The method for making of electric control optical switch array micro-fluidic chip
Technical field
The present invention relates to a kind of integrated method for making of electric-tuning micro-fluidic array of photoswitch chip of novelty, belong to optical communication network device integrated technology field.
Background technology
Micro-fluidic optical is a significant new technology, it combines modern microflow control technique and low-light electronic technology, develop a class and can change, have the optical integrated device and the system of structural rearrangement and adaptive adjustment capability, will have important application prospects in fields such as sensing, communication, information processings according to external environment.
Microflow control technique is a research emphasis in the MEMS field as the key and the core of micro-total analysis system always.Along with the microflow control technique level improve constantly and with the continuous infiltration and the fusion of other subject, emerged a collection of compelling research focus in recent years, wherein the micro-fluidic optical device is exactly its typical case's representative.The fusion of microflow control technique and optical device, for microminiaturization, array, cost degradation and the High Accuracy Control of traditional optical device provides may.The recent research achievement of new optical devices comprises some varifocal optical lenss based on microflow control technique, display device, photoswitch and adjustable optic fibre grating etc.
Although existing photoswitch respectively has unique advantage, also let us is seen this parameter of the weak point of existing photoswitch, particularly switching matrix.Except the photoswitch of a few types such as MEMS, the exchange capacity of existing photoswitch is always limited, is difficult to make big array; And originally also there is weak point in mems optical switch in aspects such as high port density and anti-mechanical friction, wearing and tearing or vibrations.The present invention will propose a kind of new design philosophy, combine with present microflow control technique, produce a kind of novel array light switch.
The principal character of micro-fluidic chip is that its resulting structure of holding fluid is the micron order yardstick at least on a dimension, has enlarged markedly the area/volume ratio example of fluid environment.This feature causes a series of body surfaces relevant in microfluidic system, determines the peculiar effect of its property.
List of references:
[1]Demetri?Psaltis,Stephen?R.Quake2?&?Changhuei?Yang,Developingoptofluidic?technology?through?the?fusion?of?microfluidics?and?optics,Nature,Vol.442,No.27,(2006)381-386
[2]Mistuhiro?Makihara,Makoto?Sato,Fusao?Shimokawa.MicromechanicalOptical?Switches?Based?on?Thermocapillary?Integrated?in?WaveguideSubstrate.JOURNAL?OF?LIGHTWAVE?TECHNOLOGY.1999,17(1):14-18.
[3]David?A.Chang-Yen,Richard?K.Eich,Bruce?K.Gale.A?Monolithic?PDMSWaveguide?System?Fabricated?Using?Soft-Lithography?Techniques.JOURNAL?OFLIGHTWAVE?TECHNOLOGY.2005,23(6):2088-2093.
[4] Zhao Bo, Li Hong gives birth to the research and the progress [J] of .MEMS photoswitch. micro-nano electronic technology, 2004, (2)
[5] Xu Shujie, Duan Yugang, fourth is kindly helped secure the success of, and Lu grasps the novel fast method for preparing [J] of permanent .PDMS micro-fluidic chip mould. mechanical engineering journal, 2007, (06).
[6] Luo Yuan, still honest and clean .MEMS photoswitch of Zhang Yi, Huang and main technique Study on Technology [J]. laser magazine, 2001, (06).
Summary of the invention
Technical matters: the objective of the invention is to propose a kind of method for making of electric control optical switch array micro-fluidic chip, solve the integrated manufacture method problem of micro-fluidic array of photoswitch, the implementation structure function.
Technical scheme:
1, ultimate principle and chip structure:
The basic structure of micro-fluidic array of photoswitch of the present invention as shown in Figure 1, it is the sandwich structure of " insulation course+upper cover plate of light waveguide-layer+end conductive layer+band conducting film piece ".In the cellular construction, ground floor is a cover plate, leaves air hole, liquid injection hole and electrode hole above, the groove that the also useful fluid channel technology in bottom is made; The second layer is an insulation course, is coated with conduction membranelle piece on it, and with the air hole and the liquid injection hole of the corresponding coupling of aperture on the cover plate; The 3rd layer is light waveguide-layer, and except the fluid channel that fluid channel technology is made, the middle part is liquid storage sulculus and the tubule that passes thereof; The 4th layer is base plate, is coated with one deck conducting film on the PDMS of base plate.In optical switch construction, cover plate, light waveguide-layer and base plate all adopt dimethyl silicone polymer (PDMS) as base material.
In the two-dimensional structure of the front of light waveguide-layer, tubule also has a little to stretch out at the other end of liquid storage sulculus.This is that the zone corresponding with the conducting film piece, liquid injection hole position intersects on the insulation course, one has made things convenient for the injection of liquid, guarantees that liquid is full of sulculus, its two envelope of filling out that has also made things convenient for liquid injection hole after the fluid injection.
