| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 94 === Last year, we set out to study the mechanism of living cells, and we purchased the optical instruments to set up an optical tweezer system. This thesis contains two parts. In the first part we introduce the theory of the optical trapping, the working theory of optical tweezers, the constructing and alignment procedure. Now we have constructed a system that can be applied to study the living cells. We also experimented with the 5μm microspheres to investigate the trapping force and the stiffness of our optical tweezers, preparing for the future work of biologically research. In the second part we focus on the Brownian motion and the measurement of viscosity. We used the microscope to observe the Brownian motion of 1μm microspheres and recorded them by CCD camera. Using the theoretical formula we can obtain the relation between the mean squared displacement of the particles and the medium’s viscosity. By experimenting repeatedly we got a lot of data and use the statistical method to compute the viscosity of water. The experimental value is precise and satisfactory. Therefore we used the same method to examine the unknown liquids. We only needed a small quantity of liquid to measure the liquid’s viscosity, and the method is different from any other traditional method. In the future, we can apply the technique to explore the microcosmos.
|
|---|
