429 results match your criteria Applied Physics Letters[Journal]


A directional fibre optic ultrasound transmitter based on a reduced graphene oxide and polydimethylsiloxane composite.

Appl Phys Lett 2019 Mar 21;114(11):113505. Epub 2019 Mar 21.

Strongly directional ultrasound sources are desirable for many minimally invasive applications, as they enable high-quality imaging in the presence of positioning uncertainty. All-optical ultrasound is an emerging paradigm that exhibits high frequencies, large bandwidths, and a strong miniaturisation potential. Here, we report the design, modelling, and fabrication of a highly directional fibre-optic ultrasound transmitter that uses a composite of reduced graphene oxide and polydimethylsiloxane as the optical ultrasound generator. Read More

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http://dx.doi.org/10.1063/1.5089750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6428661PMC

Probing drug-DNA interactions using super-resolution force spectroscopy.

Appl Phys Lett 2018 Nov 6;113(19):193702. Epub 2018 Nov 6.

Department of Chemistry, University of Houston, Houston, Texas 77204, USA.

Atomic magnetometry and ultrasound, as individual techniques, have been used extensively in various physical, chemical, and biomedical fields. Their combined application, however, has been rare. We report that super-resolution force spectroscopy, which is based on the integration of the two techniques, can find unique biophysical applications in studying drug-DNA interactions. Read More

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http://dx.doi.org/10.1063/1.5045787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6219894PMC
November 2018
14 Reads

Synthetic Bessel light needle for extended depth-of-field microscopy.

Appl Phys Lett 2018 Oct 2;113(18):181104. Epub 2018 Nov 2.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

An ultra-long light needle is highly desired in optical microscopy for its ability to improve the lateral resolution over a large depth of field (DOF). However, its use in image acquisition usually relies on mechanical raster scanning, which compromises between imaging speed and stability and thereby restricts imaging performance. Here, we propose a synthetic Bessel light needle (SBLN) that can be generated and scanned digitally by complex field modulation using a digital micromirror device. Read More

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http://dx.doi.org/10.1063/1.5058163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214810PMC
October 2018
1 Read
3.302 Impact Factor

Capillary assisted deposition of carbon nanotube film for strain sensing.

Appl Phys Lett 2017 Oct 26;111(17):173105. Epub 2017 Oct 26.

Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.

Advances in stretchable electronics offer the possibility of developing skin-like motion sensors. Carbon nanotubes (CNTs), owing to their superior electrical properties, have great potential for applications in such sensors. In this paper, we report a method for deposition and patterning of CNTs on soft, elastic polydimethylsiloxane (PDMS) substrates using capillary action. Read More

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http://aip.scitation.org/doi/10.1063/1.5001754
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http://dx.doi.org/10.1063/1.5001754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207349PMC
October 2017
22 Reads

Direct-coupled micro-magnetometer with Y-Ba-Cu-O nano-slit SQUID fabricated with a focused helium ion beam.

Appl Phys Lett 2018 Oct;113(16):162602

Department of Physics, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093, USA.

Direct write patterning of high-transition temperature (high-) superconducting oxide thin films with a focused helium ion beam is a formidable approach for the scaling of high- circuit feature sizes down to the nanoscale. In this letter, we report using this technique to create a sensitive micro superconducting quantum interference device (SQUID) magnetometer with a sensing area of about 100 × 100 m. The device is fabricated from a single 35-nm thick YBaCuO film. Read More

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http://aip.scitation.org/doi/10.1063/1.5048776
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http://dx.doi.org/10.1063/1.5048776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6188902PMC
October 2018
10 Reads

Automated motion-artifact correction in an OCTA image using tensor voting approach.

Appl Phys Lett 2018 Sep 4;113(10):101102. Epub 2018 Sep 4.

Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 1194-5281, USA.

Optical coherence tomography angiography (OCTA) is a promising tool for imaging subsurface microvascular networks owing to its micron-level resolution and high sensitivity. However, it is not uncommon that OCTA imaging suffers from strip artifacts induced by tissue motion. Although various algorithms for motion correction have been reported, a method that enables motion correction on a single OCTA image remains a challenge. Read More

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http://dx.doi.org/10.1063/1.5036965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123061PMC
September 2018
2 Reads

Pulse inversion enhances the passive mapping of microbubble-based ultrasound therapy.

