Microfluidic Drive Using Surface Acoustic Waves In Liquid

It is well known that propellers in fluids have been the subject of important research in military surveillance,aerospace,and biomedical fields.For example,small probing aquatic vehicles can be used for exploration,and swimming micro-robots are planned for minimally invasive surgery and endoscopy.There are no moving parts to achieve anti-radar stealth underwater robots or submarines,and so on.In recent years,with the continuous advancement of technology,surface acoustic wave(SAW)technology has been developed with application value,which has generated a large number of market demands,most of which are concentrated in the field of microsensors and actuators.When it is applied to the field of fluid drive,the surface acoustic wave excitation method is simpler and more efficient,the control method is more stable and reliable,and the microfluidics technology can interact with different fluid media and produce different driving effects.SAW devices made with SAW as the core technology have obvious advantages,such as simple structure,low cost,high performance,high frequency response,control,electronic control,programmable,compatible with CMOS technology.Strong in nature,etc.,and thus caused widespread concern and research in the field of fluid drive.In this work,the application of micro-propellers in liquid-driven motion based on the surface acoustic wave is studied.The devices studied are mainly SAW devices with LiNbO3 as the base material and A1 as the metal electrode.The SAW device size parameters and design and manufacture,the micro-flow drive thruster was prepared and the test system was built for performance verification.The microfluidic actuator of this work initiates fluid motion through microfluidic technology,without any advancement of moving parts,and can be driven under silent conditions,with no physical contact between the electrodes and the liquid to be manipulated;and due to the characteristics of the SAW device,It also has low manufacturing cost and can be electronically controlled,high speed,programmable,and high frequency response.At the same time,based on the above research,this topic innovatively explores the relevant factors affecting the microfluidic drive thruster and combines the experimental results to propose the optimal solution of various factors.The main research work and innovative achievements of this thesis are as follows:1.Discussed and explain the principle and characteristics of bulk acoustic wave generation and surface acoustic wave,also explain the piezoelectric effect and piezoelectric material and summarize the development process of surface acoustic wave technology;2.According to the conventional SAW devices working principle and latest SAW design methods for microfluidics,the proposed design and proposed substare was choosen by simulation.We choose 128°Y-cut Lithium(LiNbO3)material as a piezoelectric substrate,and the thickness of the wafer is about 0.5 mm,thereby achieving maximum SAW driving efficiency and stable floating effect.The structural design of the interdigital transducer has been innovated.The interdigital finger width and the interdigital finger pitch are set to 50 ?m,the interdigitated index is N=50,and the acoustic aperture is set to 9 mm,thereby maximizing the acoustic power.3.On the basis of the traditional surface acoustic wave fabrication process,the fabrication process of surface acoustic wave micro-driving device is optimized by experiments,and the surface acoustic wave micro-actuator with various size parameters is innovatively produced,and the optimal scheme is selected according to the experiment.4.Combining the new target design and setting up the driving experimental platform to test the SAW device,the innovative research enumerates the conditional factors affecting the surface acoustic wave micro-driving,including SAW incident angle,device wetting angle,electrical signal input power,liquid viscosity,etc.Conditional factors,and through the control experiment to explore the optimal solution driven by these factors.Finally,this paper looks forward to the future research direction of surface acoustic wave micro-actuators.