Innovative low-cost optical sensor platform for water quality monitoring

Lead Research Organisation: City, University of London
Department Name: Sch of Engineering and Mathematical Sci

Abstract

Water is essential to life. Access to safe drinking water may be norm in developed countries, but two billion people in developing countries, like India have limited access to clean water and according to the WHO, mortality of water associated diseases exceeds 5 million people per year. Waste water from geological sources contains pollutants like arsenic and fluorides or discharge from industries, agricultural farms, and household wastes contain pharmaceutical, heavy metals, pesticides, fertilisers, organic waste, and faeces discharged to rivers and lakes.

Waterborne diseases are caused by pathogenic microorganisms that mostly are transmitted in contaminated fresh water and results from bathing, washing, drinking and in the preparation of food. Bacterial pathogens, cause major diarrhoea, resulting in millions of avoidable deaths, with more suffering of children. Industrial wastes such as heavy metals are toxic to marine life and subsequently to humans who eat those causing birth defects and cancers. Effect of many industrial wastes can be very slow, often identified very late. Waste organic matter, fertilisers, and nutrients deplete oxygen from water and cause suffocation to fish and other aquatic organisms and ultimately human consuming these infected fish.
CITY has excellent facilities for fabricating FBG and LPG, complements IISc expertise. Several concatenated gratings can be fabricated on the same optical fibres to detect several species simultaneously and each grating can be prepared for different selectivity with different Bragg wavelengths for multiplexing. Advanced micro-fibres, micro-knots and micro-spheres can also be functionalised for more compact optical sensors. On the other hand, silicon nanophotonics is an exciting emerging area of research and innovation, which exploits the well developed CMOS technology developed by highly matured semiconductor industries. Exotic slot waveguide, where light is confined in a low-index region, can easily be functionalised for much more compact optical sensors, often just several micron long. Highly sensitive silicon ring resonator less than 5 micron in radius which can detect 10E-5 refractive index change and 2 micron diameter micro-resonators supporting whispering gallery modes are capable of detecting a single molecule. Such tiny sensors can be mass manufactured at vastly reduced cost, hundreds of them in a mm-square wafer, and then multiplexed and excited by a single 500 nm nanowire optical bus for rapid multi-parameters sensing. IISc has expertise in functionalisation and bio-sensing complements CITY expertise in physical and chemical sensing.

The present water quality monitoring systems over the whole India, from large metropolis to small towns and remote villages are of diverse quality. There is a lack of standardised criteria for defining the safe limits of various key pollutants. Effect of some pollutants can be very slow, such as that of heavy metals, and this can be even more difficult to identify at a low level of contaminations until prolonged suffering by people. A solution to this problem is to improve the surveillance systems, both for fast acting bio-pathogens and slow-acting chemical pollutants and one way to achieve this is to develop methods to rapidly, in-situ, accurate and continuous monitoring of water quality and identify any potential breakdown in quality control well before it can be identified from the outbreak of any major diseases with many avoidable sufferings.

The objective of this research proposal is to develop frugal, compact multi-channel optical sensors for innovative and cost-effective development of multi species rapidly, reliably and selectively to detect protein, peptides, cytokine, from bacterial and viral pathogens and chemical residues for in-situ and real-time drinking, general use and waste water monitoring, which can be deployable to large metropolis to small rural community.

Planned Impact

The full-partnership comprises skilled, highly motivated members who will succeed through a series of tangible deliverables and thus create a substantial research impact. Key facilities in India and the UK will be exploited to support this project and, in turn, the facilities will strengthen.

Although the pressing need in India has driven this proposal, the successful outcomes of the project will have positive impact on other countries. The rapid economic development in India over past decades has been coupled with rapid growth of populations, and urbanization. Unfortunately, low-investment, under-developed and often crumbling urban infrastructure, has resulted in severe environmental and human suffering arising directly from the urban sprawl. In addition, up to 1 billion people could be living in an urban environment in the next few decades - many of whom will be financially disadvantaged and unable to afford access to the good quality healthcare. Ultimately, rapid economic development brings opportunity and hope but this needs to be delivered to all. Infrastructures that support a safe, healthy and vibrant society require monitoring and timely, protective measures. On the other hand, people in remote areas are also vulnerable to often lack of water quality monitoring systems. There is an urgent need to address the key development challenges that can result in safer water providing better healthcare, better water supply infrastructure and wellbeing of all the citizens.