Appl Phys Lett 2018 Jul 24;113(4):044102. Epub 2018 Jul 24.

Department of Biomedical Engineering, Columbia University, New York City, New York 10032, USA.

Therapeutic ultrasound combined with preformed circulating microbubbles has enabled non-invasive and targeted drug delivery into the brain, tumors, and blood clots. Monitoring the microbubble activity is essential for the success of such therapies; however, skull and tissues limit our ability to detect low acoustic signals. Here, we show that by emitting consecutive therapeutic pulses of inverse polarity, the sensitivity in the detection of weak bubble acoustic signals during blood-brain barrier opening is enhanced compared to therapeutic pulses of the same polarity. Read More

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http://aip.scitation.org/doi/10.1063/1.5036516
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http://dx.doi.org/10.1063/1.5036516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6057789PMC
July 2018
18 Reads

Imaging the three-dimensional orientation and rotational mobility of fluorescent emitters using the Tri-spot point spread function.

Appl Phys Lett 2018 Jul 17;113(3):031103. Epub 2018 Jul 17.

Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA.

Fluorescence photons emitted by single molecules contain rich information regarding their rotational motions, but adapting single-molecule localization microscopy (SMLM) to measure their orientations and rotational mobilities with high precision remains a challenge. Inspired by dipole radiation patterns, we design and implement a Tri-spot point spread function (PSF) that simultaneously measures the three-dimensional orientation and the rotational mobility of dipole-like emitters across a large field of view. We show that the orientation measurements done using the Tri-spot PSF are sufficiently accurate to correct the anisotropy-based localization bias, from 30 nm to 7 nm, in SMLM. Read More

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http://dx.doi.org/10.1063/1.5031759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050162PMC
July 2018
3 Reads

Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography.

Appl Phys Lett 2018 Jul 3;113(1):011106. Epub 2018 Jul 3.

Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92612, USA.

Multiple scattering in biomedical tissue limits the imaging depth within a range of 1-2 mm for conventional optical imaging techniques. To extend the imaging depth into the scattering medium, a computational method based on the reflection matrix measurement has been developed to retrieve the singly back-scattered signal light from the dominant detrimental multiple-scattered background. After applying singular value decomposition on the measured matrix in the post-process, the target image underneath the turbid media is clearly recovered. Read More

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http://dx.doi.org/10.1063/1.5036661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6029932PMC
July 2018
2 Reads
3.300 Impact Factor

Strain-induced modulation of near-field radiative transfer.

Appl Phys Lett 2018 Jun 14;112(24):241104. Epub 2018 Jun 14.

Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island 02881, USA.

In this theoretical study, we present a near-field thermal modulator that exhibits change in radiative heat transfer when subjected to mechanical stress/strain. The device has two terminals at different temperatures separated by vacuum: one fixed and one stretchable. The stretchable side contains one-dimensional grating. Read More

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http://dx.doi.org/10.1063/1.5037468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002272PMC
June 2018
3 Reads

Brillouin micro-spectroscopy through aberrations via sensorless adaptive optics.

Appl Phys Lett 2018 Apr;112(16):163701

Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, USA.

Brillouin spectroscopy is a powerful optical technique for non-contact viscoelastic characterizations which has recently found applications in three-dimensional mapping of biological samples. Brillouin spectroscopy performances are rapidly degraded by optical aberrations and have therefore been limited to homogenous transparent samples. In this work, we developed an adaptive optics (AO) configuration designed for Brillouin scattering spectroscopy to engineer the incident wavefront and correct for aberrations. Read More

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http://dx.doi.org/10.1063/1.5027838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902333PMC

Photoacoustic technique to measure temperature effects on microbubble viscoelastic properties.

Appl Phys Lett 2018 Mar 14;112(11):111905. Epub 2018 Mar 14.

Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA.

Phospholipid-coated microbubbles are being developed for several biomedical applications, but little is known about the effect of temperature on the viscoelastic properties of the shell. Here, we report on the use of a photoacoustic technique to study the shell properties of individual microbubbles as a function of temperature. The microbubbles were driven into small-amplitude oscillations by ultrasound waves generated from the absorption of an intensity-modulated infrared laser, and these oscillations were detected by forward-light scattering of a second blue laser. Read More

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http://dx.doi.org/10.1063/1.5005548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5851782PMC

Individually grown cobalt nanowires as magnetic force microscopy probes.

