liquid single direction in pipeline, simultaneously, the cascade of a plurality of diffusing tube structures can also effectively improve the reverse fluid stopping performance of pipeline.This capable ripple Micropump can only be realized unidirectional pumping, but can effectively improve Peak Flow Rate and back pressure.

Summary of the invention

The objective of the invention is: complicated to existing micro-pump structure, the present situation that efficient is lower has proposed a kind of multistage diffusion miniflow pipeline travelling-wave-type Valveless piezoelectric Micropump, and the characteristics of this Micropump are: simple in structure, pump liquid efficient is high, is convenient to miniaturization and integrated manufacturing.

Travelling-wave-type Valveless piezoelectric microfluid drives and control technique; Be that to produce a plurality of amplitudes, frequency, direction of vibration through Drive and Control Circuit identical; And have the drive signal of certain phase difference, and change electrical signal into mechanical vibration by the inverse piezoelectric effect of piezo actuator, on the miniflow pipeline, evoke capable ripple; Make the interior liquid of pipeline follow the ripple direction and flow, this is a kind of novel microfluid Driving technique.And flow rate of liquid can be controlled through the voltage and the frequency of drive signal.

Piezo actuator is a piezoelectric bimorph, adopts the piezoceramic material of PZTS (lead zirconate titanate), has high coupling coefficient and high-tension electricity strain constant, and dynamo-electric parameter has excellent time and temperature stability.Piezoelectric bimorph is a kind of transducer that utilizes the horizontal inverse piezoelectric effect of piezoelectric constant to make, and adopts double-deck lamination, and the extra electric field direction is vertical each other with direction of vibration.Its displacement can be expressed as:

$u=\frac{3d_{31}{U}_s}{4D^2}{H}^2---\left(1\right)$

Wherein, d31 is the horizontal piezoelectric crystal of piezoceramic material; Us is an applied voltage; H and D are respectively the length and the thickness of monolithic piezoelectric ceramic in the piezoelectric bimorph.

Utilize the piezoelectric bimorph chip arrays on the miniflow pipeline, to excite one group of amplitude, standing wave that frequency is identical, synthetic capable ripple makes ducted liquid along certain orientation continuous-flow.In order to reduce the backflow phenomenon of liquid in pipeline, the mode that laterally superposes with a plurality of diffusing tubes replaces the original straight pipeline in pump district, and this structure has played the effect of one-way valve, has suppressed liquid in ducted reverse flow.Multistage diffusion miniflow pipeline is driven piezoelectric structure with the row ripple combine, can realize the one-way flow of liquid, and flow velocity and back pressure improve greatly.

The row ripple is that the form passing in time of ripple is constantly pushed ahead formed along certain orientation in medium.The each point that is in fluctuation is in its place, equilibrium position vibration, and its vibrational state, energy are propagated along the direct of travel of ripple.Standing wave and row have close contact between the ripple, and the standing wave that two row satisfy certain condition just can superpose and become the capable ripple of row.The function of supposing two row standing waves is:

This two row standing wave is superposed to one is listed as the row ripple, the condition that can obtain positive x direction in row ripple edge and the propagation of negative x direction is respectively:

More than two formulas provided the relation of each piezoelectric bimorph spacing and each drive signal phase difference in the piezo actuator array: (θ ₂-θ ₁) (λ/2 π) be the spacing of two row standing wave anti-node location,

It is the phase difference of two row standing waves.

With the driving array that adopts four piezo actuators is example; Their amplitude, frequency, direction of vibration are identical; And phase place differs the adjacent piezo actuator spacing of pi/2 successively is that four/delegation wave-wave is long, and it is long that promptly the standing wave anti-node location on the miniflow pipeline differs four/delegation wave-wave.The mode of its synthetic row ripple can be represented as follows:

$y_A={\mathrm{\ϵ}}_0\sin \frac{2\mathrm{\π}}{\mathrm{\λ}}x\·\sin {\mathrm{\ω}}_{0}t---\left(6\right)$

$y_B={\mathrm{\&epsiv;}}_0\sin (\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x+\frac{\mathrm{\&pi;}}{2})\&CenterDot;\sin ({\mathrm{\&omega;}}_{0}t+\frac{\mathrm{\&pi;}}{2})={\mathrm{\&epsiv;}}_0\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HSA00000449248400011.png,HSA00000449248400031.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x\&CenterDot;\cos {\mathrm{\&omega;}}_{0}t---\left(7\right)$

$y_C={\mathrm{\&epsiv;}}_0\sin (\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x+\mathrm{\&pi;})\&CenterDot;\sin ({\mathrm{\&omega;}}_{0}t+\mathrm{\&pi;})={\mathrm{\&epsiv;}}_0\sin \frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x\&CenterDot;\sin {\mathrm{\&omega;}}_{0}t---\left(8\right)$

