Research On MEMS Endoscopic Scanning System For Medical In Vivo Detection

With the development and progress of minimally invasive surgery,endoscopes are playing an increasingly important role in medical assisted diagnosis due to their advantages such as small wounds and fast postoperative recovery.Medical endoscopes are often used for diagnosis,treatment and biopsy sampling in surgical applications.Doctors can observe human pathological changes in a minimally invasive environment through an endoscope,so as to make timely diagnosis of the disease.In recent years,the endoscopic scanning systems based on Micro-electromechanical Systems(MEMS),have some advantages such as compact structure,miniaturization,convenient portability,and fast scanning speed.MEMS has attracted the attention of researchers in medical and biological fields,which is one of the current research hotspots.At the same time,the main components of the traditional MEMS endoscopic scanning probe developed in the past include single-mode fiber,gradient index lens(G-Lens),MEMS micromirror,convergent lens,and flexible printed circuit board.Although the G-Lens has been widely used in previous applications,the short working distance of G-Lens will limit the scanning range of the probe.Compared with G-Lens,the cylindrical lens(C-Lens)has better focusing ability,longer working distance and easier manufacturing than G-Lens.These advantages show that it is a good component for constructing MEMS endoscopic scanning probe.First,the single-mode fiber and C-Lens were combined to form an optical component;then,the optical component and MEMS micromirror were used as the main components to complete the packaging of the endoscopic scanning probe;finally,the endoscopic scanning probe was used for achieving the system test.The main research contents and results were as follows:1.The optical path diagram of MEMS endoscopic scanning probe was drawn by the optical design software to complete simulation evaluation.The working distance of the C-Lens and the distance between the C-Lens and the end of fiber were determined via the optical path design diagram;in addition,the distance between the lens and the micromirror,the scanning angle and the scanning range of the micromirror were also determined.2.According to the various parameters of the simulation design,3D drawing software was used for 3D modeling of the endoscopic scanning probe.After the processing parameters were obtained,the design and packaging of the endoscopic scanning probe were completed.The outer diameter of packaged probe was 2.6 mm and the length was 8.8 mm.3.QT was used as a software development tool to build the image acquisition interface of the system.Scanned images of overlapping slides were obtained by the operating interface of the system image acquisition and the MEMS endoscopic scanning probe.The results showed that the lateral resolution of the system was 75μm and the axial resolution was 12μm.Moreover,scanned images of human skin,pig small intestine and pig stomach were also obtained,its the scanning range of the probe was 4.0×4.0 mm~2and the imaging depth was2.5 mm.The MEMS endoscopic scanning system designed in this paper had the advantages of long working distance,large scanning range,high resolution,compact structure,etc..It is expected to be used in the field of biological scanning detection and imaging analysis in the future.