Appl Phys Lett 2018 Feb;112(9):092401

Department of Physics, Morgan State University, 1700 East Cold Spring Lane, Baltimore, Maryland 21215, USA.

AC electric fields were utilized in the growth of individual high-aspect ratio cobalt nanowires from simple salt solutions using the Directed Electrochemical Nanowire Assembly method. Nanowire diameters were tuned from the submicron scale to 40 nm by adjusting the AC voltage frequency and the growth solution concentration. The structural properties of the nanowires, including shape and crystallinity, were identified using electron microscopy. Read More

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http://dx.doi.org/10.1063/1.4997310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826737PMC
February 2018
22 Reads

Role of temperature and oxygen content on structural and electrical properties of LaBaCoO thin films.

Appl Phys Lett 2018 Feb 15;112(7):073905. Epub 2018 Feb 15.

Department of Materials Design and Innovation, University at Buffalo-the State University of New York, Buffalo, New York 14260, USA.

The role of temperature and the oxygen content in the structural transformation and electrical conductivity of epitaxial double perovskite LaBaCoO (0≤ δ ≤ 1) thin films was systematically investigated. Reciprocal space mapping and ω-2θ x-ray diffraction performed at different temperatures in vacuum indicate that oxygen vacancies in the films become ordered at high temperature in a reducing environment. The changes of the oxygen content and the degree of oxygen vacancy ordering in the films result in a strong in-plane anisotropic lattice deformation and a large thermal expansion coefficient along the c-axis direction. Read More

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http://dx.doi.org/10.1063/1.5009245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5814307PMC
February 2018
2 Reads

Plasmonic micropillars for precision cell force measurement across a large field-of-view.

Appl Phys Lett 2018 Jan 17;112(3):033701. Epub 2018 Jan 17.

Department of Bioengineering, University of California at Los Angeles (UCLA), Los Angeles, California 90095, USA.

A plasmonic micropillar platform with self-organized gold nanospheres is reported for the precision cell traction force measurement across a large field-of-view (FOV). Gold nanospheres were implanted into the tips of polymer micropillars by annealing gold microdisks with nanosecond laser pulses. Each gold nanosphere is physically anchored in the center of a pillar tip and serves as a strong, point-source-like light scattering center for each micropillar. Read More

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http://dx.doi.org/10.1063/1.5005525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771753PMC
January 2018
2 Reads

Microwave SQUID Multiplexer Demonstration for Cosmic Microwave Background Imagers.

Appl Phys Lett 2017 Dec 14;111(24). Epub 2017 Dec 14.

National Institute of Standards and Technology, Boulder, CO 80305, USA.

Key performance characteristics are demonstrated for the microwave SQUID multiplexer (µmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the µmux produces a white, input referred current noise level of [Formula: see text] at -77 dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure [Formula: see text] in the TES-coupled channels biased at 65% of the sensor normal resistance. Read More

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http://dx.doi.org/10.1063/1.5008527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5766014PMC
December 2017

Approaching the intrinsic quality factor limit for micromechanical bulk acoustic resonators using phononic crystal tethers.

Appl Phys Lett 2017 5;111(1). Epub 2017 Jul 5.

National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

We systematically demonstrate that one-dimensional phononic crystal (1-D PnC) tethers can significantly reduce tether loss in micromechanical resonators to a point where the total energy loss is dominated by intrinsic mechanisms, particularly phonon damping. Multiple silicon resonators are designed, fabricated, and tested to provide comparisons in terms of the number of periods in the PnC and the resonance frequency, as well as a comparison with conventional straight-beam tethers. The product of resonance frequency and measured quality factor () is the critical figure of merit, as it is inversely related to the total energy dissipation in a resonator. Read More

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http://dx.doi.org/10.1063/1.4990960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5749427PMC
July 2017
2 Reads

Revealing the glass transition in shape memory polymers using Brillouin spectroscopy.

Appl Phys Lett 2017 Dec 13;111(24):241904. Epub 2017 Dec 13.

Texas A&M University, 101 Bizzell St., College Station, Texas 77840, USA.

