scholarly journals A Systematic Study on Transit Time and Its Impact on Accuracy of Concentration Measured by Microfluidic Devices

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 14 ◽  
Author(s):  
Yushan Zhang ◽  
Tianyi Guo ◽  
Changqing Xu
Keyword(s):  
Transit Time ◽  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Microfluidic Devices ◽  
Relative Difference ◽  
Scattering Data ◽  
Fluorescent Light ◽  
Positive Events ◽  
Improve Measurement ◽  
Microflow Cytometer

Gating or threshold selection is very important in analyzing data from a microflow cytometer, which is especially critical in analyzing weak signals from particles/cells with small sizes. It has been reported that using the amplitude gating alone may result in false positive events in analyzing data with a poor signal-to-noise ratio. Transit time (τ) can be set as a gating threshold along with side-scattered light or fluorescent light signals in the detection of particles/cells using a microflow cytometer. In this study, transit time of microspheres was studied systematically when the microspheres passed through a laser beam in a microflow cytometer and side-scattered light was detected. A clear linear relationship between the inverse of the average transit time and total flow rate was found. Transit time was used as another gate (other than the amplitude of side-scattering signals) to distinguish real scattering signals from noise. It was shown that the relative difference of the measured microsphere concentration can be reduced significantly from the range of 3.43%–8.77% to the range of 8.42%–111.76% by employing both amplitude and transit time as gates in analysis of collected scattering data. By using optimized transit time and amplitude gate thresholds, a good correlation with the traditional hemocytometer-based particle counting was achieved (R2 > 0.94). The obtained results suggest that the transit time could be used as another gate together with the amplitude gate to improve measurement accuracy of particle/cell concentration for microfluidic devices.

A Time-Resolved Low-Angle Light Scattering Apparatus. Application to Phase Separation Problems in Polymer Systems

2001 ◽  
Vol 66 (6) ◽  
pp. 973-982 ◽  
Author(s):  
Čestmír Koňák ◽  
Jaroslav Holoubek ◽  
Petr Štěpánek
Keyword(s):  
Phase Separation ◽  
Light Scattering ◽  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Ccd Camera ◽  
Time Resolved ◽  
Polymer Systems ◽  
Software Analysis ◽  
Phase Separation Kinetics ◽  
Small Angle Light Scattering

A time-resolved small-angle light scattering apparatus equipped with azimuthal integration by means of a conical lens or software analysis of scattering patterns detected with a CCD camera was developed. Averaging allows a significant reduction of the signal-to-noise ratio of scattered light and makes this technique suitable for investigation of phase separation kinetics. Examples of applications to time evolution of phase separation in concentrated statistical copolymer solutions and dissolution of phase-separated domains in polymer blends are given.

scholarly journals Photonic resonator interferometric scattering microscopy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nantao Li ◽  
Taylor D. Canady ◽  
Qinglan Huang ◽  
Xing Wang ◽  
Glenn A. Fried ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Near Field ◽  
Field Enhancement ◽  
Protein Detection ◽  
Significant Loss ◽  
Photonic Band Structure ◽  
Large Intensity ◽  
Photonic Band ◽  
Intensity Contrast

AbstractInterferometric scattering microscopy is increasingly employed in biomedical research owing to its extraordinary capability of detecting nano-objects individually through their intrinsic elastic scattering. To significantly improve the signal-to-noise ratio without increasing illumination intensity, we developed photonic resonator interferometric scattering microscopy (PRISM) in which a dielectric photonic crystal (PC) resonator is utilized as the sample substrate. The scattered light is amplified by the PC through resonant near-field enhancement, which then interferes with the <1% transmitted light to create a large intensity contrast. Importantly, the scattered photons assume the wavevectors delineated by PC’s photonic band structure, resulting in the ability to utilize a non-immersion objective without significant loss at illumination density as low as 25 W cm−2. An analytical model of the scattering process is discussed, followed by demonstration of virus and protein detection. The results showcase the promise of nanophotonic surfaces in the development of resonance-enhanced interferometric microscopies.

