| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 106 === In the past decade, microfluidic system has become an important platform in the field of biological testing and chemical analysis. According to desired functions, various experimental analysis processes are integrated in a small system to conduct transmission, separation, classification, and mixing of biological samples and other applications. As compared with traditional biotechnology, microfluidic system has the advantages of fast analysis, less sample dosage, and able to perform a large number of sample operations.
In this thesis, high-frequency surface acoustic waves were used as the driving force of microfluidic system. It involved injecting the standing acoustic waves into the microfluid formed by the interference of two surface acoustic waves, which would further generate a sound pressure field and acoustic radiation force inside the microfluid to allow the particles in the fluid to move towards the pressure node due to the actions of sound pressure field and sound radiation force. A square filter area was added on the standing surface wave action region through two sets of interdigitated electrodes setting at an angle of 45° towards the flowing gateway, thus allowing the particles to slow down while passing through it. A comparison was made on the particle capturing effect with the numerical analysis result through regulating the interdigitated electrode design and power under different frequencies, and their results were then used to achieve the goal of particle filtration. To design the specific surface acoustic wave frequencies and pressure node in the microchannel, the theory of acoustic microfluidics was first developed and a simulation was further made using the finite element method to analyze and explore the functions, relevant dimensions and performance parameter design of the acoustic microfluidic device. Then, the microelectromechanical system (MEMS) process was used to fabricate the acoustic microfluidic device based on the results of simulation and design. The experimental measurement on the control of microfluidic particles was conducted to observe the performance of the designed and fabricated device on the control of particle movement.
The experimental results show that the design of interdigitated electrodes setting at an angle towards the microchannel proposed by the study is able to achieve the filtering effect of impurities in a mixed solution through capturing the targets of larger dimensions. This can be achieved through setting a square-shaped filter area in the microchannel, and using the acoustic energy generated by the interdigitated electrode modal excited by different frequencies on the lithium niobate to capture the particles.
In this study, an acoustic microfluidic control device was developed to filter unwanted impurities in a solution through the use of finite element method to simulate, analyze and design the device. The MEMS process was used to fabricate the acoustic microfluidic device based on the results of simulation and design, and experimental measurement was made to control the microfluidic particles to observe the control status of the designed and fabricated device. The experimental results have successfully demonstrated the capture and filtration of the microparticles,.
Keywords: Surface acoustic wave, standing surface acoustic wave, microfluid, particle trapping, particle filtering
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