Shams B. Ali

Shams B. Ali |Clyto Access

Newcastle Upon Tyne University, UK


Expertise: Laser science, Nanotechnology


Shams B. Ali is a Post graduate student of the final year at Newcastle Upon Tyne University, UK. Her project focuses on using carbon nanotubes to sense different types of gases and Volatile organic compounds VOCs under different conditions. Her BSc and MSc degree in Laser Physics and preparing detectors. Currently she is interested in the nanoscience, laser application and has published with six publications also in the same field.



Title: Carbon Nanotubes As a Gas and Vapour Sensor


The problem of urban air pollution is a major political issue. In Britain especially in the urban areas, e.g., inner London, suffers from adverse health effects for this reason. A recent BBc report СС50 schools in areas exceeding legal pollution limitsТТ indicates the scale of the problem [1]. Many substances are of concern, in particular anthropogenic NOx, volatile organic compounds VOCs and ozone created at low altitudes. These gases have been associated with cancer, liver damage and central nervous system problems in addition to their effects on the respiratory system. Monitoring of air pollution levels is therefore urgent; it requires multiple dispersed sensor, which must therefore be cheap and miniaturizable. Electronic devices are therefore most promising. This research concerns the physical and structural properties of hybrid carbon nanotubes as electronic gas sensors for Vapour organic compounds VOCs and ozone gas. A good sensor should be sensitive, reliable and low cost, with fast response and a short recovery time. Carbon nanotubes (CNTs) are well-suited because of their unique properties; their small size, hollow centre, large surface area, good electric Conductivity and change in electrical properties when in the presence of different gases at room temperature. However, it has been shown that bare CNTs have a low response for VOCs therefore we attempted to improve this property of CNTs by templating pyrrole on CNTs, while these nanotubes demonstrated a good response for ozone gas but with long recover time; therefore Boron nitried nanotubes templated on CNTs to improve the recovery time. Polypyrrole is simple to prepare by oxidation of the monomer and its resistance is very sensitive to organic vapours, although much larger than that of CNTs. From TEM images there are significant changes in the average diameters of nano tubes for example from (9nm) to (50nm) for MWCNTs. For CNTs/BNNTs,TEM images show BNNTs roll successfully CNTs. CNTs/Ppy were tested for the variation in their resistance upon exposure to a range of organic vapours (CHCl3, MeOH, EtOH and C3H6O). The sensing devices comprised simple two-terminal devices over which a layer of the composite was applied by drop-coating. We investigated the effect of the CNTs: Ppy ratio on the sensor response, S= (R-R0)/R0 *100% where R0 is the resistance in an air atmosphere and R is the resistance at steady-state after exposure to an air/analyte mixture[2]. In general, bare CNTs show a rapid response time, but very low response ~ S<7%. As the amount of polypyrrole in the composite is increased, the sensivity increases S>20%,the response time deteriorates. Interestingly, the response of the composites may even change sign as a function of target analyse concentration. For ozone, CNTs have a good response with this gas but with a long recovery time and the recover period increased with increased the concentration of ozone therefore with heating we can reduce the recover time successfully and compared with the privouse studies in this feild the temperature can be above 623K [3] but we abled to sense O3 in maximum temperature 343K.


Related Conferences :

2nd world summit on Nanotechnology and Nanomedicine Research