James Friend

James Friend
University of California, San Diego | UCSD · Department of Mechanical and Aerospace Engineering (MAE)

About

302
Publications
45,272
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,064
Citations
Introduction
James is a Professor in the Center for Medical Devices and Instrumentation, Department of Mechanical and Aerospace Engineering, University of California, San Diego, with research interests in micro/nanodevices for biomedical applications, and is a world leader in the burgeoning field of acoustic micro/nanofluidics.
Additional affiliations
December 2011 - October 2014
RMIT University
Position
  • Professor, Vice-Chancellor's Senior Research Fellow, Director of the Micro Nano Research Facility

Publications

Publications (302)
Article
Full-text available
The local delivery of therapeutic small interfering RNA or siRNA to the lungs has the potential to improve the prognosis for patients suffering debilitating lung diseases. Recent advances in materials science have been aimed at addressing delivery challenges including biodistribution, bioavailability and cell internalization, but an equally importa...
Article
Atomization of fluids using ultrasonic irradiation of a fluid interface is well-known, yet the underlying physics is surprisingly complex and rather poorly understood. We review classical and modern theories of capillary waveformation and droplet atomization, from Michael Faraday in 1831 onwards, and show how the atomization process occurs via indu...
Article
We consider the choice of vibration modes and piezoelectric materials for acoustically driven atomization, an attractive method for a broad range of applications, particularly pulmonary drug delivery. Whether by the definition of a figure of merit, a product of the resonator quality factor and electromechanical coupling coefficient, its output vibr...
Article
Cell agglomeration is essential both to the success of drug testing and to the development of tissue engineering. Here, a MHz-order acoustic wave is used to generate acoustic streaming in the wells of a 24-well plate to drive particle and cell agglomeration. Acoustic streaming is known to manipulate particles in microfluidic devices, and even provi...
Article
Controlled nanoscale manipulation of fluids and colloids is made exceptionally difficult by the dominance of surface and viscous forces. Acoustic waves have recently been found to overcome similar problems in microfluidics, but their ability to do so at the nanoscale remains curiously unexplored. Here, we show that 20 MHz surface acoustic waves (SA...
Article
Controlled nanoscale manipulation of fluids and colloids is made exceptionally difficult by the dominance of surface and viscous forces. Acoustic waves have recently been found to overcome similar problems in microfluidics, but their ability to do so at the nanoscale remains curiously unexplored. Here, it is shown that 20 MHz surface acoustic waves...
Article
Cell detachment and reseeding are typical operations in cell culturing, often using trypsin exposure and pipetting, even though this process is known to damage the cells. Reducing the number of detachment and reseeding steps might consequently improve the overall quality of the culture, but to date this has not been an option. This study proposes t...
Article
Full-text available
Nebulizers have considerable advantages over conventional inhalers for pulmonary drug administration, particularly because they do not require coordinated breath actuation to generate and deliver the aerosols. Nevertheless, besides being less amenable to miniaturization and hence portability, some nebulizers are prone to denature macromolecular dru...
Article
Full-text available
Suspensions of copper nanowires are emerging as new electronic inks for next-generation flexible electronics. Using a novel surface acoustic wave driven extensional flow technique we are able to perform currently lacking analysis of these suspensions and their complex buffer. We observe extensional viscosities from 3 mPa$\cdot$s (1 mPa$\cdot$s shea...
Article
S. Sriram and co-workers report a new way to control the photoluminescence (PL) response in atomically thin, quasi-2D molybdenum disulphide. On page 888, it is shown that high-frequency surface acoustic waves alter the behaviour of charge carriers, interfering with the time lag between photon absorption and light emission. This mechanism is exploit...
Article
Full-text available
Furthering the promise of graphene-based planar nanofluidic devices as flexible, robust, low cost, and facile large-scale alternatives to conventional nanochannels for ion transport, we show how the nonlinear current–voltage (I–V) characteristics and ion current rectification in these platforms can be enhanced by increasing the system asymmetry. As...
Article
Overall precision of the simplified calibration method in J. E. Sader et al., Rev. Sci. Instrum. 83, 103705 (2012), Sec. III D, is dominated by the spring constant of the reference cantilever. The question arises: How does one take measurements from multiple reference cantilevers, and combine these results, to improve uncertainty of the reference c...
