A5090392500- Magnetic properties of thin films
- Mechanical and Optical Resonators
- Force Microscopy Techniques and Applications
- Advanced MEMS and NEMS Technologies
- Physics of Superconductivity and Magnetism
- Photonic and Optical Devices
- Characterization and Applications of Magnetic Nanoparticles
- Magnetic Properties and Applications
- Quantum and electron transport phenomena
- Advanced Fiber Laser Technologies
- Theoretical and Computational Physics
- Magneto-Optical Properties and Applications
- Photonic Crystals and Applications
- Near-Field Optical Microscopy
- Nanofabrication and Lithography Techniques
- Microfluidic and Capillary Electrophoresis Applications
- Advanced Fluorescence Microscopy Techniques
- Acoustic Wave Resonator Technologies
- Surface and Thin Film Phenomena
- Microfluidic and Bio-sensing Technologies
- Quantum, superfluid, helium dynamics
- Integrated Circuits and Semiconductor Failure Analysis
- Atomic and Subatomic Physics Research
- Plasmonic and Surface Plasmon Research
- Advanced Electron Microscopy Techniques and Applications
National Institute of Standards and Technology
2015-2024
National Institute of Standards
2015-2024
Maastricht University
2024
Center for Nanoscale Science and Technology
2015-2023
Physical Measurement Laboratory
2018-2020
Cornell University
2007-2018
University of Illinois Chicago
1998-2010
Tel Aviv University
2005-2008
University of California, Santa Barbara
2005
University of Cambridge
2000-2002
We report on the fabrication of nanometer-scale mass sensors with subattogram sensitivity. Surface micromachined polycrystalline silicon and nitride nanomechanical oscillators were used to detect presence well-defined loading. Controlled deposition thiolate self-assembled monolayers lithographically defined gold dots for calibrated a dinitrophenyl poly(ethylene glycol) undecanthiol-based molecule (DNP-PEG4-C11thiol) as model ligand this study. Due fact that is attached at distance l0 from...
Laboratory optical atomic clocks achieve remarkable accuracy (now counted to 18 digits or more), opening possibilities for exploring fundamental physics and enabling new measurements.However, their size the use of bulk components prevent them from being more widely adopted in applications that require precision timing.By leveraging silicon-chip photonics integration reduce component complexity, we demonstrate a compact optical-clock architecture.Here semiconductor laser is stabilized an...
The ability to detect small amounts of materials, especially pathogenic bacteria, is important for medical diagnostics and monitoring the food supply. Engineered micro- nanomechanical systems can serve as multifunctional, highly sensitive, immunospecific biological detectors. We present a resonant frequency-based mass sensor, comprised low-stress silicon nitride cantilever beams detection Escherichia coli (E. coli)-cell-antibody binding events with sensitivity down single cell. involved...
We have demonstrated high-sensitivity detection of bacteria using an array bulk micromachined resonant cantilevers. The biological sensor is a micromechanical oscillator that consists silicon-nitride cantilevers with immobilized antibody layer on the surface resonator. Measured frequency shift as function additional cell loading was observed and correlated to mass specifically bound Escherichia coli O157:H7 cells. Deposition subsequent E. cells achieved under ambient conditions.
We have used a resonating mechanical cantilever to detect immunospecific binding of viruses, captured from liquid. As model virus, we nonpathogenic insect baculovirus test the ability specifically bind and small numbers virus particles. Arrays surface micromachined, antibody-coated polycrystalline silicon nanomechanical beams were various concentrations baculoviruses in buffer solution. Because their mass, 0.5μm×6μm cantilevers mass sensitivities on order 10−19g∕Hz, enabling detection an...
Graphene's unparalleled strength, stiffness, and low mass per unit area make it an ideal material for nanomechanical resonators, but its relatively quality factor is important drawback that has been difficult to overcome. Here, we use a simple procedure fabricate circular mechanical resonators of various diameters from graphene grown by chemical vapor deposition. In addition highly reproducible resonance frequencies mode shapes, observe striking improvement the membrane with increasing size....
Resonant nanoelectromechanical systems (NEMS) are being actively investigated as sensitive mass detectors for applications such chemical and biological sensing. We demonstrate that highly uniform arrays of nanomechanical resonators can be used to detect the binding individual DNA molecules through resonant frequency shifts resulting from added bound analyte. Localized sites created with gold nanodots create a calibrated response sufficient sensitivity accuracy count small numbers molecules....
We demonstrate experimentally that structural perturbations imposed on highly dispersive photonic crystal-based waveguides give rise to spectral features bear signatures of Anderson localization. Sharp resonances with effective Q's over 30 000 are found in scattering spectra disordered waveguides. The observed a approximately 20-nm bandwidth centered at the cutoff slowly guided Bloch modes. origin can be explained by interference coherently scattered electromagnetic waves which results...