The exploitation of advanced biosensors for rapid and continuous detection of some critical bio-pathogens and incriminating chemical pollutants can save suffering from infections and diseases and ultimately human lives and often more of children.

This consortium involves the leading research group in India in the field of optical sensors and instrumentation, who, with the help of participation of water supply agency of Bangalore, also know the key parameter which must be monitored, national shortcomings best, collaborating with the world-leading research group from UK, in optical sensors, and photonics modelling.

These are potentially low-cost, easily transportable and stored and can be used by tens of thousands of small utility suppliers, village community centres, rather than only in a few large metropolises or even smaller towns.

The findings will be publicised both to academia and industry, to exploit them further. SME and local industries will also benefit from the likely exploitation of the better designed integrated optical sensors. It will have an impact on not only for water quality monitoring sensors but also other optical sensor development through development of relevant technologies.
The major impact benefit is planned to be on individual citizens who will gain from the monitoring measures we are developing in this project. The impact from the expected research output will have major societal benefits from better spatial and temporal real-time information, to warn about and mitigate impending outbreak major disaster or continuous development of slow-acting pollutants. Thus whole populations will benefit from better water quality and also authority from information gained from the study about the local or regional water quality problems and from better protection from possible impeding developments. Some geological pollutants, such as arsenic, do not confine within a geographical boundary and early identification of its build-up, the impact will be felt more widely, so a policy framework on this trans-boundary contamination, affecting countries in Indian sub-continents can be formulated and this, in the longer term, will have a larger impact on policy and planning, from having a suite of evidence-based data which can guide their attendant actions and activities.

Publications

10 25 50
 
Title Simulation and material characterisation 
Description We are working with the fibre based long period grating (LPG). An LPG model is developed using Limerical FDTD is developed and simulated results are verified with the laboratory developed LPG. LPG is coated with the polymerised graphene oxide nanocomposite material. A sub-micron layer has been coated on the fibre and that coating thickness is measured form fibre cross-sectional images taken by scanning electron microscope (SEM). The nanocomposite materials are characterised using Fourier-transform infrared spectroscopy (FTIR). 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? No  
Impact The FDTD LPG simulated results were used to optimised and fabricate the long period grating (LPG) inside the fibre core. The SEM cross-sectional images were utilised to measure and optimise the sub-micron level nanocomposite coating thickness. Different FTIR spectra were used to characterise the developed polymerised nanocomposite material which acts as a potential adsorbent for the heavy metal ions such as lead, mercury and many antibiotic components. 
 
Title FEM and FDTD modelling 
Description Frequency based optical modal analysis using full-vectorial Finite Element Method (FEM) Finite Difference Time Domain (FDTD) analysis for optical modal analysis and wave propagation in a waveguide and resonantors. 
Type Of Material Computer model/algorithm 
Year Produced 2018 
Provided To Others? Yes  
Impact FEM based optical modal analysis has been used for various complex waveguide design and optimisation. FDTD based modelling method has been used for simulation of transmission and absorption spectra of the waveguides, grating and resonating devices. 
 
Description IISc collaboration 
Organisation Indian Institute of Science Bangalore
Country India 
Sector Academic/University 
PI Contribution we have fabricated long period grating in optical fibre for sensor development
Collaborator Contribution IISc have helped us in the chemical etching of LPG to evaluate sensor performances.
Impact new sensor designs
Start Year 2019
 
Description Photonics and Sensor Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact 68 attendee from around the world joined the 1st Photonics and Sensors Workshop in London 2019 on 27 to 28th June at the City, University of London, UK campus. The workshop was inaugurated by the Sir Professor David N Payne, FRS, form University of Southampton, UK. The workshop was showcased to motivate the undergraduate and postgraduate students with ongoing research problems and outcomes.
Year(s) Of Engagement Activity 2019
URL https://www.city.ac.uk/events/2019/june/photonics-and-sensor-workshop-in-london