Sensores óticos altamente sensíveis baseados em nanoestruturas inovadoras para excitarem ondas eletromagnéticas de superfície aplicados na deteção de contaminantes da água

The project aims to develop artificially structured materials to generate and control electromagnetic surface waves (ESW), commonly referred as metamaterials, for sensing chemical, biochemical and biologic substances in water streams, lakes, groundwater, and wastewater to enable quality management, according to the EU Water Framework Directive (WFD). Water contaminants, which pose significant risks to ecosystems and human health, exist in low or very low concentrations, rising challenges in design and fabrication of sensing systems, requiring high sensitivity and accurate specificity. When designing metamaterials to support ESW, one key challenge is optimizing the structure to enhance light confinement and control surface propagation. Additionally, ensuring low losses and broad wavelength operation in ESW is crucial for practical applications. To design Molecularly Imprinted Polymers (MIPs) for detecting organic contaminants pose important challenges in achieving high selectivity and sensitivity towards the target molecules while minimizing non-specific binding. Additionally, optimizing the synthesis process to ensure the stability and reproducibility of the imprinted cavities within the polymer is a key challenge. When designing and fabricating nanostructures on surfaces using femtosecond laser direct writing (FLDW), maintaining uniformity and structural integrity is crucial. Additionally, controlling the profile of the structures and minimizing roughness accurately poses a significant challenge to achieve the desired optical properties. The project lies on the improvement of optical sensing systems by overcoming limitations in existing approaches and configurations. This will be achieved through innovative exploration and creation of optical structures, in one- and two- dimensions, on planar substrates, leveraging nanotechnology to generate and manipulate ESW, whose spectral behavior adapts to the surrounding environment. This will be achieved by tailoring the dispersion properties of 1D and 2D hyperbolic metamaterials and metasurfaces fabricated using cutting-edge materials deposition and nanolithography methods. The project will design and fabricate new geometries of 1D and 2D metamaterials and metasurfaces with precise shape, size, orientation, and arrangement to enable ESW. The latest advancements in nanophotonics research focus on hyperbolic metamaterials and metasurfaces, a kind of nano-engineered materials exhibiting extreme anisotropy. Despite being already reported, alternative designs will be explored. Simultaneous excitation of ESW by prism coupling and a metasurface, will enable improvement on sensitivity and figure of merit. MIPs have shown great potential in sensing applications, using synthetic recognition sites to detect specific molecules with high sensitivity and selectivity. By functionalizing hyperbolic metamaterials and metasurfaces with MIPs will result in new optical sensors, achievable by merging the existing team members knowledge of different disciplines. A functional prototype will be built to demonstrate the application of this technology for autonomous sample monitoring. Unlike conventional optical sensors that detect only one substance, this innovative approach targets multiple analytes through the implementation of dedicated microfluidic channels in conjunction with spectral interrogation in different electromagnetic bands.