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We report the discovery of a new class of sound waveshybrid surface and bulk waves, coined surface reflected bulk waves, that are generated on a piezoelectric device. Besides elucidating the underlying physical mechanisms associated with their origin, we demonstrate that the unprecedented surface acceleration of these waveson the order of 10 million g’s, provides an efficient means for driving fluid nebulisation at extremely high rates of several ml/minan order of magnitude larger than conventional nebulisers. At these rates, aerosolised drugs can be delivered to the lung at sufficiently adequate doses over inhalation times that are commensurate for practical administration. Moreover, unlike most nebulisers, we show that the high frequency (10 MHz order) excitation does not lead to denaturation of biological drugs (large molecules such as DNA, RNAi, peptides and proteins) as well as stem cells, therefore enabling efficacious delivery of these next generation therapeutics via inhalation through a miniaturised platform amenable for portable handheld use at the point of need. Further, it is possible to encapsulate the therapeutic molecules within single- and multi-layer polymeric nanocapsules for simultaneous delivery. In addition, we also demonstrate the nebulisation platform as an effective one-step method for synthesizing novel bulk crystalline materials with unique crystal morphologies that have yet to be reported to date, or to exfoliate bulk crystals of transition metal dichalcogenides into two-dimensional single- and few-layer nanosheets. Given the high nebulisation rates and the low cost of the chipscale platform, we envisage the possibility of achieving industrial-scale synthesis yields but with much lower energy requirements through massive device parallelisation, therefore offering a paradigm-shifting alternative for economically-viable process intensification.
Leslie Yeo is a Professor of Chemical Engineering at RMIT University, Australia. He received his PhD from Imperial College London in 2002, for which he was awarded the Dudley Newitt prize for a computational/theoretical thesis of outstanding merit. Prior to joining RMIT University, he was a postdoctoral research associate in the Department of Chemical & Biomolecular Engineering at the University of Notre Dame, USA, after which he held a faculty position at Monash University. He also held the Australian Research Fellowship and Australian Research Council Future Fellowship from 2009 to 2017. Dr Yeo was the recipient of the 2007 Young Tall Poppy Science Award from the Australian Institute for Policy & Science ‘in recognition of the achievements of outstanding young researchers in the sciences including physical, biomedical, applied sciences, engineering and technology’, and the Dean’s and Vice-Chancellor’s awards for excellence in early career research at Monash University. Dr Yeo is co-author of the book Electrokinetically Driven Microfluidics & Nanofluidics (Cambridge University Press), and the author of over 200 research publications and 20 patent applications. He is also the Editor of the American Institute of Physics journal Biomicrofluidics and an editorial board member of Interfacial Phenomena & Heat Transfer and Scientific Reports.