3 Cleary, John Maher, Damien Slater, Conor Diamond, Dermot 2010 In: SAS 2010 - IEEE Sensors Applications Symposium Limerick, Ireland Institute of Electrical and Electronics Engineers 23-25 Feb 2010 978-1-4244-4988-0 RP1 <p>An autonomous microfluidic sensor for phosphate in environmental waters has been developed and assessed in laboratory and field trials. The sensor is based on the molybdenum yellow method for phosphate detection in which a phosphate-containing sample is mixed with a reagent containing ammonium molybdate and ammonium metavanadate in an acidic medium. The yellow-colored compound which is formed absorbs strongly below 400nm and its absorbance is proportional to the concentration of phosphate in the original sample. The sensor utilizes a microfluidic manifold where mixing, reaction and detection take place. Optical detection is performed using a LED (light emitting diode) light source and a photodiode detector. The sensor also combines pumping system, power supply, reagent and waste storage, and wireless communications into a compact and portable device. Here we report the successful use of the sensor to monitor phosphate levels in an estuarine environment.</p> http://doras.dcu.ie/15249/ 31 Maher, Damien Cleary, John Healy, John Fay, Cormac Carroll, Gary Diamond, Dermot 2010 In: Environ 2010 Limerick, Ireland 17-19 Feb 2010 RP1 RP2 <p>Environmental legislation such as the EU Water Framework Directive is providing a significant impetus towards increased monitoring of natural waters. The widespread availability of autonomous, field deployable systems which can provide long-term, reliable, high frequency data on key water quality parameters via wireless communications would allow a significant improvement in our ability to monitor the quality of our natural water resources. An autonomous sensor for the analysis of a key nutrient, phosphate, in water has been developed by National Centre for Sensor Research (NCSR) researchers in Dublin City University. This sensor incorporates microfluidic technology, colorimetric chemical detection, and wireless communications into a compact and rugged portable device. The prototype system has been successfully deployed for extended periods at Osberstown Wastewater Treatment Plant, Co. Kildare, and at Swords Estuary, Co. Dublin to monitor phosphate levels over periods of up to several months. Current work is focused on the commercialisation of the prototype phosphate analyser. This work is being performed in collaboration with EpiSensor Ltd., a Limerick based SME with expertise in wireless communications, sensor design and data collection systems. The next generation phosphate system will be linked with EpiSensor&rsquo;s reliable and secure &lsquo;sensor to database&rsquo; or SiCA platform. All major components of the analyser have been evaluated and redesigned with a view to reducing cost, power consumption and size, while maintaining sensor accuracy and reliability. The commercial system mass and internal volume have both been reduced by a factor of 7 compared with the prototype system, while component costs have been reduced by a factor of 10. GSM communications on the prototype were replaced with EpiSensors ultra low power ZigBee radio. The system uses 20&mu;l of reagent per reaction cycle and can carry out approximately 1400 measurements using a single lithium battery. The result is a low cost, low power and portable phosphate analyser. The system has been successfully deployed for short term trials at Swords Estuary, Co. Dublin.</p> http://doras.dcu.ie/15247/