Research Of Inline Infrared Analyzer For Biological Process

As a kind of emerging technology, industrial biotechnology is an effective means to sovle the energy shortage, economic recession, climate change, population growth, food safety, and environment deterioration. Industrial biotechnology has been highly developed in developed countries; there is a big gap between China and developed countries. In order to implement the "Scientific Outlook on Development", and improve the national core competitiveness, the Chinese goverment has paid more close attention to industrial biotechnology technology. This work is supported by the "National Science and Technology Support Program" and the aim of this work is to design an in-line infrared analyzer to monitor the biological process. The work carried out to explore and research on the key technologies of in-line infrared analyzer.Compared to the traditional analysis methods, infrared in-line situ analysis has lots of advantages, such as rapid, non-destructive, and simple operation. To design an in-line infrared analyzer right, the knowledge of instrumention, optical, precision machinery, electronics, software, chemical quantitative analysis, and biological technology are required. A novel interferometer system that based on the combinations of cube-corner reflectors and fixed plane mirrors was designed to be suitable for the field measurement. A probe that based on the principle of total reflection, can be inserted into the bioreactor, achieve a zero delay detection. Through the processing of spectral data, the information of the component and content in bio-process can be got directly. The main contents of this work include:1. By analysising the basic principle of Fourier Transform Spectrometer (FTS) and interference signal offset theory, compared to a traditional interferometer, the novel interferometer can solve the main problems by optical method. It consists of a pair of cube corner reflectors, two fixed perpendicular plane mirrors and one beam splitter. By analyzing the modulation depth and phase error, the tilt and shearing of the cube corner reflectors, the deviation angle of cube corner reflector, the tilt of fixed plane mirrors and the deviation angle of two fixed plane mirrors is analyzed. It was proved that the tilt and shearing of the cube corner reflectors, the deviation angle of two fixed plane mirrors have no affections to the modulation depth and phase error of this new interferometer system, and the effect from the vibration, temperature fluctuations and other external environmental factors also can be effectively reduced, which can significantly improve the spectral resolution and quality. It was found that the instrument has a simple structure, good sealing, high resolution, strong stability and other advantages.2. The integration beamsplitter is a key optical component of the interferometer, the precisions of the integration beamsplitter affect the modulation efficiency of the interference signal most. Optical adhesive was used to fix all the optical components together; a precision dynamic alignment system was designed to ensure the components staying in the right place, to reduce the tilt error between each component.3. Moving mirror system is the only moving part in FTS, the accuracy of scan and the distance of scan, would affect the signal to noise ratio (SNR), repeatability and resolution of the instrument directly. Two kinds of moving mirror mechanism was designed, one used a linear guide and another used a swing mechanism to support the moving mirror. A suitable feedback control system was designed, to control the sacning precision, the control effect is better than97%.4. By analysising the main parameters of the DTGS and MCT detector, considering the main factors affecting the noise of amplification circuit, a low noise preamplifier and analog filter was designed to ensure the instrument has good SNR. According to the characteristics and problems of the original sampling mothed, a uniform time sampling strategy was designed. The reference laser and infrared interference signals were acquired at the same time, infrared interference signals can be recover through interpolation, and the infrared interference signals were oversampled, digital filtering can be used to improve the SNR and repetition.5. Attenuation total reflection (ATR) technology is a powerful means in situ in-line measurement. Basic principle and characteristics of ATR technique was discussed. The ATR probe can be made up by either Mid-IR fiber optics or Mid-IR hollow waveguide. The ATR probe can be inserted into the bioreactor directly to monitor the bio-process in line.6. In order to realize the quantitative analysis on the reaction of bio-process, a series of spectra preprocess was needed, such as spectra smoothing, baseline correction, and ATR correction, various extraneous information was eliminated to improve the sensitivity and repeatability of the quantitative analysis. By establishing the quantitative model, and can be used to analysis the properties of samples or concertration of components. Ultimately, the bio-process can be tracked and measured in time.