scholarly journals Photometric Characteristics of Data from the Hubble Space Telescope Goddard-High Resolution Spectrograph

1988 ◽  
Vol 132 ◽  
pp. 35-38
Author(s):  
Dennis C. Ebbets ◽  
Sara R. Heap ◽  
Don J. Lindler
Keyword(s):  
Exposure Time ◽  
Hubble Space Telescope ◽  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Signal To Noise ◽  
Space Telescope ◽  
Additional Noise ◽  
Reduction Strategies ◽  
Noise Ratio

The G-HRS is one of four axial scientific instruments which will fly aboard the Hubble Space Telescope (ref 1,2). It will produce spectroscopic observations in the 1050 A ≤ λ ≤ 3300 A region with greater spectral, spatial and temporal resolution than has been possible with previous space-based instruments. Five first order diffraction gratings and one Echelle provide three modes of spectroscopic operation with resolving powers of R = λ/ΔΔ = 2000, 20000 and 90000. Two magnetically focused, pulse-counting digicon detectors, which differ only in the nature of their photocathodes, produce data whose photometric quality is usually determined by statistical noise in the signal (ref 3). Under ideal circumstances the signal to noise ratio increases as the square root of the exposure time. For some observations detector dark count, instrumental scattered light or granularity in the pixel to pixel sensitivity will cause additional noise. The signal to noise ratio of the net spectrum will then depend on several parameters, and will increase more slowly with exposure time. We have analyzed data from the ground based calibration programs, and have developed a theoretical model of the HRS performance (ref 4). Our results allow observing and data reduction strategies to be optimized when factors other than photon statistics influence the photometric quality of the data.

scholarly journals Validation of Satellite Estimated Solar Ultraviolet Radiation Data with Ground Based data in Kathmandu, Nepal

2016 ◽  
Vol 11 (1) ◽  
pp. 101-107
Author(s):  
Niranjan Prasad Sharma
Keyword(s):  
Ultraviolet Radiation ◽  
Scattered Light ◽  
Visible Spectrum ◽  
Relative Difference ◽  
Ozone Monitoring Instrument ◽  
Solar Ultraviolet Radiation ◽  
Radiation Data ◽  
Uv Irradiance ◽  
Relative Differences ◽  
Solar Ultraviolet

The main objective of this study is to validate the satellite estimated solar Ultraviolet radiation data with ground based data in  Kathmandu (27.72 N, 85.32 E), located at an elevation of 1350m,  from the sea level. The ground based measurement and the satellite estimation were performed by NILU-UV irradiance meter and EOS Aura OMI satellite respectively. The NILU-UV irradiance meter is a six channel 0 0 radiometer designed to measure hemispherical irradiances on a fat surface. Meanwhile the Ozone Monitoring Instrument (OMI) on board, the NASA EOS Aura space craft is a nadir viewing spectrometer that measures solar refected and back scattered light in ultraviolet and visible spectrum. The study is based on OMI and ground based (GB), Ultraviolet Radiation (UVR) data. Considering these data the relative differences between predicted OMI and ground based Ultraviolet Index (UVI) assuming normal distribution ±1σ was found to be 24.8±13.7% in July. Further study showed that the ratio of predicted OMI, UVI to that determined from ground based measurement is 1.14. Also the relative difference in UVI in corrected condition in summer season was found to be 5.8%. The correlation between predicted UVI and ground based UVI was found to be signifcant. Journal of the Institute of Engineering, 2015, 11(1): 101-107

Listening to Colloidal Silica Samples: Simultaneous Measurement of Absorbed and Scattered Light Using Pulsed-Laser Photoacoustics

2000 ◽  
Vol 54 (8) ◽  
pp. 1142-1150 ◽  
Author(s):  
Jeanne Rudzki Small ◽  
Nancy S. Foster ◽  
James E. Amonette ◽  
Tom Autrey
Keyword(s):  
Colloidal Silica ◽  
Scattered Light ◽  
Ultrasonic Transducer ◽  
Quantitative Information ◽  
Potassium Chromate ◽  
Fluorescent Light ◽  
Incident Laser Pulse ◽  
Laser Photoacoustic Spectroscopy ◽  
Light Signals ◽  
Experimental Geometry

