| With the characteristics of micro-scale, compact-size and multi-function, Micro Electro-Mechanical System (MEMS) has been broad applied in the related fields of economy, national defense and high technology and has become the one of the most potential economic growth points in the 21st century. After more than half a century of development, MEMS has forward to the integration of the multi-functional complex hybrid system from focusing on the production of micro components in the past and the demand for the micro-assembly technology has become more and more strong. Meanwhile, with many challenges due to the dimension miniaturization of the application objects, the three-dimensional manufacture with high depth-to-width ratio, the diversity of manufacture process and material in MEMS, the micro-assembly technology becomes even more important and urgent. Moreover, the technical characteristics of the micro-assembly technology are totally different with the macro-assembly technology. Hence, exploring new theories and mechanisms to develop this technology is the most basic and key research subject in MEMS area at present.According to the background above, the research on theory and application of ultrasound-based automatic manipulation for micro-assembly is carried out in this dissertation, which is supported by Key Project of Natural Science Foundation of Zhejiang Province "Research on theory and application of automatic 3D micro-assembly technology based on acoustic manipulation (No. Z1110393)" and National Natural Science Foundation of China "Research on Key Technology of Direct Writing Biological Tissue Based on Acoustic Radiation Force (No.51205351)". The situation and development trend of the micro-assembly and acoustic manipulation technologies are systematically understood. A theory for calculating the acoustic radiation force and torque acting on micro-component with complicated shape in arbitrary sound field is carried out by T-matrix theory. The technologies of long-range transportation based on phase shifting, continuously attitude-controlling based on amplitude adjusting, and compound manipulation based on multi-parameters controlling are proposed and optimized. Meanwhile, micro vision is used to recognize and track the micro-components. By combining the close-loop control strategy of Look and Move and the acoustic manipulation technologies above, the automatic ultrasound-based micro-manipulation is carried out, which lays the technical foundation for micro-assembly technology. The detailed contents and innovative points of this dissertation are presented as below:In chapter one, the signification of the research on the micro-assembly technology and the advantages of applying acoustic manipulation on micro-assembly are systematically elaborated. Through comprehensively analyzing the present research status and development trends of micro-assembly technology and acoustic manipulation technology, the problems and bottlenecks on theory, technique and application of acoustic manipulation are clarified. Meanwhile, the research direction is pointed out and the detailed contents of this dissertation are also listed.In chapter two, the T-matrix-based theory of calculating the acoustic radiation force and torque acting on micro-component with irregularly shape in arbitrary sound field is carried out. By implementing T-matrix to calculate the scattering field of an irregular scatters in arbitrary sound field, a theoretical expressions of acoustic radiation force and torque based on the T-matrix and the G-matrix is derived. Due to reusing of T-matrix and G-matrix, the acoustic radiation force and torque could be easily calculated though the positions and attitudes of micro-components are varied during the process of micro-assembly. The improvement of calculation efficiency lays a foundation for the following study.In chapter three, the methodology of effectively transporting micro-component by shifting the phases of incident ultrasounds is proposed. By controlling the phase-shifting step and phase-shifting velocity of incident ultrasounds, the acoustic potential well is dynamically moved to keep the micro-component in the optimal region. Due to the stable amplitude and same direction as transporting direction of the driving force, the problem of low transporting efficiency caused by unstable driving force is solved. Meanwhile, an zirconium bead is adopted to the transportation experiment, the maximum reliable transporting velocity is up to 29 mm/s and the transporting efficiency is obviously improved.In chapter four, the methodology of continuously controlling the attitude of micro-component by adjusting the amplitudes of incident ultrasounds is proposed, on the basis of analyzing the quantitative relation between the amplitudes of incident ultrasounds and the orientation of the acoustic potential well, the orientation of acoustic potential well is controlled by adjusting the amplitudes of the incident ultrasounds. Thus, the attitude of micro-component could be continuously controlled by the acoustic radiation torque. Meanwhile, the feasibility of 360°attitude-controlling is verified by the experiments with an elongated Si-based micro-particle.In chapter five, the methodology of realizing compound manipulation of micro-components is proposed. By altering the amplitudes and phases of the incident ultrasounds simultaneously, acoustic potential wells with different characteristics are synthesized in a 3D half-space standing wave field. Thus, a compound manipulation of micro-components including trapping, transporting, attitude adjusting and releasing could be realized. Meanwhile, the feasibility and applicability of this method is verified by experiments with the Si-based micro-particles.In chapter six, a methodology of recognizing and tracking micro-component based on micro vision is proposed. On the basis of auto-focus technology using the focusing evaluation function of DCT and the focus-searching algorithm of SOM neural network, the location of micro-component in the multi-scale fields of vision is identified by particle filter algorithm and the detailed position and attitude of micro-component is identified by minimum enclosing rectangle method.In chapter seven, on the basis of recognizing and tracking the micro-component basing on micro vision, an automatic acoustic manipulation is realized combining the close-loop control strategy of Look and Move and the acoustic manipulation technologies above. And an experimental setup for the automatic acoustic manipulation is also established. Meanwhile, the experiment is performed to verify the feasibility and applicability of the methodology proposed in this dissertation.In chapter eight, the research results and the innovative points of this dissertation were summarized, and the future research works are also forecasted. |
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