| Capillary electrophoresis microchip is an important branch of microfluidic analysis system, which has many advantages such as high-efficiency, high-speed, high-throught, low cost and so on. It has become a significant method in the research field of clinical medicine, genetic diagnosis, drug screening and protein. The composition and content of sample are determined by the detection system in the process of biomedical analysis with capillary electrophoresis microchip. So, the accuracy, sensitivity, response time and application range of microfluidic analysis system are determined by the performance of detection system. Compared with traditional analytical instruments, higher signal to noise ratio, higher accuracy and integration, faster response, and smaller size of detection system are required in the application of capillary electrophoresis microchip analysis system. Therefore, capillary array electrophoresis microchip and detection system has been studied aiming to integration and miniaturization.In this dissertation, fabrication technique of microfluidic channels were studied and capillary array electrophoresis microchip were also fabricated using the chrome blank as substrate on the basis of detection principle and system structure for capillary electrophoresis microchip. Immediately afterwords, a scanning laser induced fluorescence detection system for capillary electrophoresis microchip based on single-mode optical fiber has been established using a green diode pumped solid-state laser as excitation source. It includes laser induced fluorescence detection subsystem, capillary electrophoresis microchip, mechanical scanning platform, channel identification unit and fluorescent signal processing subsystem. Two V-shaped detecting probes composed of optical fiber for transmitting the excitation light and detecting the induced fluorescence were constructed. Parallel four-channel signal analysis of capillary electrophoresis was performed by this system using Rhodamine B sample solution. Furthermore, the separation and distinction of different concentrations of Rhodamine B sample were achieved with the constructed detection system. The lowest detected concentration is1.4×10-5mol/L for Rhodamine B sample. The results show that the constructed detection system possesses some advantages of compact structure, low cost, and better stability which could be used as reference to the design and optimization of laser induced fluorescence detection system for capillary electrophoresis microchip. A cross-polarization scheme and vertical multi-layer structure is presented to filter out the excitation light from the emission spectrum of fluorescent dyes using green light emitting diodes as a light source and a linear charge coupled device as an intensity detector in order to improve signal to noise ratio and decrease detection limit of system. The excitation light was linearly polarized and was then used to illuminate the fluorescent dyes in the microchannels of a capillary electrophoresis microchip. The detector was shielded by the second polarizer, oriented perpendicular to the excitation light. The fluorescent signals from Rhodamine B dyes were measured in a dilution series with resulting emission signals and four different concentrations of fluorescent dyes were detected simultaneously with the same excitation source and detector. A limit-of-detection of1.4×10-6mol/L was demonstrated for Rhodamine B dye sample under the optimal conditions including the driving voltage of light emitting diode, the two polarizers’ polarization angle, and the diameter of pinhole.Organic light emitting diode devices were designed and fabricated using POAPF:Ir(ppy)3as the emitter layer in order to be integrated with the detection system as the light source easily. The detection system is composed of green organic light emitting diode light source, two polarizers, capillary array electrophoresis microchip, pinhole, photoelectric device, high-voltage power supply, data acquisition card, and data processing unit. At the same time, the sensitivity can be adjusted by the electronic shutter feature of charge coupled device. The flexibility and reliability were improved with the random set of data acquisition channel through the programming of host computer. Micro lens array films were affixed on green organic light emitting diode device’s glass base to enhance the light intensity of incident light. LightTools software was utilized to simulate the influences of hemispherical micro lens array’s duty cycle, contact angle and lens’ diameter on green organic light emitting diode device’s external quantum efficiency and then optimal structural parameters were confirmed. At last, the electrophoretic separation of Rhodamine B sample solution were made using the green organic light emitting diode as light source, the cross polarization method coupled with the adjustable sensitivity of charge coupled device and the limt-of-detection of system is1.2×10-6mol/L... |
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