Organisms detect odors with great specificity and sensitivity using highly evolved olfactory systems. While the structure and specificity of olfactory organs and systems varies species to species, there are two common themes -- high surface area for interaction with odors and odorant receptor proteins for capture of specific odors. The combination of high surface area and odorant receptor proteins allows the detection of multiple odors that are of interest to the organism and that are present in a wide range of concentrations, for example the detection of different flower scents by insects. The insect olfactory organ, the antenna, is the bio-inspiration for our proposed research: fabrication of a highly sensitive and selective micromechanical sensor that uses both high surface area and specific capture proteins for odor detection. This new biosensors will be significantly more sensitive than current analogs and will enable earlier and more precise detection of volatile organic compounds. Such compounds are important for applications ranging from explosives detection to cancer diagnostics, therefore proposed technology will have significant societal impact.
proposed sensor platform, the micromechanical cantilever, will be fabricated with high surface area silicon dioxide nanostructure to which odorant receptor proteins will be tethered thereby mimicking the two principles widely found in biological olfactory systems. We will explore a fundamental cantilever-based sensing modality: dynamic-mode operation in which the mass of the bound odor molecules changes the frequency of a resonant cantilever. In an innovative approach, the silicon dioxide nanostructures are created using low-temperature glancing angle deposition (GLAD) of silicon dioxide in a post-processing manner, i.e. after the fabrication of the cantilever platforms. GLAD deposition facilitates fabrication of selectable (nanostructure elemental composition) and tunable (density, shape, aspect ratio) surface structure. Nanostructured surfaces will be locally functionalized with receptor peptides derived from human odorant receptor proteins sequences, which selectively bind the volatile organic compounds (VOCs) of interest. Microcantilever technology allows fabrication of multiple cantilever sensor arrays in which the elements of the array are individually functionalized to sense a number of target analytes simultaneously. This interdisciplinary project integrates biological sensing with micromechanical nanostructured sensors for low-level (parts per billion) detection of VOC analytes.
