Research On The Fabrication Of Absorbance And Contactless Conductivity Flow Through Detection Cell By 3D Printing

Some of the customized devices used in scientific research instruments have complex structure,high accuracy requirement,but low commercial demanding.When using the traditional techniques to manufacture these devices,there are many problems,such as high time and labor consuming,large waste rate,high cost and long processing cycle.These problems also limit the promotion of new devices,making it difficult for the users to learn from each other.Compared with traditional manufacturing methods,3D printing has the advantages of integration of design and manufacturing,low-cost realization of complex space structure,which provides a lot of convenience for the flexibility and miniaturization of instrument manufacturing.In view of this,the study intends to take the advantages of 3D printing to study the manufacturing methods of absorbance flow cell and capillary contactless conductance detection cell by 3D printing,to provide a technical support for the development of miniaturized online absorbance photometer and portable electrophoresis apparatus.The content of this paper is divided into three parts:(1)A colorimetric absorption detection flow cell made by Fused Deposition Molding(FDM)is developed.The flow cell adopts colored transparent material to print the flow cell body to filter stray light,which realizes the single material and one-step 3D printing to make the flow cell for colorimetric absorption detection,reducing the manufacturing cost and the manual assembly.The effective pathlengths of 10,20,30,40 and 50 mm printed flow cells were 8.4,19.2,28.2,33.9 and 45.7 mm,respectively.The 10,30 and 50mm pathlength detection cells were combined with a flow injection analysis instrument.The linear fitting equations of the obtained calibration curves had R~2?0.9991,and the limits of detection(LODs)were 0.27,0.087 and 0.045?m,respectively.(2)In order to solve the problems of large size and difficult assembly and alignment of the Capacitively Coupled Contactless Conductivity Detection(C~4D)cell,the multi-material 3D printing technology is used.A conductive material was employed to print the shielding shell of C~4D cell and a non-conductive material prints the insulation support,which reduces the size of the detection cell and simplifies the manufacturing process.In order to test the performance of the printed detection cell,an automatic sample injection capillary electrophoresis platform was built.The electrophoresis platform included the human-computer interaction interface programmed by Lab VIEW,the hardware circuit with STM32F103 series chip as the control core,and the controlled components for sample flow-through injection and electrophoresis.According to the experiment,when the excitation frequency was 153.8 k Hz,the 3D-printed C~4D cell had good performance.Under this condition,the peak area of the printed detection cell had a good linear correlation with analytes concentration.The sensitivity of the printed detection cell could reach 79.41-84.33%of that of the commercial detection cell.When the effective capillary lengths were 18 cm and 22 cm,the LODs were 0.673-1.359?M and 0.322-0.670?M,respectively.The repeatability of the detection cell expressed as RSD%were between 3.674-4.568%.(3)A method of building capillary colorimetric absorption detection cell by FDM printing was developed,and a test platform was designed and built to test the performance of the detection cell.To solve the problems of high cost,difficulty in manufacture and low success rate of capillary scale detection equipment,a on capillary colorimetric absorption detection cell was designed by taking advantage of the 3D printing technique in making hollow structure and in flexibility of design and manufacture.The detection cell adopted a double-slit staggered structure,and the two wide slits that could be made repeatable and stable were staggered along the optical path in the axial direction,creating a thin slit of about 100?m.The detection cell had an effective optical path length of 35.7?m for a capillary with an inner diameter of 50?m.Compared with a literature reported detection cell made by 3D printing,the effective optical path length of this detection cell was longer and the success rate of manufacture was higher.