Research On Humidity Sensor Based On Cu(OH)₂ Nanowires/Graphene Oxide Composites Modified Quartz Crystal Microbalance

Humidity plays an important role in many fields,such as human health,meteorology,agriculture,forestry,manufacturing and medicine.With the development of technology,traditional humidity sensors cannot meet the actual requirements,therefore humidity sensors with satisfied humidity performances,cost-effective and mass production are attracting more and more attention.This thesis conducts research on humidity sensor based on Cu(OH)₂ nanowires/graphene oxide composites modified quartz crystal microbalance(QCM),mainly including:1.Different saturated salt solutions were used to generated RH levels between 0 and80%,The frequencies of the QCM humidity sensors under different RH levels were recorded by a data-logger which was connected to a computer through GPIB-USB adapter.One side of the pre-cleaned QCM was covered by Cu through magnetron sputtering coating system,and then Cu(OH)₂ nanowires were grown on the surface of the QCM by controlling the ratio of the Na OH and(NH)₄S₂O₈ aqueous solution and the immersion time,finally Cu(OH)₂-QCM humidity sensors with stable humidity performances were obtained through adjusting the ethanol cleaning time.2.GO dispersion was dropped on the Cu(OH)₂-QCM humidity sensor by a micropipette to obtain Cu(OH)₂/GO-QCM humidity sensor.The morphology and structure of Cu(OH)₂/GO composites were researched by means of SEM,TEM,STEM,Raman,FT-IR,XRD and EDS,and the successful combination of these two materials were proved.The effect of the GO coating amount on the humidity sensing performance of sensor was studied,indicating that the device with 10 droplets of GO dispersion showed excellent sensing performance of high sensitivity(52.1 Hz/%RH),good linearity(R²=0.9968),satisfied long-term stability and displays fast response and recovery time within 1.9 s and 7.6 s respectively,when changing RH between 0 to 80%.The humidity sensing mechanism was discussed,it was found that the Cu(OH)₂/GO composites combined the advantages of these two materials,providing more water molecule adsorption sites,resulting in better humidity sensing performances.3.Based on the characteristics that humidity will change during breathing,and human skin has a certain humidity,the potential applications of Cu(OH)₂/GO-QCM humidity sensor in real-time respiration monitoring and noncontract sensing were researched,indicating that different breathing patterns can be distinguished by the sensor,and also the approach of finger can be sensed.