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- 摘要
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Damage characteristics of laser plasma shock wave on rear surface of fused silica glass
摘要： The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface, which hinders the improvement in the energy of the high power laser device. For optical components, the ionization breakdown by laser is a main factor causing damage, particularly with laser plasma shock waves, which can cause large-scale fracture damage in fused silica. In this study, the damage morphology is experimentally investigated, and the characteristics of the damage point are obtained. In the theoretical study, the coupling and transmission of the shock wave in glass are investigated based on the ?nite element method. Thus, both the magnitude and the orientation of stress are obtained. The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum. In addition, the in?uence of the glass thickness on the damage morphology is investigated. The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.
关键词： different thickness,Raman spectroscopy,rear surface of fused silica,laser-induced plasma,?nite element method
更新于2025-09-23 15:19:57
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Soft material perforation via double-bubble laser-induced cavitation microjets
摘要： The resulting jet of two interacting laser-induced cavitation bubbles is optimized and studied as a technique for micro-scale targeting of soft materials. High controllability of double-bubble microjets can make such configurations favorable over single bubbles for applications where risk of ablation or thermal damage should be minimized such as in soft biological structures. In this study, double-bubble jets are directed toward an agar gel-based skin phantom to explore the application of micro-scale injection and toward a soft paraffin to quantify the targeting effectiveness of double-bubble over single-bubble jetting. The sharp elongation during the double-bubble process leads to fast, focused jets reaching average magnitudes of Ujet = 87.6 ± 9.9 m/s. When directed to agar, the penetration length and injected volume increase at ～250 μm and 5 nl per subsequent jets. Such values are achieved without the use of fabricated micro-nozzles seen in existing needle-free laser injection systems. In soft paraffin, double-bubble jetting produces the same penetration length as single-bubble jetting, but with ～45% reduction in damage area at a 3× greater target distance. Thus, double-bubble jetting can achieve smaller impact areas and greater target distances, potentially reducing collateral thermal damage and effects of strong shockwave pressures.
关键词： microjets,double-bubble jetting,soft materials,laser-induced cavitation,needle-free injection
更新于2025-09-23 15:19:57
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Laser Induced Backward Transfer of ultra-thin metal structures
摘要： Ultra-thin, flexible and stretchable interfaces comprising thin metal films and polymers are attracting increasing interest for applications in sensors and optoelectronics. The transfer of ultra-thin gold films for the digital fabrication of such interfaces was investigated in this study using the Laser-Induced Backward Transfer (LIBT) technique. In particular, the transfer of thin and ultra-thin gold films (60, 10 and 5 nm thick) on Polydimethylosiloxane substrate has been achieved using ps pulses and low laser fluences for controllable material transfer. As the size of the nanograins comprising the Au films decreases, their melting point also decreases, enabling the transfer of intact disk-shaped Au nanostructures at low laser fluence values, with form factors and thickness equal to the pristine films. Moreover, the contribution of the substrate has been clarified: the two substrates (silicon, glass) which were used in this work, have significantly different reflectivity to the selected laser wavelength (532 nm), which can considerably influence the thickness and the quality of the transferred disk. The results presented in this work clearly demonstrate the compatibility of LIBT with ultra-thin metal film/ polymer interfaces and highlight the potential application of this digital process for a variety of optoelectronic applications.
关键词： ultra-thin films,Laser Induced Backward Transfer,metal/ polymer interface,short pulsed heating,nanostructures
更新于2025-09-23 15:19:57
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Investigation of minor elemental species within tablets using in situ depth profiling via laser-induced breakdown spectroscopy hyperspectral imaging
摘要： Laser-induced breakdown spectroscopy (LIBS) hyperspectral imaging allows for the determination of two-dimensional and three-dimensional spatial distributions of elemental species throughout complex samples. In this work, LIBS hyperspectral imaging was utilized to investigate minor elemental species within tablets. Representative LIBS spectra were initially collected on four complex, heterogeneous tablets, showing high concentrations of Ti in the tablet coating, with low and variable abundance of Na, Mg, and K. Principal component analysis revealed distinct resolution of the four tablets due to differences in Na, Mg, and K. Using two-dimensional LIBS hyperspectral imaging, spatial distributions of Na, Mg, and K within defined x and y regions of the tablet coating were generated. Subsequent three-dimensional LIBS hyperspectral imaging further elucidated the full x, y, and z spatial distributions of these minor elemental species within the tablet surface, tablet coating, and tablet core. As such, in situ depth profiling of the minor elemental species within each tablet was accomplished. Quantification of the homogeneity and uniformity of each tablet was determined. To our knowledge, this is the first report of multivariate analysis, LIBS, and LIBS hyperspectral imaging being utilized for the determination of both 2D and 3D spatial distributions of minor elemental species, along with quantification of tablet homogeneity, within tablets.
关键词： Chemical imaging,Laser-induced breakdown spectroscopy,Chemometrics,Pharmaceutical analysis,Atomic spectroscopy
更新于2025-09-23 15:19:57
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A chemically modified laser-induced porous graphene based flexible and ultrasensitive electrochemical biosensor for sweat glucose detection
摘要： Porous laser-induced graphene (LIG) is an attractive and promising carbon material for electrochemical applications because it can immobilize various proteins, such as enzymes, antibodies, and receptors. However, poor inherent electrical properties caused by low surface conductivity is still a critical drawback for various applications. Here, we have proposed a surface modification method for the LIG electrode using acetic acid treatment via facile and practicable dipping technique. This simple acetic acid treatment dramatically increased the ratio of carbon-carbon bonds which effectively increased conductivity and decreased sheet resistance. Importantly, these unique properties also facilitated the stable and uniform dispersion of highly catalytic Pt nanoparticles (PtNPs) on LIG by avoiding the concentration of electric field on nanoparticles that can cause aggregation during electrodeposition. Finally, chitosan-glucose oxidase (GOx) composite was successfully immobilized onto the LIG/PtNPs electrode to fabricate a sweat glucose biosensor. The as-prepared LIG/PtNPs electrode exhibited a high sensitivity of 4.622 μA/mM as well as an ultra-low limit of detection (signal to noise ratio is 3) which was less than 300 nM and dynamic linear range up to 2.1 mM. Furthermore, we tested the variation of blood glucose level before and after meal using the amperometric response of the sensor which demonstrates the commercial potential of this unique sweat glucose biosensor.
