| Recently,with the development of petroleum,chemical industry,pharmaceutical and etc,gas analysis and detection are required urgently and widely.As an efficient and highly sensitive gas detection technology,gas chromatography has been widely applied in various detection fields.Thermal conductivity detector（TCD）play an important role in gas chromatography system.Compared with traditional thermal conductivity detector,micro thermal conductivity detector（μTCD）exhibit the advantages of light weight,small size and high sensitivity.However,μTCDs require complex manufacturing processes,high manufacturing precision and high cost,troubling further development of micro thermal conductivity detectors.Consequently,no commercial domestic product appear to date.In this thesis,we investigated the optimization and fabrication of the micro thermal conductivity detector,reduction of the difficulty of fabrication,increase of the yield,thus realizing large-scale production ofμTCDs.The main results of thiswork are as follows:（1）We optimized the shape of the thermistor and the structure of the airflow channel,designed various shapes of thermistors,and simulated by COMSOL software.The results show that the stability of the arc type is superior to that of the polygonal type.In addition,thermal and mechanical simulations were carried out through arcs with different angles to investigate the effects of the arc angles on the deformation variables.Comparison revealed that the 180°arc angle exhibits the best thermodynamic stability.The mechanical properties of reticular and interdigital thermistor need to be controlled by reasonable design.（2）The manufacturing processes of thermistors were investigated.Consequently,thermistors with different process conditions and shapes were successivefuly fabricated.Results reveald that the arc-shaped thermal element is more rasily to be peeld than that of the traditional angled thermaistor.Moreover,the resistivity of the Pt metal film deposited by the magnetron sputtering method is 14.8×10-8Ω·m,which is about 12%lower than that of the Pt metal film deposited by electron beam evaporation.（3）The manufacturing processes of the micro-bridge structure were investigated,by which the air flow channel with high aspect ratio were fabrication by dry etching.Double layer common glue or single layer thick glue were used to prepare thick glue masks,respectively.After optimizing the manufacturing parameters,thick glue masks that meet the etching requirements have been yielded.（4）After layout design,mask manufacturing,process optimization and etc.μTCDs with the size of 5×5 mm~2 have been successfully fabricated,and their performance were tested.The test results show that the device can detect five gases,including methane,propane,isobutane,n-butane and n-pentane,where the analysis time is about 18s,and the time from injection to analysis is 2 min.In addition,the detector package strength test shows that the bonding strength of the self-design and fabricatedμTCDs can reach 11MPa,which meeting the strength requirements of the device. |
