Preparation And Properties Of Organic-Inorganic Hybrid Nickel Iodide Colorimetric Humidity Sensor

The rapid development of the Internet is vigorously promoting the arrival of epc system networks era,sensors as the cornerstone of epc system networks,its importance is self-evident.Humidity sensor plays an important role in microelectronics manufacturing,military industry,aerospace and other fields.The inorganicsalt type humidity sensor widely used at present has problems such as poor stability and complex monitoring and response process,which cannot keep up with the development demand of epc system networks.Colorimetric humidity sensor has attracted extensive attentions because of it can intuitively and accurately know the relative humidity value by observing the surface chromaticity or electrical signal response of the devices.However,the humidity response recovery,characteristic color discrimination and stability of colorimetric humidity sensor still need to be improved.Organic-inorganic hybrid materials is an effective modification method,based on iodide nickel which is relatively superior of inorganic ligands,with strong polarity tetramethylammonium iodide and stable polyimide as the organic ligands,the design and preparation of tetramethyl ammonium iodide iodide nickel,polyimide iodide nickel organic-inorganic humidity sensitive material and the humidity sensor,specific work content and the results are as follows:(1)A nickel iodide colorimetric humidity sensor was prepared using nickel iodide as the sensitive material,and the moisture sensing mechanism and humidity response performance were analyzed.The results show that the moisture sensing mechanism of nickel iodide is the reversible delirification under low humidity.The device can work normally in an environment of 0~70% RH;The humidity response time of the device is about 10 s and recovery time is about 600 s,with more than two characteristic colors of black and red humidity.The surface moisture and dendrtization of sensitive materials are the main causes of device failure.(2)Tetramethylammonium-nickel iodide colorimetric humidity sensitive material and its humidity sensor were prepared with tetramethylammonium iodide as the organic ligand,and the humidity response mechanism,phase structure,thermal stability and electrical properties were analyzed.The results show that ammonium tetramethyliodide-nickel iodide has good thermal stability and colorimetric humidity sensitivity.The normal working range of the device is 0~95% RH;The response time of the device is about 3 s,the recovery time is about 300 s,and the humidity is about 13%.With black,red,yellow,transparent and other humidity characteristics color;Compared with nickel based devices,the spongy surface structure of devices is an important factor to improve the colorimetric humidity sensitivity.(3)Polyimide-nickel iodide colorimetric humidity sensitive material and its humidity sensor were prepared by using polyimide as organic ligand.The results show that polyimide-nickel iodide has better stability and moisture colorimetric properties than tetramethylammonium-nickel iodide.The working range of the device is 0~95% RH;Humidity response time is less than 1 s,recovery time is about 150 s,and humidity lag is about 3%.Several characteristic colors of humidity,such as black,red,dark yellow and light yellow all can be observed.Compared with nickel iodide and tetramethylammonium-nickel iodide devices,the hyperbranched surface structure of polyimide-nickel iodide devices is the key reason for their excellent performance.