Study On The Rapid Detection Of Breath Biomarker-acetone Based On Nano-SnO₂ Gas Sensor

Modern medical development has promoted multidisciplinary cross-fertilization,and breath gas marker detection technology for major disease diagnosis has been vigorously developed as a new non-invasive method for disease diagnosis.Acetone is used as a typical breath gas marker in the pre and onset of diseases such as diabetes,asthma,and breast cancer,and the change of acetone concentration can provide important information of human vital biochemical changes for clinical diagnosis.Therefore,it is imperative to develop a simple device based on changes in breath acetone concentration and to establish a monitoring system for health warning/disease diagnosis by using human breath gas.Compared with traditional gas chromatography-mass spectrometry technology,gas sensing technology has the advantages of low price,easy operation,real-time transmission and high sensitivity,and has broad application prospects for convenient and rapid analysis of exhaled gases,while its key components（gas-sensitive materials）are the most important for the development of high-performance gas sensors.SnO₂ semiconductor materials are widely used in gas sensing research because of their high conductivity and stability,and have been used in commercial gas sensors.However,these devices still have some disadvantages,such as high operating temperature and poor selectivity/interference resistance.Therefore,combined with the current status of SnO₂ sensor research and the demand for rapid detection of acetone in breath gas,this study intends to prepare and screen sensitive materials with high sensitivity,high selectivity,low temperature operation and rapid response to acetone with the methods of structural modulation,noble metal loading and heterostructure construction of SnO₂ nanomaterials.The response behavior and interaction data of SnO₂ nanomaterials with respiratory acetone gas,and further optimization of the material synthesis scheme were also in-depth analyzed.The results have important theoretical implications for the design and development of new high-performance gas sensors to detect respiratory gas marker-acetone.The main results are as follows:1.Two-dimensional SnO₂ nanofilms with different structures（grain size,thickness）were prepared by controlling the calcination temperature of the SnO₂precursors,and the material calcined at 450^oC had the largest specific surface area.In the gas sensitivity test,the sensor based on the material calcined at 450^oC has a response value close to 3 for acetone down to 0.3 ppm at the optimal operating temperature of 200^oC.And several gases that tend to interfere in the exhaled breath were tested（NH₃,H₂S,NO,CO₂）,among which acetone showed the best response.The two-dimensional SnO₂ film has the potential to detect acetone in breath gas,and the method also provides a reference for the synthesis of other two-dimensional functional materials.2.The complexes of Au nanoparticles（Au-NPs）and SnO₂ nanofibers were prepared by electrostatic spinning,and the noble metal modification caused an electron"spillover effect"on the surface of the material,thus increasing the active sites on the surface of the nanomaterials and enhancing the gas-sensitive response to detect low concentrations of exhaled acetone.The working temperature of SnO₂/Au-NPs used to detect acetone was reduced from 225^oC to 175^oC in gas-sensitive tests compared to the control group of pure-phase SnO₂ nanofibers prepared by electrospinning.The sensor operating temperature was significantly lower compared to the previous job,which reduced energy consumption.The SnO₂/Au-NPs sensor had a response of 2.6 at 175^oC for low acetone concentration（0.5 ppm）,and acetone had the highest response during several interfering gases（NH₃,H₂S,NO,CO₂）in the exhaled breath.3.This work combined the excellent properties exhibited by low-dimensional SnO₂ nanomaterials in the previous work.Hollow nanofibers（HNF）with four different WO₃（WO₃:0%,0.1%,0.3%,0.9%）contents were prepared by electrospinning.The large specific surface area properties of the hollow structure and the enhanced surface activity as the grain size decreases to the nanoscale provide good conditions for gas entry into the semiconductor material.This work exhibited a minimum operating temperature of 170^oC compared to the previous two jobs.And the WO₃/SnO₂（0.3%）component displays the best selectivity for acetone in several typical interfering gases.In particular,the response was good at acetone concentrations as low as 100 ppb（4.7）with response/recovery times of 80/200 s.The synergistic effect of constructing heterojunctions to achieve enhanced acetone sensitivity as well as improved selectivity for acetone also provides an important reference for the development of acetone gas sensors with low detection limits at lower temperatures.