Research On Micromachining Method And Its Application Based On An Adhesive Dispenser

Microstructures have been applied in a range of fields,including micro electro mechanical system(MEMS),microfluidic device,and micro-optics.However,existing microfabrication techniques are hard to make a compromise between rapid production,simplicity of implementation,design flexibility,and machining resolution,which is limited to its extensive use.In the paper,to overcome the proposed shortages,we research some microfabrications based on robotic adhesive dispenser using fluidic ink with various functions,with the prerequisite of customizing the robotic adhesive dispenser and theoretical analysis of the working process.The main content of this research includes the following parts:At first,a robotic adhesive dispenser with a capability to enable a 4 μm-diameter micronozzle to securely approach the substrate is developed by means of the microscopic visual feedback.The basic scheme of the microfabrication is introduced.Next,theoretical analysis of the working process is conduced.According to the rheological properties of fluidic ink,both flow model of newtonian fluid and non-newtonian fluid in tapered micropipette were established respectively.Based on the Young-Laplace equation considerating a contact angle hysteresis,the ink transfer mode from micropipette tip to the substrate surface was obtained.The relationship between the working parameters and the capillary structure of the liquid bridge and the capillary force between the micropipette tip and the substrate surface was obtained by simulation study.A continuous flow ink etching(CFIE)method is presented to directly create micropatterns on a silicon dioxide(Si O2)layer.Both dot and line features with well-defined edge were fabricated and used as hardmasks for silicon etching.The ultimate resolution and edge roughness of the etching method were analyzed theoretically.The relationship between working parameters,including printing speed and applied pressure,and the shape and size of the linear feature was experimentally researched.The effectiveness of the etched silicon dioxide layer as a hardmask for selective anisotropic etching of single crystal silicon was verified.We present an extrusion printing technique for producing spherical and cylindrical plano-convex microlens arrays with controllable feature dimensions.The influence of dewell time and applied pressure on the diameter of spherical microlens is studied experimentally.The minimum spherical microlens diameter and cylindrical microlens width that the method can obtain were demanstrated.The surface morphology,size stability and light focusing capability of our printed spherical and cylindrical microlens array were characterized,respectively.and the effectiveness and reliability of the robotized adhesive dispensing method were verified.we demonstrate a facile approach to programmably generate customized 3D microstructures with smooth surfaces by forming capillary bridges between pre-pinned domes.By controlling the position of the liquid bridge droplet,this method can obtain the dot-type feature in the manner of "point merging",and obtain the linear feature in the manner of "point-contecting-point".The three-dimensional structure with various morphologies can be conveniently obtained by changing the hydrophobicity of the substrate surface,adjusting the size of the liquid bridge volume and designing the shape and the relative size of the pre-fixed features,including straight lines,triangles,quadrilateral,pentagons,Hexagonal limit feature.Finally,the method is applied to the casting mold of circular cross-section microfluidic channel in the field of microfluidics.It is used in the manufacture of semi-elliptical and cylindrical plane-convex microlens and its array in micro optics.A direct-write strategy that rapidly produces rounded cross-sectional molds for casting of microfluidic channels in polydimethylsiloxane(PDMS),was proposed.Robotically controlled microextrusion of a thixotropic ink through a micronozzle onto a substrate surface generates user-defined positive relief structures that serve as molds.Printed lateral resolutions of less than 10 μm can be achieved by using a micronozzle with dimensions of a few micrometers and microscopic visual feedback.The cross-sectional geometries of the microchannels can be easily adjusted by regulating parameters such as the printing speed,applied pressure,micronozzle-substrate distance,and number of stacks.As a result of the “liquid rope coiling” effect,this technique provides a straightforward way of producing a serpentine microchannel.A direct-write lithographic technique for surface patterning of various materials with feature width down to 5 μm was presented.Three modes of the silicone transfer from the micronozzle onto the substrate are observed,which can be switched by changing the printing conditions.Moreover,the width and height of silicone patterns can be conveniently adjusted by regulation of the printing parameters including the printing speed,applied pressure and micronozzle-substrate distance.Combining with wet etching technique,the patterned thin layers of copper,silica and chrome are adopted in fabrications of the microelectrode,hardmask and photomask,respectively,demonstrating its high versatility.