Smart nutrient sensor networks using miniaturised optical and electrochemical detection

Director of Studies: Dr Simon Ussher
2nd Supervisor: Dr Angela Milne
3rd Supervisor: Dr Paul Davey
4th Supervisor: Malcolm Woodward (email:emsw@pml.ac.uk), Plymouth Marine Laboratory
Project partner: Rob Passmore, Additive Catchments

Applications are invited for a 3.5 years PhD studentship within the Environmental Intelligence doctoral training programme at the University of Plymouth. The studentship will start on 01 October 2024. 

Phosphorus (P) and nitrogen (N) are essential elements for life but excess quantities of fixed nutrients in catchments cause eutrophication, toxicity and affect catchment ecosystem function [1]. Dissolved ammonia (NH3) is a critical chemical parameter required by UK legislation [2], whereas P is often the growth limiting element in catchments, particularly in areas of high N (Nitrate Vulnerable Zones) [3]. Recent legal standards (e.g. Nutrient Neutrality Programme and Environment Act 2021) require nutrient emissions to be determined at catchment scale and concentration limits to be legally enforced. Hence, there is a demand for better spatial and temporal data from water quality monitoring networks [4] and application of emerging technology, including off-the shelf Internet of Things (IoT) sensors and novel miniaturised chemical sensors (nanomaterials, microfluidic spectrophotometric/fluorescence, fiber-optic, microelectrodes) [5-7]. As data flow increases in size and complexity, well designed systems-based approaches are needed to improve cost, efficiency, reduce carbon emissions, minimise computing requirements and support the deployment of sensing systems. Real-time data offers the opportunity for Artificial Intelligence (AI) integration, with the potential for predictive models for phosphate [8] and ammonia [9] from other water parameters, with the final goal of developing catchment digital twins [10]. 

Starting with commercial sensors (e.g. conductivity, pH), ion selective electrodes and liquid core waveguides (PO43- and NH4+) [11,12], the student will automate these using established interfaces developed at University of Plymouth (UoP) [13]. Novel detection methods will be explored, including microfluidic spectrophotometry, fibre-optics, and microelectrodes for detection of PO43- and NH3-N (Co-S Woodward). Microcontroller engineering, optical detection and telemetry (Co-S Davey) will allow custom design, miniaturisation, data acquisition and fabrication of novel sensors [14,15]. Through the project partner, sensor data flow will be integrated with AI to develop and validate next-generation water monitoring solutions that interface with catchment management platforms.

The student will receive tuition in environmental sensing, networks and data processing. Initial training in nutrient analysis and automation will be provided using existing sensors and established interfaces at UoP running on LabVIEW. The student will develop skills in big data analysis and programming (R and Python) alongside instruction in analytical quality assurance in ISO 9001 laboratories. Training in microcontroller engineering and fabrication of optical detectors (Co-S Davey) and expertise in sub-micromolar nutrient analysis and cutting-edge techniques (Co-S Woodward) will be offered, as well as training opportunities in AI and industry experience will be provided by project partner Additive Catchments.

We are looking for a graduate with practical hands-on skills with a will to develop knowledge and desirable skill set bridging physical and environmental science, analytical chemistry and engineering.

[1] Jarvie HP, Sharpley AN, Flaten D, Kleinman PJ, Jenkins A, Simmons T. The Pivotal Role of Phosphorus in a Resilient Water-Energy-Food Security Nexus. J Environ Qual. 2015 Jul;44(4):1049-62. doi: 10.2134/jeq2015.01.0030. 

[2] Environment Act 2021, c. 30, Available at: https://www.legislation.gov.uk/ukpga/2021/30/contents (Accessed 29 November 2023).

[3] Jarvie, H. P., et al. (2018). Phosphorus and nitrogen limitation and impairment of headwater streams relative to rivers in Great Britain: A national perspective on eutrophication. Science of the Total Environment 621: 849-862.