Emerging medical devices which employ shape memory polymers (SMPs) require precise measurements of the glass transition temperature (T) to ensure highly controlled shape recovery kinetics. Conventional techniques like differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) have limitations that prevent utilization for certain devices, including limited accuracy and the need for sacrificial samples. In this report, we employ an approach based on Brillouin spectroscopy to probe the glass transition of SMPs rapidly, remotely, and nondestructively. Read More

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http://dx.doi.org/10.1063/1.4999803DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729035PMC
December 2017
1 Read

Photonic-band-gap gyrotron amplifier with picosecond pulses.

Appl Phys Lett 2017 Dec 5;111(23):233504. Epub 2017 Dec 5.

Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Mass. Ave., Cambridge, Massachusetts 02139, USA.

We report the amplification of 250 GHz pulses as short as 260 ps without observation of pulse broadening using a photonic-band-gap circuit gyrotron traveling-wave-amplifier. The gyrotron amplifier operates with a device gain of 38 dB and an instantaneous bandwidth of 8 GHz. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the operating voltage of the electron beam and the magnetic field. Read More

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http://dx.doi.org/10.1063/1.5006348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718917PMC
December 2017
2 Reads

High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping.

Appl Phys Lett 2017 Nov 30;111(22):221109. Epub 2017 Nov 30.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ∼1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. Read More

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http://dx.doi.org/10.1063/1.5009113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709093PMC
November 2017
13 Reads

Reflective Small Angle Electron Scattering to Characterize Nanostructures on Opaque Substrates.

Appl Phys Lett 2017 Sep 22;111(12). Epub 2017 Sep 22.

Center of Measurement Science, Industrial Technology Research Institute, Hsinchu 30011, Taiwan.

Features sizes in integrated circuits (ICs) are often at the scale of 10 nm and are ever shrinking. ICs appearing in today's computers and hand held devices are perhaps the most prominent examples. These smaller feature sizes demand equivalent advances in fast and accurate dimensional metrology for both development and manufacturing. Read More

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http://dx.doi.org/10.1063/1.4991696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726286PMC
September 2017
1 Read

Focusing light through scattering media by polarization modulation based generalized digital optical phase conjugation.

Appl Phys Lett 2017 Nov 16;111(20):201108. Epub 2017 Nov 16.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

Optical scattering prevents light from being focused through thick biological tissue at depths greater than ∼1 mm. To break this optical diffusion limit, digital optical phase conjugation (DOPC) based wavefront shaping techniques are being actively developed. Previous DOPC systems employed spatial light modulators that modulated either the phase or the amplitude of the conjugate light field. Read More

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http://dx.doi.org/10.1063/1.5005831DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5690666PMC
November 2017
9 Reads
2 Citations
3.302 Impact Factor

Quantitative angle-insensitive flow measurement using relative standard deviation OCT.

Appl Phys Lett 2017 Oct 31;111(18):181101. Epub 2017 Oct 31.

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.

Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. Read More

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http://dx.doi.org/10.1063/1.5009200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663647PMC
October 2017
7 Reads

Ultra-thin metasurface microwave flat lens for broadband applications.

Appl Phys Lett 2017 May 31;110(22):224101. Epub 2017 May 31.

Center for Integrated Nanotechnologies, Los Alamos National Laboratory, MS K771, Los Alamos, New Mexico 87545, USA.

We demonstrate a metasurface-based ultrathin flat lens operating at microwave frequencies. A series of subwavelength metallic split-ring resonators, which are sandwiched between two cross-polarized metallic gratings, are defined to obtain a radially symmetric parabolic phase distribution, covering relative phase differences ranging from 0 to 2.5π radians to create a lens. Read More

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http://dx.doi.org/10.1063/1.4984219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648571PMC
May 2017
4 Reads

Emission enhancement through Nd-Yb energy transfer in multifunctional NaGdF nanocrystals.

Appl Phys Lett 2017 May 31;110(22):223107. Epub 2017 May 31.

Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249, USA.

The growing need for biomedical contrast agents has led to the current development of multi-functional materials such as lanthanide-based nanoparticles (NPs). The optical and magnetic properties these nanoparticles (NPs) possess are important to enhance current biomedical imaging techniques. To increase the optical emissions of the nanoparticles, neodymium (Nd) and ytterbium (Yb) were introduced into a magnetic host of NaGdF. Read More

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http://dx.doi.org/10.1063/1.4984140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552399PMC
May 2017
26 Reads

A capacitive ultrasonic transducer based on parametric resonance.

