Preparation And Properties Of PEDOT:PSS/TiO₂ Micro-nanofiber-based Gas Sensor

With the rapid development of electronic technology and industry,electronic products and instruments have been widely used,causing electromagnetic radiation everywhere,which not only has a great impact on the generation,transmission and reception of signals in the communication field,but also has a great impact on human health.Here comes a hazard that cannot be ignored.Air pollution and industrial waste gas have brought a certain degree of harm to people,and the leakage of combustible gas caused explosions and fires,causing huge losses to people’s lives and properties.Under the influence of the Internet of Things and wearable technology,wearable textile gas sensors have received eager attention.This type of sensor can instantaneously detect whether people’s surrounding environment is safe,thereby bringing safety guarantee to people.In order to reduce the harm of electromagnetic radiation to the human body and the interference to instruments and equipment,it is particularly important to develop wearable gas sensors with electromagnetic shielding performance and gas detection performance.Because PEDOT:PSS has the advantages of high conductivity,stable chemical properties and environmental protection compared with other conductive polymers such as PANI and PPy.The nano-TiO₂gas-sensitive material has unique advantages such as low working temperature,good performance,and simple preparation.And choose PEDOT:PSS and TiO₂to build a P-N heterojunction structure to enhance the gas sensing performance of the textile gas sensor.In view of this,this article prepares a wearable,high-sensitivity PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor through three parts.The main research results obtained are as follows:（1）Obtain the best conductive woven fabric.The special spinning feeding device uses stainless steel wire and copper wire as the core yarn,and polyester-cotton roving as the covering material to prepare polyester/stainless steel wire wrapped yarn and polyester/cotton/copper wire wrapped yarn.The best two kinds of self-made wrapping yarns are used as weft yarns,polyester-cotton yarns are used as warp yarns,and SS/Pc-70 and Cu/Pc-80 conductive woven fabrics are prepared by the plain weave structure design.Through a series of characterization and testing,the results show that the overall performance of Cu/Pc-80 conductive woven fabric is better.Changing the stacking angle can form a complete network and enhance the electromagnetic shielding performance.The air permeability of the fabric is the best when it is a single layer,but the air permeability decreases with the increase of the number of fabric layers.（2）Preparation of PEDOT/composite conductive woven fabric with high conductivity.On the basis of the first part of the research,through a new in-situ polymerization method,the conductive woven fabric is combined with the highly conductive,chemically stable,and more environmentally friendly PEDOT to prepare the PEDOT/composite conductive woven fabric.It has high conductivity and simple sensing performance,and the sensitivity increases with the increase of alcohol concentration.At a concentration of 62.5 ppm alcohol,the sensitivity of PEDOT conductive woven fabric is 0.43%.At a concentration of 6250ppm alcohol,the sensitivity of PEDOT conductive woven fabric can reach 5.37%.The higher the conductivity of PEDOT/conductive woven fabric,the better its electromagnetic shielding effectiveness may be.In addition,the higher the conductivity of PEDOT/conductive woven fabric,the better its electromagnetic shielding effectiveness.Electromagnetic shielding can be used to characterize the integrity of the conductive network.This also provides a new strategy for the development of wearable textile gas sensors.（3）Preparation of PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor.The PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor is combined with PEDOT/composite conductive woven fabric through the electrospinning process to make a wearable,room-temperature operable,high-sensitivity PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor.Using thermal field characteristic X-ray spectrometer（EDS）and Fourier transform infrared spectrometer（FT-IR）analysis found the existence of PEDOT,PEDOT:PSS and TiO₂.And use scanning electron microscope（SEM）,four-point probe（ST2253）,WS-30B gas sensor test system to characterize and test the material.The test analyzed the response sensitivity of PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor to different concentrations of alcohol（12.5ppm-6250ppm）.The gas sensor response of PEDOT:PSS/TiO₂micro/nano fiber based gas sensor,PEDOT:PSS micro/nano fiber based gas sensor and PEDOT/composite conductive woven fabric to 625ppm alcohol was compared and analyzed.The influence of different relative humidity on PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor was studied.The results show that the PEDOT:PSS/TiO₂textile gas sensor has a better response to alcohol.The resistance of the sensor decreases with the increase of alcohol concentration.The minimum detection limit for alcohol concentration is 12.5ppm,and the response can reach 3.46%.When the alcohol concentration is 6250ppm,the sensor’s response can reach12.06%.Compared with the PEDOT/composite conductive fabric and the PEDOT:PSS micro-nano fiber-based gas sensor without adding TiO₂,the increase was 5.52%and 2.35%,respectively.The gas response capability shows a linear increase when the relative humidity changes below 75%,and shows a highly non-linear response when it exceeds 75%.In addition,the sensor can avoid the interference of other electromagnetic signals during gas-sensitive detection,ensuring the stability of the sensor.In summary,the gas sensor performance of the prepared PEDOT:PSS/TiO₂micro-nano fiber-based gas sensor is improved by 2.35%and 5.52%compared with the PEDOT:PSS micro-nano fiber-based gas sensor and the in-situ polymerized PEDOT/composite conductive fabric prepared under the same process conditions.The research results play an important role and provide new ideas for the development of highly sensitive,flexible,and room temperature operable fabrics for wearable gas sensor platforms.At the same time,it provides a new strategy for the development of smart clothing.