Article
We derive a generalized equation that governs the spreading of liquid films under high-frequency (MHz-order) substrate vibration in the form of propagating surface waves and show that this single relationship is universally sufficient to collectively describe the rich and diverse dynamic phenomena recently observed for the transport of oil films un...
Article
A renaissance in surface acoustic waves (SAW) has occurred, due mainly to their enormously powerful ability to manipulate fluids and colloids for microfluidics. Beyond the routine manipulation of drops, mixing, and separation and concentration of colloids using SAW, we have found fascinating behavior in the formation and propulsion of thin fluid fi...
Article
A surface acoustic wave (SAW) is shown to effectively and reversibly modulate the photoluminescence in quasi-2D MoS2. This technique does not result in any structural or compositional change, which suggests the tremendous potential of integrating 2D materials on to SAW platforms for designing controllable, state-of-the-art optoelectronic systems.
Article
Open droplet microfluidic platforms offer attractive alternatives to closed microchannel devices, including lower fabrication cost and complexity, significantly smaller sample and reagent volumes, reduced surface contact and adsorption, as well as drop scalability, reconfigurability, and individual addressability. For these platforms to be effectiv...
Article
Full-text available
Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions. The influence of motility on viscosities of cell suspensions i...
Article
A simple, dry, rapid, and chemical-free approach is developed by J. R. Friend and team for the deagglomeration and shear-induced alignment of commercially sourced, pristine multi-walled carbon nanotubes in air. On page 1014 the surface acoustic waves in a piezoelectric substrate are used to generate extremely large accelerations of ≈10 Mm/s2 that,...
Article
Full-text available
Surface acoustic wave (SAW) atomization is an attractive approach for generating monodispersed microdroplets for a diversity of applications, from drug delivery to mass spectrometry, due to its reliability, miniaturizability, and portability. Here, we demonstrate a nozzleless spray cooling technique based on SAW atomization, with the key advantage...
Article
The dissolution dynamics of microscopic oil droplets (less than 1 μm in height, i.e. nanodroplets) on a hydrophobilized silicon surface in water was experimentally studied. The lateral diameter was monitored using confocal microscopy, whereas the contact angle was measured by (disruptive) droplet polymerisation of the droplet. In general, we observ...
Article
The exhibition of plasmon resonances in two-dimensional (2D) semiconductor compounds is desirable for many applications. Here, by electrochemically intercalating lithium into 2D molybdenum disulfide (MoS2) nanoflakes, plasmon resonances in the visible and near UV wavelength ranges are achieved. These plasmon resonances are controlled by the high do...
Article
Full-text available
The synthesis of metal frameworks perforated with nanotunnels is a challenge because metals have high surface energies that favor low surface area structures; traditional liquid-crystal templating techniques cannot achieve the synthetic control required. We report a synthetic strategy to fabricate metal nanomaterials with highly ordered, tunable me...
Article
Carbon nanotubes (CNTs) are widely known to agglomerate into difficult to separate, 10–100 μm bundles, even after suspension in solution. Here, a dry and rapid (≈10 s) method to deagglomerate bulk, unbound multi-walled CNT bundles due to surface acoustic waves (SAW) in a piezoelectric substrate is reported for the first time. The process first form...
Article
We theoretically and experimentally demonstrate the existence of complete surface acoustic wave band gaps in surface phonon-polariton phononic crystals, in a completely monolithic structure formed from a two-dimensional honeycomb array of hexagonal shape domain-inverted inclusions in single crystal piezoelectric Z-cut lithium niobate. The band gaps...
Article
A simplified method for calibrating atomic force microscope cantilevers was recently proposed by Sader et al. [Rev. Sci. Instrum. 83, 103705 (2012); Sec. III D] that relies solely on the resonant frequency and quality factor of the cantilever in fluid (typically air). This method eliminates the need to measure the hydrodynamic function of the canti...
Article
We present a versatile and very low-power traveling SAW microfluidic sorting device able to displace and separate particles of different diameter in aqueous suspension; the travelling wave propagates through the fluid bulk and diffuses via a Schröder diffuser, adopted from its typical use in concert hall acoustics to be the smallest such diffuser d...
