Lab-on-chip technology for in situ determination of dissolved organic nutrients

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This proposal addresses a critical technology gap: dissolved organic nutrients cannot with current technology be measured routinely in situ. This is despite their importance in the cycling of nitrogen and phosphate in the natural environment. These chemicals are essential to plant growth and regulate the production of food at the base of the food chain. They can also act as pollutants through direct toxicity at elevated levels, and by stimulation of unwanted plant or bacterial growth that can lead to eutrophication (causing oxygen depletion and damage in aquatic environments). These processes are important in a wide range of aquatic and terrestrial environments, for studies of environmental change, and for management of natural and anthropogenic (human mediated) processes. This includes but is not limited to land use change, agriculture and aquaculture management, soil impoverishment, erosion, urbanisation, and waste water (human waste) management. The potential impact of a solution includes commercial exploitation of the technology, and a transformative effect on the practice of nutrient measurement for both science and industrial applications. This potential is amplified by recent successes at Southampton in the development of robust, accurate and sensitive instrumentation for determination of dissolved inorganic nutrients in situ based on lab on chip (LOC) technology. The availability of technology for both organic and inorganic forms would enable holistic and accurate assessment of the total nutrient processes.The project will address this technology gap by developing a device that converts dissolved organic nutrients (which are difficult to measure directly) in inorganic forms that can be readily measured with technology that we have already developed. Both the new and existing technologies will be (are) based on Lab on chip technology which uses fabrication of channels and engineering features on the scale of a tenths of a millimetre to perform complex analytical chemistry. The new device will expose sample water to UV radiation and carefully optimised chemical conditions to convert organic nutrients into inorganic nutrients. The existing device measures the concentration of inorganic nutrients by mixing the sample with chemicals which react and result in a colour change. The intensity of the colour change is proportional to the concentration of the nutrient targetted and is measured electrically using LEDs and optical detectors integrated into our microfluidic device.Once this technology concept is proved it will be (in subsequent research) further developed into a routinely deployable system for freshwater, groundwater, estuaries and marine environments. This system will be proposed as an important element of a future project in the next round of research undertaken for the NERC macronutrient cycles programme specifically targeting catchment scale monitoring of the Hampshire Avon catchment.