Fast and high-sensitivity chemical imaging via compressive Raman microspectroscopy (Conference Presentation)

2020 ◽  
Author(s):  
Hilton Barbosa de Aguiar
Keyword(s):  
High Sensitivity ◽  
Chemical Imaging ◽  
Raman Microspectroscopy

High Sensitivity Label-Free Imaging with Doppler Raman Microspectroscopy

2019 ◽  
Author(s):  
David R. Smith ◽  
Jeffrey J. Field ◽  
David Winters ◽  
Scott Domingue ◽  
Jesse W. Wilson ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Raman Microspectroscopy ◽  
Label Free

scholarly journals Raman and AFM-IR chemical imaging of stratum corneum model membranes

2020 ◽  
Vol 98 (9) ◽  
pp. 495-501
Author(s):  
Adrian Paz Ramos ◽  
Gert Gooris ◽  
Joke Bouwstra ◽  
Michael Molinari ◽  
Michel Lafleur
Keyword(s):  
Fatty Acids ◽  
Stratum Corneum ◽  
Free Fatty Acids ◽  
Percutaneous Absorption ◽  
Lipid Fraction ◽  
Chemical Imaging ◽  
Raman Microspectroscopy ◽  
Central Layer ◽  
Lipid Matrix ◽  
Lipid Environment

Stratum corneum (SC), the outermost layer of the epidermis, is the primary barrier to percutaneous absorption. The diffusion of substances through the skin occurs through the SC lipid fraction, which is essentially constituted of an equimolar mixture of ceramides, free fatty acids, and cholesterol. The lipid constituents of SC are mainly forming continuous multilamellar membranes in the solid/crystalline state. However, recent findings suggest the presence of a highly disordered (liquid) phase formed by the unsaturated C18 chain of ceramide EOS, surrounded by a highly ordered lipid environment. The aim of the present work was to study the lipid spatial distribution of model SC membranes composed of ceramide EOS, ceramide NS, a mixture of free fatty acids, and cholesterol, using Raman microspectroscopy and AFM-IR spectroscopy techniques. The enhanced spatial resolution at the tens of nanometers scale of the AFM-IR technique revealed that the lipid matrix is overall homogeneous, with the presence of small, slightly enriched, and depleted regions in a lipid component. No liquid domains of ceramide EOS were observed at this scale, a result that is consistent with the model proposing that the oleate nanodrops are concentrated in the central layer of the three-layer organization of the SC membranes forming the long periodicity phase. In addition, both Raman microspectroscopy and AFM-IR techniques confirmed the fluid nature of the unsaturated chain of ceramide EOS while the rest of the lipid matrix was found highly ordered.

scholarly journals Gas-Phase Chemical Imaging System by Biofluorometry for Human VOCs Measurement

2021 ◽  
Vol 6 (1) ◽  
pp. 73
Author(s):  
Kenta Iitani ◽  
Koji Toma ◽  
Takahiro Arakawa ◽  
Kohji Mitsubayashi
Keyword(s):  
Gas Phase ◽  
Imaging System ◽  
High Sensitivity ◽  
Ethanol Vapor ◽  
Chemical Imaging ◽  
Fluorescent Imaging ◽  
Uv Led ◽  
Highly Sensitive ◽  
Exhaled Air ◽  
Vapor Distribution

Many gas-phase biosensors have been developed for human volatiles (acetone, methyl mercaptan, trimethylamine, ethanol, isopropanol, etc.) and for residential harmful VOCs (formaldehyde, toluene, nicotine) causing some diseases. A novel gas-imaging system by biofluorometry with an enzyme immobilized mesh was investigated to demonstrate spatiotemporal gas-imaging for human volatiles (i.e., ethanol and acetaldehyde after drinking). A biofluorometric technique was applied to improve the performance (sensitivity, calibration range, gas-selectivity, etc.) of the gas-imaging system. The biofluorometric sniff-cam for ethanol was fabricated with an ADH (alcohol dehydrogenase) immobilized mesh and an NADH fluorescent visualization unit (UV-LED sheet array and highly sensitive camera); thus, showing the two-dimensional real-time imaging of ethanol vapor distribution (0.5–200 ppm). The system showed rapid and accurate responses and a visible measurement of ethanol in the gas phase. The intensity of fluorescence was linearly related to the concentration of ethanol vapor. The high sensitivity fluorescent imaging of ethanol vapor allows to successfully visualize gaseous ethanol from the human body (exhaled air and skin gas) after drinking. The sniff-cam system would be useful for the conventional detecting and imaging of the volatile biomarkers.

scholarly journals High-throughput quantum cascade laser (QCL) spectral histopathology: a practical approach towards clinical translation

2016 ◽  
Vol 187 ◽  
pp. 135-154 ◽  
Author(s):  
Michael J. Pilling ◽  
Alex Henderson ◽  
Benjamin Bird ◽  
Mick D. Brown ◽  
Noel W. Clarke ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
High Throughput ◽  
Quantum Cascade Laser ◽  
High Sensitivity ◽  
Chemical Imaging ◽  
Clinical Translation ◽  
Infrared Microscopy ◽  
Discrete Frequency ◽  
Quantum Cascade ◽  
Spectral Histopathology

