Browsing by Author "Mills, Daniel W."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Open Access New Techniques in Monitoring Water Pollution - Development of Sonochemically Fabricated Microarrays for the Determination of Pollutants.(Teknoscienze Srl, 2007-01-01T00:00:00Z) Davis, Frank; Collyer, Stuart D.; Gornall, Davinia D.; Law, Karen A.; Mills, Daniel W.; Higson, Seamus P. J.The focus of this article is to describe a simple-to-use, disposable sensor suitable for the rapid determination of pollutants in aqueous media, utilising a novel sonochemical microelectrode fabrication technique. The use of screen- printing, electrochemical and sonochemical methods allows the production of microelectrode arrays capable of stir-independent determination of chlorine in water. These arrays permit the simultaneous measurement of free and total chlorine at concentrations between 0-20 ppm. Developments leading to production on a mass scale will be briefly discussed. A further system incorporating enzyme containing conductive polymers to give microelectrode arrays capable of detection of ultra-low levels of organophosphate pesticides will also be described. Acetylcholine esterase could be entrapped within conductive polyaniline protrusions and the effects of pesticides on its activity determined. Ultra low concentrations of pesticide were found to reduce the enzymes activity as measured electrochemically. These systems allow the detection of organophosphates at concentrations as low as (10-17 M).Item Open Access Sonochemically fabricated microelectrode arrays for biosensors offering widespread applicability. Part I(Elsevier Science B.V., Amsterdam., 2004-09-15T00:00:00Z) Barton, Andrew C.; Collyer, Stuart D.; Davis, Frank; Gornall, Davinia D.; Law, Karen A.; Lawrence, Emma C. D.; Mills, Daniel W.; Myler, Suzy; Pritchard, Jeanette A.; Thompson, Mark; Higson, Seamus P. J.A novel and patented procedure is described for the sonochemical fabrication of a new class of microelectrode array based sensor with electrode element populations of up to 2 x 105 cm-2. For some years it has been accepted that microelectrode arrays offer an attractive route for lowering minimum limits of detection and imparting stir (convectional mass transport) independence to sensor responses; despite this no commercial biosensors, to date, have employed microelectrode arrays, largely due to the cost of conventional fabrication routes that have not proved commercially viable for disposable devices. Biosensors formed by our sonochemical approach offer unrivalled sensitivity and impart stir independence to sensor responses. This format lends itself for mass fabrication due to the simplicity and inexpensiveness of the approach; in the first instance impedimetric and amperometric sensors are reported for glucose as model systems. Sensors already developed for ethanol, oxalate and a number of pesticide determinations will be reported in subsequent publications.Item Open Access Towards a commerical microelectrode array based sensor for improved chlorine detection.(Cranfield University, 2005-03-31) Mills, Daniel W.; Higson, Seamus P. J.The commercial development of a disposable aqueous chlorine sensor based on a novel microelectrode array fabrication process is described. Non-conducting poly(o-phenylenediamine) films are firstly used to passivate conductive surfaces. Ultrasonic ablation of passivated electrode assemblies then results in the formation of a plurality of wells to expose the underlying conductive substrate, thereby forming a microelectrode array. Microelectrode arrays produced in this manner can be exploited within many electrochemical sensing applications; however, portable aqueous chlorine detection has been selected by Microarray Limited (the industrial sponsors of this project) as a primary vehicle for launching its generic production technology. The scale of microelectrode array production has been extended from that of individual gold sputtercoated glass slide electrodes - to the simultaneous production of hundreds of low-cost screen printed carbon-ink based sensors. A focus has been directed at all stages towards permitting the cost-effective large-scale mass production of sensors with a view to challenging existing portable aqueous chlorine measurement technologies both in terms of performance and unit cost. Based on volume batches of 250,000, it has been calculated that Microarray Limited sensors can be manufactured for a unit cost of approximately 2.5 pence, sufficiently low to provide scope for a competitive yet profitable sale price. The Microarray Limited aqueous chlorine detection system has improved the limit of detection from 0.01 ppm to 0.005 ppm total chlorine without sacrificing accuracy. Furthermore, this novel approach to aqueous chlorine detection offers numerous key benefits to the customer including reduced testing time, a more straightforward operation and the elimination of harmful reagents. Product development has been described from an initial concept through to a pre-production phase. The development of an innovative generic sensor packaging technology is also described.