Abstract
Bacteria exist in our daily environment widely. There are a lot of bacteria in our body. The number of bacteria in the body and the skin is about 10 times larger than the human cells. Bacteria are pathogens of many diseases such as E. coli and Staphylococcus aureus. These lead to disease, causing cystitis, peritonitis, food poisoning and so on. For treating diseases, we need to obtain a specimen to analyze. Generally, different kinds of bacteria cluster together. Therefore, we need to sort the bacteria from the specimen for analysis and study. Owing to the well-development in MEMS technology, to miniaturize the traditional large-scale equipment is the main trends. In this master study, a miniaturized photoelectric-actuated microsystem for bacteria sorting is my main research focus. In this study, Optoelectronic tweezers and positive dielectrophoresis (p-DEP) are two of the main techniques to be utilized for bacteria sorting. The p-DEP force is used to manipulate bacteria. For the microfluidic chip design, the hybrid structure is also integrated at the front end for mixing the specimen and the dielectrophoresis buffer to make bacteria be manipulated by using p-DEP force. After mixing, the unsymmetrical herringbone narrow-gap structure is used to focus the bacteria one by one in a line, and the efficiency of the centralized arrangement over 85%. In the sorting area, Optoelectronic tweezers (OET) is integrated in to make mobile electrode pattern. We use two ITO glasses to form both top cover and bottom substrate. The bottom ITO glass substrate is spin-coated with a photoconductive material named TiOPc (Titanyl Phthalocyanine). When irradiated with a light source of red wavelengths about 700-870 nm, this TiOPc material would become conductive. Therefore, we use different light pattern to induce mobile electrodes to guide desired bacteria to specific direction via p-DEP force. Through this master studies, my goals are to develop miniaturized, low-cost, disposable, low-sample-consumption bacteria sorting microsystem chip which avoids complicated operation and minimizes the waste of the specimen.