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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Laser ablation in biliary tree: analysis of the intraductal and superficial thermal effects during the treatment
摘要： The treatment of choice for the unresectable cholangiocarcinoma is based on biliary decompression procedures. Despite stent placement is the standard of care, it is related to well-known complications. Hence, alternative techniques were proposed. Ideally, they should guarantee an adequate intraductal disobstruction, without injuring the surrounding tissues. This pre-clinical study aims to investigate the thermal effects of the laser ablation (LA) in the biliary tree, in terms of intraductal and surrounding tissue temperature achieved with different laser settings. The common bile ducts (in their upper and lower portions) of two pigs were ablated for 6 minutes with a diode laser at 3 W and 5 W. A custom-made laser applicator was used to obtain a circumferential ablation within the ducts. The intraductal temperature (Tid) was monitored by means of a fiber Bragg grating (FBG) sensor, while an infrared thermal camera monitored the T distribution in the surrounding tissues (Tsup). A maximum T difference of 65 °C and 57 °C was evidenced between the two power settings for the Tid measured in the upper and lower ducts, respectively. The mean difference between Tid and the averaged Tsup values was evaluated. At 5 W, a difference of 37±3 °C and 44±10 °C were obtained for the upper and lower ducts, respectively. At 3 W, a T difference of 2±1 °C was obtained for the upper biliary duct, while a difference of 8±1 °C was documented for the lower duct. Based on the results obtained in this preliminary study, the possibility to equip the laser probe with temperature sensor can improve the control and the safety of the procedure; this solution will guarantee the monitoring of the treatment while preserving the lumen and the surrounding structures.
关键词： thermal effects,fiber Bragg grating,biliary tree,cholangiocarcinoma,infrared thermal camera,laser ablation
更新于2025-09-19 17:13:59
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Spectroscopic and Microscopic Analyses of Fe3O4/Au Nanoparticles Obtained by Laser Ablation in Water
摘要： Magneto-plasmonic nanoparticles constituted of gold and iron oxide were obtained in an aqueous environment by laser ablation of iron and gold targets in two successive steps. Gold nanoparticles are embedded in a mucilaginous matrix of iron oxide, which was identified as magnetite by both microscopic and spectroscopic analyses. The plasmonic properties of the obtained colloids, as well as their adsorption capability, were tested by surface-enhanced Raman scattering (SERS) spectroscopy using 2,2'-bipyridine as a probe molecule. DFT calculations allowed for obtaining information on the adsorption of the ligand molecules that strongly interact with positively charged surface active sites of the gold nanoparticles, thus providing efficient SERS enhancement. The presence of iron oxide gives the bimetallic colloid new possibilities of adsorption in addition to those inherent to gold nanoparticles, especially regarding organic pollutants and heavy metals, allowing to remove them from the aqueous environment by applying a magnetic field. Moreover, these nanoparticles, thanks to their low toxicity, are potentially useful not only in the field of sensors, but also for biomedical applications.
关键词： SERS,magnetite,gold,2,2'-bipyridine,laser ablation
更新于2025-09-19 17:13:59
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Bacterial killing efficacy of synthesized rod shaped cuprous oxide nanoparticles using laser ablation technique
摘要： Recent interests with copper nanoparticles (Cu-NPs) has arisen because of its low cost and antibacterial properties, as it may be one of the very important alternatives to silver NPs. Pulsed laser ablation of a solid target (copper) in liquid media is used to synthesize colloidal oxide copper (Cu2O and CuO NPs) NPs. These oxides of copper NPs were synthesized using Nd:YAG laser energy to maintain a 40 mJ/pulse wavelength at 1064 nm. During the synthesis of colloidal NPs only two conditions were opted, employing double distilled water (without PEG) and 10% preparation of PEG. Both NPs were prepared under the similar parameters such as optimized instrument settings, laser energy and time of laser exposure (1 h ablation). Further, these copper oxide NPs were characterized by advance technologies including UV–visible, X-ray diffraction, transmission electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy techniques. The significant antibacterial properties of synthesized materials were also observed. The cuprous oxide NPs, showed remarkable antibacterial effect conducted using disc diffusion techniques. The minimum inhibitory concentration and minimum bactericidal concentration of synthesized Cu2O NPs were recorded as 120 and 140 μg/L respectively against Staphylococcus aureus used as positive control. Therefore, based on the findings of present study Cu2O NPs can be exploited as stable antimicrobial agents for multipurpose uses.
关键词： Polyethylene glycol,Laser ablation,Antibacterial,UV–visible,Copper oxide NPs
更新于2025-09-19 17:13:59
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Ultrafast pump-probe ellipsometry and microscopy reveal the surface dynamics of femtosecond laser ablation of aluminium and stainless steel
摘要： An ultra-short laser pulse irradiated surface passes through a sequence of physical processes that occur over a wide temporal range, from femtoseconds to microseconds. In this paper for the first time, the complete laser ablation process for industrially relevant metals, aluminium (Al) and stainless steel (AISI 304) is tracked from the initial pulse impact to the final state. Time-resolved surface analytical techniques provide a complementary description of the surface dynamics. The pump-probe ellipsometry reveals changes of the complex refractive index for the first tens of picoseconds and time-resolved microscopy of the irradiated surface gives access to changes of the relative reflectivity from the initial femtosecond pulse impact to the final state at 10 μs. The changes in optical indices are affected by an ultrafast decrease in the density of the surface within the pressure unloading process in the first picoseconds and reveal spallation as the dominant mechanism for laser ablation in Al and stainless steel. The study also implies that the ablation volume is kept at an optimum when the ablation is initiated with ultrafast pulses within the pressure unloading process and is able to evolve over eight orders of magnitude without external perturbations.