[4] O'Grady J, Zhang, D, O'Connor,  N, Regan, F, 2021, A comprehensive review of catchment water quality monitoring using a tiered framework of integrated sensing technologies, Science of the Total Environment Volume 765, 142766

[5] Li, D. L., et al. (2020). Detection methods of ammonia in water: A review. TrAC Trends in Analytical Chemistry 127.

[6] Zhu, X. and J. Ma (2020). Recent advances in the determination of phosphate in environmental water samples: Insights from practical perspectives. TrAC Trends in Analytical Chemistry 127: 115908.

[7] Vikesland, P.J. Nanosensors for water quality monitoring. Nature Nanotech 13, 651–660 (2018). https://doi.org/10.1038/s41565-018-0209-9

[8] Latif, SD., Birima, AH, Ahmed, AN, Hatem, DM, Al-Ansari, N, Fai, CM, El-Shafie, A, 2022, Development of prediction model for phosphate in reservoir water system based machine learning algorithms, Ain Shams Engineering Journal, 13 (1),101523, https://doi.org/10.1016/j.asej.2021.06.009.

[9] Zhang, M.,  Dong, X., Li, X., Jiang, Y., Li, Y., Liang, Y., 2020, Review of separation methods for the determination of ammonium/ammonia in natural water, Trends in Environmental Analytical Chemistry, 27, e00098, https://doi.org/10.1016/j.teac.2020.e00098.

[10] Gourbesville, P. and Q. Ma (2022). "Smart river management: What is next?" River 1(1): 37-46.

[11] Zhang, J.-Z. and J. Chi (2002). Automated Analysis of Nanomolar Concentrations of Phosphate in Natural Waters with Liquid Waveguide. Environmental Science & Technology 36(5): 1048-1053.

[12] Li, J., et al. (1999). Transversely illuminated liquid core waveguide based fluorescence detection: Fluorometric flow injection determination of aqueous ammonium/ammonia. Talanta 50(3): 617-623.

[13] Bowie, A. R., et al. (2005). Design of an Automated Flow Injection-Chemiluminescence Instrument Incorporating a Miniature Photomultiplier Tube for Monitoring Picomolar Concentrations of Iron in Seawater. Journal of Automated Methods and Management in Chemistry 2005: 802137

[14] Allsop T, Mou C, Neal R, Kundrát V, Wang C, Kalli K, Webb D, Liu X, Davey P & Culverhouse P (2020) 'Generation of a Conjoint Surface Plasmon by an Infrared Nano‐Antenna Array' Advanced Photonics Research 2, (2).

[15] Allsop T, Al Araimi M, Neal R, Wang C, Culverhouse P, Ania-Castañón JD, Webb DJ, Davey P, Gilbert JM & Rozhin A (2020) 'Detection of nitrous oxide using infrared optical plasmonics coupled with carbon nanotubes' Nanoscale Advances 2, (10) 4615-4626. 

Applicants should have a first or upper second class honours degree in engineering, environmental, physical sciences or a relevant masters qualification. 

If your first language is not English, you will need to meet the minimum English requirements for the programme, IELTS Academic score of 6.5 (with no less than 5.5 in each component test area) or equivalent. 

The studentship is supported for 3.5 years and includes full home tuition fees plus a stipend of £19,088 2024/25 rate (TBC). The studentship will only fully fund those applicants who are eligible for home fees with relevant qualifications. Applicants normally required to cover international fees will have to cover the difference between the home and the international tuition fee rates approximately £12,697 per annum 2023/24 rate (2024/25 rate TBC).

NB: The studentship is supported for 3.5 years of the four-year registration period. The subsequent 6 months of registration is a self-funded ‘writing-up’ period.

If you wish to discuss this project further informally, please contact Dr Simon Ussher.

Please see our how to apply for a research degree page for a list of supporting documents to upload with your application.

For more information on the admissions process generally, please visit our how to apply for a research degree webpage or contact The Doctoral College at research.degree.admissions@plymouth.ac.uk.

Shortlisted candidates will be invited for interview after the deadline. We regret that we may not be able to respond to all applications.  Applicants who have not received a response within six weeks of the closing date should consider their application has been unsuccessful on this occasion.