Development Of Oscillometric Non-invasive Blood Pressure Simulation System

Background Blood pressure simulator is a device that simulates cuff pulse wave during inflation and deflation by oscillometry,and is an important instrument for daily verification of electronic sphygmomanometers.In 1975,Burton Klein of Cambridge University and his team applied for a patent for an ambulatory blood pressure simulator in the United States.This patent proposes to use a pressure chamber with flexible volume to simulate the vascular environment of human body,and then to simulate the dynamic blood pressure of human body by monitoring and changing the pressure change in the pressure chamber.Cufflink can not only realize dynamic blood pressure simulation by envelope playback method,but also has the functions of static pressure measurement,leak test and bleeder valve test.the abnormal blood pressure value is stored in the product at the same time,which is convenient for simulation of abnormal blood pressure value.At present,although domestic non-invasive blood pressure simulators have entered the market continuously in recent years,the market share of domestic non-invasive blood pressure simulators is quite different from that of imported products.Apart from a certain gap in product stability,one of the reasons is the small number of research teams on this subject.At the same time,the share of electronic sphygmomanometers in our country is still at a relatively low level.With the increasing awareness of people’s health,the demand for non-invasive electronic sphygmomanometers is bound to continue to increase,which also puts forward higher requirements for non-invasive blood pressure simulators used to verify non-invasive electronic sphygmomanometers.Therefore,it is an inevitable trend to study noninvasive blood pressure simulator.Objective To design a noninvasive blood pressure simulation system that can be used for noninvasive electronic sphygmomanometer detection based on oscillography using STM32 series microcontroller.The system is required to have two functions: static pressure test and dynamic blood pressure simulation.Methods Blood pressure simulation system is divided into three parts: mechanical platform design,hardware circuit design and software program design.The design of mechanical platform includes pulse wave generating platform and pneumatic device.Hardware circuit design includes power supply circuit design,core control circuit design,LCD display circuit design,pressure acquisition circuit design,A/D conversion circuit design,stepping motor and pneumatic device drive circuit design and matrix keyboard drive circuit design,with a total of six parts.The software program design includes two parts: hardware bottom driver and system function program.Results The static pressure test function of the blood pressure simulator was realized by controlling pneumatic devices such as air pump,electromagnetic valve and pressure sensors,i.e.pressurizing the air chamber to a certain pressure and maintaining or deflating it.The maximum pressure that the simulator can generate is 255 mm Hg.By controlling the stepping motor to generate a pulse waveform with a specific amplitude at a certain pressure value,the pressure waveform of the blood pressure group of systolic blood pressure 120 mm Hg,diastolic blood pressure 80 mm Hg,and pulse rate 80 bpm was achieved.Conclusion The noninvasive blood pressure simulator based on oscillography designed by this subject uses simple mechanical device and STM32 series microcontroller to realize the two major functions of verifying the noninvasive electronic sphygmomanometer based on oscillography,namely static pressure test and dynamic blood pressure simulation.The realization of the system is based on the flexible application of embedded system,including LCD display,matrix keyboard control,precise control of stepping motor,etc.,which further promotes the application of embedded system in the field of medical electronics.