James Friend
(BS Magna cum laude Aero Engr 1992, MS Mech Engr 1994, PhD Mech Engr 1998) directs the new MicroNano Research Facility at RMIT University, and co-founded and co-directs the $7.25 million MicroNanophysics Research Laboratory with clean room and biolab, a current staff of four academics, two post-doctorates and twelve PhD students. He is a professor and Vice-Chancellor's Senior Research Fellow in the School of Electrical and Computer Engineering at RMIT University and an MCN Senior Tech Fellow with the Melbourne Centre for Nanofabrication with research interests in micro/nanodevices for biomedical applications.
Publication list and PDFs of papers
He is an associate editor of Biomicrofludics, a senior member of IEEE, a member of ASME and Golden Key, and a committee member of IEEE Nanotechnology for Biology, and has over one hundred sixty peer-reviewed publications, with seven book chapters, ninety-six peer-reviewed journal papers, and twenty-five patents and patent applications.
He received excellence in teaching, early career researcher and research awards from the Monash Faculty of Engineering in 2006, 2008 and 2010, respectively, a Future Leader award from the Davos Future Summit in Sydney in 2008, and was awarded membership in the Top 100 emerging leaders/Top 10 emerging scientific leaders of Australia by Microsoft and The Australian newspaper in 2009. He recently received a Distinguished Young Alumni and Alumni of Influence awards from his alma mater, the University of Missouri-Rolla (now MST)
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More liked postsMicroscale Capillary Wave Turbulence Excited by High Frequency Vibration
From DOI: 10.1021/la304608a
Low frequency (O(10 Hz–10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling due to the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this frequency in superharmonic waves. Less understood, however, are the dynamics of capillary waves driven by high frequency vibration (>O(100 kHz)) and small interface length scales, an arrangement ideal for a broad variety of applications, from nebulisers for pulmonary drug delivery to complex nanoparticle synthesis. In the few studies conducted to date, a marked departure from the predictions of classical Faraday wave theory has been shown, with the appearance of broadband capillary wave generation from 100 Hz to the excitation frequency and beyond, but there has not yet been a clear explanation. We show that weak wave turbulence is the dominant mechanism in the behavior of the system, evident from wave height frequency spectra that closely follows the Rayleigh-Jeans spectral response η ∼ ω^(−17/12) as a consequence of a period-halving, weakly turbulent cascade that appears within a 1 mm water drop whether driven by thickness-mode or surface acoustic Rayleigh wave excitation. However, such a cascade is one-way, from low to high frequencies. The mechanism of exciting the cascade with high frequency acoustic waves is an acoustic streaming-driven turbulent jet in the fluid bulk, driving the fundamental capillary wave resonance through the well-known coupling between bulk flow and surface waves. Unlike capillary waves, turbulent acoustic streaming can exhibit subharmonic cascades from high to low frequencies; here it appears from the excitation frequency all the way to the fundamental modes of the capillary wave some four orders of magnitude in frequency less than the excitation frequency, enabling the capillary weakly turbulent wave cascade to form from the fundamental capillary wave upwards. Paper here.
Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films
From DOI: 10.1038/ncomms2168
Figure: (a) The setup with oil drop, (b) top view with fluorescence, (c) exposure to SAW draws a film toward the acoustic source, (d) the leading edge of the film deepens and forms rapidly moving drops away from the source, and (e) this develops into a broadly occurring phenomenon that maintains mass conservation.
Acoustic–fluid interactions not only has had a long history but has recently experienced renewed scrutiny because of their vast potential for microscale fluid and particle manipula- tion. Here we unravel a fascinating and anomalous ensemble of dynamic ‘acoustowetting’ phenomena in which a thin film drawn from a sessile drop first spreads in opposition to the acoustic wave propagation direction. The advancing film front then exhibits fingering instabilities akin to classical viscous fingering, but arising through a different and novel mechanism: transverse Fresnel diffraction of the underlying acoustic wave. Peculiar ‘soliton-like’ wave pulses are observed to grow above these fingers, which, on reaching a critical size, translate away along the wave propagation direction. By elucidating the complex hydrodynamics underpinning the spreading, and associated flow reversal and instability phenomena, we offer insight into the possibility of acoustically controlling fast and uniform film spreading, constituting a flexible and powerful alternative for microfluidic transport. Paper here.
Bright-field video here.
Dark-field fluorescence video here, showing complete phenomena.
Fast surface acoustic wave-matrix-assisted laser desorption ionization mass spectrometry [MALDI-MS] of cell response from islets of Langerhans
From DOI: 10.1021/ac3019125
A desire for higher speed and performance in molecular profiling analysis at a reduced cost is driving a trend in miniaturization and simplification of procedures. Here we report the use of a surface acoustic wave (SAW) atomizer for fast sample handling in matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) peptide and protein profiling of Islets of Langerhans, for future type 2 diabetes (T2D) studies. Here the SAW atomizer was used for ultrasound (acoustic) extraction of insulin and other peptide hormones released from freshly prepared islets, stimulated directly on a membrane. A high energy propagating SAW atomizes the membrane-bound liquid into approximately 2 μm diameter droplets, rich in cell-released molecules. Besides acting as a sample carrier, the membrane provides a purification step by entrapping cell clusters and other impurities within its fibers. A new SAW-based sample-matrix deposition method for MALDI MS was developed and characterized by a strong insulin signal, and a limit of detection (LOD) lower than 100 amol was achieved. Our results support previous work reporting the SAW atomizer as a fast and inexpensive tool for ultrasound, membrane-based sample extraction. When interfaced with MALDI MS, the SAW atomizer constitutes a valuable tool for rapid cell studies. Other biomedical applications of SAW-MALDI MS are currently being developed, aiming at fast profiling of biofluids. Paper here.
