Research And Design Of Portable Colloidal Solution Concentration Measuring Instrument Based On STM32

The development of science and technology is accompanied by the development of natural resources,among which concentration detection is of great significance in the fields of water resources exploration,environmental monitoring and scientific research.At present,the domestic and foreign liquid concentration measurement technology is relatively mature,but these methods and equipment are mostly applicable to laboratories due to environmental restrictions,and it is difficult to bring them to the field for field investigation and measurement.The source project of this subject involves the measurement of the concentration of unstable colloidal solutions.After field sampling,it cannot be placed and carried to the laboratory for a long time for measurement.Therefore,it is necessary to design a portable colloidal solution concentration measurement instrument to meet the requirements of field measurement.To improve the timeliness and accuracy of outdoor measurement.This research is mainly aimed at measuring the concentration of colloidal solutions in the field.The colloidal solution has Tyndall phenomenon,and it will change with the change of the concentration of the colloidal solution.Under the condition of a constant light source signal,the light intensity of the Tyndall phenomenon has a certain correlation with the concentration of the colloidal solution.Therefore,the Tyndall intensity can be calculated by detecting the optical characteristics of the Tyndall light path to obtain the colloidal concentration parameters.The early members of the project team used the image sensor as the component to measure the Tyndall strength,calculate the concentration of the colloidal solution,and achieved certain research results.In order to improve the measurement accuracy and practical effect of the instrument,this thesis uses photoelectric sensors to measure the Tyndall intensity.By recording the Tyndall strength of a large number of colloidal solutions of different concentrations,the relationship model between it and the concentration of the colloidal solution is established,and the model coefficients are calibrated and determined by using a gradient dilution sample within a certain range,and the colloidal solution concentration can be calculated finally.Design a portable automatic concentration measuring instrument according to project requirements.Which can operate the sample to be measured to an appropriate measurement station under the control of a stepper motor,and the semiconductor laser light source can output a red laser source with a wavelength of 650nm and a power of 10m W under the drive control circuit Irradiate the reagent bottle,use 2DU6silicon photocell sensor and OV5640 image sensor to collect Tyndall optical path information in the direction perpendicular to the optical path.Completed the design and production of the"portable colloidal solution concentration measuring instrument",using STM32H743ZIT6core processor and USART HMI display screen.Independently write instrument software under the support of STM32H7**library functions.Finally,uses the designed instrument to conduct colloidal solution concentration measurement experiments to verify the feasibility and accuracy of the measurement method,and compare the measurement results of the two methods with two different colloidal solutions.The experimental samples selected the nano gold colloidal solution with a concentration of 5.518×10^-5g/ml and the ferric hydroxide colloidal solution with a concentration of 2.230×10^-2g/ml,and obtained 20 samples with different concentrations after quantitative gradient dilution.In view of the error caused by the operation,in the actual test,5sets of solutions were independently configured,and the Tyndall strength was measured separately,and then the data was regression analyzed using the least square method to establish the relationship between Tyndall strength and concentration,and use the established model to calculate concentration.The experimental results show that the instrument can realize real-time measurement of the concentration of colloidal solution without being affected by the external environment,and meet the requirement of taking and measuring immediately after on-site sampling.And within the selected concentration range,compared with the image sensor,the measurement accuracy is improved when the photoelectric sensor is used,and the measurement error is stably controlled within the expected range.