Browsing by Author "Perold, W. J."
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- ItemBiosensors for the detection of Escherichia coli(South African Water Research Commission, 2017-10) Maas, M. B.; Perold, W. J.; Dicks, L. M. T.ENGLISH ABSTRACT: The supply of safe potable water, free from pathogens and chemicals, requires routine analyses and the application of several diagnostic techniques. Apart from being expensive, many of the detection methods require trained personnel and are often time-consuming. With drastic climate changes, severe droughts, increases in population and pollution of natural water systems, the need to develop ultrasensitive, low-cost and hand-held, point-of-use detection kits to monitor water quality is critical. Although Escherichia coli is still considered the best indicator of water quality, cell numbers may be below detection limits, or the cells may be non-culturable and thus only detected by DNA amplification. A number of different biosensors have been developed to detect viable, dead or non-culturable microbial cells and chemicals in water. This review discusses the differences in these biosensors and evaluates the application of microfluidics in the design of ultra-sensitive nano-biosensors.
- ItemZnO nanowire gas sensor with UV-light for improved sensitivity(SciDoc Publishers, 2013-04) Van den Heever, T. S.; Hardie, G. L.; Perold, W. J.ZnO nanowires are synthesised on a patterned substrate in order to see the response to different gases. Under ambient conditions the sensor shows very little response to any gas. A UV-light source is used to increase the sensitivity of the sensor by increasing the conductivity of the ZnO nanowires. The UV-light decreases the number of oxygen ions present on the surface of the ZnO nanowires which leads to better sensitivity. The sensor, with the aid of the laser, can distinguish between the different gases that were used, argon, oxygen, carbon dioxide and nitrogen. When a mixture of two gases was used the response fell in between the response of the individual gases. The obtained results are repeatable and consistent over different sensors.