Microresonator frequency combs can be an enabling technology for optical synthesis and timekeeping in low size, weight, power architectures. Such systems require comb operation low-noise, phase-coherent states such as solitons, with broad spectral bandwidths (e.g., octave-spanning) self-referencing to detect the carrier-envelope offset frequency. However, stably accessing is complicated by thermo-optic dispersion. For example, Si3N4 platform, precisely dispersion-engineered structures...
The nitroxide-mediated polymerization of styrenic monomers containing oligo(ethylene glycol) (OEGn) moieties was chosen for the preparation biocompatible polymer brushes tethered to silicon oxide surfaces due broad range monomer structures available and use a nonmetallic initiator. These were characterized by near-edge X-ray absorption fine structure water contact angle measurements. biocompatibility these grown studied compared with deposited assemblies surface-bound OEGn-terminated silanes...
We report a method of optical excitation nanomechanical cantilever-type oscillators. The periodic driving signal with controlled modulation amplitude was provided by 415 nm diode laser, wherein the laser spot located at some distance away from clamped end cantilever. measured resonant response cantilever obtained distances in excess 160μm varying oscillator dimensions. effectiveness mode is studied for different combinations materials, namely Si–SiO2 and Si3N4–SiO2. These observations were...
Mechanical dissipation poses an ubiquitous challenge to the performance of nanomechanical devices. Here we analyze support-induced high-stress resonators. We develop a model for this loss mechanism and test it on silicon nitride membranes with circular square geometries. The measured Q-values different harmonics present non-monotonic behavior which is successfully explained. For azimuthal geometry predict that destructive interference radiated waves leads exponential suppression clamping in...
We report accurate phase stabilization of an interlocking pair Kerr-microresonator frequency combs. The two combs, one based on silicon nitride and silica, feature nearly harmonic repetition frequencies can be generated with laser. silicon-nitride comb supports ultrafast-laser regime three-optical-cycle, 1-picosecond-period soliton pulses a total dispersive-wave-enhanced bandwidth 170 THz, while providing stable phase-link between optical microwave frequencies. demonstrate nanofabrication...
We demonstrate that a square lattice of artificial pinning centers in superconducting Nb film induces the formation highly ordered interstitial vortex phases with different symmetries for external magnetic fields as high eighth matching field. These ``supermatching'' are identified by distinct differences behavior their critical currents, magnetoresistivity, and magnetization. Our results consistent predictions supermatching recent numerical simulations.
Micromechanical oscillators in the rf range were fabricated form of silicon discs supported by a SiO2 pillar at disk center. A low-power laser beam, (Plaser∼100 μW), focused periphery disk, causes significant change effective spring constant producing frequency shift, Δf(Δf/f∼10−4). The high quality factor, Q, oscillator (Q∼104) allows us to realize parametric amplification disk’s vibrations through double modulation power. An amplitude gain up 30 was demonstrated, with further increase...
The magnetization reversal mechanism in an array of submicron elliptical Permalloy elements with aspect ratio 1.4:1 is investigated using the diffracted magneto-optic Kerr effect technique, Lorentz scanning transmission electron microscopy, and microscopy. experimental results are interpreted from a comparison micromagnetic simulations. found to be dependent on direction magnetic field occur via formation one or two vortices; vortex state nucleated when applied along short axis. For long...
We investigate the transport properties of superconducting films with periodic arrays in-plane magnetized micromagnets. Two different magnetic textures are studied: a square array bars and close-packed triangular microrings. As confirmed by force microscopy imaging, state both systems can be adjusted to produce almost pointlike dipoles. By carrying out measurements ac drive, we observed experimentally recently predicted ratchet effect induced interaction between vortices Moreover, find that...
Material properties of atomic layer deposited (ALD) thin films are interest for applications ranging from wear resistance to high-k dielectrics in electronic circuits. We demonstrate the ability simultaneously measure Young’s modulus (E) and density (ρ) 21.2–21.5 nm ALD hafnia, alumina, aluminum nitride ultrathin by observing vibrations nanomechanical cantilever beams. The structures were fabricated a 250 thick single crystal silicon with varying length width 6 μm 10 45 1 μm, respectively....
Thermal properties of materials are often determined by measuring thermalization processes; however, such measurements at the nanoscale challenging because they require high sensitivity concurrently with temporal and spatial resolutions. Here, we develop an optomechanical cantilever probe customize atomic force microscope low detection noise ≈1 fm/Hz1/2 over a wide (>100 MHz) bandwidth that measures dynamics ≈10 ns resolution, ≈35 nm sensitivity. This setup enables fast nanoimaging thermal...
Self-generated vibration of a disk-shaped, single-crystal silicon micromechanical oscillator was observed when the power continuous wave laser, focused on periphery disk exceeded threshold few hundred μW. With laser set to just below self-generation threshold, quality factor for driven oscillations increases by an order magnitude from Q=10 000 Qenh=110 000. Laser heating-induced thermal stress modulates effective spring constant via motion within interference pattern incident and reflected...