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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Quantitative Phase Microscopy with Molecular Vibrational Sensitivity
摘要： Quantitative phase imaging (QPI) has become a valuable tool for studying optically transparent samples such as biological cells and tissues. It yields the sample-specific optical path-length delay at each spatial point of the field of view with a nanometer resolution, enabling high-contrast and objective analysis. The major advantage of QPI is its wide-field, label-free measurement capability of the transparent morphology. This allows for high-speed imaging limited by the image sensor’s frame rate while reducing optical and/or chemical damages to the sample which are troublesome in other imaging techniques such as fluorescence and Raman imaging. To date, QPI has been used for pathology diagnosis, phenotyping of live cancer cells, non-destructive measurement of cellular volume and dry-mass, study of cellular membrane dynamics, to just name a few. However, QPI lacks chemical sensitivity which limits its application to morphology-based diagnosis. Here, we report on our wide-field label-free molecular-vibrational (MV) microscopy method realized in the framework of QPI utilizing mid-infrared (MIR) photothermal effect. We measure local changes in the optical phase delay occurring upon absorption of the MIR light in the vicinity of the MV-resonant molecules, which is called photothermal effect, by means of QPI. This imaging scheme yields high-molecular-detection sensitivity based on MV-resonant MIR absorption having ~8 orders of magnitude larger cross-section compared to Raman scattering. Meanwhile, it also maintains the visible-light spatial resolution, high temporal resolution limited by the image sensor’s frame rate, and low photodamage to the sample with the wide-field, low-fluence optical illumination. Notably, our wide-field, parallelized detection scheme could even surpass the imaging speed of conventional label-free imaging methods such as coherent Raman imaging by an order of magnitude, as they typically employ a point-scanning mechanism for image synthesis. Our MV-sensitive QPI (MV-QPI) could offer new insights for optically-transparent complex dynamics by enabling high-speed, label-free cross-correlative analysis based on the quantitative morphology and the MV-spectroscopic chemical contrasts.
关键词： molecular-vibrational microscopy,Quantitative phase imaging,chemical sensitivity,label-free imaging,mid-infrared photothermal effect
更新于2025-09-12 10:27:22
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Long pulse millisecond pumped high-average-power linearly polarized single Nd:YAG rod laser
摘要： Human sensitivity to changes in luminance or chromaticity differ as a function of temporal or spatial frequency. Luminance sensitivity is band-pass in shape, while chromatic sensitivity curves are low-pass, along both L–M cone opponent (red–green) and S-cone opponent (blue–yellow) axes, where L, M, and S refer to the long-wavelength middle-wavelength and short-wavelength sensitive cones. Temporal sensitivity curves are supported by the magnocellular pathway for luminance, the parvocellular pathway for L–M modulation and the koniocellular pathway for S-cone modulation. This division largely holds for spatial contrast sensitivity. But there are discrepancies. For example, parvo and konio cells respond to higher temporal and spatial frequencies than can be perceived. Also, the role of eye movements in spatial contrast sensitivity – and spatial vision as a whole – is now debated; the spatial and temporal properties of eye movements profoundly influence the spatiotemporal signal leaving the retina. Finally, human psychophysical thresholds for color and luminance seem largely independent. Yet recent cortical data show much combination of magno, parvo, and konio signals in the cortex. This oddity remains puzzling but may have to do with the segregation of different types of information into dorsal and ventral cortical streams.
关键词： cortical processing,magnocellular pathway,luminance contrast sensitivity,koniocellular pathway,eye movements,temporal frequency,parvocellular pathway,spatial frequency,chromatic contrast sensitivity
更新于2025-09-11 14:15:04
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Evaluation of Staphylococcus aureus Subtyping Module for Methicillin-Resistant Staphylococcus aureus Detection Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry
摘要： A recent developed S. aureus subtyping module for rapidly differentiate methicillin-resistant Staphylococcus aureus (MRSA) from methicillin-susceptible S. aureus (MSSA) had been introduced into China. The principle of this method was to identify the methicillin resistance through detection of a specific phenol soluble modulin-mec peak (PSM-mec) by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). A total of 347 non-duplicated S. aureus strains were collected from the Second Affiliated Hospital of Zhejiang University School of Medicine during January 2014 to February 2019. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the automated subtyping module in identifying MRSA were evaluated. The specificity and PPV of this method were both 100% and the sensitivity was 60.2%. PSM-bearing MRSA were reported with different prevalence from different parts of world, our sample collection has the highest percentage so far. The repeatability showed that 1.7% (6/347) and 18.4% (64/347) were reported differently in the intra- and inter- batch analysis, respectively, which demonstrated that the threshold of this method could be further optimized to increase the sensitivity of MRSA detection. Overall, Bruker? MALDI Biotyper can detect S. aureus isolates with a quite high specificity and expedite the identification of MRSA isolates without using extra reagent, labor or time. The reduced turnaround time of MRSA identification is essential for appropriate therapeutic management and timely intervention for infection control.
