Microphotoelectric Detection Design Of Cell Fermenter

Cell fermenter bioreactors are generally used to grow biopharmaceuticals such as vaccines.Now the cell culture of cell fermenters is observed by opening the fermenter directly and then observing it with an inverted microscope.This kind of observation is easy to cause pollution inside the tank in the process of opening the fermenter.Therefore,this paper proposes a photodetection scheme for non-contact cell observation by erecting a microscopic system outside the fermenter.The existing inverted biological microscope has insufficient working distance,and its own light source has a large divergence angle and low energy to illuminate the cells;while the industrial microscope with sufficient working distance has a resolution of at least 10 ?m,but the size of the plant and animal cells cultivated is 10-20 ?m,so clear cell images could not be obtained.In order to meet the system specifications,a non-contact,anti-reflection combined long working distance zoom photodetection system is designed.The system adopts xenon lamp as the light source;innovatively proposes the combination of Cassegrain system and Liszt objective lens to solve the shortcomings of large refractive aberration of the refractive structure,meanwhile,the circular aperture solves the problem that the Cassegrain system produces stray light.The system magnification is 3-5 times,the working distance is 40 mm,the object side numerical aperture is 0.18-0.3,the resolution can reach 1.17-1.96?m,and the on-axis point is greater than 0.1 at the CCD cutoff frequency of 133lp/mm,which is larger than the human eye's limit resolution threshold 0.05.In this paper,the image quality is analyzed.The ZEMAX macro program is used to draw the cam curve of the system,and the system is sampled and tolerance analyzed.According to the characteristics of low illumination and uneven illumination of the images collected by the system,in order to improve the effect of cell observation,the improved Retinex algorithm is used to enhance the image,and the collected images are subjected to cell counting.Because the cell spacing in the captured image is too small,and makes it difficult to segment the cells,this paper proposes an algorithm,which using the Otsu threshold coarse segmentation first,and then employing K-means fine segmentation,next,using the mathematical image processing and median filtering to smooth the segmented images,and finally using the connected region labeling method for cell counting.Its counting accuracy can reach more than 97%.The detection system realizes non-contact observation of the whole and the part of the cells under different working conditions at different magnifications,thereby avoiding contamination of the cell fermentation tank during the observation of the cells.