To improve light absorption, previously various antireflection material layers were created on solar wafer surface including multilayer dielectric film, nanoparticle sludges, microtextures, noble metal plasmonic nanoparticles and 3D silicon nanostructure arrays. All of these approaches involve nanoscale prepatterning, surface-area-sensitive assembly processes or extreme fabrication conditions; therefore, they are often limited by the associated high cost and low yield as well as the consequent industry incompatibility. In comparison, our nanomanufacturing, an unique synchronized and simultaneous top-down and bottom-up nanofabrication approach called simultaneous plasma enhanced reactive ion synthesis and etching (SPERISE), offers a better antireflection solution along with the potential to increase p-n junction surface area. High density and high aspect ratio anechoic nanocone arrays are repeatedly and reliably created on the entire surface of single and poly crystalline silicon wafers as well as amorphous silicon thin films within 5 minutes under room temperature. The nanocone surface had lower than 5% reflection over the entire solar spectrum and a desirable omnidirectional absorption property. Using the nanotextured solar wafer, a 156mm × 156mm 18.1%-efficient black silicon solar cell was fabricated, which was an 18.3% enhancement over the cell fabricated by standard industrial processes. This process also reduces silicon loss during the texturing step and enables tighter process control by creating more uniform surface structures. Considering all the above advantages, the demonstrated nanomanufacturing process can be readily translated into current industrial silicon solar cell fabrication lines to replace the costly and ineffective wet chemical texturing and antireflective coatings.
The interaction of biomolecules and solid-state nanomaterials at the nano-bio interfaces is a long-lasting research topic in nanotechnology. Historically, fundamental problems, such as the electron transfer, energy transfer, and plasmonic interaction at the bio-nano interfaces, have been intensively studied, and revolutionary technologies, such as molecular electronics, peptide chips, nanoplasmonic sensors, have been created. With the combined effort of molecular dynamics simulation and surface-enhanced Raman spectroscopy, we studied the external electric field-induced conformation changes of dodecapeptide probes tethered to a nanostructured metallic surface. Through this study, we demonstrated a reversible manipulation of the biomolecule conformations as well as an in situ eletro-optical detection of the subnanometer conformational changes at the bio-nano interfaces. Based on the proof-of-concept established in this study, we further propose a novel nanophotonic peptide phosphorylation sensor for high-sensitive peptide kinase profiling. We have also demonstrated the same SERS nano-bio-chip can be used for environmental monitoring applications, such as detection of contaminants in drinking water at ultralow concentrates. The fabrication of this nanosensor is based on a single step, lithography-less nanomanufacturing process, which can produce hundreds of these chips in several minutes with nearly 100% yield and uniformity. Therefore, the demonstrated research can be readily translated into industrial mass productions.
With the goal of improving photo-absorption of photovoltaic device and for plasmonic application we have fabricated
nanopillar black silicon devices through etching-passivation technique which does not require any photomask and whole
wafer scale uniformity is achieved at room temperature in a short time. We have carried out thorough optical
characterization for nanopillar black silicon devices to be used for solar cell and plasmonic applications.
Cathodoluminescence (CL), current dependent CL spectroscopy, photoluminescence (at room temperature and 77 K),
Raman spectroscopy, reflectance and absorption measurement have been performed on the device. A thin layer of Ag is
deposited to render with plasmonic property and the plasmonic effect is probed using surface plasmon enhanced
fluorescence, angle dependent reflectance measurements, high resolution cathodoluminescence (CL), surface enhanced
Raman spectroscopy (SERS) measurement and Fluorescence Lifetime Imaging Microscopy (FLIM) experiment. We
obtained reduction in optical reflection of ~ 12 times on b-Si substrate from UV to NIR range, the nanostructured
fluorescence enhancement of ~40 times and the Raman scattering enhancement factor of 6.4×107.
We demonstrate surface plasmon-induced enhancements in optical imaging and spectroscopy on silver coated silicon
nanocones which we call black silver substrate. The black silver substrate with dense and homogeneous nanocone forest
structure is fabricated on wafer level with a mass producible nanomanufacturing method. The black silver substrate is
able to efficiently trap and convert incident photons into localized plasmons in a broad wavelength range, which permits
the enhancement in optical absorption from UV to NIR range by 12 times, the visible fluorescence enhancement of ~30
times and the NIR Raman scattering enhancement factor up to ~108. We show a considerable potential of the black silver
substrate in high sensitivity and broadband optical sensing and imaging of chemical and biological molecules.one)
KEYWORDS: Luminescence, Nanoplasmonics, Silver, Confocal microscopy, Metals, Resonance enhancement, 3D image processing, Near field optics, 3D image enhancement, Surface plasmons
We have created an enhanced cell-imaging platform for 3D confocal fluorescence cell imaging where fluorescence
sensitivity is amplified for more than 100 folds especially for cell membrane and cytoplasm. The observed
unprecedented three-dimensional fluorescence intensity enhancement on the entire cell microstructure including cell
membrane 10 μm above the substrate surface is attributed to a novel far field enhancement mechanism, nanoplasmon
coupled optical resonance excitation (CORE) mechanism which permits enhanced surface plasmon on the substrate
being evanescently coupled to Whispering Gallery mode optical resonance inside the spheroidal cell membrane
microcavity. Theoretical model of the hypothesis is explained using coupled mode theory. In addition, preliminary result
has been provided for the observation of early stage of transfection in a cancer cell.
Foot ulcers affect millions of Americans annually. Conventional methods used to assess skin integrity, including inspection and palpation, may be valuable approaches, but they usually do not detect changes in skin integrity until an ulcer has already developed. We analyze the feasibility of thermal imaging as a technique to assess the integrity of the skin and its many layers. Thermal images are analyzed using an asymmetry analysis, combined with a genetic algorithm, to examine the infrared images for early detection of foot ulcers. Preliminary results show that the proposed technique can reliably and efficiently detect inflammation and hence effectively predict potential ulceration.
Foot ulcers affect millions of Americans annually. Areas that are likely to ulcerate have been associated with increased
local skin temperatures due to inflammation and enzymatic autolysis of tissue. Conventional methods to assess skin,
including inspection and palpation, may be valuable approaches, but usually they do not detect changes in skin integrity
until an ulcer has already developed. Conversely, infrared imaging is a technology able to assess the integrity of the skin
and its many layers, thus having the potential to index the cascade of physiological events in the prevention, assessment,
and management of foot ulcers. In this paper, we propose a technique, asymmetry analysis, to automatically analyze the
infrared images in order to detect inflammation. Preliminary results show that the proposed technique can be reliable
and efficient to detect inflammation and, hence, predict potential ulceration.
Foot ulcers affect millions of Americans annually. Conventional methods to assess skin, including inspection and palpation, may be valuable approaches, but usually they do not detect changes in skin integrity until an ulcer has already developed. Conversely, thermal imaging is a technology able to assess the integrity of the skin and its many layers, thus having the potential to index the cascade of physiological events in the prevention, assessment, and
management of foot ulcers. In this paper, we propose a methodology based on an asymmetry analysis and a genetic algorithm to analyze the infrared images for early detection of foot ulcers. Preliminary results show that the proposed technique can be reliable and efficient to detect and, hence, predict inflammation and potential ulceration.
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