Research On Printing Technology Based On Acoustofluidic Driven Micronozzle

Micro-nano fabrication technology is a key technology to promote the development of MEMS.The pursuit of higher precision,higher resolution,and wider material applicability has been the hot direction of micro-nano fabrication technology.Micronozzle-based printing technology is widely used in the printing of bio-ink,liquid metals,and polymer because of its advantages of high resolution,high controllability,and low cost.However,current micronozzle-based printing driven by mechanical pressure,piezoelectric,thermal,and electro-hydraulic are disadvantageous for high pressure,high temperature,and strong electric field in the printing process.And limited by ink’s viscosity and surface tension,current methods have the problems such as simple processing form,poor material applicability,and low resolution.micronozzle-based printing technology is seriously restricted in the application of bio-ink and functional ink.To address the above problems,the printing technology based on acoustofluidic driven micronozzle is proposed.By applying the acoustic wave in the fluid to excite acoustic streaming and generate gradient pressure to print the fluid.In this paper,the mechanism of acoustofluidic driven micronozzle printing is theoretically analyzed,and an experimental system was built to study the micronozzle driven by surface acoustic wave(SAW)and bulk acoustic wave(BAW).And its applications are expanded in inkjet printing,functional material printing,bioprinting,etc.Theoretical analysis of the mechanism of acoustic-driven flow in micronozzle.The theoretical model of microfluid in micronozzle was established,and the key parameters such as volume,velocity,and pressure of the fluid inner micronozzle during the printing process were simulated.The acoustic-driven micronozzle model was established.The mechanism of SAW and BAW in microfluid was analyzed,and the mechanism of acoustic streaming drag force and acoustic radiation force was analyzed.The finite element models of the SAW device and the BAW device were established respectively.The generation and focusing mechanism of the SAW were studied,and the device’s displacement and the acoustic pressure excited by acoustic waves after passing the acoustic-structure interface were obtained.The pressure and volume forces were calculated.The mechanism of focusing BAW by conical micronozzle is studied,the gradient pressure and volume force generated by the device were calculated,and the influence of the voltage amplitude and the taper of the micronozzle on the sound pressure and the volume force were obtained.A glass micronozzle-based direct-writing system was built to study the mechanism of the flow of micro fluids inner micronozzle.The technology for processing liquid metals based on rigid glass micronozzle is developed.Processed different morphologies and scales of liquid metals.Built a platform for graphical printing of liquid metals.A flexible micronozzle-based machining method is proposed to further improve the machining resolution,and its mechanical model was established and analyzed.This method can directly write liquid metal wires with a minimum size of 10μm.The analysis of the flow of fluid inner micronozzle sets the foundation for the study of acoustofluidic micronozzle.Designed and fabricated focused SAW devices and BAW devices for generating acoustic waves to drive fluids inner micronozzle.An experimental study of acoustofluidic micronozzle is presented.Firstly,the mechanism of the SAW-based acoustofluidic micronozzle device was investigated.A conventional lithium niobate wafer-based SAW device was designed and fabricated,and an experimental system was built to characterize the device for micro and nano particles’ manipulation.To further improve the device’s power,a focused SAW device was developed.The action of the focused SAW device on particles and fluids was verified experimentally,respectively.Finally,the mechanism of BAW-driven micronozzle printing was studied.A PZT-based BAW-driven micronozzle device was developed,an experimental system was built.The four operating modes of the device were characterized as inkjet,atomization,pumping,and jet.Developed BAW-driven micronozzle-based printing technology.An inkjet printing system based on BAW-driven was built to analyze the effects of ink properties,micronozzle diameter,pulse width,and voltage on resolution,and a graphical printing system was established to pattern the droplets.The results show that this system can stably produce a minimum droplet volume of 0.02μl.Then the device was used to print functional materials.The micro-nano particles,droplets,and fibers were processed using different modes of the device with high viscosity UV glue,high surface tension liquid metal,and hydrogel as ink,respectively.Its applications in micro-nano optics,flexible electronics,and bioprinting were demonstrated.Finally,a bio-ink containing cells was printed to verify the biocompatibility of the system.For bioprinting,a soft-couplingbased disposable bioprinting method is proposed to solve the problems of crosscontamination and rapid ink change through independent fluidic and acoustic sub-systems.In conclusion,a printing technology based on acoustofluidic driven micronozzle is developed for the problems of traditional micronozzle processing.A mathematical model was established and validated by simulation,and the mechanism and working characteristics of micronozzle-based direct writing and acoustofluidic-driven micronozzle were studied experimentally respectively,and finally,the acoustofluidic micronozzle based processing method was proposed by combining the advantages of both,and its potential applications were explored.The results show that this method can be widely applied to the microfabrication of various materials with the advantages of diverse modes,high resolution,fast speed,good biocompatibility,and scalability.It shows potential applications in the fields of flexible electronics,MEMS devices,and bioprinting.