In this talk, we demonstrate the intriguing possibility of harnessing phonon sources, in particular, MHz order surface acoustic waves (SAW), for synthesizing, processing or manipulating a variety of nanoscale and biological materials. The large surface accelerations associated with the SAW substrate vibration—on the order of 10 million g’s, for instance, can be employed for micro/nanoscale material processing such as the debundling of carbon nanotube agglomerates.
The large mechanical stresses, particularly that arising from the highly nonlinear fluid-structural interaction as the SAW is coupled into a liquid suspension resulting in its nebulisation, together with the high intensity electric field inherent in the electromechanical coupling of the acoustic wave, can also be used to rapidly exfoliate bulk three-dimensional crystalline transitional metal dichalcogenides such as molybdenum disulphide (MoS2) and tungsten disulphide (WS2) into monolayer and few-layer nanosheets with comparative yield to other large scale exfoliation methods. Additionally, the SAW can be exploited for the manipulation of quasiparticles in these two-dimensional materials.
As an example, we show the possibility for reversibly modulating trion to exciton transition, and their subsequent transport and hence spatial separation within the material. In the second part of the talk, we demonstrate the same SAW nebulisation platform for pulmonary drug, gene and stem cell delivery. Whilst we specifically show the use of the device for inhaled DNA vaccination against influenza, this generic platform technology can also be easily adapted for the administration of other macromolecular drugs such as RNAi, peptides and proteins (e.g., monoclonal
antibodies) to treat a wide range of respiratory diseases including lung cancer, as well as stem cells for lung tissue regeneration and repair.
Further, the technology constitutes a rapid, efficient and straightforward means for synthesising 100 nm order biodegradable polymeric particles within which the therapeutic molecules can be encapsulated. Finally, the ability to synthesise multiple polyelectrolyte coatings encapsulating these biomolecules is shown as a fast and efficient alternative to conventional layer-by-layer assembly. The low cost, particle size control, low power requirement, delivery efficiency, and miniaturisability of the device altogether suggests the platform constitutes an attractive alternative to conventional nebulisers and inhalers, and could comprise the next-generation of devices that can potentially revolutionise inhaled biological therapeutics.
Leslie Yeo is currently an Australian Research Council Future Fellow, Professor of Chemical Engineering and Director of the MicroNanomedical Research Centre 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 Mathematical Modeller at Det Norske Veritas UK and 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. 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 both the Dean’s and Vice-Chancellor’s awards for excellence in early career research at Monash University. His work on microfluidics has been featured widely in the media, for example, on the Australian Broadcasting Corporation’s science television
program Catalyst, 3RRR and SBS radio broadcasts, and in various articles in The Economist, New Scientist and The Washington Times, in addition to being highlighted in Nature and Science.
Dr Yeo is co-author of the book Electrokinetically Driven Microfluidics & Nanofluidics (Cambridge University Press), and the author of over 185 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.