Research On Flexible Ultrasonic Micro Sensor For Arterial Blood Pressure Detection

Hypertension,coronary heart disease,blood viscosity and many other cardiovascular diseases have become serious diseases that threaten human health worldwide.The number of deaths due to cardiovascular diseases is increasing year by year.Therefore,early prediction of cardiovascular diseases has become a research in the medical field.One of the key points.At present,rigid probes are used in clinics to continuously detect arterial pressure of the human body,but these commercial detection products cannot achieve real-time,continuous and long-term monitoring of the human body.Therefore,this research group intends to develop a flexible ultrasonic micro sensor that can realize miniaturization,integration and intelligence,which can be worn on the human wrist to realize real-time blood pressure waveform monitoring.This non-invasive monitoring method provides hardware support for the prevention of cardiovascular diseases and the improvement of smart medical micro-systems.First,explore the propagation mechanism of ultrasound in human tissues,study the basic principle of pulse echo method for detecting the diameter of human blood vessels,and consult relevant literature to obtain a model of the relationship between human arterial pressure waveform and blood vessel lumen diameter.Then study all the components of the flexible sensor unit: encapsulation layer,flexible electrode layer,piezoelectric layer,adhesive layer and acoustic matching layer,combined with the finite element simulation software Comsol multi-physics coupling function to explore the performance of the sensor and the influence of the sensor’s emission sound field distribution The rules thus design the layout,materials and important physical parameters of each component.Secondly,refer to the relevant literature to find the most suitable preparation process for each component of the flexible ultrasonic microsensor,and prepare the corresponding samples.The feasible design is the assembly and packaging process of the sensor.In actual operation,the assembly and packaging process is continuously improved to obtain a more adaptable and easy-to-operate process flow.Next,the performance of the prepared flexible ultrasonic sensor is tested,and a blood pressure detection platform is built to test the transmitter/receiving performance of the sensor.The main test is to test whether the signal pulse reflected by the sensor back to the sensor is clear and obvious.The comprehensive test results continuously optimize the design of the sensor system,and finally achieve its relatively excellent performance.Finally,the optimized flexible ultrasonic micro-sensor was glued to the radial artery for human arterial pressure detection,the program was written to convert the collected pulse signal into the radial artery pressure waveform,and a control experiment was designed to measure the diastolic blood pressure with the flexible device and the medical electronic sphygmomanometer Compared with the systolic blood pressure,the error of the flexible device is verified.The experiment shows that the error of the systolic blood pressure of the flexible device is within 5 mm Hg,the error of diastolic blood pressure is within 7 mm Hg,and the error range of systolic and diastolic blood pressure is within 8mm Hg.Next,design a set of numerical standards to initially judge the tendency of human vascular sclerosis,and analyze the pulse wave waveform of the experimental subjects using the established standards to verify that the established standards have a certain feasibility.Experiments have proved that the flexible ultrasonic micro-sensor can realize the non-invasive real-time detection of blood pressure in the human wrist,and provide theoretical and technical guidance for establishing continuous blood pressure monitoring.