Project highlights

  • sustainable approaches to plant production, utilising less land, water and energy are needed, with vertical stack hydroponics offering a very promising approach; 
  • Nanomaterials-based sensors offer an important route to achieving real-time precision approaches to hydroponics, by tuning the composition of the growth medium based on changes in the macro- and micro-nutrient composition and/or in response to the presence of biomarkers of disease. 
  • The project will develop a graphene-based Zn ion-selective electrode for real-time monitoring of the Zn concentration in the growth medium and for binding of Zn-fingerprint proteins secreted by plants in response to stress (climate, nutrient or disease).  


The global agriculture sector is facing a wide spectrum of challenges such as stagnation in crop yields, notoriously low nutrient use efficiency, poor soil health, shrinking arable land and water availability etc. Moreover, changing climates (elevated CO2, increasing temperatures and changing soil moisture) will make ensuring food security harder; they are likely to reduce yields for many primary crops in future [1]. Nanotechnology offers great potential to tailor fertilizer and pesticide delivery and targeting, improve the nutrient and pesticide use efficiency to boost plant productivity and simultaneously reduce environmental quality deterioration, as well as for developed of sensors to monitor plant health in real time [2].  

Vertical farming is a practical technology through which large quantities of food crops and medicinal plants can be produced in a very small space only with the help of advanced technology [3]. Hydroponics (Figure 1) is an approach to developing vegetation in the absence of soil, whereby instead of having their roots supported and nourished by soil, the plant is irrigated and supported with the aid of an inert developing medium and is fed through nutrient-rich water that is indispensable to maintain plant growth [4]. Hydroponic structures use 60–70% less water than regular conventional agriculture, and by utilising vertical space can increase crop density 3-4 fold/m3 compared to traditional soil-based agriculture.  

The image shows lettuce plants growing in white pots that are stacked vertically around a pole to resemble a tree, with the stacks organised in rows in a glasshouse, as a means of optimising space and farming vertically rather than the traditional horizontal farming.

Figure 1: Illustration of Vertical farm grown lettuces from UK-based hydroponics company, Saturn Bioponics (Birmingham, United Kingdom). From Ref. [4}.

Zn deficiency in plants leads to a 25–35% reduction in crop yield and quality, reducing also the nutritional value of the crop, and affecting its appearance and sales value. However, too much Zn leads to toxicity, so ensuring the correct balance is key to optimising yield and return on investment. Within this PhD project, two interlinked challenges will be addressed – multi-analyte detection of essential plant micronutrients such as Zn and Fe in the growth medium [5], and dynamic secretion of biomolecules indicate of nutrient stress into the growth medium, such as zinc fingerprint proteins (ZIP) [6], integrating output signals into real-time titrators to allow adjustment of medium composition. Device optimization will be to increase selectivity and sensitivity of combined ion-selective electrode (ISE) and targeted biomolecule binding (e.g., via molecular imprinting) while extending the useful life of the sensors by decreasing non-specific binding/surface fouling. 

Case funding

This project is suitable for CASE funding


University of Birmingham


  • Organisms and Ecosystems


Project investigator

Prof. Iseult Lynch, University of Birmingham, [email protected] 


Dr. Kieran Khamis, University of Birmingham, ([email protected])

Stefan Krause, University of Birmingham, ([email protected])

Dave Spurgeon, UKCEH

How to apply


The PhD project will develop a 2d-graphene Zn ion-selective electrode sensor for monitoring and adjusting the Zn concentration and the form available in the nutrient broth, with the goal of reducing plant loss to disease and increasing crop yield. The next step will be to develop a molecularly imprinted polymer coating for the 2-d graphene electrode to selectively recognise a specific Zn-fingerprint protein secreted by the target crop plant (e.g., lettuce or pak choi) in response to stress (e.g., nutrient stress, disease, climate stress) as a real-time biomarker to indicate when corrective action is needed, such as addition of an anti-fungal or antibacterial agent.  The sensors will be tested in a research vertical hydroponic stack, recording the outputs to a mobile phone to allow real-time tuning of the nutrient parameters in response to sensor readings as a first step towards nano-enabled precision agriculture and water management. 

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.  

Training in nanomaterials synthesis, functionalisation and characterisation, electrode testing and evaluation, and plant culturing and hydroponics will be provided, along with training in all necessary methodologies for sensor design, fabrication and testing and evaluation of performance.  During the placement, working in a research-intensive small company will provide insights into the process of entrepreneurship, and the challenges of commercial processes and research towards product and process optimisation and improvement.  The student will also learn how research and development is planned, implemented and evaluated, with a focus always on the product improvement rather than purely curiosity-driven research.  

