UK-Further development of droplet microfluidic based chemical sensors for rapid measurement of nutrients in water

Traditionally chemicals in the aquatic environment (e.g. nitrate, phosphate) are measured by manual collection and laboratory analysis of discrete water samples. Microfluidic sensors offer an attractive alternative: by taking and analysing samples autonomously in the environment, they remove the need for manual sampling and allow real-time monitoring of water composition and quality.

The current state-of-the-art sensors are not widespread due to a range of issues, most notably complicated fluidic control and their inefficient use of chemical reagent. This increases the size of the sensor and its power consumption, limits the frequency that measurements can be taken and duration the sensor can be deployed each time.

Droplet microfluidics (in which nanolitre water samples are taken and subsequently operated on as droplets within an immiscible oil) is a novel microfluidic method that, in addition to other advantages, crucially offers higher analytical throughput and much more efficient use of consumables (reagent consumption being orders of magnitude lower).

We have previously developed and demonstrated the first-ever droplet microfluidic sensor prototype for measuring nitrate and nitrite that uses drastically lower reagent consumption relative to the current state of the art. In this project we will mature the technology and demonstrate it in real-world operation in partnership with end users, including a UK public body and Chinese water company. These demonstrations will help us to refine the sensor, demonstrate its effectiveness, and ready it for commercial exploitation.

This project will contribute to UK's economy and industry for environmental sensing and monitoring technologies, by providing matured competitive sensor technology. We aim to transfer the knowhow and IP generated to a partner SME - increasing their competitiveness and encouraging growth, providing a route to marketplace for the technology, and boosting the UK's capability in sensor technology.

More long-term, the ongoing development of this technology will benefit society through reducing cost and improving the quantity and quality of data from monitoring the aquatic environment. This in turn will lead to 1) earlier detection of pollution and improved management of water resources, 2) improved prediction and management of the changing environment through regulatory testing and compliance. These impacts will be achieved by engaging with industrial, regulatory, and academic end users by deploying autonomous (i.e. left on site or location unattended) or hand-held instruments that will produce better, cheaper data at higher spatial and temporal density.

We envisage this project will have significant impact on the field of microfluidics and lab-on-a-chip. Droplet microfluidics, as an emerging new area of microfluidics, is still largely a 'lab-technique' with successful applications mainly limited to polymerase chain reaction and single cell analysis. This project will champion the use of droplet microfluidics in wider industrial applications, tackling the existing challenges of chemical sensing from a fresh angle. Meanwhile, the harsh environmental challenges faced in water analysis (e.g. elevated ambient pressures, varied temperature, complex samples, long-term operation etc.) may catalyse new science and technology in robust microfluidics instrumentation, better interfacing of microdevices to the real world, miniaturised sensitive detection, and selective chemical assaying.

To ensure the maximum uptake of this new technology, once any new technological developments are protected we will disseminate the research results via journal publications, national and international conferences, providing prototypes and technical support, and collaborating with our academic and industrial end user partners.

Last but not least, the development of the postdoctoral engineer/scientist employed in this project will help enhance the leading position of UK in water analysis and sensor technology.