Droplet microfluidic based chemical sensors for rapid measurement of nutrients in water

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment

Abstract

Traditionally most chemical parameters (e.g. nitrate, phosphate) in aquatic environment are measured by laboratory analysis of discrete water samples. Microfluidic sensors offer an attractive alternative: by taking and analysing samples autonomously in situ, they obviate sampling allowing larger datasets particularly when used in conjunction with autonomous systems.
The current state-of-the-art sensors have temporal resolution of minutes due to Taylor dispersion (fluid flow effectively smears chemical composition within the device) and complex valve controls, making them high-cost and unsuitable for deployments requiring high frequency measurement - most notably on profiling vehicles (e.g. Argo floats, oceanic gliders) that rapidly transect the water column.
Droplet microfluidics (in which nano litre 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 zero Taylor dispersion and much higher analytical throughput.
This project will develop the first-ever droplet-flow based field-deployable sensor for autonomous systems. Low-cost, low-powered and fully functional; the device will be a step-change in high-frequency autonomous aquatic chemical analysis.

Planned Impact

This project will benefit society through enabling new capabilities and services to reduce cost and improve the quantity and quality of data from the aquatic environment monitoring. This in turn will lead to 1) earlier detection of pollution and improved management of water resources, 2) improved prediction of climate change and environment monitoring through regulatory testing and compliance management. These impact will be achieved through industrial and regulatory user groups via 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.
This project will contribute to UK's economy and industry for environmental sensing and monitoring technologies, by providing competitive technologies on sensor systems. This will in particular benefit SMEs that we have already collaborated with.
The project will deliver new knowledge and scientific advances in micro systems engineering. With the future application of the sensor system, we expect to collect unprecedented environmental data. These results will be disseminated via publication, seminar, conference and uptake by the respected agencies to a much wider end-user community.
Last but not least, young scientists (postdoc and PhD student) and engineers will be trained in this project and following programs to enhance the leading position of UK in water analysis.

Publications

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Bhuiyan W. (2019) Micro peristaltic pump system for the generation of arbitrary droplet sequence and multiple-step biochemical assays in 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019

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Evans G.W.H. (2020) A drop in the ocean: Monitoring of water chemistry using droplet microfluidics in 21st International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2017

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Nightingale A.M. (2019) A droplet microfluidic-based sensor for monitoring river nitrate/nitrite concentrations in 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019

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Nightingale A.M. (2018) Gas-mediated crosstalk in droplet flow - Characterisation and correction in 22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018

 
Description Prototypes of water sensor has been developed to measure Nitrite, Nitrate and phosphate in fresh and sea water. The prototype has been tested in River Itchen and River Thames, showing high frequency measurement.
Exploitation Route we will further develop the technology and make it into product via spinout company for general use.
Sectors Agriculture

Food and Drink

Chemicals

Environment

Healthcare

 
Description The water sensors have been tested by multiple users including the Environmental agency, Wastewater treatment company and water product providers. We have also demonstrated our sensor at the WWEM conference and World Water Summit.
Sector Agriculture, Food and Drink,Environment
Impact Types Societal

Economic

Policy & public services

 
Description UK-Further development of droplet microfluidic based chemical sensors for rapid measurement of nutrients in water
Amount £154,499 (GBP)
Funding ID NE/S013458/1 
Organisation Research Councils UK (RCUK) 
Sector Public
Country United Kingdom
Start 05/2019 
End 12/2020
 
Description Nitrate water sensor deployment 
Organisation UK Centre for Ecology & Hydrology
Country United Kingdom 
Sector Public 
PI Contribution University of Southampton provide newly developed water sensor to CEH and test the sensors at River Thames for monitoring of water quality.
Collaborator Contribution CEH helps the sensor deployment and data interpretation.
Impact Continuous data on water quality at the testing site of River Thames
Start Year 2017
 
Title METHODS AND APPARATUS FOR GENERATING DROPLETS 
Description Methods and apparatus for generating droplets are disclosed. In one arrangement a peristaltic screw pump is configured to drive pulsatile flows of fluids in different conduits which are phased relative to each other such that a sequence of droplets are formed at a junction downstream from the pump. 
IP Reference WO2015166248 
Protection Patent application published
Year Protection Granted 2015
Licensed Yes
Impact The is bring a new type of water sensor to the industry. the new sensor is small in footprint, yet can provide high frequency and accurate measurement for chemicals in water. Therefore there will be substantial economic and society benefit.
 
Description STEM4Britain poster competition - Parliament poster presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact This is a national competition for Postdoc and young fellows to present the most exciting results to politicians and other general audiences.
Well-accepted.
Year(s) Of Engagement Activity 2007
 
Description School demonstration 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Demonstration of the sensor device to school students and parents. They were absolutely fascinated. We were even asked where to buy the device!
Year(s) Of Engagement Activity 2007