Construction Of Microcavity Structure Based On Constrained Inverted Gas Expansion Method

The microcavity structure refers to the regular micro-concave structure inside or on the surface of the material that has a specific effect with the action substance or electromagnetic wave,and has received extensive attention in the engineering and scientific circles.Constructing a microcavity structure on the surface of a material can realize the regulation of the friction and lubrication properties of the material surface.By constructing a microcavity structure inside a microfluidic pipe,functions such as focusing of substances,selective capture of substances,and single-atom detection can be realized.Due to the many functions of the microcavity structure,it has a wide range of applications in the fields of surface engineering,microfluidic chips,precision measurement,cavity quantum electrodynamics and biomedicine.In recent years,it has been found that the complex curved microcavity structure has special functions.For the stable regulation of the shape and depth of the microcavity structure,the current existing mechanical processing,dry etching,wet etching,laser processing,surface tension driving Processing methods such as technology,3D printing,and liquid metal sacrificial molding have certain limitations.Therefore,in order to realize the stable regulation of the complex-shaped microcavity structure,this paper proposes an inverted gas expansion forming method to explore the influence of the curved microcavity structure by the template structure,and further expand the application scope of the controllable microcavity structure.The main conclusions are as follows:(1)First,taking the polymer spherical cap as an example,the effect of template hole depth,hole spacing,hole size,and opening shape on the shape of the spherical cap microcavity was analyzed and discussed.The experimental results showed that:(1)Spherical cap microcavity The diameter and height increase with the increase of hole depth,hole spacing and pore size,and are less affected by the hole depth;(2)The template holes with the hole depth below 65 μm or the pore diameter below 50 μm cannot form spherical capped microcavities;(3)The shape of the template hole affects the shape of the formed microcavity,and the larger the inner angle of the regular polygon,the easier the microcavity is to form.(2)Further expand the control of the shape of the smooth microcavity,and explore the competitive gas expansion forming process of the high aspect ratio microcavity structure.The effects of template hole spacing,arrangement,and inclination angle on the shape of the micro-cavity are analyzed and discussed.According to the experiments,it is concluded that:(1)The micro-cavity expands anisotropically under high pressure difference,resulting in a larger aspect ratio;(2)The micro-cavity expands anisotropically,the width and depth of the cavity increase with the increase of the template hole spacing,and the aspect ratio decreases with the increase of the hole spacing;(3)The array of smaller apertures is included in the template hole array,and the generated smaller microcavity can provide supporting force,so that the top-view topography of the larger microcavity tends to be more circular;(4)Adjusting the angle between the gas template and the horizontal plane can prepare a high aspect ratio micro-cavity with the same inclination angle.(3)To further expand the lateral development capability of the smooth surface microcavity structure,a preparation method of the near-cylindrical microgroove array surface based on the inverted gas expansion forming method is proposed.Based on the viscosity at 40 °C for 30 min,the effects of template hole spacing,hole size,groove depth and groove width on the microcavity morphology were investigated.Through experiments,it was concluded that:(1)With the increase of template hole spacing,the microcavity under each pressure difference The merging phenomenon follows the four steps of merging expansion,just merging,contact extrusion,and unmerging.As the pressure difference increases,the hole spacing corresponding to the smallest microcavity width under each pressure difference also increases;(2)The microcavity width increases with the increase of the pressure difference.The pore size increases with the increase of the pore size,and the microcavity with the smallest pore diameter merges and expands first;(3)The greater the depth of the groove,the more the microcavity tends to grow in the direction of the groove,forming a nearcylindrical microcavity structure;The microcavity has a strong expansion restriction ability,but it is only suitable for low pressure difference.A larger groove width has a limited ability to limit the expansion of the microcavity,but has a larger pressure difference adaptation range.(4)To further control the depth of the smooth surface microcavity structure,a preparation method of the porous channel polymer film based on the additivedeformation method is proposed.Combining the microscopic image analysis of the formed porous channel with a theoretical model of the porous channel forming shows that the method is able to deform the microcavity simultaneously with additive manufacturing by only controlling the positioning and pressure difference,for the preparation of more complex microcavities Provides a certain experimental basis and theoretical basis.