Appl Phys Lett 2017 Jul;111(4):043503

G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f frequency in the RLC circuit. Read More

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http://dx.doi.org/10.1063/1.4995564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524589PMC
July 2017
1 Read

Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption.

Appl Phys Lett 2017 May 1;110(22):223903. Epub 2017 Jun 1.

King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia.

Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene-poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C-butyric acid methyl ester (PCBM)-top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. Read More

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http://dx.doi.org/10.1063/1.4984023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453788PMC
May 2017
41 Reads

Optical fiber ultrasound transmitter with electrospun carbon nanotube-polymer composite.

Appl Phys Lett 2017 May 1;110(22):223701. Epub 2017 Jun 1.

Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom.

All-optical ultrasound transducers are promising for imaging applications in minimally invasive surgery. In these devices, ultrasound is transmitted and received through laser modulation, and they can be readily miniaturized using optical fibers for light delivery. Here, we report optical ultrasound transmitters fabricated by electrospinning an absorbing polymer composite directly onto the end-face of optical fibers. Read More

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http://dx.doi.org/10.1063/1.4984838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453807PMC
May 2017
18 Reads

High-precision deformation mapping in finFET transistors with two nanometre spatial resolution by precession electron diffraction.

Appl Phys Lett 2017 May 1;110(22):223109. Epub 2017 Jun 1.

IBM Research, 257 Fuller Road, Albany, New York 12203, USA.

Precession electron diffraction has been used to systematically measure the deformation in Si/SiGe blanket films and patterned finFET test structures grown on silicon-on-insulator type wafers. Deformation maps have been obtained with a spatial resolution of 2.0 nm and a precision of ±0. Read More

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http://dx.doi.org/10.1063/1.4983124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453792PMC
May 2017
5 Reads

Texture Evolution during Isothermal, Isostrain and Isobaric Loading of Polycrystalline Shape Memory NiTi.

Appl Phys Lett 2017 Jun 23;110(25). Epub 2017 Jun 23.

Advanced Materials Processing and Analysis Center (AMPAC); Materials Science and Engineering Department; Mechanical and Aerospace Engineering Department; University of Central Florida, 12760 Pegasus Drive, Orlando, FL 32816, USA.

neutron diffraction was used to provide insight into martensite variant microstructures during isothermal, isobaric, and isostrain loading in shape memory NiTi. Results show variant microstructures were equivalent for the corresponding strain and more importantly, the reversibility and equivalency was immediately evident in variant microstructures that were first formed isobarically but then reoriented to a near random self-accommodated microstructure following isothermal deformation. Variant microstructures formed isothermally were not significantly affected by a subsequent thermal cycle under constant strain. Read More

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http://dx.doi.org/10.1063/1.4989523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288671PMC

Athermal synchronization of laser source with WDM filter in a silicon photonics platform.

Appl Phys Lett 2017 May;110(21):211105

Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.

In an optical interconnect circuit, microring resonators (MRRs) are commonly used in wavelength division multiplexing systems. To make the MRR and laser synchronized, the resonance wavelength of the MRR needs to be thermally controlled, and the power consumption becomes significant with a high-channel count. Here, we demonstrate an athermally synchronized rare-earth-doped laser and MRR. Read More

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http://dx.doi.org/10.1063/1.4984022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440232PMC
May 2017
16 Reads

Quantitative measurements of dielectrophoresis in a nanoscale electrode array with an atomic force microscopy.

Appl Phys Lett 2017 May 17;110(20):203701. Epub 2017 May 17.

Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.

Nanoelectronic devices integrated with dielectrophoresis (DEP) have been promoted as promising platforms for trapping, separating, and concentrating target biomarkers and cancer cells from a complex medium. Here, we visualized DEP and DEP gradients in conventional nanoelectronic devices by using multi-pass atomic force microcopy techniques. Our measurements directly demonstrated a short range DEP only at sharp step edges of electrodes, frequency dependent DEP polarity, and separation distance dependent DEP strength. Read More

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http://dx.doi.org/10.1063/1.4983785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435496PMC
May 2017
2 Reads

Frequency dependence of the coercive field of 0.71Pb(MgNb)O-0.29PbTiO single crystal from 0.01 Hz to 5 MHz.

Appl Phys Lett 2017 May 17;110(20):202904. Epub 2017 May 17.