$y_D={\mathrm{\&epsiv;}}_0\sin (\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x+\frac{3\mathrm{\&pi;}}{2})\&CenterDot;\sin ({\mathrm{\&omega;}}_{0}t+\frac{3\mathrm{\&pi;}}{2})={\mathrm{\&epsiv;}}_0\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HSA00000449248400011.png,HSA00000449248400031.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x\&CenterDot;\cos {\mathrm{\&omega;}}_{0}t---\left(9\right)$

In elastomer, the synthetic row row ripple of four row standing waves:

$y=y_A+y_B+y_C+y_D=2{\mathrm{\&epsiv;}}_0(\sin \frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x\&CenterDot;\sin {\mathrm{\&omega;}}_{0}t+\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="HSA00000449248400011.png,HSA00000449248400031.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x\&CenterDot;\cos {\mathrm{\&omega;}}_{0}t)$

$=2{\mathrm{\&epsiv;}}_0\cos (\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}x-{\mathrm{\&omega;}}_{0}t)---\left(10\right)$

The material of multistage diffusion miniflow pipeline is PDMS, and performed polymer fully mixes by 10: 1 volume ratios with curing agent, in mould, is shaped and curing fully.Again PDMS miniflow pipeline and Micropump substrate are bonded together, process the complete pump housing.Multistage diffusion miniflow pipeline upper surface is distributed with one group of trapezoidal protrusion; Every twin lamella correspondence in the piezoelectric driven array places on each trapezoidal protrusion; Spacing between the piezoelectric bimorph should meet the rule of formula (4), (5), makes its standing wave that excites can synthesize the capable ripple of certain orientation.In the special case for formula (6～10), the spacing between the piezoelectric bimorph is a quarter wavelength, and wavelength X can be obtained by row wave-wave speed, and the transverse wave speed v in the elastomer is expressed as:

$v=\sqrt{G/\mathrm{\&rho;}}---\left(11\right)$

Wherein ρ is an elastomer density, and G is elastomeric shear modulus.

Each diffusing tube structure of multistage diffusion miniflow pipeline can be divided into two-part: two different diffusing openings of subtended angle connect relatively.The angle of two diffusing opening joints is 90 °, the therefore subtended angle of two diffusing openings complementary angle each other, and one of them subtended angle is much smaller than another.In order to obtain best performance; The physical dimension of Micropump can correspondingly be adjusted, and the present invention is used dimensional parameters in test: the subtended angle of two diffusing openings is about 6.5 ° and 83.5 ° respectively, single diffusing tube minimum width 200 μ m; Extreme breadth 700 μ m, length is about 2.2mm.

Description of drawings

In the accompanying drawing, the substrate of 1-Micropump; The multistage diffusion miniflow of 2-pipeline; The capable ripple of 3-drives array; 4-drives the array draw-in groove; 5-miniflow pipeline bonding region; The 6-sample inlet; The 7-sample export; 8-miniflow pipeline formpiston; 9-miniflow pipeline former; Profile formpiston in the multistage diffusion miniflow of the 10-pipeline; The multistage diffusion miniflow of 11-pipeline external frame former; 12-trapezoidal protrusion former; The 13-trapezoidal protrusion.

Fig. 1 is the Micropump overall schematic.

Fig. 2 is a Micropump substrate schematic representation.

Fig. 3 is a miniflow pipeline mould formpiston schematic representation.

Fig. 4 is a miniflow pipeline mold cavity block schematic representation.

Fig. 5 is multistage diffusion miniflow pipeline structural representation.

Fig. 6 is piezo actuator array drive signals figure.

Embodiment

The working process and the material chosen of Micropump are closely related, and material different adopts different micro-processing methods.Micropump substrate and miniflow pipeline die material can adopt silicon or PMMA (polymethylmethacrylate), and silicon materials can use plasma etching industrial, and be compatible mutually with the MEMS technology of maturation; And PMMA has good optical character, chemical stability and mechanical property, is widely used in the structural material of Micropump, can use micro-machining.

Use micro-machining to make the Micropump substrate and the miniflow pipeline mould of PMMA material, make the piezoelectric driven array draw-in groove of dark miniflow pipeline bonding region of 100 μ m and certain depth at the Micropump substrate surface; And the high 100 μ m of the pipe interior of miniflow pipeline mould, pipeline wall thickness 300 μ m; Two subtended angles of the multistage diffusion structure in pump district are about 6.5 ° and 83.5 ° respectively, single diffusing tube minimum width 200 μ m, and Extreme breadth 700 μ m, length is about 2.2mm; The about 120 μ m of pipeline upper surface trapezoidal protrusion height, the physical dimension of projection is slightly less than miniflow pipeline Inner Dimension.Make the more careful miniflow pipeline of structure if desired, can adopt methods such as plasma etching on silicon chip, to make mould.

