Synthesis and gas sensing property of electrospun titanium dioxide microfiber for the application of personal protective equipment

• Main Author: Apiwattanadej, Thanit
• Other Authors: Li King Ho Holden
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Materials::Nanostructured materials; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/143508
• Institution: Nanyang Technological University

Gas sensing microfiber is one of the most challenging electronic textile components, whose development is hindered by limitations of gas sensing materials, including the brittleness of metal oxides and the slow response of chemiresistive polymers. Hence, current trend on the microfiber gas sensor is moving toward the composite microfiber fabrication. In this report, the basis for the fabrication and the characterization of gas sensing microfiber are established. To initiate the study, titanium dioxide (TiO2), which is a common chemiresistive metal oxide, has been used as a model sensing material for the gas sensing microfiber fabrication owning to its high sensitivity, fast response and low cost. The fabrication of TiO2 microfiber membrane begins with the electrospinning of titanium nitride nanoparticles in polyvinylpyrrolidone (TiN-NPs/PVP). The composite microfiber membranes are subsequently heated in the furnace to burn away PVP substrate and oxidize TiN to TiO2. The electrospinning parameters are optimized to produce mesoporous TiO2 microfiber membrane with fiber diameter in the range of 200 – 700 nm. The x-ray diffraction results show that the crystallite structures of TiO2 microfiber are controllable by the annealing temperature. The anatase phase tends to dominate in TiO2 microfiber at the curing temperature of 500oC, while rutile phase is dominant at the curing temperature of 700oC. The carbon monoxide (CO) gas sensing properties of mesoporous TiO2 microfiber membrane with rutile phase dominant are investigated using custom-design gas sensor characterization system. The resistance of mesoporous TiO2 microfiber membrane decreases from 6.40 GΩ to 3.86 GΩ upon exposing to CO gas concentration of 200 ppm at 350oC. The response and the recovery time of the sample are 120 seconds and 102 seconds respectively. The subsequent study on mesoporous TiO2 microfiber membrane will focus on the optimum working temperature and the improvement of the sensitivity and the selectivity of the sensor. The understanding in both electrospinning process and gas sensor characterization lays strong foundation for the fabrication of composite microfiber gas sensors. Subsequent studies on chemiresistive polymer microfibers and the fabrication of flexible gas sensors have been planned to achieve high-performance gas sensors for personal protective equipment.