Research On SAW Humidity Sensor Suitable For Human Breath Detection

Humidity is one of the important conventional environmental indicators.Its detection plays a vital role in agricultural management,civil engineering,electronics manufacturing,food and drug storage,and health care.In addition,in recent years,the role of humidity detection in respiratory diagnosis in medical diagnosis has gradually attracted attention.With the development of the Internet of Things technology,the demand for sensing technology has increased,and it has important application value to develop a new type of humidity sensor with high sensitivity,fast response recovery,miniaturization,intelligence,and easy integration.In this paper,a 3DAG/PVA/SiO₂/SAW structured delay-line surface acoustic wave(SAW)humidity sensor is designed and prepared.The humidity response test analysis of the sensor is carried out,and the sampling test is performed for the breath detection function.The details are as follows:1.Designed a 3DAG/PVA/SiO₂/SAW surface acoustic wave humidity sensor,prepared a SiO₂ film on the surface of the SAW device by RF magnetron sputtering,and prepared a high-quality 3DAG film on the Ta substrate by CVD method.The polymer PVA was used to achieve the complete mechanical peeling and transfer of 3DAG,and a 3DAG/PVA/SiO₂/SAW structured surface acoustic wave humidity sensor was prepared.The components of the sensitive film were characterized and analyzed.2.In a standard air environment,the humidity response test of the SAW humidity sensor is performed.Experiments show that the sensor can reach a sensitivity of-2.429 k Hz/% and a resolution of 0.10% in a high humidity environment(55%–90%RH),The response recovers quickly in the full range,strong repeatability,good stability in the temperature environment of 15-55?,stable long-term performance within 10 days,and good selectivity to the gas.3.Tested the breathing detection function of SAW humidity sensor,collected and analyzed the breathing process of 12 volunteers,and obtained the breathing rate(RR)and breathing depth(RD)data of the volunteers.Application value in clinical respiratory detection.