Signal Detecting And Wavelet Denoising For Capillary Electrophoresis Microchip Based On Optical Fiber Embedded

Microchip capillary electrophoresis(CE) has been recognized as a powerful tool for biochemical analyses due to its micro size, fast separation and low sample requirement. CE microchip based on optical fiber embedded arouses people's attention for its small volume, simple detection optical route. However, some noises which affect system's detection sensitivity are introduced into the signal because of the influence of high voltage, instrument, chip structure and some other factors. So the study of signal detection of optical fiber embedded CE microchip and signal denoising disposal is discussed in this paper base on the theory of laser-induced fluorescence.Cross and curving CE micro chips were designed and manufactured using MEMS technics upon many experiments in this papaer. The high voltage system was improved which realized operations of repeated injection and separation and signal auto-detection. The system application software based on VC++ was developed which realized functions of data communication, display, saving and so on. The whole detection system was constructed and the lowest concentration detection and separation detection of Rhodamine B and Rhodamine 6G were completed. According to the character of CE signal and noise, the simulated CE signal was produced using Matlab software. Three typical wavelet sets, level of decomposition and threshholding method were evaluated by choosing denoising criterion. The sym4 wavelet with a level decomposition of 5 and the all levels thresholding method were conformed as the optimum denoising strategy. Compared with Fourier transform, wavelet denoising could remove the noise adequately, reserve the character of useful signal and achieve a better preservation of the shapes of signal. Using the optimum denoising strategy, a good result was obtained. The result shows that, this detection system has some characteristics, such as compact structure, high sensitivity and repetition, which are favour to the development of micrmation and integration of micro CE chip.