Development Of Floating Bacteria Sampler With Automatic Flow Calibration

With the rapid development of society and the continuous improvement of living standards,people pay more and more attention to food safety and medical safety,which prompts such enterprises to have more and more stringent requirements for the concentration of plankton bacteria in the production workshop,and the research of plankton samplers has also been used.The Anderson impact method principle is widely used in plankton samplers,and a microporous planktonic bacteria sampler with self-calibrated flow rate was designed based on the Anderson impact method.The main research contents of the paper include:1.According to the research content,the research status of planktonic bacteria sampler at home and abroad was introduced.The application of Anderson impact principle and the importance of stable flow rate of the planktonic bacteria sampler were emphatically analyzed,and several common impinging planktonic bacteria sampling methods were compared.Several common impingerent plankton sampling methods were compared,and finally the microporous method was used to collect planktonic bacteria,and the method and direction were determined for subsequent research.2.Aiming at the research on sampling flow control of planktonic bacteria sampler,the Venturi differential pressure flow method was used to monitor the collection flow.The atmospheric pressure,temperature and humidity compensation formulas were researched to overcome the problems affecting the accuracy of collection flow under different environments and different altitudes.Finally,the current collected flow value was calculated using the flow calculation formula with atmospheric pressure and temperature and humidity compensation.The current collected flow value was fed back to the system,and the system uses the anti-saturation integral PID algorithm to control the fan to stabilize the collected flow at about 100L/min.3.According to the specific circuit requirements,first of all,for the overall power demand and peripheral circuit drive,the corresponding boost and step-down modules were designed to provide stable power for the system;Secondly,in view of the problem that small signals were easy to receive interference and signal acquisition,the instrument operational amplifier was used to design the signal amplification circuit,and the external shield was used in the acquisition signal circuit to prevent the external environment from interfering with the signal;Then for the switch circuit research,the membrane button one key switch circuit was designed,and the traditional mechanical button was no longer used to switch the machine.4.According to the functional requirements of the software,the software of the planktonic bacteria sampler was developed based on the RT Thread operating system,and the serial port screen is used to realize the human-computer interaction design;Wireless printing and data transmission through Bluetooth;Restrict the function permission according to the password;Realize operator and workshop input and selection,and design corresponding scheme for differential pressure calibration method.All indicators of the whole machine is tested according to the national GMP standards and specifications.After the differential pressure calibration,the measurement accuracy can reach±0.5%,and the flow control accuracy can reach within ±1%.The test results can meet the requirements of the calibration specifications.