Article
Conventional flow injection systems for aquatic environmental analysis typically comprise large laboratory benchscale equipment which place considerable constraints for portable field use. Here, we demonstrate the use of an integrated acoustically-driven microfluidic mixing scheme to enhance detection of a chemiluminescent species tris(2,2'-bipyrid...
Article
Compared with preformed anisotropic matrices, an anisotropic matrix that allows users to alter its properties and structure in situ after synthesis offers the important advantage of being able to mimic dynamic in vivo microenvironments, such as in tissues undergoing morphogenesis or in wounds undergoing tissue repair. In this study, porous gradient...
Article
Structurally symmetric two-dimensional multilayered graphene oxide films, which facilitate ion transport through "nanochannels" comprising the interstitial spaces between each stacked sheet within the film, are for the first time shown to exhibit peculiar ion current rectification and nonlinear current-voltage characteristics below a critical elect...
Article
In this paper, we report a UV/ozone-assisted method for low temperature preparation of mesoporous TiO2 with controlled crystalline phase. The results showed that the crystallization of mesoporous TiO2 can occur at temperature as low as 100 oC under the UV/ozone irradiation. Highly crystalline mesoporous anatase TiO2 were obtained after UV/ozone tre...
Article
Arising from an interplay between capillary, acoustic and intermolecular forces, surface acoustic waves (SAWs) are observed to drive a unique and curious double flow reversal in the spreading of thin films. With a thickness at or less than the submicrometre viscous penetration depth, the film is seen to advance along the SAW propagation direction,...
Article
Poloidal flow is curiously formed in a microliter sessile water drop over 157 to 225 MHz due to acoustic streaming from three-dimensional standing Lamb waves in a lithium niobate substrate. The flow possesses radial symmetry with downwelling at the center and upwelling at the periphery of the drop. Outside this frequency range the attenuation occur...
Article
Full-text available
On-chip flow cytometry provides a powerful tool to characterize cell samples for point-of-care diagnosis. In particular, sample focusing at specific locations along the microchannel is crucial to ensure the accuracy of detection. In this paper, we present a simple strategy of interfacing an RF-activated standing surface acoustic wave (SSAW) substra...
Article
A new and highly versatile domain patterning method—ultraviolet direct write metal enhanced redox (UV direct write MER)—achieves deep domains with practically no thermally-induced damage on the surface of lithium niobate crystals. In UV direct write MER, after coating with a thin layer of chromium, the domain inversion is generated by a redox proce...
Article
The development of new strategies and photocatalytic materials for practical environmental solutions remains a great challenge, particularly due to the large energy demands associated with various remediation processes. In this paper, we report the fabrication of self-assembled ordered mesoporous TiO2 with highly crystalline anatase structures as w...
Article
Full-text available
Background Pulmonary-delivered gene therapy promises to mitigate vaccine safety issues and reduce the need for needles and skilled personnel to use them. While plasmid DNA (pDNA) offers a rapid route to vaccine production without side effects or reliance on cold chain storage, its delivery to the lung has proved challenging. Conventional methods, i...
Article
It is now possible to circumvent costly and complex cleanroom fabrication procedures to produce MHz-order acoustically-driven microfluidic platforms through the use of electrode strips cut simply from kitchen aluminium foil and pressed against piezoelectric substrates. Cleanroom deposition, lithographic patterning, and etching are entirely avoided...
Article
Full-text available
A practical, commercially viable microfluidic device relies upon the miniaturization and integration of all its components-including pumps, circuitry, and power supply-onto a chip-based platform. Surface acoustic waves (SAW) have become popular in microfluidic manipulation, in solving the problems of microfluidic manipulation, but practical applica...
Article
Full-text available
In addition to the choice of appropriate material properties of the tissue construct to be used, such as its biocompatibility, biodegradability, cytocompatibility, and mechanical rigidity, the ability to incorporate microarchitectural patterns in the construct to mimic that found in the cellular microenvironment is an important consideration in tis...