关键词： MRSA,MALDI-TOF MS,resistant,specificity,sensitivity
更新于2025-09-11 14:15:04
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Size effect of metal nanodome arrays on performance of plasmonic biosensor
摘要： Size effect of metal nanodome arrays on performance characteristics of a plasmonic biosensor is investigated using reflection spectroscopy. Ag and Au nanodome arrays are created by a bottom-up nanofabrication process by which the dome diameter and metal thickness can be controlled. Reflectivity measurements of metal nanodome arrays showed that the wavelengths and width of resonance dip were changed by the dome diameter and metal thickness, respectively. Bulk refractive index (RI) sensing and detection of DNA hybridization were performed to characterize the sensing performance of metal nanodome arrays. Bulk RI sensitivity were significantly improved as the dome diameter enlarged from 100 to 500 nm. In contrast, metal nanodome arrays with smaller diameter exhibited higher sensor signals against the immobilization of DNA modified gold nanoparticles used for signal amplification indicating strong plasmonic coupling effects. With respect to the dome diameter, the effect of metal thickness was moderate for the presented sensing scheme.
关键词： plasmonic biosensor,metal nanodome arrays,bulk refractive index sensitivity,DNA hybridization,reflection spectroscopy
更新于2025-09-11 14:15:04
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Novel Triamcinolone Acetonide-Loaded Liposomal Topical Formulation Improves Contrast Sensitivity Outcome After Femtosecond Laser-Assisted Cataract Surgery
摘要： Purpose: To assess visual results, macular modi?cations, and the incidence of clinically signi?cant macular edema (CSME) in patients using a topical triamcinolone acetonide-loaded liposomal formulation (TA-LF) after femtosecond laser-assisted cataract surgery (FLACS). Methods: Fifty-six eyes after FLACS were selected. Twenty-eight eyes in the combined therapy group (P + N) were treated with prednisolone 1% and nepafenac 0.1% for 21 days postoperatively, whereas 28 eyes in the TA-LF group received a liposomal formulation containing 2 mg/mL of TA (0.2%) for the same period of time. Follow-up visits at 1 day, 6 weeks, and 12 weeks after surgery consisted of visual acuity, contrast sensitivity (CS), central foveal thickness (CFT), total macular volume (TMV) measurements, and the detection of CSME. Results: CS improved in the TA-LF group (basal value: 1.087 – 0.339 vs. 1.276 – 0.147 at week 12, P = 0.0346), whereas in the P + N group, CS was not different from the baseline (basal value: 1.130 – 0.331 vs. 1.274 – 0.133 at week 12, P = 0.1276). There were similar increases in postoperative CFT and TMV in both groups. CFT and TMV signi?cantly correlate with CS only in the TA-LF group. The r2 for CFT and CS was 0.1963 (P = 0.0206), whereas the r2 for TMV and CS was 0.3615 (P = 0.0007) at 12 weeks. No difference was observed in the incidence of CSME between the groups. Conclusion: TA-LF is associated with better CS outcomes compared to combined therapy after FLACS.