Partners and collaboration

Agriculture is critical to feeding the growing global population, whilst being threatened by competition for land-use and by decreasing soil quality, driving a need for alternative approaches such as sustainable soil-less vertical solutions for crop production. 

Saturn Bioponics have >10 years research experience, with 6 years of commercial agricultural trials, and have won numerous awards for innovation and entrepreneurial skills.  They are the only company named in the 25 year environmental plan. In 2020, Saturn Bioponics deployed its first commercial farm and has seen great interest in the capacity of the Saturn Grower to increase the crop quality. 

Further details

Further details on how to contact the supervisor for this project and how to apply for this project can be found here: 

For any enquiries related to this project please contact Prof. Iseult Lynch,  [email protected].

To apply to this project: 

  • You must include a CENTA studentship application form, downloadable from: CENTA Studentship Application Form 2024. 
  • You must include a CV with the names of at least two referees (preferably three) who can comment on your academic abilities. 
  • Please submit your application and complete the host institution application process via:   Please select the PhD Geography and Environmental Science (CENTA) 2024/25 Apply Now button. The CENTA application form 2024 and CV can be uploaded to the Application Information section of the online form.  Please quote CENTA 2024-B32  when completing the application form. 

Applications must be submitted by 23:59 GMT on Wednesday 10th January 2024. 

Possible timeline

Year 1

Development of graphene-based ion-selective electrode: Ion-selective electrodes (ISEs) and reference electrodes are an affordable, portable, and disposable potentiometric sensing method using low sample volumes, and which can be tailored to have good sensitivity and selectivity for target ions. The prepared graphene-based electrode will be coupled with an Ag /AgCl reference electrode and functionalised to optimse its metal ion binding capacity

Year 2

Functionalisation and MIP on graphene with target analytes: A molecularly imprinted (MIP) decorated graphene oxide will be designed and optimised in terms of its ratio to the imprinting molecule (Zn-fingerprint proteins from the target plants) for the selective adsorption. The resulting GO/MIP will be characterised by FTIR spectroscopy, elemental analysis, Raman spectroscopy, thermogravimetric analysis, SEM, AFM and adsorption measurements. 

Year 3

Performance analysis of the sensor: The equilibrium time and adsorption capacity of the GO/MIP towards the target Zn-fingerprint proteins, extracted from plants and secreted from the roots into the hydroponic medium will be determined. The adsorption data will be modelled using various kinetic and isotherm models (e.g., Langmuir isotherm model). Competing adsorption tests will confirm the molecular recognition and binding affinity using the target ZIP proteins and 3 others to confirm the recognition ability, adsorption kinetics/capacity and selectivity for the target protein.

Year 4: Integration into a biosensor device and user-friendly phone app for real time control of nutrient status and plant growth via the IoT: A miniaturised electronic hardware, based on flexible electronics and featuring wireless data transfer, will be designed for the electrochemical sensors. Optimisation of input/output signals to enable dynamic alterations of nutrient content of medium, introduce pesticide or switch to fresh medium, based on changes in the macronutrient and/or biomarker content in the medium. 

Further reading

[1] Pozza LE, Field DJ. The science of Soil Security and Food Security. Soil Security, 2020, 1, 100002.  

[2] Zhang P, Guo Z, Ullah S, Melagraki G, Afantitis A, Lynch I. Nanotechnology and artificial intelligence to enable sustainable and precision agriculture. Nat Plants. 2021, 7(7): 864-876.    

[3] Saad MHM, Hamdan NM, Sarker MR. State of the Art of Urban Smart Vertical Farming Automation System: Advanced Topologies, Issues and Recommendations. Electronics, 2021, 10, 1422.  

[4] Chadwick JJ, Witteveen A, Zhang P, Lynch I. Chapter 10 – Hydroponics and alternative forms of agriculture: opportunities from nanotechnology. In: Nano-Enabled Sustainable and Precision Agriculture, Editors: Peng Zhang, Iseult Lynch, Jason C. White, Richard D. Handy. Academic Press, 2023, 259-272.  

[5] Jaworska E, Lewandowski W, Mieczkowski J, Maksymiuk K, Michalska A. Non-covalently functionalized graphene for the potentiometric sensing of zinc ions. Analyst, 2012, 137, 1895. https://doi.org10.1039/c2an16016a    

[6] Gupta K, Rai K, Kanwar SS, Sharma TR, Comparative Analysis of Zinc Finger Proteins Involved in Plant Disease Resistance. PLoS One, 2012, 7, e42578.