Laser photoacoustic spectroscopy (LPAS) has been used to simultaneously measure scattered light and absorbed light with the use of a single piezoelectric transducer detector. Samples of Ludox™ colloidal silica, with and without added potassium chromate, were illuminated with pulses of 308 or 355 nm light. Signals were measured with a 1 MHz ultrasonic transducer clamped to the side of the cuvette. The resulting oscilloscope tracing shows a pattern of signals originating from light scatter and light absorption that is consistent with experimental geometry and the speeds of light and sound, and linear with incident laser pulse energy. The absorbed light signals are independent of the distance of the laser beam from the transducer, while the scattered light signals are strongly distance-dependent. The absorbed light signals are more indicative of true sample absorbance than are readings from a standard spectrophotometer. A spectrophotometer sums contributions from scattering and absorbance to give an optical density reading, while LPAS separates scattering from absorbance to give quantitative information on each function. Scattered light and fluorescent light behave very similarly in the LPAS technique. Our experiments were done with well-characterized colloidal silica samples, but the technique is readily extended to larger, more heterogeneous, and photochemically complex biological and environmental samples.

Structure Data from Light Scattering Studies of Aerogel

1984 ◽  
Vol 32 ◽  
Author(s):  
Arlon J. Hunt ◽  
Paul Berdahl
Keyword(s):  
Light Scattering ◽  
Optical Materials ◽  
Scattered Light ◽  
Average Density ◽  
Scattering Data ◽  
Small Scale ◽  
Material Structure ◽  
Structure Parameters ◽  
Microporous Structure ◽  
The Fourier Transform

ABSTRACTThis paper reports a recent advance in the understanding of the structure of microporous optical materials such as aerogel through the interpretation of light scattering data. The Fourier transform of the densitydensity correlation function is used to relate measurements of the angular dependence of scattered light to material structure parameters. The results of the approach fit the unusual dependence of the intensity of scattered light as a function of angle for two polarizations. The fit shows that light scattering from aerogels may be interpreted as having two origins; one from the small scale structure of linked particles that comprise the material, and the second due to weak fluctuations in the average density of the microporous structure over distances significantly larger than the pore size.

Particles small angle forward-scattered light measurement based on photovoltaic cell microflow cytometer

2013 ◽  
Vol 35 (2-3) ◽  
pp. 337-344 ◽  
Author(s):  
Han-Taw Chen ◽  
Lung-Ming Fu ◽  
Hsing-Hui Huang ◽  
Wei-En Shu ◽  
Yao-Nan Wang
Keyword(s):  
Small Angle ◽  
Scattered Light ◽  
Photovoltaic Cell ◽  
Light Measurement ◽  
Microflow Cytometer

Distributed Optical Fiber Raman Signal Noise Cancellation Based on Empirical Mode Decomposition

2012 ◽  
Vol 198-199 ◽  
pp. 1621-1626 ◽  
Author(s):  
You Ping Zhong ◽  
Qi Zhang ◽  
Di Zhou
Keyword(s):  
Optical Fiber ◽  
Empirical Mode Decomposition ◽  
Signal To Noise Ratio ◽  
Noise Cancellation ◽  
Raman Signal ◽  
Signal To Noise ◽  
Mode Decomposition ◽  
Improve Measurement ◽  
Distributed Optical Fiber ◽  
Anti Stokes

The distributed optical fiber Raman sensor system was widely used for real-time measurement temperature, but the Anti-Stokes and Stokes scattering Raman signal is very weak. In order to improve measurement accuracy the signal must be denoised before obtaining the temperature. In this paper, a new noise cancellation of empirical mode decomposition is proposed for enhancing signal-to-noise ration of the Anti-Stokes and Stokes scattering Raman signal. The signal-to-noise ratio was enhanced by using this method and it is easy to be realized in computer.