关键词： femtosecond laser-assisted cataract surgery,macular edema,liposomes,visual outcomes,contrast sensitivity
更新于2025-09-11 14:15:04
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Proceedings [EAGE Publications BV 76th EAGE Conference and Exhibition 2014 - Amsterdam, Netherlands (2014.06.16-2014.06.19)] Proceedings 76th EAGE Conference and Exhibition 2014 - Fundamentals of Vibration Sensing with Distributed Fibre Optic Sensors through Downscaled Experiments
摘要： In the past few years the Distributed Vibration Sensing of fibre optic sensors (also called Distributed Acoustic Sensing) has gained great interest in geophysics, despite the fundamentals of the measurement being poorly understood. The technology offers immense improvement in terms of efficiency when compared with current geophysical methods and also could be preferred for applications such as permanent reservoir monitoring. We present a method for downscaled experimentation that enabled us to define the fundamentals of the optical fibre measurement. We show seismic data that were recorded simultaneously by both the fibre optical interferometer and conventional geophones, thus enabling the comparison of sensor performance. We present results focused on wave-polarity sensitivity and the directionality of fibre measurements. The current interrogation method of optical fibre cables cannot distinguish between wavefields coming from opposite azimuthal directions, which can be an issue in certain applications where the identification of up-going and down-going wavefields is essential. Observations are also presented that describe the relationship between the velocity signal that is measured using a geophone array and the phase difference measurement from the fibre optic sensing system.
关键词： directionality,Distributed Vibration Sensing,Distributed Acoustic Sensing,optical fibre measurement,geophones,wave-polarity sensitivity,seismic data,fibre optic sensors,geophysics
更新于2025-09-11 14:15:04
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Temperature sensitivity investigation of tapered plastic optical fiber-Mach Zehnder interferometer for sensor application
摘要： Mach Zehnder interferometer (MZI) based on plastic optical fiber (POF) is interesting due to its robustness and simple fabrication. In this work, MZI-POF was designed and its sensitivity to temperature change was characterized to investigate its performance for sensor application. The MZI-POF was fabricated by forming two tapers at several distance by simple heat-pull method. The spectra was investigated by launching white light emitting diode (LED) and the output were observed using VIS-NIR spectrometer. It is shown that the wavelength of spectrum peak and spectrum dip were shifted compared to that of un-tapered POF which indicates that the structure serves well as MZI. Sensor sensitivity to temperature was determined by measuring the spectrum for various temperature which was varied from 40oC to 80oC with increment of 5oC. The result showed that the sensor sensitivity is 0.0693nm/oC in terms of peak measurement and 0.0487nm/oC for dip measurement. Therefore, MZI-POF is a potential candidate for temperature sensor.
关键词： Mach Zehnder interferometer,temperature sensitivity,sensor application,plastic optical fiber
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - High Sensitivity All-Fibre Methane Sensor with Gas Permeable Teflon/Cryptophane-A Membrane
摘要： We demonstrate a simple, cheap and compact all fibre methane sensor, with record sensitivity of 0.16 nm/ppm, composed of a D-shaped cross section optical fibre in between two fibre Bragg gratings. The flat side of the fibre is coated with a unique membrane used to solely detect methane, made by a gas permeable Teflon layer and doped with cryptophane-A molecules.
关键词： Teflon,high sensitivity,methane sensor,Cryptophane-A,all-fibre
更新于2025-09-11 14:15:04
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Enhanced photo-sensitivity in a Si photodetector using a near-field assisted excitation
摘要： Silicon is an indispensable material in electric device technology. However, Si is an indirect bandgap material; therefore, its excitation efficiency, which requires phonon assistance, is low under propagating far-field light. To improve the excitation efficiency, herein we performed optical near-field excitation, which is confined in a nano-scale, where the interband transitions between different wave numbers are excited according to the uncertainty principle; thus, optical near-field can directly excite the carrier in the indirect bandgap. To evaluate the effect of optical near-field confined in a nano-scale, we fabricate the lateral Si p–n junction with Au nanoparticles as sources to generate the field confinement. We observed a 47.0% increase in the photo-sensitivity rate. In addition, by using the thin lateral p–n junction, which eliminates the far-field excitation, we confirmed a 42.3% increase in the photo-sensitivity rate.
关键词： optical near-field,Au nanoparticles,photo-sensitivity,Silicon,photodetector
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Simultaneous Nanoplasmonic Sensing and Transmission Electron Microscopy Characterization
摘要： The research focuses on the development of a novel optoelectronic device for sensing applications, utilizing advanced materials and fabrication techniques to achieve high sensitivity and specificity. The study demonstrates the device's potential in real-world applications through a series of experimental validations.
关键词： sensing,high sensitivity,advanced materials,optoelectronics,fabrication techniques
更新于2025-09-11 14:15:04