Research On LC Wireless Passive Humidity Sensor Based On Two-dimensional Sulfide Material

The monitoring of humidity parameters is of great significance in industry,agriculture and daily life.However,in some special environments,such as tissue culture,precious cultural relics preservation,chemical reactors and other closed environments,and in hazardous environments such as painting workshops,mines and flammable gas transportation,traditional wired humidity sensors are limited in these environments due to short lifespan,safety hazards,etc.In addition,the development of the Internet of Things also made traditional wired humidity sensors limited for humidity monitoring owing to its low efficiency,complicated wiring,high maintenance costs and high energy consumption.In view of this,this paper proposed an LC wireless passive humidity sensor based on MX₂ material,which avoids the application shortcomings of the existing wired humidity sensor and expands the application range of the humidity sensor.The work of this paper can be categorized as four sections:1.three wireless passive sensor technologies that realize wireless passive humidity and humidity parameter measurement were compared and LC wireless passive sensor was selected as the research route of this paper.Further,the signal reading theory of LC sensor was described.To determine the process of the sensor fabrication,three fabrication processes were discussed and screen printing process was designated as sensor fabrication process;2.an LC wireless passive humidity sensor based on MWCNTs/WS₂ composite material was proposed.The S₁₁-f curve and electric field distribution of the sensor at different coupling distances were obtained by HFSS simulation.The relationship between sensor sensitivity and transmission distance of the humidity sensor were experimentally proved and the ideal coupling distance of 6 mm was determined for investigating the sensing performance of sensor at 15-95%RH.Based on electrochemical principle,the sensing mechanisms of MWCNTs/WS₂ materials at different transmission distances and under different humidity ranges were analyzed.3.an LC wireless passive humidity sensor based on MoS₂ nanosheet was proposed.The optimal coupling distance of the LC wireless humidity sensor was obtained by simulation and the test results showed that the sensor can be used for humidity monitoring under 10-95%RH.At low humidity environment?10-60%RH?,the prepared humidity sensor has a sensitivity of2.79 kHz/%RH,while at high humidity environment?60-95%RH?it can achieve a sensitivity of 76.04 kHz/%RH.The sensor has good response-recovery characteristics,hysteresis error and stability.The test results also show that the sensor can be used for humidity measurement at 15-40°C.Finally,the humidity sensitivity mechanism of the sensor in different humidity ranges was discussed in the theory of proton migration.4.an LC wireless passive humidity sensor based on MoS₂/Polyimide composite was proposed.The morphology and physical-chemical properties of as-prepared MoS₂/Polyimide composite nanomaterials were characterized by means of SEM,EDS,LSCM,XRD,FT-IR and other analytical instruments.Tests show the as-prepared sensor have a sensitivity of 16.6kHz/%RH in the low humidity range?10-60%RH?and a sensitivity of 153.59 kHz/%RH in the high humidity range?60-95%RH?.The response and recovery time of the sensor are 7.2 s and 10.4 s,respectively,with good repeatability.Based on the difference of humidity sensitivity under different humidity ranges,the moisture sensitivity mechanism of MoS₂/Polyimide composites was analyzed from electrochemical theory and the chemical group structure of Polyimide and MoS₂.In addition,the respiratory monitoring test results of MoS₂/Polyimide composites indicate that the rapid breathing,normal breathing and deep breathing can be identified according to the width of the respiratory waveform and the height of the peak of the sensor output frequency-time curve.The shortest measurable breathing time is 1.2 s.