Article
Full-text available
In this paper we demonstrate the use of an energy-efficient surface acoustic wave (SAW) device for driving closed-vessel SAW-assisted (CVSAW), ligand-free Suzuki couplings in aqueous media. The reactions were carried out on a mmolar scale with low to ultra-low catalyst loadings. The reactions were driven by heating resulting from the penetration of...
Article
Full-text available
We report the morphogenesis and self-assembly of bismutite nanocrystals with fully tunable morphologies from square plates, octagonal sheets, and round disks into three-dimensional hierarchical nanostructures. The results show that the nucleation, growth and self-assembly of bismutite nanocrystals strongly depend on the synergistic effect between h...
Article
Full-text available
Direct UV laser writing on chromium coated lithium niobate (LiNbO3) crystals is found to produce spontaneous domain inversion associated with the exposed UV laser tracks. Experimental evidence suggests that this effect is attributed to local out-diffusion of oxygen, reducing the LiNbO3 crystal surface due to the presence of chromium. The thin chrom...
Article
Full-text available
Thermal noise spectra of nanomechanical resonators are used widely to characterize their physical properties. These spectra typically exhibit a Lorentzian response, with additional white noise due to extraneous processes. Least-squares fits of these measurements enable extraction of key parameters of the resonator, including its resonant frequency,...
Article
Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies...
Article
We have designed and characterized a surface acoustic wave (SAW) fluid actuation platform that significantly improves the transmission of sound energy from the SAW device into the fluid in order to obtain enhanced performance. This is in distinct contrast to previous SAW microfluidic devices where the SAW substrate is simply interfaced with a micro...
Conference Paper
In this study, we developed a novel and rapid method to generate in vitro three-dimensional (3D) multicellular tumor spheroids using a surface acoustic wave (SAW) device. A SAW device with single-phase unidirectional transducer electrodes (SPUTD) on lithium niobate substrate was fabricated using standing UV photolithography and wet-etching techniqu...
Conference Paper
Microfluidics is based on the performance of fluids in a microenvironment. As the microfluidics research advances in the cellular behaviour, the need for improved micro devices grows. This work introduces the design and fabrication of a micro ridge waveguide to be employed in fluids manipulations. Then it investigates the characteristics of the dev...
Article
Two-dimensional (2D) transition metal dichalcogenide semiconductors offer unique electronic and optical properties, which are significantly different from their bulk counterparts. It is known that the electronic structure of 2D MoS2, which is the most popular member of the family, depends on the number of layers. Its electronic structure alters dra...
Article
The dominance of surface and viscous forces at small scales, in particular, render the actuation and manipulation of fluids and particles in microfluidic systems a significant challenge, especially if integration into a portable handheld platform is desired, for example, in miniaturized devices for point-of-care diagnostics and biosensing. We provi...
Article
We report the presence of surface acoustic wave (SAW) band gap on acoustic superlattice (ASL) in a single-crystal lithium niobate structure. The band gap behavior is determined by calculating the SAW band structure and also by simulating the transmission of an acoustic wave through a finite length section of ASL using finite element analysis. The c...
Conference Paper
Domain engineering 128° YX-cut lithium niobate crystals by ultraviolet direct-domain writing is reported. The evidence of the inverted domains were shown from both piezoresponse force microscopy and hydrofluoric acid etching.
Conference Paper
Surface acoustic wave (SAW) generation on 128° YX acoustic superlattice has been investigated by considering the finite-depth of the domain created by the UV direct-domain writing. We found that bound and localized SAW will be generated when the domain depth of the ASL structure, underlying the transducer, is smaller and bigger than the lattice per...
Patent
A piezoelectric actuator including a piezoelectric element and an elongate transducer mounted on the piezoelectric element. The transducer is formed from an elongate cylindrical member, and at least one helical slot is provided around the outer surface of the cylindrical member to enable coupling of resonance modes of the transducer when actuated b...
Article
Full-text available
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...
Article
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 as a result of the finite displacement of the wave, most often at one-half the excitation frequen...
Article
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...
Article
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 MALDI MS peptide and protein profiling of Islets of Langerhans, for future Type 2 Diabetes (T...
Article
Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-sca...
Article
Full-text available
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 manipulation. 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 oppositio...
Article
Full-text available
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 ato...