College of Mathematics, Physics and Information Engineering, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.

The frequency dependence of the coercive field in [001] poled 0.71Pb(MgNb)O-0.29PbTiO single crystals was investigated as a function of frequency from 0. Read More

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http://aip.scitation.org/doi/10.1063/1.4983712
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http://dx.doi.org/10.1063/1.4983712DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435517PMC
May 2017
7 Reads

Chemical etching of silicon carbide in pure water by using platinum catalyst.

Appl Phys Lett 2017 May;110(20):201601

Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan.

Chemical etching of SiC was found to proceed in pure water with the assistance of a Pt catalyst. A 4H-SiC (0001) wafer was placed and slid on a polishing pad in pure water, on which a thin Pt film was deposited to give a catalytic nature. Etching of the wafer surface was observed to remove protrusions preferentially by interacting with the Pt film more frequently, thus flattening the surface. Read More

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http://dx.doi.org/10.1063/1.4983206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432371PMC
May 2017
8 Reads

Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography.

Appl Phys Lett 2017 May;110(20):201101

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.

Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Previous transverse shear wave measurements could detect the shear modulus in the lateral region of the force; however, they could not provide the elastic information in the axial region of the force. Read More

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http://dx.doi.org/10.1063/1.4983292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432373PMC
May 2017
10 Reads

Nonlinear ultrasound imaging of nanoscale acoustic biomolecules.

Appl Phys Lett 2017 Feb 17;110(7):073704. Epub 2017 Feb 17.

Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, USA.

Ultrasound imaging is widely used to probe the mechanical structure of tissues and visualize blood flow. However, the ability of ultrasound to observe specific molecular and cellular signals is limited. Recently, a unique class of gas-filled protein nanostructures called gas vesicles (GVs) was introduced as nanoscale (∼250 nm) contrast agents for ultrasound, accompanied by the possibilities of genetic engineering, imaging of targets outside the vasculature and monitoring of cellular signals such as gene expression. Read More

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http://dx.doi.org/10.1063/1.4976105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5315666PMC
February 2017
1 Read

Controlled electrochemical growth of ultra-long gold nanoribbons.

Appl Phys Lett 2017 Feb 14;110(7):073106. Epub 2017 Feb 14.

Department of Physics, Kansas State University , Manhattan, Kansas 66506, USA.

This paper describes the electrochemical growth of branchless gold nanoribbons with ∼40 nm × ∼300 nm cross sections and >100 m lengths (giving length-to-thickness aspect ratios of >10). These structures are useful for opto-electronic studies and as nanoscale electrodes. The 0. Read More

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http://dx.doi.org/10.1063/1.4976027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5315663PMC
February 2017
1 Read

The mechanical response in a fluid of synthetic antiferromagnetic and ferrimagnetic microdiscs with perpendicular magnetic anisotropy.

Appl Phys Lett 2017 Jan 24;110(4):042402. Epub 2017 Jan 24.

Cavendish Laboratory, University of Cambridge , JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.

In this article, we demonstrate the magneto-mechanic behavior in a fluid environment of perpendicularly magnetized microdiscs with antiferromagnetic interlayer coupling. When suspended in a fluid and under the influence of a simple uniaxial applied magnetic field sequence, the microdiscs mechanically rotate to access the magnetic saturation processes that are either that of the easy axis, hard axis, or in-between the two, in order to lower their energy. Further, these transitions enable the magnetic particles to form reconfigurable magnetic chains, and transduce torque from uniaxial applied fields. Read More

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http://dx.doi.org/10.1063/1.4974211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5272821PMC
January 2017

A microfabricated optically-pumped magnetic gradiometer.

Appl Phys Lett 2017 Jan 18;110(3):031106. Epub 2017 Jan 18.

Time and Frequency Division, National Institute of Standards and Technology , 325 Broadway, Boulder, Colorado 80305, USA.

We report on the development of a microfabricated atomic magnetic gradiometer based on optical spectroscopy of alkali atoms in the vapor phase. The gradiometer, which operates in the spin-exchange relaxation free regime, has a length of 60 mm and cross sectional diameter of 12 mm, and consists of two chip-scale atomic magnetometers which are interrogated by a common laser light. The sensor can measure differences in magnetic fields, over a 20 mm baseline, of 10 fT/[Formula: see text] at frequencies above 20 Hz. Read More

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http://dx.doi.org/10.1063/1.4974349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5250637PMC
January 2017
2 Reads

Unique heating curves generated by radiofrequency electric-field interactions with semi-aqueous solutions.

