EAGER: Towards Simultaneous Optical Sensing of Multiple Analytes With a Multiple Surface-Plasmon-Polariton-Wave Platform

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1106503 Lakhtakia Intellectual Merit. The dispersal of chemical wastes from industrial processes, pesticides from agricultural run-offs, metal leaching from landfills, all exemplify the growing problem of pollution of water resources. The deliberate introduction of pesticides and bacteria by terrorists in the nation's water resources is a related potential problem. Today's optical sensors are designed to detect one analyte at a time. If each sensor could sense more than one analyte, the rapidity of detection would be greatly enhanced.Theory has shown that more than one surface- plasmon-polariton (SPP) wave can be excited at the planar interface of a metal film and a nanomaterial called a chiral sculptured thin film (CSTF) at a specific free-space wavelength, in contrast to the only one SPP wave that can be excited in conventional platforms for SPP-based optical sensing technology. The aim of this 1-year EAGER project to theoretically and experimentally understand the underlying principles towards the use of a metal/CSTF interface for multi-analyte sensing with just one optical sensor.With experimental data available for titanium-oxide and tantalum-oxide columnar thin films and aluminum thin films, calculations will be made to reasonably map the occurrence of multiple SPP-wave modes in relation to the deposition conditions of CSTFs. Aluminum and CSTFs will be deposited in the commonplace Kretschmann configuration to verify the prediction of multiple SPP-wave modes experimentally. Lastly, a proof-of-concept sensing experiment will be performed by infiltrating a CSTF with water and noting the angular shifts in the Kretschmann configuration. Two incomplete links exist between the theoretical foundation and the realization of a multi-analyte sensor. First, clear and comprehensive experimental verification of the multiple SPP-wave modes guided by the metal/CSTF interface has to be carried out. Second, the sputtered metal film will also be porous, in addition to the CSTF being porous, so that the characteristics of the proposed sensor could be more complicated than thought. Hence, this is a high-risk proposal for non-EAGER funding mechanisms to be fruitfully invoked. Success will result in a high pay-off, as the capacity for sensing biochemicals in fluids would be greatly enhanced.Broader Impact. This project will engage one US graduate student in interdisciplinary research that bridges topics in nanomaterials synthesis and optical reflectance/transmittance measurements. The PI's endowed professorial chair will fund the participation of an undergraduate engineering student at Penn State in the proposed research. Both students will be required to develop their presentation skills by participating in the annual student-run College of Engineering Research Symposium at Penn State. The project will also initiate a tight collaboration with Groupe GDG Énvironmente Lte, Quebec, Canada, an industrial leader in environmental health technology, with a strong focus on new diagnostics tools based on sensors and lab-on-a-chip technology.