Did you know it is possible to detect contaminants in water using optical systems? INESC TEC aims to take this detection to a new level, by developing a new generation of optical sensors based on metamaterials, capable of achieving superior results in terms of sensitivity, selectivity, and the ability to analyse multiple compounds simultaneously. This is the approach proposed by the WaveSense project, which seeks to overcome the limitations of current optical detection systems.
Using optical systems to test for water contaminants is not new: sensors observe how light changes as it interacts with water, to identify which substances are present and in what quantity. The innovation lies in optical sensors based on metamaterials – artificial materials designed with tiny structures that make it possible to control light in ways that natural materials cannot. More sensitive to surface light waves, they can analyse several types of pollutants at once and with greater accuracy. The first step will be to develop these materials and then apply them to sensors.
“Our goal is to contribute to advanced solutions for continuous water quality monitoring in natural and industrial environments, in line with European Union directives. We expect to achieve this through the optimisation of metamaterials and metasurfaces that support the efficient propagation of surface electromagnetic waves, and through the development of highly selective molecularly imprinted polymers. In addition, we aim to apply advanced micro- and nanofabrication techniques and coat the metamaterial surfaces with MIPs (molecularly imprinted polymer) to create hybrid sensors capable of selectively recognising various contaminants. Integrating all these technologies into a prototype will enable autonomous and simultaneous monitoring of multiple contaminants,” explained INESC TEC researcher Luís Coelho, who leads the project.
By the end of the project, the goal is to have a real prototype tested in rivers, lakes, groundwater, and wastewater, to prove that it works outside the laboratory and can be used for real-world environmental monitoring.
Manufacture, build and test: INESC TEC takes the lead
INESC TEC’s role will be crucial to the success of the project. In the first phase, the team will be responsible for designing and simulating the metamaterials, exploring new architectures capable of maximising light confinement and, consequently, sensor sensitivity. In the manufacturing phase, advanced nanofabrication technologies will be used – machines that draw microscopic patterns with lasers, visible only under a microscope. After that, it will be time to assemble it all into a real sensor, combining the metamaterials with the molecularly imprinted polymers.
“This integration will result in a prototype equipped with microchannels to guide liquids and spectral reading modules, combining firmware and the data acquisition interfaces required for autonomous device operation. The final stage will involve validating the technology in real aquatic ecosystems – rivers, lakes, coastal or groundwater – strengthening INESC TEC’s strategic commitment to maritime and environmental initiatives, such as INESCTEC.Ocean,” explained the researcher, who also leads the Applied Photonics area at INESC TEC.
The project will have an impact across multiple sectors, beginning with the scientific community, which will benefit from new advances in nanophotonics, metamaterials, and detection technologies. Society will also benefit from more effective mechanisms for water quality monitoring, which are essential for public health and the preservation of aquatic ecosystems. “Agencies responsible for managing and monitoring water quality will have access to more accurate and sensitive tools, while the industrial sector and the Blue Economy will be able to integrate these sensors into observation platforms and intelligent environmental detection systems,” added Luís Coelho.
The technology developed paves the way for future advances in metamaterial-based sensing and reinforces INESC TEC’s role in creating a new generation of more precise and selective sensors. According to the researcher, “integrating this approach with marine and environmental monitoring systems also ensures a sustainable and multidisciplinary research pathway.”
The WaveSense project also involves the University of Porto’s Chemistry Centre and builds on the SurfWave Seed Project (INESC TEC’s internally funded projects), which established the scientific foundation for generating and controlling surface electromagnetic waves and demonstrated the transformative potential of these technologies.
The researcher mentioned in this news piece is associated with INESC TEC
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