In the optical switch construction, all increased air hole at cover plate and insulation course.Reason has 2 points, at first makes things convenient for entering of liquid injection hole liquid in the optical switch construction of sealing, avoids the capillary action of the opposite pressure resistance liquid of gas pressure intensity, helps the flow of controlling liquid simultaneously; Secondly,,, produce bubble and influence optical waveguide and produce optical loss, just need the non-polar gas of removal tubule and sulculus so enter fluid channel for fear of non-polar gas because PDMS permeates a little for most non-polar gases.
The cover plate bottom adopts micro-fluidic technology to make groove.Reason is that at first the conducting film piece has certain thickness, and the unevenness that this has caused sublevel (insulation course) is an impediment to the involution of chip; Secondly, when switch is in state ' pass ', at this moment the electric charge on the base plate and the electrically charged same sex of insulation course upper conductive film piece, will produce repulsive force upwards to the membranelle piece, cause the membranelle piece projection bonding with insulation course, therefore for photoswitch can better be worked, the groove of cover plate bottom is essential.
2, integrated chip method for making;
The integrated making of the insulation course of adopting machining, make the PDMS micro-fluidic chip, plated film, involution realizing comprising light waveguide-layer, end conductive layer, band conducting film piece and the sandwich structure of upper cover plate, its step comprises:
1) making of light waveguide-layer: adopt the method for making photomask, with crossing CAD design microchannel network, it is printed on the transparent film as mask, on silicon chip, get rid of and be coated with the skim photoresist, by ultraviolet exposure, the unexposed area developing solution dissolution, remaining protruding SU-8 structure is gone up as the formpiston of making the PDMS substrate in silicon chip and surface, the silicon male mold surfaces is handled with the silylating reagent of fluoridizing, and then the PDMS that solidifies is peeled off from formpiston, makes the substrate with specific microchannel;
2) making of driving switch structure: adopt CAD to design and produce the PVA mask, by get rid of resist coating, developing obtains conductive module and distributes, and produces air hole and liquid injection hole with boring cutter then on the PVA film;
3) plated film: adopt evaporation coating technique to carry out plated film, heating target metal under vacuum, make its evaporating pressure surpass environmental pressure, thereby quicken evaporation, coated substrate be placed on source material in the vacuum chamber near, when steam touched colder substrate surface, metal vapors was compressed, and granule boundary grows rete on substrate;
4) making of base plate conductive layer: with PDMS is substrate, uses evaporation or additive method metal-coated membrane on substrate, can realize the making of end conductive layer;
5) chip involution: the involution between four layers of the photoswitches, be the involution of involution, metallic diaphragm and the PDMS of PVA rete and PDMS, these two kinds of involutions are all assisted bonding with plasma, insulation course after the making and cover plate elder generation involution, break away from substrate, again with the light waveguide-layer involution.
Ultraviolet ray makes resist exposure by photomask, the unexposed area developing solution dissolution.Remaining protruding SU-8 structure is gone up as the formpiston of making the PDMS substrate in silicon chip and surface.Can obtain higher depth-to-width ratio like this, its structure side wall is vertical with matrix surface.Involution between four layers of the photoswitches, the i.e. involution of the involution of PVA rete and PDMS, metallic diaphragm and PDMS.The all available plasma of these two kinds of involutions is assisted bonding, and oxygen plasma helps surface clean, can improve the surfactivity of chemical mobility of the surface, particularly polymeric material simultaneously.The PDMS of oxygen plasma treatment can realize permanent involution.
Beneficial effect: according to above narration as can be known, the present invention has following characteristics:
The electric charge that the present invention directly utilizes electric control signal is controlled receiving the liquid that rises magnitude in the microchannel, has embodied the advantage of microflow control technique well, and big exchange capacity that has and higher efficiency help constructing the high-speed optical switch of current expectation.
The innovation part is:
(1) owing to avoided the complicated processes of control energy transmission layer by layer, its high-speed performance will be a big advantage.
(2) directly just can be influenced the speed of photoswitch by external voltage, this makes the range of application of this photoswitch extend to each field different to the switch rate request.
(3) array structure requires very lowly to the control circuit of periphery, can directly use electrical addressing, just can reach the switch effect as long as change the polarity of controlling voltage, and when promptly opposite with the polarity of voltage of base plate, photoswitch just shows as " opening "; When identical with the polarity of voltage of base plate, photoswitch then shows as " pass ".
(4) no wavelength selectivity and polarization sensitivity.
Description of drawings
Fig. 1 is structure of the present invention and principle of work synoptic diagram.(a) array of photoswitch four-layer structure synoptic diagram (b) is cover plate polycrystalline substance synoptic diagram.Air hole 1, electrode 2, liquid injection hole 3, cover plate 4, insulation course 5, conduction membranelle piece 6, light waveguide-layer 7, tubule 8, liquid storage sulculus 9, PDMS10, base plate 11, conducting film 12, air hole 13, groove 14, electrode hole 15, liquid injection hole 16 are arranged among the figure.
