Study Of Photothermal Actuator Technology And The Development Of Micro Photothermal Drive Mechanism

Micro/nano technology is a newly developed interdisciplinary subject since the end of 20th century. With the rapid development of micro/nano technology, there are new requirements on micron, submicron and nanometer order drive and positioning technology. Research and development of new micro drive mechanism, which has more excellent performance, easy miniaturization and new power source, is important and urgent. A novel type of photothermal micro drive technique is introduced and developed in this dissertation for the first time, and a variety of micro photothermal drive mechanisms are designed and manufactured, which has new principle,simple structure, adjustable displacement output, convenient operation, easy integration and the advantages of remote control. It is a kind of innovate micro drive mechanism with comprehensive application prospect, and will be quite useful for the applications in the fields of micro/nano-technology.The dissertation carries out complete and systematic research on micro photothermal drive mechnism, and establishes its thermotics and structural mechanics model. By analyzing micro photothermal expansion effect, thermotics model of photothermal mcro drive is built. Based on simplified one-dimensional model, we get general expressions of static temperature distribution of photo thermal expansion arm and its static length increment. Furthermore, based on virtual work principle of the linear deformation system and actuators'actural structure, we analyze the deflection law of photothermal actuators composed of flexible hinge, and establish structural statics models of basic, single-arm optimized and dual-arm optimized photothermal micro atuators. By deducing these analytical solution, the theoretical deflection formulas are gained. Thermal and structural dynamics models are provided on the basis of the static models, that bring up expressions of transient deflection and dynamic response while actuated by periodic laser pulse. These models and analyses provide a certain theoretical basis for micro photothermal drive mechanism design.Based on theoretical models and analyses, the structural parameters of photothermal micro actuators and drive mechanisms are optimized. High density polyethylene (HDPE) has large expansion coefficient, low thermal conductivity and well-matched spectral characteristics, therefore it is chosen as optimal photothermal expansion material. Using excimer laser micromachining technique, we design and manufacture a variety of structures, sizes and types of micro photothermal drive mechanism, including micro expansion arms, asymmetric photothermal micro actuators, symmetric photothermal micro actuators, unidirection switching photothermal micro actuators and bidirection switching photothermal micro actuators. Besides, photothermal motors and walking devices are designed and manufactured using of shape memory alloy material.A photothermal control and microscopic detection system is studied and developed. It consists of photothermal control module, microscopic monitor module and analytical measurement module. The drive laser beam is produced by photothermal control module with direct intensity modulation, which waveform, pulse frequency and laser power is controlled by software. Based on subpixel image matching algorithm, CCD coupled microscopic monitor system has subpixel resolution, that can real-time observe and measure the deflection of micro photothermal mechanisms actuated by different laser pulse, and analyse their static and dynamic micro displacement characteristics.Experimental study of micro photothermal drive mechanism is carried out by using self-produced photothermal control and microscopic detection system. Micro photothermal actuator activated by laser source with different frequncy and laser power, is put into practic for the first time. Experimental study of static and dynamic response characteristics of photothermal micro expansion arm, indicates that the one-dimensional model is correct and feasible. Based on these, we also carried out experimental study of motion characteristics of micro photothermal drive mechanism, (including asymmetric photothermal micro actuators, symmetric photothermal micro actuators, unidirection switching photothermal micro actuators and bidirection switching photothermal micro actuators), and measure and analyse their static and dynamic response characteristics. The results agree with the theoretical predictions, that prove the accuracy and feasibility of the structural mechnics model. The experiments show that, the drive performance is quite well,and optimized micro drive mechanisms will be quite useful for the applications in the fields of micro/nano technology.The achievements and innovations of this whole subject are concluded at the end of this dissertation. Meanwhile some insufficient points of our works are pointed out, and some directional advices on how to continuing future work are provided as well.