SGER: Fractal Surface Enhanced Chemical & Biological Sensors

Purdue University, West Lafayette IN

Investigators

Abstract

This is a Small Grants for Exploratory Research (SGER) award. It is in response to the "Next Generation Chemical and Biological Sensors and Sensing Systems" Dear Colleague letter, NSF-02-112. In this project, novel nanostructured fractal and fractal-microcavity sensors will be fabricated. These sensors are expected to provide unsurpassed sensitivity in optical detection of molecules in minute quantities, including small amounts of biological and chemical agents. The sensors are based on fractal metal-dielectric composites, which can support various plasmon modes resulting in giant enhancement of optical responses. Plasmon modes in fractal materials experience localization so that the electromagnetic energy is accumulated and concentrated in nanometer-scale areas, "hot spots," leading to the strongly enhanced local fields. The resonating areas, hot spots, can act as nano-antennas with different resonance frequencies. Combining the energy-concentrating effects from localized optical excitations in plasmonic nano-resonators with micro-resonators based on dielectric cavities, can result in record-high enhancement of optical phenomena. This research could lead to new optical sensors with unsurpassed sensitivity. The proposed research, supported by synergistic activities with Center for Sensing Science and Technology at Purdue will integrate cutting-edge research in sensor science and technology with top-flight education and training. This is a Small Grants for Exploratory Research (SGER) award. It is in response to the "Next Generation Chemical and Biological Sensors and Sensing Systems" Dear Colleague letter, NSF-02-112. In this project, novel nanostructured fractal and fractal-microcavity sensors will be fabricated. These sensors are expected to provide unsurpassed sensitivity in optical detection of molecules in minute quantities, including small amounts of biological and chemical agents. The sensors are based on fractal metal-dielectric composites, which can support various plasmon modes resulting in giant enhancement of optical responses. Plasmons represent collective oscillations of electrons in metals and metal-dielectric composites and they are known to be a major reason for surface-enhanced spectroscopy, in which plasmonic nanostructures lead to many orders of magnitude increases in the sensitivities of optical spectroscopies. Plasmon modes in fractal materials experience localization so that the electromagnetic energy is accumulated and concentrated in nanometer-scale areas, "hot spots," leading to the strongly enhanced local fields. Combining the energy-concentrating effects from localized optical excitations in plasmonic fractal modes with micro-resonators based on dielectric cavities can result in record-high enhancement of optical phenomena. This research can eventually lead to developing new optical sensors with unsurpassed sensitivity. The research, supported by synergistic activities with the Center for Sensing Science and Technology at Purdue will integrate cutting-edge research in sensor science and technology with top-flight education and training.