RFID-based System For Locating,Tracking And Detecting Physiological Parameters In Mice

Mice are often used as experimental subjects in drug research because they are easy to keep and have similar physiopathology to humans.Monitoring their activity trajectory and physiological parameters after drug administration can help in drug optimization and development.Traditional location tracking techniques can be less accurate when tracking mice due to their small range and similarity in appearance,while satellite telemetry is only suitable for monitoring physiological parameters in animals with a large range of activity due to its high cost and the need for a dedicated receiving station for data processing.In order to monitor the activity trajectory and physiological parameters of mice after drug administration for a long period of time,this paper proposes and designs an RFID-based system for locating and tracking mice in cages and monitoring their physiological parameters,as follows:Firstly,the positioning tracking system is designed for the measurement of mouse activity trajectory,which consists of reader multi-antenna array board,multi-antenna selection board,multi-antenna control board and upper computer software.Considering the size of mice,an antenna model was established for the antenna cells of the antenna array board.After analysing the influence of relevant parameters on the equivalent inductance of the antenna,the cell size was determined to be 45x45 mm,and after adding the antenna matching circuit,there was a more uniform magnetic field distribution inside the antenna cells.After designing a reasonable antenna spacing,it was verified that the system could accurately locate the tag position.In order to reduce potential antenna array effects and energy wastage,a multi-antenna selection board was designed,which can control each antenna cell by controlling the timing and RF signals.The setting of the timing signal timer time in the multi-antenna control board and the selection of the relevant chip in the antenna selection board allows the switching time interval between two consecutive antenna cells to be less than 25 ms,ensuring that the antenna cells can identify the mouse’s internal tag during its passage.Secondly,a physiological parameter monitoring system is designed for the monitoring of physiological parameters of mice,which consists of a wireless energy transmission module,an implantable electronic tag,an RFID reader and an upper computer software.The in vitro part of the wireless energy transmission module is composed of the antenna connection board of the read-write,which uses a multi-turn rectangular coil around the mouse feeding cage to power the implantable electronic tag;the in vivo part is mainly composed of the implantable electronic tag antenna and its resonant circuit,and the tag is not loaded with batteries.Considering that the two parameters of body temperature and activity of the mice change most significantly after drug administration,the tag has integrated sensors to measure these parameters.To reduce the burden of the tag on the mouse,the tag was miniaturised throughout the design process,with an overall size of 20x10x2 mm,smaller than a dime.Finally,simulations and biological experiments were carried out after the system was built.In the simulation experiments,the ability of a single antenna cell to read the tag in the positioning tracking system and the temperature measurement performance and activity measurement performance of the implantable electronic tag in the physiological parameter monitoring system were verified respectively,which proved the feasibility of the system performance and provided a theoretical basis for the biological experiments.In the biological experiments,two small subadult mice of around 15 g were used as experimental subjects,and a dose of anaesthetic was administered to the mice followed by implantation surgery.Real-time tracking showed the activity trajectory of the two mice over a period of 5 minutes,with the mice being kept away from each other for the first 1-2 minutes,and then interacting rapidly and frequently over time.The mice were then monitored for physiological parameters for up to 10 minutes,and the results showed that the mice were hypothermic and did not exhibit vigorous activity throughout the monitoring period due to the effects of the anaesthetic,with a body temperature range of34.5-35.5°C and activity levels mostly below 15 mg/LSB.In order to better study the effects of the anaesthetic on the mice,the mice were continuously observed for a further3 hours for changes in body temperature,and after the experiment had been conducted After about an hour and a half,the body temperature of the mice gradually increased and returned to about 37°C,which was the normal body temperature of mice.The experiment proved that the system was able to display the mouse’s activity trajectory in real time and to measure the effective body temperature and activity level.