Appl Phys Lett 2017 Jan 4;110(1):013701. Epub 2017 Jan 4.

Department of Chemistry and Smalley-Curl Institute, Rice University , Houston, Texas 77005, USA.

Aqueous and nanoparticle-based solutions have been reported to heat when exposed to an alternating radiofrequency (RF) electric-field. Although the theoretical models have been developed to accurately model such a behavior given the solution composition as well as the geometrical constraints of the sample holder, these models have not been investigated across a wide-range of solutions where the dielectric properties differ, especially with regard to the real permittivity. In this work, we investigate the RF heating properties of non-aqueous solutions composed of ethanol, propylene glycol, and glycine betaine with and without varying amounts of NaCl and LiCl. Read More

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http://dx.doi.org/10.1063/1.4973218DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5218968PMC
January 2017
7 Reads

Volumetric Doppler angle correction for ultrahigh-resolution optical coherence Doppler tomography.

Appl Phys Lett 2017 Jan 3;110(1):011102. Epub 2017 Jan 3.

Department of Biomedical Engineering, Stony Brook University , Stony Brook, New York 11794, USA.

Ultrahigh-resolution optical coherence Doppler tomography (μODT) demonstrates great potential for quantitative blood flow imaging owing to its large field of view and capillary resolution. However, μODT only detects the axial flow velocity and requires Doppler angle correction to retrieve the absolute velocity. Although methods for Doppler angle tracking of single or few large vessels have been reported, a method that enables angle correction of the entire 3D microvascular networks remains a challenge. Read More

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http://aip.scitation.org/doi/10.1063/1.4973367
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http://dx.doi.org/10.1063/1.4973367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5218966PMC
January 2017
2 Reads

Effects of gold nanoparticles on lipid packing and membrane pore formation.

Appl Phys Lett 2016 12 30;109(26):263106. Epub 2016 Dec 30.

Department of Physics and Engineering, Delaware State University , Dover, Delaware 19901, USA.

Gold nanoparticles (AuNPs) have been increasingly integrated in biological systems, making it imperative to understand their interactions with cell membranes, the first barriers to be crossed to enter cells. Herein, liposomes composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) as a model membrane system were treated with citrate stabilized AuNPs from 5 to 30 nm at various concentrations. The fluorescence shifts of Laurdan probes reveal that AuNPs in general made liposomes more fluidic. Read More

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http://dx.doi.org/10.1063/1.4972868DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5201603PMC
December 2016
5 Reads

Generation of Shear Waves by Laser in Soft Media in the Ablative and Thermoelastic Regimes.

Appl Phys Lett 2016 11;109(22):2219011-2219015

Laboratory of Biorheology and Medical Ultrasonics, Montreal Hospital Research Center, Montreal (QC), H1X0A9, Canada; Institute of Biomedical Engineering, École Polytechnique and University of Montreal, Montreal (QC), H3T1J4, Canada; Departement of Radiology, Radio-oncology and Nuclear Medicine, University of Montreal, Montreal (QC), H3C3J7, Canada.

This article describes the generation of elastic shear waves in a soft medium using a laser beam. Our experiments show two different regimes depending on laser energy. Physical modeling of the underlying phenomena reveals a thermoelastic regime caused by a local dilatation resulting from temperature increase, and an ablative regime caused by a partial vaporization of the medium by the laser. Read More

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http://dx.doi.org/10.1063/1.4968538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5226822PMC
November 2016

Circular Photogalvanic Effect in Organometal Halide Perovskite CHNHPbI.

Appl Phys Lett 2016 11;109(19)

Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

We study the circular photogalvanic effect in the organometal halide perovskite solar cell absorber CHNHPbI. The calculated photocurrent density for a system with broken inversion symmetry is about 10 A/W, comparable to the previously studied quantum well and bulk Rashba systems. The circular photogalvanic effect relies on inversion symmetry breaking, so that by tuning the optical penetration depth, the degree of inversion symmetry breaking can be probed at different depths from the sample surface. Read More

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http://dx.doi.org/10.1063/1.4967176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5207220PMC
November 2016
1 Read

Magnetic microscopy and simulation of strain-mediated control of magnetization in Ni/PMN-PT nanostructures.

