The Design Of Lung Cancer Breath Detection Instrument Started From Structural Design

Lung cancer is one of the most dangerous diseases, the mortality of it topped the list of all tumor diseases at present. The early detection of lung cancer can increase the cure rate of patients obviously, but a special lung cancer detection instrument that can achieve high-efficiency and low-cost is lacked still in clinical application. Some special materials in human exhaled air are closely related to lung cancer that can be used to judge whether a man has lung cancer or not, that is to say, we can use these materials as tumor markers when detection. The novel breath detection method based on chemical sensors has the advantages of fast-response, high-sensitive, low-cost, etc. It is a promising way to achieve the early screening of lung cancer, and then increase the survival rate of patients.The development steps of traditional instrument that without reference machine as followings: fundamental research, making principal prototype, designing production machine. The design of principal prototype takes top-down approaches in most cases, and focuses on function design of electric and machinery, which includes electric and machinery schemes, module division, parameter calculation, parts selection, etc. For some of research steps, if the structure of principal prototype is simple, or have basic reference machine already, or the accuracy of instrument can be influenced by structural design, we should take structural design into consideration at the beginning of whole research plan. For the lung cancer breath detection instrument mentioned in this paper, the accuracy and function and market prospect of this instrument could be influenced by the results of structural design, so that we take structural design as a very important step. We take top-down approach as design strategy to design the instrument structure at first, so that can shorten the development circle and present the instrument's function finally. On the other hand, this design can provide significant reference for other instrument design, the research of this paper has very important realistic significance in promoting rapid development of modern instrument.Based on related design requires, the major work of this paper includes the following aspects:1.According to the functional requirements. Design the shape structure of lung cancer breath detection instrument, put forward the advantages of the instrument design based on top-down approach, card the overall structural design processes of instrument, and make use of ergonomics, styling science, color science, materials science and other related science in appearance design method into the shell design of lung cancer breath detection instrument, accomplish the modeling and fabrication of the shell finally.2.Analysize the detection processes of breath gas of lung cancer, summarize the demands which should met in design process and the shortages in the old system that our team designed before. Optimize the gas path structure, set gas detection module as design core to simplify the design of gas path, solve some shortages in old system such as poor leakproofness of reaction gas chamber and inconvenience when pick and place porphyrin sensor chip. Design a novel device that can adjust the camera in multi-directions, solve the shortage that cannot adjust the location of camera, improve the accuracy and flexibility of instrument. Design a absorber used in micro air pump, solve the shortage that micro air pump vibrate too fierce in old system, improve the stability of instrument.3.According to the over-all structure of instrument and its functional requirements, use upper and lower machine control mode as hardware structure. Take Tiny6410 as upper computer as master platform for image capture, image procession, feature extraction, pattern recognition, result analysis and issue orders for lower machine to complete related actions. Take PIC16F877 A as lower machine as control core, according to different actions and functional requirements, design a whole lower machine system with temp control module, temp and humidity monitor module, power module, micro air pump speed-control module, solenoid valve control module, gas detection module and communication module. According to the requirements of different module and detection processes, use MAPLAB software to complete programming of whole upper-lower control system, which including temp control program, micro air pump speed control program, temp and humidity monitoring module program, etc.4.Test the working performance of main functional modules in instrument and main parameters, and take one of tumor markers in exhaled air as sampling object to test the effect of whole assembled instrument, set up testing matching template through massive experimental data finally.