The Experimental Research Of Controllably Synthesizing Gold Nanoparticles Based On Surface Acoustic Wave

As a new way to drive microfluid, microfluidic actuation based on surface acoustic wave(SAW) has not only great academic significance in microfluidic field, but also high application value in chemical, biological, pharmacal and other fields.Based on the previous study of using pulsed mixing method with piezoelectric actuator to synthesize gold nanoparticles, a method of controllably synthesizing gold nanoparticles using the SAW technology is presented. By changing peak-to-peak load voltage of two types of SAW microfluid disturbance systems and function time on gold nanoparticles, the disturbed synthesis of gold nanoparticles can be controlled. The main contents of the thesis are as follows.First, the basic structure and operation principle of SAW device are introduced. The selection of piezoelectric material is discussed, and the 128° YX-LiNbO3 crystal is finally used as the substrate material in this experimental research. With the analysis of the basic structure and δ function analysis model of inter digital transducer(IDT), the basic parameters of this experimental research are designed, and the piezoelectric constitutive equation is sketched.By MATLAB simulation, the number of IDT and input signal frequency are optimized. The results, which are obtained by piezoelectric simulation of the SAW systems in this experiment by ANSYS, are nearly in agreement with theory. After simulating the PDMS microreactor without SAW by the software FLUENT, the distribution of fluid velocity in microreactor is obtained, which provides the gist for subsequent experimental research.The two kinds of SAW microfluid disturbance systems designed in this paper are orthorhombic system and rotary system, which are different in the arrangement of IDTs. The micro-fabrication technique of SAW devices is studied, and the SAW devices are manufactured by lift-off technology. PDMS microreactor is made by cast molding, and then the two kinds of SAW microfluid disturbance systems are produced with encapsulation and bounding post processes.Finally, the SAW microfluid disturbance systems made by the author were used in the experiment of the controllable synthesis of gold nanoparticles. The related experimental apparatus and the specific experimental procedures are introduced. By adjusting IDT peak-to-peak load voltage, changing function time on gold nanoparticle solution and using different types of SAW microfluid disturbance system, gold nanoparticles with different concentrations, morphologies and dispersities are synthesized, which verifies the controllability of gold nanoparticles synthesis using SAW. The experimental results suggest that, under the condition of using rotary SAW microfluid disturbance system with peak-to-peak load voltage of 35 V and function time of180 s, the effect of gold nanoparticles synthesis is the best.