Appl Phys Lett 2016 10 17;109(16). Epub 2016 Oct 17.

Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095.

Strain-mediated thin film multiferroics comprising piezoelectric/ferromagnetic heterostructures enable the electrical manipulation of magnetization with much greater efficiency than other methods; however, the investigation of nanostructures fabricated from these materials is limited. Here we characterize ferromagnetic Ni nanostructures grown on a ferroelectric PMN-PT substrate using scanning electron microscopy with polarization analysis (SEMPA) and micromagnetic simulations. The magnetization of the Ni nanostructures can be controlled with a combination of sample geometry and applied electric field, which strains the ferroelectric substrate and changes the magnetization via magnetoelastic coupling. Read More

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http://dx.doi.org/10.1063/1.4965028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5207223PMC
October 2016
8 Reads

Laser-enhanced high-intensity focused ultrasound heating in an small animal model.

Appl Phys Lett 2016 11 22;109(21):213702. Epub 2016 Nov 22.

KU Bioengineering Research Center and Department of Mechanical Engineering, University of Kansas , 1530 W. 15th Street, 5109 Learned Hall, Lawrence, Kansas 66045, USA.

The enhanced heating effect during the combination of high-intensity focused ultrasound (HIFU) and low-optical-fluence laser illumination was investigated by using an murine animal model. The thighs of murine animals were synergistically irradiated by HIFU and pulsed nano-second laser light. The temperature increases in the target region were measured by a thermocouple under different HIFU pressures, which were 6. Read More

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http://dx.doi.org/10.1063/1.4968509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5123994PMC
November 2016
3 Reads

High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays.

Appl Phys Lett 2016 11 9;109(19):191103. Epub 2016 Nov 9.

Electrical Engineering Department, University of California-Los Angeles , Los Angeles, California 90095, USA.

We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. Read More

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http://dx.doi.org/10.1063/1.4967440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5106429PMC
November 2016
35 Reads

Influence of internal geometry on magnetization reversal in asymmetric permalloy rings.

Appl Phys Lett 2016 26;109(8). Epub 2016 Aug 26.

Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

We report the magnetization reversal behavior of microstructured NiFe rings using magneto-optic indicator film imaging and magnetometry. While the reversal behavior of rings with a symmetric (circular) interior hole agrees with micromagnetic simulations of an onion → vortex → onion transition, we experimentally demonstrate that rings possessing an elliptical hole with an aspect ratio of 2 exhibit complex reversal behavior comprising incoherent domain propagation in the rings. Magneto optic images reveal metastable magnetic configurations that illustrate this incoherent behavior. Read More

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http://dx.doi.org/10.1063/1.4961881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5117655PMC

Contactless microparticle control via ultrahigh frequency needle type single beam acoustic tweezers.

Appl Phys Lett 2016 10 27;109(17):173509. Epub 2016 Oct 27.

NIH Resource Center for Medical Ultrasonic Transducer Technology and Department of Biomedical Engineering, University of Southern California , Los Angeles, California 90089, USA.

This paper reports on contactless microparticle manipulation including single-particle controlled trapping, transportation, and patterning via single beam acoustic radiation forces. As the core component of single beam acoustic tweezers, a needle type ultrasonic transducer was designed and fabricated with center frequency higher than 300 MHz and -6 dB fractional bandwidth as large as 64%. The transducer was built for an -number close to 1. Read More

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http://dx.doi.org/10.1063/1.4966285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5085970PMC
October 2016
22 Reads

Continuous-flow multi-pulse electroporation at low DC voltages by microfluidic flipping of the voltage space topology.

Appl Phys Lett 2016 10;109(16):163702

Department of Bioengineering, University of Washington , Seattle, Washington 98195, USA.

Concerns over biosafety, cost, and carrying capacity of viral vectors have accelerated research into physical techniques for gene delivery such as electroporation and mechanoporation. Advances in microfabrication have made it possible to create high electric fields over microscales, resulting in more efficient DNA delivery and higher cell viability. Continuous-flow microfluidic methods are typically more suitable for cellular therapies where a large number of cells need to be transfected under sterile conditions. Read More

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http://dx.doi.org/10.1063/1.4963316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5075000PMC
October 2016