Study On The Process Of Piezoelectric Micro-actuated Near-field Direct Writing Controllable Wavy Fiber

In recent years,the optimization design of micro-nano structures has attracted the attention and research of researchers all over the world.Particularly,waveform structures in micro/nano scale have merit mechanical properties such as large elongation,controllability and stability,leads to varies application potentials and requirements.For example,flexible electronic devices,membranes of biological functional devices,and etc.In electrospinning technology,especially near-field direct writing technology,has unique advantages for the fabrication of micro/nano fibers.It can easily prepare micro/nano fibers with advantages of low cost,good continuity and high compatibility.However,in near-field direct writing technology,the approach to control wavy structures and the regulation of wavy structures mechanism are remained to be researched.Based on the melt near-field direct writing technology with good stability,this dissertation proposes a piezoelectric micro-actuated near-field direct writing process based on the idea of ‘macro-motion control trajectory and micro-motion control structure'.(1)The piezoelectric micro-actuated near-field direct writing experimental equipment is constructed,which mainly includes two parts: the motion system and the key instrument.Specifically,piezoelectric micro-actuated near-field direct writing components(including piezoelectric micro-actuated devices and micro-heating devices)are designed based on the laboratory triaxle moving platform.The moving platform is responsible for controlling the trajectory,and the piezoelectric micro-actuated devices are responsible for regulating the structure.Then,appropriate high-voltage power supply and visual detection instruments are selected,providing equipment basis for subsequent experiments.(2)In order to meet the requirements of waveform structure control of piezoelectric micro-actuated near-field direct writing process,the piezoelectric micro-actuated device is designed.The device is mainly composed of a piezoelectric actuator and a flexible amplifying mechanism.In order to solve the problem of small stroke of the piezoelectric actuator,a lever amplification mechanism is adopted.Its amplification ratio,stiffness,working stress and characteristic frequency were analyzed through theoretical design,finite element simulation and test experiments to ensure that its functions basically met the needs of the subject research.(3)In order to meet the basic conditions of the stability and directness of the piezoelectric micro-actuated near-field direct writing process,the influence law of the process parameters and the speed matching mechanism of the melt near field direct writing technology were revealed,and a group of better parameters oriented by stability and directness were analyzed and screened.Firstly,the influence law of temperature,height,voltage and other parameters on process stability was explored,and the process parameters with good stability were obtained,that is,the temperature was 90 ?,the height was 1 mm and the voltage was 1.9 k V-2.0 k V.Then,by controlling the velocity of the collection substrate,the matching relationship and influence rule of "jet velocity-collection velocity" were explored,especially the coil-rope effect and the hysteresis effect.The collection speed with good directness was obtained to be4 mm/s?5 mm/s.This will lay a foundation for the subsequent process of piezoelectric microactuated near-field direct writing wavy fiber.(4)The experimental verification and analysis of near field direct writing controllable waveforms are carried out.Firstly,two waveforms that sinusoidal and triangular,were selected to conduct wavelength control and amplitude control experiments.Through observation and statistics,the feasibility and stability of the piezoelectric micro-actuated near-field direct writing technology were verified.Then,the linear mesh fiber membrane and the sinusoidal mesh fiber membrane with different amplitudes were made.The mechanical properties of the linear mesh fiber membrane and the sinusoidal mesh fiber membrane with different amplitudes were tested to verify that the waveforms structure had better mechanical properties.This method has the characteristics of simple operation and high controllability,and can accurately prepare the fiber with controllable waveform structure.Its mechanical properties are excellent,and it has great application potential and development prospect.