Research On The Mask-free Forming Technologies For Patterned Microstructure Arrays Via Surface Acoustic Waves

Micro-patterns are widely used in cell culture,drug screening,chemical examination and many other fields.Now,the major methods to fabricate micro-patterns are lithography,soft-lithography,inkjet printing,and stereo-lithography.Those methods all need some forms of mold,for example,mask plate.And it takes a long time period to fabricate those micro-patterns.Usually,one mold can only be used to fabricate a unique pattern.Based on the problems above,we need a method to produce various micro-patterns rapidly in one device.Considering that the surface acoustic waves propagating though the piezoelectric substrate could form a stable acoustic pressure field in the thin liquid placing on the piezoelectric substrate,and can causing a stable deformation of the surface of the liquid,we could use stereo-lithography to obtain the micro-patterms of the surface deformation.That is the undulate micro-pattern fabrication using standing surface acoustic waves.The micro-patterned fabrication using standing surface acoustic waves is a method using several couples of interdigital transducers to produce surface acoustic waves.If thin liquids were putted on the piezoelectric substrate,those SAWs travelling through the substrate can cause stable deformation on the surface of the liquid.Using ultraviolet polymerization method to obtain the surface deformation to form a micro-pattern.The research contents and innovation points are as follows:In chapter 1,the fabrication methods of the micro-patterns are introduced.This chapter introduced the usage of surface acoustic waves and the microfluidics using surface acoustic waves.The fabrication method of micro-patterns using surface acoustic waves presented.Meanwhile,the research direction was advanced and the direction of the following chapters was indicated.In chapter 2,the experimental system of micro-patterns fabrication based on surface acoustic waves are made.The apparatus includes the interdigital transducers,high frequency signal generators and an anaerobic environment,observation system and the measurement system.In chapter 3,theoretically explanations of the methods of micro-patterns fabricated based on surface acoustic waves are presented.A combination of numerical simulations and theoretical analysis are used to analyze the acoustic pressure field in the liquid.For the positive correlation of acoustic pressure field and surface deformation of liquid,the distribution of acoustic pressure field can be used to predict the surface deformation of liquid.In chapter 4,the experiment procedures are introduced.The results of the micro-pattern fabrication are presented,including one pair of interdigital transducers be used for fabrication,two pairs and three pairs of interdigital transducers be used for micro-patterns fabrication,and focal interdigital transducers be used for micro-patterns fabrication.The distinctions of different kinds of interdigital transducers in micro-patterns' fabrication are analyzed.In chapter 5,the parameters in micro-patterns fabrication based on surface acoustic waves are analyzed.The frequency of the input signals,the phase-difference of different interdigital transducers and the peak-to-peak voltage of input signals have effects on the performance of the micro-pattern fabrication.Thus,an evaluation criterion is presented.Based on the parameters we studied,we came up with some suggestions for the improvement of micro-patterns fabrication using surface acoustic waves.In chapter 6,research contents of this dissertation are summarized,and future works are prospected.