The material of miniflow pipeline is then selected PDMS (dimethyl silicone polymer) for use, and it is the main Manufacturing material of miniflow pipeline in the micro-fluidic technologies field.The PDMS miniflow pipeline of micro-fluid chip mainly adopts injection method to machine at present, and this method has the accuracy height; Reusable, to make simply, process cycle is short; Processing environment there are not outstanding advantages such as specific (special) requirements; It can accurately duplicate the microstructure of micron level, compares with traditional micro fabrication, has great advantage.

PDMS miniflow pipeline is that PDMS performed polymer and curing agent are fully mixed by a certain percentage, is injected into after the vacuum outgas in the mould, and the isothermal curing certain hour makes in constant temperature oven.The performed polymer of the PDMS miniflow pipeline here and the ratio of curing agent are 10: 1; Put into vacuum dryer degassing 30min after fully mixing, degree of vacuum is 10 ^-1Kg/cm ², divide afterwards to be injected in the miniflow pipeline mould.The miniflow pipeline mould that will be marked with PDMS is again put in 65 ℃ the constant temperature oven, isothermal curing 30min.This moment, PDMS did not solidify as yet fully; With the demoulding of PDMS miniflow pipeline; And be placed on the miniflow pipeline bonding region (bonding region applies the PDMS film of one deck 100 μ m in advance, and the ratio of performed polymer and curing agent is 5: 1, and in constant temperature oven, solidifies 10min) of PMMA Micropump substrate; Utilize Van der Waals force, pipeline and substrate are bonded together.This moment, PDMS miniflow pipeline and substrate film did not all solidify fully, at 65 ℃ of following isothermal curing 60min, it were solidified fully again, were placed in the drying basin for use afterwards.

Piezoelectric driven array one end that piezoelectric bimorph is formed is fixed in the draw-in groove of substrate, and the other end is pressed in respectively on the trapezoidal protrusion of the multistage diffusion structure of pump district miniflow pipeline.Piezoelectric bimorph is driven by four road sine waves, square wave or the triangular signal of phase difference of pi/4, in the miniflow pipeline, evokes capable ripple, promotes ducted flow of fluid.

Claims (5)

1. the travelling-wave-type Valveless piezoelectric Micropump of a multistage diffusion miniflow pipeline; Adopt the row ripple to drive array as the Micropump driver part; The miniflow pipeline that drives pump district, array below is multistage diffusing tube structure; Make each piezo actuator be positioned at corresponding diffusing tube directly over, and closely contact with the projection at miniflow pipeline top.

2. according to the said Micropump of claim 1, its structure comprises the Micropump substrate, and the miniflow pipeline drives array with the row ripple; Be manufactured with a miniflow pipeline bonding region, a sample inlet, a sample export and a driving array draw-in groove in the Micropump substrate; The pump district, middle part of miniflow pipeline is the multistage diffusing tube structure that laterally superposes, and the groove of pipeline bottom surface does not seal, and after being bonded together with the Micropump substrate, forms the complete pump housing; Be manufactured with trapezoidal protrusion at the pipeline upper surface, each trapezoidal protrusion correspondence is positioned over the top of single-stage diffusion structure, and boundary dimension and diffusing tube internal diameter match; The row ripple drives array and adopts the parallel distribution of piezoelectric bimorph, and an end of every piezoelectric bimorph places on the corresponding trapezoidal protrusion of multistage diffusing tube, and the other end is fixed in the Micropump substrate.

3. according to claim 1,2 said Micropumps, the material of miniflow pipeline is PDMS, with bonding method employing oxygen plasma bonding, ultraviolet bonding or the thermal bonding method of Micropump substrate; In the thermal bonding method, need apply skim PDMS at the bonding region of Micropump substrate, the PDMS that makes the miniflow pipeline adopts 10: 1 performed polymer and curing agent proportioning, and the PDMS that covers in the Micropump substrate adopts 5: 1 proportioning.

4. according to claim 1,2 said Micropumps, the material of Micropump substrate and miniflow pipeline mould is PMMA or silicon, and processing method adopts plasma etching or micromachined technology.

5. according to claim 1,2 said Micropumps; The driving array is arranged in parallel by the multi-disc piezoelectric bimorph and forms; Drive signal is sine wave, square wave or the triangle wave voltage signal with certain phase difference; Through regulating the piezoelectric bimorph spacing, driving signal frequency, phase place are controlled the synthetic of miniflow pipeline upgoing wave.

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