3,211 research outputs found
Nanoscale diffractive probing of strain dynamics in ultrafast transmission electron microscopy
The control of optically driven high-frequency strain waves in nanostructured
systems is an essential ingredient for the further development of
nanophononics. However, broadly applicable experimental means to quantitatively
map such structural distortion on their intrinsic ultrafast time and nanometer
length scales are still lacking. Here, we introduce ultrafast convergent beam
electron diffraction (U-CBED) with a nanoscale probe beam for the quantitative
retrieval of the time-dependent local distortion tensor. We demonstrate its
capabilities by investigating the ultrafast acoustic deformations close to the
edge of a single-crystalline graphite membrane. Tracking the structural
distortion with a 28-nm/700-fs spatio-temporal resolution, we observe an
acoustic membrane breathing mode with spatially modulated amplitude, governed
by the optical near field structure at the membrane edge. Furthermore, an
in-plane polarized acoustic shock wave is launched at the membrane edge, which
triggers secondary acoustic shear waves with a pronounced spatio-temporal
dependency. The experimental findings are compared to numerical acoustic wave
simulations in the continuous medium limit, highlighting the importance of
microscopic dissipation mechanisms and ballistic transport channels
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Synthetic Nanoelectronic Probes for Biological Cells and Tissues
Research at the interface between nanoscience and biology could yield breakthroughs in fundamental science and lead to revolutionary technologies. In this review, we focus on the interfaces between nanoelectronics and biology. First, we discuss nanoscale field effect transistors (nanoFETs) as probes to study cellular systems; specifically, we describe the development of nanoFETs that are comparable in size to biological nanostructures involved in communication through synthesized nanowires. Second, we review current progress in multiplexed extracellular sensing using planar nanoFET arrays. Third, we describe the designs and implementation of three distinct nanoFETs used to perform the first intracellular electrical recording from single cells. Fourth, we present recent progress in merging electronic and biological systems at the three-dimensional tissue level by use of macro-porous nanoelectronic scaffolds. Finally, we discuss future developments in this research area, unique challenges and opportunities, and the tremendous impact these nanoFET-based technologies might have on biological and medical sciences.Chemistry and Chemical BiologyEngineering and Applied Science
Far-field Super-resolution Chemical Microscopy
Far-field chemical microscopy providing molecular electronic or vibrational
fingerprint information opens a new window for the study of three-dimensional
biological, material, and chemical systems. Chemical microscopy provides a
nondestructive way of chemical identification without exterior labels. However,
the diffraction limit of optics hindered it from discovering more details under
the resolution limit. Recent development of super-resolution techniques gives
enlightenment to open this door behind far-field chemical microscopy. Here, we
review recent advances that have pushed the boundary of far-field chemical
microscopy in terms of spatial resolution. We further highlight applications in
biomedical research, material characterization, environmental study, cultural
heritage conservation, and integrated chip inspection.Comment: 34 pages, 8 figures,1 tabl
Chalcogenide Glass-on-Graphene Photonics
Two-dimensional (2-D) materials are of tremendous interest to integrated
photonics given their singular optical characteristics spanning light emission,
modulation, saturable absorption, and nonlinear optics. To harness their
optical properties, these atomically thin materials are usually attached onto
prefabricated devices via a transfer process. In this paper, we present a new
route for 2-D material integration with planar photonics. Central to this
approach is the use of chalcogenide glass, a multifunctional material which can
be directly deposited and patterned on a wide variety of 2-D materials and can
simultaneously function as the light guiding medium, a gate dielectric, and a
passivation layer for 2-D materials. Besides claiming improved fabrication
yield and throughput compared to the traditional transfer process, our
technique also enables unconventional multilayer device geometries optimally
designed for enhancing light-matter interactions in the 2-D layers.
Capitalizing on this facile integration method, we demonstrate a series of
high-performance glass-on-graphene devices including ultra-broadband on-chip
polarizers, energy-efficient thermo-optic switches, as well as graphene-based
mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators
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