Designing And Implementation Of Sampling Device Based On The Space Station’s Automatic Air Microbial Collection

With the implementation of the three-step development strategy of the manned space flight project,China is on the point of entering into the third stage of permanent space laboratory and space station where astronauts stay for a long time.It is necessary that making effective monitoring of space station microbes,as well as conducting risk control and prevention according to the test results to ensure compliance with the requirements.The microbes in the cabin pose a threat not only to the health of the astronauts,but also to the material of space station,resulting in the equipment to malfunction,in severe cases,will lead to even system paralysis.Studies have shown that the chance of microbial mutation is greatly increased,and the toxicity of microbes can be enhanced under the action of complex environmental factors.So it has becoming an increasingly urgent need for automatic collection,rapid detection,as well as effective prevention and control.In order to achieve the target of automatic air microorganism collection and detection on the space station,this study designs and implements a set of automatic air microorganism acquisition and detection device based on microfluidic chip and fluorescence detection technology.The small air pump,liquid pump and solenoid valve are integrated in a small space and the MSP430 as the core of the device after making comparison with the commonly used microbial sampling technology at home and abroad,and combined with the station’s requirement for small load volume,simple operation and high degree of automation.Then the automatic microbiological collection and real-time optical detection can be completed by using oblique excitation fluorescence detection.The volume of device is 200 mm long,150 mm wide,130 mm high.It’s less than 5Kg in weight and less than 10 W in power consumption that meets the basic needs in space stationIn this paper,the design of microfluidic chip is carried out in a lot of work.The material of microfluidic chip is PMMA.The sampling principle is resistance current.The membrane material of microfluidic chip is 0.22 μm cellulose acetate membrane.Layered cross-type structure is designed for the result of separation of gas and liquid.The finite element simulation of microfluidic chip is carried out.According to the simulation results,the optimal chamber size is determined.Air microbial capture rate as more than 70% will be attained.The methods of excitation fluorescence detection and culture detection were designed,in order to realize the quantification of the bacteria and the qualitative determination of the strain.The sensitivity,linearity and repeatability of the two detection methods were tested to insure the consistency.Microorganism collection has been made in different application scenarios to get the data and to confirm the effectiveness of the device.The?air microorganism sampling device of space station this project design can not only provide technical support for the microbiological surveillance and protection of space station in China,but also be applied to the rapid detection of microorganism in different fields,which has great value of space and civil service.