Infrared microscopy has become one of the key techniques in the biomedical research field for interrogating tissue. In partnership with multivariate analysis and machine learning techniques, it has become widely accepted as a method that can distinguish between normal and cancerous tissue with both high sensitivity and high specificity. While spectral histopathology (SHP) is highly promising for improved clinical diagnosis, several practical barriers currently exist, which need to be addressed before successful implementation in the clinic. Sample throughput and speed of acquisition are key barriers and have been driven by the high volume of samples awaiting histopathological examination. FTIR chemical imaging utilising FPA technology is currently state-of-the-art for infrared chemical imaging, and recent advances in its technology have dramatically reduced acquisition times. Despite this, infrared microscopy measurements on a tissue microarray (TMA), often encompassing several million spectra, takes several hours to acquire. The problem lies with the vast quantities of data that FTIR collects; each pixel in a chemical image is derived from a full infrared spectrum, itself composed of thousands of individual data points. Furthermore, data management is quickly becoming a barrier to clinical translation and poses the question of how to store these incessantly growing data sets. Recently, doubts have been raised as to whether the full spectral range is actually required for accurate disease diagnosis using SHP. These studies suggest that once spectral biomarkers have been predetermined it may be possible to diagnose disease based on a limited number of discrete spectral features. In this current study, we explore the possibility of utilising discrete frequency chemical imaging for acquiring high-throughput, high-resolution chemical images. Utilising a quantum cascade laser imaging microscope with discrete frequency collection at key diagnostic wavelengths, we demonstrate that we can diagnose prostate cancer with high sensitivity and specificity. Finally we extend the study to a large patient dataset utilising tissue microarrays, and show that high sensitivity and specificity can be achieved using high-throughput, rapid data collection, thereby paving the way for practical implementation in the clinic.

Novel X-ray Microscopic Chemical Imaging for Rapid Non-Destructive Identification of Structural and Compositional Defects from Microbumps to FinFET

2019 ◽  
Author(s):  
S. H. Lau ◽  
Benjamin Stripe ◽  
Sylvia Lewis ◽  
Xiaolin Yang ◽  
Wenbing Yun
Keyword(s):  
Process Development ◽  
High Sensitivity ◽  
Chemical Imaging ◽  
Wafer Surface ◽  
X Ray ◽  
Patterned Wafers ◽  
Integration Schemes ◽  
Advanced Packaging ◽  
Microscope Technique ◽  
Non Destructive

Abstract New heterogeneous 3D integration schemes and continuing miniaturization of semiconductor packaging components, such as micropillars, are driving demand for substantive changes to conventional PFA (physical failure analysis). In particular, desired performance capabilities include the ability to nondestructively determine failures within seconds to minutes. New tools should be quantitative, have sufficient resolution to determine sub-micron sized defects and voids in TSVs at the wafer or package level. It should also measure thickness and their material composition of multilayer structures above the wafer surface, such as microbumps, or those below the surface including UBM and RDL. In this paper we are introducing a novel x-ray fluorescence microscope technique capable of solving the above applications in advanced packaging for PFA and process development. The same technique can also be applied in the front end metrology of new gate materials, 3D FinFET structures within test structures in patterned wafers. Characterization of sub nanoscopic changes (sensitivity of sub-angstrom) in film and dopants deposited in 3D structures will also be shown. With its high sensitivity for trace materials, contamination analysis of post hard mask residue, post metal etch residue especially in high aspect ratio structures is also possible.

scholarly journals High-sensitivity nanoscale chemical imaging with hard x-ray nano-XANES

2020 ◽  
Vol 6 (37) ◽  
pp. eabb3615 ◽  
Author(s):  
A. Pattammattel ◽  
R. Tappero ◽  
M. Ge ◽  
Y. S. Chu ◽  
X. Huang ◽  
...  
Keyword(s):  
Lithium Iron Phosphate ◽  
Reference Sample ◽  
Chemical Species ◽  
High Sensitivity ◽  
Chemical Imaging ◽  
Resolving Power ◽  
X Rays ◽  
Secondary Phases ◽  
Edge Structure ◽  
X Ray

Resolving chemical species at the nanoscale is of paramount importance to many scientific and technological developments across a broad spectrum of disciplines. Hard x-rays with excellent penetration power and high chemical sensitivity are suitable for speciation of heterogeneous (thick) materials. Here, we report nanoscale chemical speciation by combining scanning nanoprobe and fluorescence-yield x-ray absorption near-edge structure (nano-XANES). First, the resolving power of nano-XANES was demonstrated by mapping Fe(0) and Fe(III) states of a reference sample composed of stainless steel and hematite nanoparticles with 50-nm scanning steps. Nano-XANES was then used to study the trace secondary phases in lithium iron phosphate (LFP) particles. We observed individual Fe-phosphide nanoparticles in pristine LFP, whereas partially (de)lithiated particles showed Fe-phosphide nanonetworks. These findings shed light on the contradictory reports on Fe-phosphide morphology in the literature. Nano-XANES bridges the capability gap of spectromicroscopy methods and provides exciting research opportunities across multiple disciplines.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Sign in / Sign up

Export Citation Format

Share Document