Research Of Uv-vis Spectrophotometer Automatic Measurement System Based On The Internet Of Things Platform

Uv-vis spectrophotometer,based on the Lambert-Beer's law,is a spectrum instrument which made use of the spectrophotometry to study the material of monochromatic light absorption and analyzed quantitatively and qualitatively for the material.It was widely used in medicine and food testing,agricultural drug residues analysis,chemical and other fields of scientif ic research and production work.In order to further enhance the automation of spectrophotometer,improve the detection accuracy and real-time performance and to meet the demand of development of the Internet of things at the same time,the thesis designed a Uv-vis spectrophotometer automatic measurement system based on Internet of things platform.In this thesis,a new automatic Uv-vis spectrophotometer,on the basis of the type 756 Uv-vis spectrophotometer,was designed by taking consideration of the detection accuracy,automation,speediness and real-time.On the mechanical structure,a simple structure of the single beam and former spectral technology was used on the spectrophotometer.Besides,all the parts of the spectrophotometer were driven by motors,such as light source,filter,grating,the pool,etc.The motors were controlled by the main control chip STM32F103ZET6 to achieve automatic measurement.On software automatic control,the thesis designed a friendly man-machine interface though the LCD and the self-inspection in order to ensure the components were rightness before the detection.What's more,a WIFI module was introduced in the spectrophotometer to connect to the Internet and communicate with the remote ones.In order to ensure the accuracy of wavelength and the stability of the wavelength motor in the process of the wavelength scanning,DC motor servo system was designed with a location and speed double closed loop control system by the encoder position and velocity feedback.A new system of automatic scanning wavelength calibration on spectrophotometer was developed to ensure the accuracy of Spectrophotometer's wavelength.The spectrophotometer automatic scanned and detected according to the instructions from the upper machine,which designed by VB6.0 on PC.The system detected and preserved holmium oxide glass' s absorbance every 0.5nm and the measurement results would be sent to the computer.The procedure of VB was designed in computer which was mainly responsible for processing data,curve plotting,fitting to get the corrected wavelength pulse function on the basis of Sine function in the characteristic wavelengths,and the results would be sent back to spectrophotometer to calibrate.For the data management on the remote,this thesis designed the data management system and remote Monitor ing Server by ASP.NET technology in Visual studio 2008.The socket technology was used for data communication between Monitoring Server and spectrophotometer on real-time.In this system,SQL Server database was used for the preservation of the testing data and user information.Finally,Users can query the management system via a browser after login for data output,and other related operations.By means of measurement experiment on automatic measurement system,the spectrophotometer wavelength accuracy was ± 0.3 nm,and the repeatability of wavelength is better than the 0.2 nm.Furthermore,the transmittance error was less than 0.5%,the repeatability of it is not greater than 0.5%,meet the metering performance ? level requirements.The wavelength scanning speed of up to 70 r/min(660 nm/s).And the remote data management system is stable and reliable.