Determining local modulus and strength of heterogeneous films by force-deflection mapping of microcantilevers.

Estimating the elastic modulus and strength of heterogeneous films requires local measurement techniques. For local mechanical film testing, microcantilevers were cut into suspended many-layer graphene using a focused ion beam. An optical transmittance technique was used to map thickness near the cantilevers, and multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers.

Quantitative STEM: A method for measuring temperature and thickness effects on thermal diffuse scattering using STEM/EELS, and for testing electron scattering models.

In the last two decades, advances in the dark field detectors and microscopes of scanning transmission electron microscopy (STEM) have inspired a resurgence of interest in quantitative STEM analysis. One promising avenue is the use of STEM as a nanothermometric probe. In this application, thermal diffuse scattering, captured by a CCD camera or an annular dark field detector, acts as an indirect measurement of the specimen temperature.

Visible and short-wavelength infrared light collimation through carbon nanotube, parallel-hole collimators.

Traditional collimators typically require large optics and/or long pathlengths which makes miniaturization difficult. Carbon nanotube templated microfabrication offers a solution to pattern small 3D structures, such as parallel hole collimators. Here we present the characterization of a carbon nanotube parallel hole collimator design and its efficacy in visible and short wavelength infrared light.

High surface-area carbon microcantilevers.

Microscale porous carbon mechanical resonators were formed using carbon nanotube templated microfabrication. These cantilever resonators exhibited nanoscale porosity resulting in a high surface area to volume ratio which could enable sensitive analyte detection in air. These resonators were shown to be mechanically robust and the porosity could be controllably varied resulting in densities from 10 to 10 kg m, with pore diameters on the order of hundreds of nanometers.

Tissue-susceptibility matched carbon nanotube electrodes for magnetic resonance imaging.

Test disk electrodes were fabricated from carbon nanotubes (CNT) using the Carbon Nanotube Templated Microfabrication (CNT-M) technique. The CNT-M process uses patterned growth of carbon nanotube forests from surfaces to form complex patterns, enabling electrode sizing and shaping. The additional carbon infiltration process stabilizes these structures for further processing and handling.

Fabrication of High Aspect Ratio Millimeter-Tall Free-Standing Carbon Nanotube-Based Microelectrode Arrays.

Microelectrode arrays of carbon nanotube (CNT)/carbon composite posts with high aspect ratio and millimeter-length were fabricated using carbon-nanotube-templated microfabrication with a sacrificial "hedge". The high aspect ratio, mechanical robustness, and electrical conductivity of these electrodes make them a potential candidate for next-generation neural interfacing. Electrochemical measurements were also demonstrated using an individual CNT post microelectrode with a diameter of 25 μm and a length of 1 mm to perform cyclic voltammetry on both methyl viologen and dopamine in a phosphate-buffered saline solution.

Thin-Film Carbon Nanofuses for Permanent Data Storage.

In this study, we have fabricated nanofuses from thin-film, arc-deposited carbon for use in permanent data storage. Thin-film carbon fuses have fewer fabrication barriers and retain the required resistivity and structural stability to act as a data-storage medium. Carbon thin films were characterized for their electrical, microstructural, and chemical bonding properties.

Multi-instrument characterization of five nanodiamond samples: a thorough example of nanomaterial characterization.

Here, we report the most comprehensive characterization of nanodiamonds (NDs) yet undertaken. Five different samples from three different vendors were analyzed by a suite of analytical techniques, including X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), inductively coupled plasma mass spectrometry (ICP-MS), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), Brunauer-Emmett-Teller (BET) surface area measurements, and particle size distribution (PSD) measurements. XPS revealed the elemental compositions of the ND surfaces (83-87 at.

High Aspect Ratio Carbon Nanotube Membranes Decorated with Pt Nanoparticle Urchins for Micro Underwater Vehicle Propulsion via H2O2 Decomposition.

The utility of unmanned micro underwater vehicles (MUVs) is paramount for exploring confined spaces, but their spatial agility is often impaired when maneuvers require burst-propulsion. Herein we develop high-aspect ratio (150:1), multiwalled carbon nanotube microarray membranes (CNT-MMs) for propulsive, MUV thrust generation by the decomposition of hydrogen peroxide (H2O2). The CNT-MMs are grown via chemical vapor deposition with diamond shaped pores (nominal diagonal dimensions of 4.

Alternative FIB TEM sample preparation method for cross-sections of thin metal films deposited on polymer substrates.

Transmission electron microscopy (TEM) and focused ion beam (FIB) are proven tools to produce site-specific samples in which to study devices from initial processing to causes for failure, as well as investigating the quality, defects, interface layers, etc. However, the use of polymer substrates presents new challenges, in the preparation of suitable site-specific TEM samples, which include sample warping, heating, charging, and melting. In addition to current options that address some of these problems such as cryo FIB, we add an alternative method and FIB sample geometry that address these challenges and produce viable samples suitable for TEM elemental analysis.

Stable, microfabricated thin layer chromatography plates without volume distortion on patterned, carbon and Al₂O₃-primed carbon nanotube forests.

Some of us recently described the fabrication of thin layer chromatography (TLC) plates from patterned carbon nanotube (CNT) forests via direct infiltration/coating of the CNTs by low pressure chemical vapor deposition (LPCVD) of silicon from SiH₄, followed by high temperature oxidation of the CNTs and Si. Herein we present an improved microfabrication process for the preparation of these TLC plates. First, a few nanometers of carbon and/or a thin film of Al₂O₃ is deposited on the CNTs.

Comparison of simulated and experimental order parameters in FePt--II.

Eight FePt thin film specimens of various thicknesses, compositions, and order parameters have been analyzed to determine the robustness and fidelity of multislice simulations in determining the chemical order parameter via electron diffraction (ED). The shape of the simulated curves depends significantly on the orientation and thickness of the specimen. The ED results are compared to kinematical scattering order parameters, from the same films, acquired from synchrotron X-ray diffraction (XRD).

Dynamical diffraction simulations in FePt--I.

A series of multislice simulations to quantify the effect of various degrees of order, composition, and thickness on the electron diffracted intensities were performed using the L1₀ FePt system as the case study. The dynamical diffraction studies were done in both a convergent electron beam diffraction and selected area electron diffraction condition. The L1₀ symmetry demonstrated some peculiar challenges in the simulation, in particular between the {111} plane normal and the <111> direction, which are not equivalent because of tetragonality.

A modified back-etch method for preparation of plan-view high-resolution transmission electron microscopy samples.

A modified back-etch method is described that has been successfully used to prepare samples of thin films and nanoparticles on Si wafer substrates for examination by high-resolution transmission electron microscopy (HRTEM). This process includes ultrasonic cutting, abrasive pre-thinning and a two-stage etching procedure. Unlike previous reports of back-etching methods, tetramethyl ammonium hydroxide, which has a very high-etching selectivity of Si to SiO(2), is used for the final etching to allow removal of the Si without degradation of the SiO(2) membrane.