Nanophotonic biosensors for environmental monitoring of chemical and microbiological residues

Environmental monitoring has made significant strides in recent years; however, despite remarkable progress, reliable on-site detection and continuous monitoring of contaminants remain challenging. Besides well-known chemical pollutants, the increasing presence of emerging contaminants in complex environmental samples has raised global concerns regarding their negative effects on human health and ecosystems. This situation underscores the need for efficient continuous monitoring and portable analytical tools that can conduct in-field and on-site analyses to detect and quantify relevant pollutants in complex environmental samples. Nanophotonic sensors are becoming powerful analytical platforms for environmental monitoring due to their high sensitivity, rapid response, label-free detection capabilities, potential for multiplexing, and compatibility with on-chip integration and miniaturization. This review provides an overview of recent advances in nanophotonic sensor technologies, including plasmonic and silicon photonic sensors, for the environmental monitoring of industrial chemicals, pharmaceutical residues, toxic by-products, microplastics, and microbiological agents. It examines key developments in device integration and multi-analyte detection strategies, highlighting representative applications across different classes of contaminants in water sources, along with selected gas-sensing examples. It also discusses current challenges and future prospects for decentralized environmental monitoring.