Low Cost Junction Sensors for Water Quality Monitoring

Monitoring water quality in several locations (mapping) and as a function of time poses a huge challenge when expensive analytical laboratory tools are required. This is currently the case for the determination of trace levels of pharmacologically active compounds (PACs, e.g. anti-inflammatory drugs such as paracetamol, antidepressants, beta-blockers, antibiotics and illicit drugs) which are recognised as emerging environmental micropollutants but also have potential applications as key markers for water quality and tell-tale indicators for drug consumption. Our recent studies on electro-analytical junction sensors with electro-formed micro- and nanogaps suggest that a 'revolution' is possible in low cost instant sensing and remote chemical analysis. In this project novel nanogap sensors will be fabricated and employed for monitoring trace impurities in sewage and water. Comparison with mass spectroscopy will provide an assessment of reliability for real samples. Low cost devices with a rate of one measurement per minute will be developed for future application in distributed sensor networks for real time sampling. Such devices have huge potential for environmental monitoring of many PACs (and other organic micropollutants) and will result in a significant advance in knowledge concerning environmental pollution. The project will be carried out by a PhD researcher with the main aim of developing new junction sensor knowledge and applications in water quality monitoring. Fundamental chemical knowledge and environmental science knowledge will be obtained and new versatile measurement tools developed. Feasibility will be demonstrated and the power of the junction electrode approach developed with the view to exploit future commercial cooperation. Key objectives are: (i) to make novel and highly sensitive sensor devices; (ii) to improve junction characteristics (gap size, surface roughness, materials, geometry, etc.); (iii) to exploit the presence of short lived intermediates during junction processes (with life times down to ca. 30 ns in 10 nm gap systems); (iv) to employ junction electrodes in modulator-sensor mode (where one or more 'modulator' electrodes generate reactive intermediates such as hydroxide or other reactive intermediates to assist the sensitive detection at the 'sensor' electrode); (v) to provide a low cost sensor device with remote operation. The project target is a 24 hour operation with one measurement per minute; (vi) to validate the device according to set analytical standards required for measurement of trace levels of organic micropollutants in the environment; (vii) to compare the performance of newly developed sensor in terms of its sensitivity and selectivity with LC-MS system equipped with Q-TOF for accurate mass measurement; and (viii) to undertake a short monitoring program in the River Avon and a local wastewater treatment plant with the usage of both remote sensing and LC-MS instrumentation in order to verify their performance in real time scenarios.