Precise drop dispensation [sic] on superhydrophobic surfaces using acoustic nebulization
From DOI: 10.1039/c3sm00016h
The adhesion forces of liquid drops on superhydrophobic surfaces are typically in the nano-Newton range which presents problems in their dispensation from pipettes. Furthermore, since the liquid adheres more strongly to the pipette tip, some portion of the liquid will tend to remain on the tip, causing inaccuracy in the volume dispensed. We advance a novel approach here, in which the spray from an acoustic nebulizer is sent to a superhydrophobic receptacle and the volume ascertained precisely using a weighing scale. The volume dispensed was found to vary linearly with the operation time of the nebulizer. Paper available here.
Atomization off thin water films generated by high-frequency substrate wave vibrations
From DOI: 10.1103/PhysRevE.86.056312
Generating aerosol droplets via the atomization of thin aqueous films with high frequency surface acoustic waves (SAWs) offers several advantages over existing nebulization methods, particularly for pulmonary drug delivery, offering droplet sizes in the 1–5 μm range ideal for effective pulmonary therapy. Nevertheless, the physics underlying SAW atomization is not well understood, especially in the context of thin liquid film formation and spreading and how this affects the aerosol production. Here, we demonstrate that the film geometry, governed primarily by the applied power and frequency of the SAW, indeed plays a crucial role in the atomization process and, in particular, the size of the atomized droplets. In contrast to the continuous spreading of low surface energy liquids atop similar platforms, high surface energy liquids such as water, in the present case, are found to undergo transient spreading due to the SAW to form a quasisteady film whose height is determined by self-selection of the energy minimum state associated with the acoustic resonance in the film and whose length arises from a competition between acoustic streaming and capillary effects. This is elucidated from a fundamental model for the thin film spreading behavior under SAW excitation, from which we show good agreement between the experimentally measured and theoretically predicted droplet dimension, both of which consistently indicate a linear relationship between the droplet diameter and the mechanical power coupled into the liquid by the SAW (the latter captured by an acoustic Weber number to the two thirds power, and the reciprocal of the SAW frequency). Paper available here.
Maryton Park, Marysville Victoria: A farm and B&B on the outskirts of town. Evidence of the fires remain.
Fluid-structure interaction in deformable microchannels
Figure: The deformation of the thin flexible membrane under pressure (as indicated in graph at right) forms a deformable channel which controls how the fluid (green) flows through the region.
A polydimethylsiloxane microfluidic device composed of a single microchannel with a thin flexible layer present over a short length along one side of the channel was fabricated and modelled in order to investigate the complex fluid-structure interaction that arises between a flowing fluid and a deformable wall. Experimental measurements of thin layer deformation and pressure drop are compared with predictions of two- and three-dimensional computational models that numerically solve the coupled set of equations governing both the elasticity of the thin layer and the fluid. It is shown that the two-dimensional model, which assumes the flexible thin layer comprises an infinitely wide elastic beam of finite thickness, reasonably approximates a three- dimensional model, and is in excellent agreement with experimental observations of the thin layer profile when the width of the thin layer is beyond a critical value, roughly twice the length of the thin layer. Paper here in Physics of Fluids. DOI: 10.1063/1.4759493
Spring constant calibration of atomic force microscope cantilevers of arbitrary shape
Measuring atomic force microscope probes using laser Doppler vibrometry permits measurement of their spring constants without excitation: the thermal excitation from the atomic motion within the cantilever drives the cantilever’s resonances at around 5 pm in amplitude, vibration we can see. (Paper here) From: Rev. Sci. Instrum. 83, 103705 (2012); doi: 10.1063/1.4757398
Jochen Schell of Polytec provides training for our new MSA-500 complete with topology and new digital decoder cards.
In celebrating the 50th Anniversary of APL, the Editor highlighted the fifty most highly cited papers published in the Journal over the past fifty years, and fifty of the many notable APL articles published in 2009 through 2012 (August), that the Editor has selected to showcase ongoing innovative research activities. Ours was one of the latter 50 to be selected in the top journal in physics in terms of citations.
The appearance of boundary layers and drift flows due to high-frequency surface waves
Image: Spatial comparison between the theoretical variation of the drift velocity along the solid boundary, from doi:10.1017/jfm.2012.293.
The classical Schlichting boundary layer theory is extended to account for the excitation of generalized surface waves in the frequency and velocity amplitude range commonly used in microfluidic applications, including Rayleigh and Sezawa surface waves and Lamb, flexural and surface-skimming bulk waves. These waves possess longitudinal and transverse displacements of similar magnitude along the boundary, often spatiotemporally out of phase, giving rise to a periodic flow shown to consist of a superposition of classical Schlichting streaming and uniaxial flow that have no net influence on the flow over a long period of time. Correcting the velocity field for weak but significant inertial effects results in a non-vanishing steady component, a drift flow, itself sensitive to both the amplitude and phase (prograde or retrograde) of the surface acoustic wave propagating along the boundary. We validate the proposed theory with experimental observations of colloidal pattern assembly in microchannels filled with dilute particle suspensions to show the complexity of the boundary layer, and suggest an asymptotic slip boundary condition for bulk flow in microfluidic applications that are actuated by surface waves. Paper is here.
Gets started from about 4 min 30 seconds at the video placed here.