Fig. 2 is a 3 D stereo sectional view of the present invention.
Fig. 3 is a relevant SU-8 structural representation among the present invention.
Embodiment
The present invention proposes a kind of array light switch structure based on microflow control technique, and its structure adopts the sandwich structure of " insulation course+upper cover plate of light waveguide-layer+end conductive layer+band conducting film piece ".Wherein, the base material of cover plate, light waveguide-layer and base plate all is dimethyl silicone polymer (PDMS).PDMS has good light transmittance, dielectricity, and inertia, nontoxic, character such as easy processing, and cheap; Liquid on the light waveguide-layer in fluid channel, tubule and the liquid storage sulculus is selected the 201# methyl-silicone oil for use.The 201# methyl-silicone oil has that the sticking coefficient of temperature is little, high-low temperature resistant, anti-oxidant, flash-point is high, volatility is little, good insulating, surface tension are little, metal is not had characteristics such as burn into is nontoxic; What insulating layer material was used is polyvinyl alcohol (PVA) (PVA) film.PVA film good toughness, pulling strengrth is big, and good weatherability can heat sealing.
The method for making of electric-tuning micro-fluidic array of photoswitch chip of the present invention mainly is divided into the making of light waveguide-layer, the making of driving switch structure, making and four basic processes of chip involution of base plate conductive layer:
1) making of light waveguide-layer: adopt to make the method for photomask, with crossing CAD design microchannel network, it is printed on the transparent film as mask, on silicon chip, get rid of and be coated with skim photoresist (as photocuring SU-8).By ultraviolet exposure, the unexposed area developing solution dissolution.Remaining protruding SU-8 structure is gone up as the formpiston of making the PDMS substrate in silicon chip and surface.The silicon male mold surfaces is handled with the silylating reagent of fluoridizing, and then the PDMS that solidifies is peeled off from formpiston, makes the substrate with specific microchannel.
Can see that the microstructure on the light waveguide-layer comprises waveguide microchannel, tubule structure and reservoir structure, what wherein directly control the optical waveguide direction is the tubule structure.The tubule structure is the core place of overall optical ducting layer; Simultaneously, also be to make the meticulousst part.The width of tubule has only several microns, helps to improve the speed of switch like this; And tubule wall should be smooth, avoids light scattering.These photomask equipment that require to make have very high resolution.
2) making of driving switch structure: technology realizes focusing on the making that the conducting film piece distributes, method for making is as follows: 1. the way that adopts the optical cement coating, earlier substrate is placed on the rolling disc of photoresist spinner, PVA solution is placed the centre of substrate, be coated with uniformly on substrate by whirl coating and apply the PVA film, under the temperature about 70 ℃, water evaporates is fallen then;
2. use evaporation or additive method coated metal film on the PVA of substrate film;
3. with CAD design film piece distribution plan, it is printed on the transparent film as mask;
4. on the metal film of substrate, get rid of the very thin photoresist of last layer with photoresist spinner;
5. make resist exposure with ultraviolet irradiates light mask, the exposure area developing solution dissolution; Remove exposed metal film with metal erosion liquid again;
6. also use developing solution dissolution with the remaining photoresist of ultraviolet ray irradiation, obtain metal film piece distributed architecture.
7. on the PVA film, produce air hole and liquid injection hole with boring cutter.
3) plated film: the design adopts evaporation coating technique to carry out plated film, and heating target metal makes its evaporating pressure surpass environmental pressure under vacuum, thereby quickens evaporation.Coated substrate be placed on source material in the vacuum chamber near.When steam touched colder substrate surface, metal vapors was compressed, and granule boundary grows rete on substrate;
4) making of base plate conductive layer: with PDMS is substrate, uses evaporation or additive method metal-coated membrane on substrate, can realize the making of end conductive layer.
5) chip involution: the involution between four layers of the photoswitches, the i.e. involution of the involution of PVA rete and PDMS, metallic diaphragm and PDMS.These two kinds of involutions are all with the auxiliary bonding of plasma, and insulation course after the making and cover plate elder generation involution break away from substrate, again with the light waveguide-layer involution.
The micro-fluidic array of photoswitch chip of the present invention adopts the sandwich structure of " insulation course+upper cover plate of light waveguide-layer+end conductive layer+band conducting film piece ".Ultraviolet ray makes resist exposure by photomask, the unexposed area developing solution dissolution.Remaining protruding SU-8 structure is gone up as the formpiston of making the PDMS substrate in silicon chip and surface.Can obtain higher depth-to-width ratio like this, its structure side wall is vertical with matrix surface.Involution between four layers of the photoswitches, the i.e. involution of the involution of PVA rete and PDMS, metallic diaphragm and PDMS.The all available plasma of these two kinds of involutions is assisted bonding, and oxygen plasma helps surface clean, can improve the surfactivity of chemical mobility of the surface, particularly polymeric material simultaneously.The PDMS of oxygen plasma treatment can realize permanent involution.