Research On The Key Techniques Of Lens-Less Microscopic Imaging And Cell Detection

Lens-less microscopic imaging is a novel microscopic technique developed in recent ten years.Because of its outstanding characteristics of small size and strong integration of the system by leaving out lens and only using image sensor,it provides a good scheme for the development of portable cell imaging and detecting instruments,and has a wide application prospect.However,there are several problems in the lens-less imaging microscopic system,such as diffraction,low resolution and so on.The images collected by the system are difficult to be directly applied for cell detection.Therefore,to improve the imaging quality of the system and to carry out real-time image processing are urgent problems to be solved.In view of the above-mentioned key problems,the following four aspects have been researchedr:1.In order to improve the imaging quality of lens-less imaging,the optical path model is established,the imaging mechanism of lens-less imaging system is studied,and the conditions of contact imaging and in-line holographic microscopic imaging are defined.The imaging recording process and the selection of main design parameters of lens-less in-line holographic microscope are further analyzed.An iterative focusing image reconstruction algorithm based on phase initial value constraint is proposed,which improves the operation speed and robustness of the twin image suppression algorithm.2.In order to improve the spatial resolution of lens-less microscopic images,the method of improving the resolution of living cell images in lens-less in-line holographic microscopic system is studied.Using the super-resolution reconstruction technique in digital image,an improving spatial resolution method based on Brownian motion for living cells is proposed.Finally,the experimental results show that this method can achieve 8 times super-resolution without increasing the volume of the system,which solves the problem of low resolution of the original image.3.The classification method of cell image in lens-less in-line holographic microscopic system is studied.The traditional image feature extraction method of PPED is used to realize the classification of leukocytes by using the distance search of feature vector.By further using the CNN algorithm to classify the leukocytes,the three-classification accuracy rate of the leukocytes images collected by the light microscope can reach 97.78%.In addition,a leukocyte image classification method based on the holographic image is proposed,and the accuracy of the three-classification of the leukocytes can reach 87.65%under the lens-less in-line holographic microscopic system;4.A flow cell counting method based on lens-less in-line holographic microscopic system is proposed.The manufacturing process of PDMS micro-fluidic chip applied to the lens-less in-line holographic microscopic system is developed,and the micro-fluidic chip is prepared.On this basis,a flow cell counting chip based on PDMS microfluidic chip and lens-less in-line holographic imaging technique is designed.The blood cells are counted by the proposed system.The results are compared with that of the full-automatic blood cell analyzer BC-5180,and the relative error is less than 3%.Through the above researches,the number of iterations of digital holographic reconstruction algorithm in lens-less in-line holographic microscopic system is reduced,and the stability is improved.Using Brownian motion inherent in the liquid,the resolution of the image of the cell in lens-less system is improved.On this basis,the classification of the leukocyte image is studied,and the method of holographic image classification of cell based on the convolution neural network is proposed.A high precision cell counting method is proposed by combining lens-less in-line holographic microscopic imaging with microfluidic techniques.These studies improve the practicability of lens-less microscopic imaging system,expand the application range of image sensor,and increase the techniques of cell detection.According to the above research,a small-volume on-chip cell detection system can be realized based on the lens-less imaging technique,a novel imaging scheme is provided for the micro-fluidic technology,an idea is provided for the miniaturization of the cell detection technology,and it is possible to combine micro-electronic technology with cell detection technology.