EAGER: Plasmonic Sensing in Liquid with Metal-Insulator-Metal Nanosensors Embedded in Soft Matrices

Water is a vital life-sustaining resource, with access to clean water being fundamental to maintaining health. Over 2 billion individuals globally are affected by significant water stress and pollution, making the development of an efficient, cost-effective, and accessible water monitoring system a top priority. Existing water monitoring technologies, including gas chromatography, mass spectrometry, and turbidity measurement, are often too costly and necessitate the operation by highly skilled personnel, rendering them unfit for broad deployment in the most needing areas. Additionally, these technologies usually lack the capability for immediate or on-site monitoring. This project aims to explore nanoscale sensor designs for immediate and on-site water quality monitoring. This system could potentially bring about transformative changes by providing communities, especially those in resource-constrained areas, with the tools needed for on-the-spot, real-time water quality assessments. The core of the detection system comprises a metal-insulator-metal (MIM) Au-SiO2-Au nanostructures and mesoporous alginate hydrogel thin films. The project's objectives will be met through three research activities: (1) Utilizing finite element analysis (FEA) to develop Au-SiO2-Au MIM nanosensors. The FEA modelling on COMSOL will probe the influences of aspects such as shape, size, and others on sensor performance, as well as study the plasmonic enhancement factors, such as the form of inner and outer Au nanoparticles, the thickness of the central silica shell, and the space between the exterior Au nanoparticles. (2) Synthesis, testing and comparative analysis of plasmonic enhancement of various Au-SiO2-Au MIM nanosensors with numerical simulation results. (3) Embedding Au-SiO2-Au MIM nanosensors into a thin alginate hydrogel film decorated with ZnO nanorods, tailored for factors like thickness, pore size, and light absorption effectiveness. The purpose of this stage is to securely attach the Au-SiO2-Au MIM nanosensors onto a fixed base, as opposed to having them floating freely in the sample solution. This project is set to offer new techniques and information to confront the difficulties in comprehending and overseeing the global water crisis. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.