关键词： Sweat glucose detection,Laser-induced graphene (LIG),Acetic acid treatment,Ultra-sensitive and -low detection limit,Electrochemical biosensor
更新于2025-09-23 15:19:57
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Optimization of measuring procedure of farmland soils using laser-induced breakdown spectroscopy
摘要： Laser-induced breakdown spectroscopy (LIBS) is an emerging multi-elemental analytical technique offering fast and simultaneous quantification of soil properties with minimal sample preparation and effective cost. Due to soil heterogeneity, spectral variation however limits the quantitative robustness. In this study, 348 soil samples were collected and prepared for acquisition of LIBS spectra. Influences of shot layer and number on LIBS quality were evaluated by spectral intensity and relative standard deviation (RSD). Effects of shot layer and number and five normalization procedures on LIBS ability to measure soil organic matter (SOM), total nitrogen (TN), and total soluble salt content (TSC), were evaluated using partial least squares regression (PLSR). Increasing shot number reduced LIBS spectral variance, thereby improving the quantitative accuracy of selected soil properties. Deep shot layers (4th or 5th shot layers) reduced the intensities of soil spectra and thereby decreased the quantitative accuracy for TSC. However, deep shot layers improved the SOM and TN prediction performances. Among the normalization approaches, the method based on the correction of Si line (DS) showed superior performance for improving quantitation of SOM and TN. The arithmetic average method (AA) was best for TSC prediction. Optimization of shot layer, number and normalization procedures of LIBS spectra resulted in fair prediction of SOM (residual prediction deviation of validation set, RPDV = 1.608), good prediction of TN (RPDV = 1.836), and very good quantitative analysis of TSC (RPDV = 2.456). Therefore, our findings illustrate very good potential for improving the quantitative accuracy of the LIBS soil spectra.
关键词： quantitative analysis,shot layer,soil properties,shot number,normalization methods,Laser-induced breakdown spectroscopy
更新于2025-09-23 15:19:57
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Characteristics of laser induced discharge tin plasma and its extreme ultraviolet radiation
摘要： In this paper, a CO2 laser induced discharge plasma extreme ultraviolet (EUV) source experimental device was established. The optical emission spectroscopy was used to diagnose the characteristics of the plasma, and the evolution of electron temperature and electron density with time was obtained. The in?uence of discharge voltage on plasma parameters was analyzed and discussed. The EUV radiation characteristics of the plasma were investigated by self-made grazing incidence EUV spectrometer. The EUV radiation intensity and conversion ef?ciency were discussed.
关键词： laser induced discharge plasma,extreme ultraviolet (EUV) radiation,electron temperature and density,optical emission spectroscopy
更新于2025-09-23 15:19:57
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Flexible laser-induced-graphene omnidirectional sound device
摘要： Flexible sound devices based on laser-induced-graphene (LIG) have attract great interests due to its excellent thermoacoustic effect. Traditional sound devices usually have a sound field with a special directivity, while the LIG-based sound device will have an omnidirectional sound field when bent into a cylinder. Besides, the sound pressure of the thermoacoustic device has a linear and inverse relationship with the input electrical power and the testing distance respectively. This novel sound device will have great application potentials in flexible electronics and can be helpful for the integration of a whole flexible electrical system.
关键词： Thermoacoustic effect,Laser-induced-graphene,Sound device,Omnidirectional
更新于2025-09-23 15:19:57
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Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
摘要： This study describes a method to quantify the chemical composition of deep-sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25% for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrate how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.
关键词： Multivariate analysis,Laser-induced breakdown spectroscopy (LIBS),Deep-sea explorations,In situ chemical analysis,Seafloor mineral resources,Partial least squares regression analysis
更新于2025-09-23 15:19:57
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Analysis of combustion instability of hydrogen fueled scramjet combustor on high-speed OH-PLIF measurements and dynamic mode decomposition
摘要： This paper investigated the combustion instability of spanwise positions in a hydrogen fueled scramjet combustor with a cavity flame holder. High-speed OH-PLIF technique was performed on a direct-connect supersonic combustion facility, and dynamic mode decomposition (DMD) as postprocessing. Combustion instability was investigated by characterizing the dominant frequencies and growth factors. By changing the equivalence ratio of hydrogen, the peak frequencies of scramjet mode and ramjet mode were obtained. Scramjet mode tended to have small oscillation at 150e200 Hz reflected by negative growth factors due to the stable flame structure. At ram-to-scram transition, oscillations at 80 e120 Hz were remarkably enhanced due to the positive growth factors. In ramjet mode, the large differences of frequency characteristics in spanwise positions were observed. The dominant DMD modes near the cavity wall appeared to have negative growth factors leading to a stable flame with small oscillations. Besides, the characteristics of frequency-shift were affected by the positions of injector.
关键词： Combustion instability,Dynamic mode decomposition,Dominant frequency,High-speed planar laser-induced fluorescence of OH radicals,Supersonic combustion
更新于2025-09-23 15:19:57