Fabrication Of MEMS Devices Used In Biomedical Detection

As MEMS (Micro Electro-Mechanical Systems) technology progresses rapidly, the synergism between MEMS and biomedical technology becomes closer than ever before. When the uTAS (Micro Total Analysis System) was introduced in the last two decades, many microfluidic chips, microelectrodes, and microreactors are being studied for drug detection, environment detection, gene analysis etc. Due to its small volume, low pollution, low consumable and good portability, uTAS plays a very important role in biomedical, biochemical, environment engineering fields.In this dissertation, microfluidic chips used in chemiluminescence and fluorescence detection, microelectrodes used in electrochemical detection, and blood separation chips based on LTCC layers were fabricated using MEMS Fabrication Process. These microchips are useful for many biomedical and biochemical detections and enable real-time lab-on-a-chip applications.Microfluidic chips were fabricated on soda-lime glass. After photoresist application, UV light exposure, developer and wet chemical etching, the micro-channels are fabricated on the glass substrate. After an oxygen plasma treatment on the PDMS and glass substrate, the PDMS layer can form a good seal on the micro-channels. This thesis discusses the process parameters in detail and compared to the process such as anodic-bonding and soft-etch process. The test results show that the PDMS can seal the glass substrates with the micro-channels tightly after the oxygen plasma process. There is no fluid leakage when a high-pressurized fluid flows through these micro-channels.Microelectrodes were fabricated on the soda-lime glass. The electrodes arrays were fabricated using a process sequence of photoresist applications, UV light exposure, developing, gold sputtering, patterning, and etching. Two types of microelectrodes with different diameters were fabricated using this process. In this thesis, the fabrication processes are discussed. N-acetylcysteine was first assembled on microelectrodes'surface to form a self-assemble monolayer, and then the modified microelectrodes were activated by EDC and NHS, monoclonal antibody enterotoxin C was immobilized on the self-assemble monolayer to form the amperometric immuno-biosensors in the end to to detect the enterotoxin C antigen. Cyclic voltammetry is used to investigate the electrochemical behaviors of Fe (CN)6^3-/4-on the SAM modified microelectrodes and the electrochemical behaviors between the antigen and antibody. From the test results, we can see the microelectrodes arrays have some good characteristics such as low detection time, high sensitivity and easier operation ways. They can be used to do the electrochemical research of the self-assemble monolayer and they can also be used to do the qualitative assay about the reaction with antigen with antibody.The blood micro-separators were fabricated using a low-temperature co-fired ceramic (LTCC) technology. The separator includes several vertical micro-jets and horizontal distributors. Separation efficiency of different blood cells depends on the centrifugal force created when the blood passes through the bent micro-channels. ANSYS software was used to simulate the flowing of blood in the separator. The LTCC fabrication process involves punching, lamination process, cutting and sintering processes. These processes are discussed in the thesis. The tests show that the LTCC blood separation can separate the white blood cells better than the red blood cells and the micro separator can be used to make the Preliminary separation.