By focussing two opposing surface acoustic waves to a point on the substrate directly beneath a liquid drop, it is possible to concentrate the leakage of acoustic energy into the drop such that sufficient inertial stresses are generated within the drop to overcome the capillary stress resulting in the deformation of its drop interface into a coherent cylindrical liquid column. The jet that eventuates remarkably persists over several centimetres in length despite originating from a millimetre order diameter drop without requiring any nozzles or orifices. Eventually, the elongated jet suffers from the classical Rayleigh-Plateau instability through which the liquid column becomes unstable to axisymmetric perturbations and consequently breaks up into one or more droplets. In addition to demonstrating the utility of the platform as a semen quality assessment tool for male fertility diagnosis, efforts are currently underway in collaboration with optometrists from the University of Melbourne to develop the technology as a portable and efficient clinical platform for diagnosing dry eye disease.
Relevant Publications
  1. MK Tan, JR Friend, LY Yeo. Interfacial Jetting Phenomena Induced by Focused Surface Vibrations. Phys Rev Lett 103, 024501 (2009).
  2. PK Bhattacharjee, AG McDonnell, R Prabhakar, LY Yeo, J Friend. Extensional Flow of Low-Viscosity Fluids in Capillary Bridges Formed by Pulsed Surface Acoustic Wave Jetting. N J Phys 13, 023005 (2011).
  3. AG McDonnell, TC Gopesh, J Lo, M O’Bryan, LY Yeo, JR Friend, R Prabhakar. Motility Induced Changes in Viscosity of Suspensions of Swimming Microbes in Extensional Flows. Soft Matter 11, 4658–4668 (2015).
  4. AG McDonnell, NN Jason, LY Yeo, JR Friend, W Cheng, R Prabhakar. Extensional Viscosity of Copper Nanowire Suspensions in an Aqueous Polymer Solution. Soft Matter 11, 8076–8082 (2015).
  5.  JO Castro, SR Ramesan, AR Rezk, LY Yeo. Continuous Tuneable Droplet Ejection via Pulsed Surface Acoustic Wave Jetting. Soft Matter 14, 5721–5727 (2018) Article coverart selected as journal front cover; Correction: pp 5937–5938].
  6. JO Castro, SR Ramesan, HD Dang, AR Rezk, LY Yeo. Acoustopipetting: Tuneable Nanoliter Sample Dispensing Using Surface Acoustic Waves. Anal Chem 91,  5621–5628 (2019).
  7. A McDonnell, J-h Lee, E Makrai, LY Yeo, LE Downie. Tear Film Extensional Viscosity is a Novel Potential Biomarker of Dry Eye Disease. Ophthamology 126, 1196–1198 (2019).
  8. JO Castro, MS Abdul Halim, LA Ambattu, AR Rezk, R Prabhakar, R Nosrati, LY Yeo. Acoustofluidic Semen Analysis for Veterinary Male Bovine Infertility Assessment. Flow 3, E6 (2023).
Press Releases
  1. Jet Stream, Nature Research Highlights 23 July 2009, Nature 460, 439 (2009).
  2. Squirting Water Without a Gun, Physical Review Focus, 13 July 2009.
  3. Game-Changing Point-of-Care Device to Diagnose and Sub-Type Dry Eye. Optometry Australia, 26 September 2019.