scholarly journals Fluorescent PIV using Atomized Liquid Particles

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Adit S. Acharya ◽  
K. Todd Lowe ◽  
Wing F. Ng
Keyword(s):  
Boundary Layer ◽  
Scattered Light ◽  
Adverse Pressure Gradient ◽  
Mie Scattering ◽  
Fluorescence Yield ◽  
Surface Measurement ◽  
Fluorescent Light ◽  
Near Surface ◽  
Freestream Velocity ◽  
Forward Facing Step

It is shown that aerosolized fluorescent particles generated using a Venturi-type atomizer, from a solution of fluorescent Kiton Red 620 dye in a water/glycol fluid, provide effective flow seeding for fluorescent PIV. The atomized liquid particles were found to be of acceptable size for PIV purposes, with 92% of detected particles by number concentration measuring < 1 μm in diameter. A PIV application was conducted in a wind tunnel (freestream velocity U∞ = 27 m/s), using the particles for measurement of the boundary layer flow approaching a forward-facing step (approach boundary layer momentum thickness Reynolds number of Reθ = 5930), to identify potential benefits in near-wall regions normally affected by unwanted laser reflections from tunnel surfaces. Particles were generated from solutions with dye molar concentrations of 2.5 × 10−3 and 1.0 × 10−2 mol/L, and PIV images were obtained for both elastic Mie scattering and filtered, Stokes-shifted fluorescent light. Raw images indicate that the fluorescence yield of the 1.0 × 10−2 mol/L solution provides PIV images with high contrast, even in the near-surface regions where Mie scattering images are highly affected by surface reflections. Boundary layer profiles are processed in the adverse pressure gradient region leading up to the forward-facing step, where the fluorescent PIV performed comparably to the most optimized Mie scattering PIV; both obtained data as near to the wall as 30 μm, or 2 viscous wall units in our flow of interest. These results indicate that the new seeding method holds excellent promise for near-surface measurement applications with more complicated three-dimensional geometries, where it is impossible to arrange PIV cameras to reject surface-scattered light.

scholarly journals Estimating signal and noise of time-resolved X-ray solution scattering data at synchrotrons and XFELs

2020 ◽  
Vol 27 (3) ◽  
pp. 633-645
Author(s):  
Jungmin Kim ◽  
Jong Goo Kim ◽  
Hosung Ki ◽  
Chi Woo Ahn ◽  
Hyotcherl Ihee
Keyword(s):  
Quantum Noise ◽  
Structural Information ◽  
Signal To Noise Ratio ◽  
Liquid Solution ◽  
Solution Phase ◽  
Scattering Data ◽  
Time Resolved ◽  
X Ray ◽  
The Future ◽  
The Difference

Elucidating the structural dynamics of small molecules and proteins in the liquid solution phase is essential to ensure a fundamental understanding of their reaction mechanisms. In this regard, time-resolved X-ray solution scattering (TRXSS), also known as time-resolved X-ray liquidography (TRXL), has been established as a powerful technique for obtaining the structural information of reaction intermediates and products in the liquid solution phase and is expected to be applied to a wider range of molecules in the future. A TRXL experiment is generally performed at the beamline of a synchrotron or an X-ray free-electron laser (XFEL) to provide intense and short X-ray pulses. Considering the limited opportunities to use these facilities, it is necessary to verify the plausibility of a target experiment prior to the actual experiment. For this purpose, a program has been developed, referred to as S-cube, which is short for a Solution Scattering Simulator. This code allows the routine estimation of the shape and signal-to-noise ratio (SNR) of TRXL data from known experimental parameters. Specifically, S-cube calculates the difference scattering curve and the associated quantum noise on the basis of the molecular structure of the target reactant and product, the target solvent, the energy of the pump laser pulse and the specifications of the beamline to be used. Employing a simplified form for the pair-distribution function required to calculate the solute–solvent cross term greatly increases the calculation speed as compared with a typical TRXL data analysis. Demonstrative applications of S-cube are presented, including the estimation of the expected TRXL data and SNR level for the future LCLS-II HE beamlines.

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