Localized Gas Phase Transport: Fundamental Research and Applications

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This interdisciplinary proposal is at the cross-section of Aerosol science and the collection and detection of Airborne particles. The proposal describes the investigation of a new transport mechanism that we discovered, which supports the localized collection of airborne particles at a higher rate than previously possible. Strongly simplified the process is a directed electrodynamic transport process. The mechanism, as far as it is understood, is based on the interplay between high mobility gas ions with airborne particles, a patterned substrate, and a carrier gas. The process leads to localized collection and concentration of airborne particles at predetermined sensing points on a patterned substrate. The discovered process is applicable to a wide range of particle sizes (15 orders of magnitude so far in terms of particle weight, 102 Da to 3x1017Da) and types (organic and inorganic). In a first publication in Nature communications [1] we demonstrate that the collection process is several orders of magnitudes faster than the commonly used diffusion only transport. Despite the fact that the process is only poorly understood several immediate applications followed. For example in a publication [2] entitled >Localized Collection of Airborne Analytes: A Transport Driven Approach to Improve the Response Time of Existing Gas Sensor Designs< the increased deposition rate was applied to detect airborne molecules. In the subsequent publication [3] entitled >Active Matrix Based Collection of Airborne Analytes: An Analyte Recording Chip Providing Exposure History and Finger Print< the idea of an analyte recording chip is discussed. In a fourth [4] and very different application the discovered process was use to collect metallic nanoparticles to grow freestanding point to point nanowire bridges at high rates. The specific project targets the fundamental study of the underlying process and applications. For example, from a theoretical transport equation point of view the observed abnormally high collection rate cannot be explained unless the reaction kinetics (sticking coefficient) is different. The proposed process utilizes the interplay between charged ions, airborne particles, a pattered substrate with programmable charge dissipating contact points, and a carrier gas. The installation of an experimental platform is proposed to gain access to the relevant process parameter (gas ion concentration, particle number concentration, localized gas flow, ionic dissipation current, and potential profile). From an application point of view we would like to focus on the recently published idea [3] which describes a generic approach to collect airborne analytes in an active matrix type fashion on chip sized substrates. Finally, we would like to extend the range of analyte particles to include Airborne pathogens within the field of aerovirobiology. In preparation for the proposal we have conducted first experiments with airborne Bacteriophages.