| With the rapid development of the Internet of Things,high-performance gas sensors have huge application prospects and consumer demands in environmental monitoring,public security and other fields.Nevertheless,the conductive type metal oxide gas sensors prepared by traditional coating or dropping technology encounter challenges in low detection limit and excellent replication,hardly meeting the actual needs of trace harmful gas detection and mass production.It is worth noting that sensitive materials are the key to the gas-sensing performance of gas sensors,and the preparation of sensitive materials with excellent properties is also an effective way to improve sensors’ performance.In recent years,due to its advantages of rapid,accurate and repeatable deposition in printing materials,inkjet printing technology,as a brand-new preparation technology of thin film,is expected to realize the low-cost and large-area production of various sensors.Here,taking copper oxide(CuO)as the research object,a uniform and high-quality CuO sensing film is formed quickly and efficiently by inkjet printing technology,which is expected to solve the problem of poor replication by dropping method and realize mass preparation of high-performance formaldehyde sensors,and the gas-sensing mechanism of thin film sensor is discussed in detail.The main research contents of this subject are as follows:1.In order to study the effect of surface morphology on the gas-sensing performance of CuO materials,pure CuO thin films were prepared on Ag-Pd interdigitated electrodes by dropping method or inkjet printing technology,and the related characterizations were carried out.Meanwhile,the optimum operating temperature,electrical and gas-sensing performance of CuO thin film sensors were tested.According to test results,the CuO thin film prepared by inkjet printing technology exhibits outstanding HCHO gas-sensing performance,and which can reach as low as 50 ppb formaldehyde detection limit,satisfying the monitor needs of the World Health Organization’s specified value(80 ppb).The performance repeatability of CuO thin films in batches was further studied.It turns out that the gas sensors of inkjet printing exhibit outstanding repeatability and stability with small deviation in each batch,and the relative mean deviations toward formaldehyde in the aspect of response,response and recovery times are all about only 5% between batches.The controllable micro-nano-level film thickness and uniform surface achieved by inkjet printing technology are the compelling reasons for low detection limit and superb reproducibility of gas sensors.Our work can offer a theoretical and experimental basis for large-scaled production of high-performance gas sensors from research to practical application.2.In order to figure out the influence of noble metal modification on the gas-sensing performance improvement of CuO films,Pd nanoparticles were modified on the surface of CuO film based on electron beam coating technology.The surface composition and morphology of the prepared film were analyzed by related characterization methods,and the gas-sensing performance was investigated.The results show as follows: the optimal operating temperature of Pd/CuO thin film gas sensor reduces from 200℃ to 100℃,the response value of 1 ppm HCHO increases to 4.881.Moreover,the HCHO detection limit can reach as low as 40 ppb,which has extensive practical application prospects.The enhanced performance of Pd/CuO thin film gas sensor can be attributed to the catalytic property and spillover effect of the noble metal Pd.This work can provide experimental guidance for fabricating high-performance HCHO sensors. |
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