关键词： Time-resolved ellipsometry,Spallation,Laser ablation,Nanostructure,Pump-probe reflectometry
更新于2025-09-19 17:13:59
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Solvents Effect on the Morphology and Stability of Cu/CuO Nanoparticles Synthesized at High Fluence Laser Ablation
摘要： Cu/CuO NPs were synthesized by ablating Cu target using nanosecond Nd:YAG pulsed laser operating at 1064 nm with 8 ns pulse duration in three different solvents viz: ethylene glycol (EG), deionized water (DI) and ethanol (Eth). The effects of these three solvents at high laser fluence of 40 J/cm2 was investigated to study the stability and morphology of nanoparticles using microscopic and spectroscopic techniques. The morphology of these nanoparticles are dependent on the physical properties of solvents (like viscosity, conductivity, polarity and enthalpy) used in laser ablation. EG and DI shows tadpole and necklace like structure whereas in Eth hollow structures were observed. The crystallinity of nanoparticles were confirmed by HRTEM, SAED and XRD analysis. In all the three solvents the characteristic absorption and emission peaks of Cu and CuO nanoparticles were observed and have been elaborately discussed in this paper. In addition, the detailed growth kinematics of nanoparticles involved in the process of laser ablation technique have been highlighted.
关键词： high fluence,Cu–CuO,laser ablation,morphology
更新于2025-09-19 17:13:59
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Role of Aging in the Formation of Non-spherical Nanostructures during Lasera??Matter Interaction in Water
摘要： Pulsed laser ablation of different surfaces in liquid environment has broad prospects to selectively synthesize nanoparticles (NPs) with specific optical properties, as well as morphology, size and composition. The dependence of the morphology and particle size on the pulse duration and other external conditions allows synthesizing nano-sized particles for various scientific, particularly, optical, and industrial needs. Most previous studies on ablation of metals in water have shown spherical shapes of NPs without elaboration on the effect of aging on those shapes. In this study, we demonstrate notable modification in the morphology of aluminum, indium, zinc and copper NPs during aging towards the non-spherical structures, contrary to other laser ablation-induced spherical NPs from different elements in the periodic table.
关键词： cuboids,multicomponent particles,laser ablation,agglomeration
更新于2025-09-19 17:13:59
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Carbon nanoparticles synthesized by laser ablation of coconut shell charcoal in liquids for glucose sensing applications
摘要： In this work, Carbon Nanoparticles (CNPs) were synthesized by one step Laser ablation of natural coconut shell charcoal in ethanol and water media. The HRTEM studies showed that the average particle size was of the order of 29 nm in ethanol with amorphous nature whereas in water, the particle average size was about 15 nm with graphitic structure. Photoluminescence (PL) properties of CNPs formed were studied. CNPs coated Nickel foil electrode (NiFE) was investigated for glucose measurement by cyclic voltammetry (CV) and chronoamperometry. The CNPs exhibited good response to glucose. The sensor was stable, wide range of detection and fabricated simply without use of any kind of binder or enzymes.
关键词： coconut shell charcoal,laser ablation,glucose sensing,CNPs
更新于2025-09-19 17:13:59
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Expedient paramagnetic properties of surfactant-free plasmonic silicon-based nanoparticles
摘要： Surfactant-free multifunctional semiconductor-metallic nanostructures possessing several modalities are formed due to laser-induced structural modification of pure silicon nanoparticles in the presence of gold. It results to variable size-dependent chemical composition examined by energy-dispersive X-ray spectroscopy. Laser-synthesized silicon-based nanocomposites exhibit remarkable both plasmonic and paramagnetic properties. Their plasmonic maxima are found to be easily adjusted in the whole visible spectral range. Influence of resonant laser irradiation on spin behaviour of silicon-gold nanoparticles is established. Their spin–lattice and spin–spin relaxation processes are investigated as well. Such multifunctional nanoparticles can reveal a huge potential for different applications in field of nanomedicine, in particular, for biosensing and bioimaging.
关键词： Nanocomposite,Silicon-gold nanoparticle,Plasmonic property,Silicon nanoparticle,EPR,Laser ablation
更新于2025-09-19 17:13:59
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Blend biopolymeric nanofibrous scaffolds of cellulose acetate/?μ-polycaprolactone containing metallic nanoparticles prepared by laser ablation for wound disinfection applications
摘要： Laser ablation technique was utilized to synthesize versatile metallic nanoparticles including ZnO, Ag and CuO which were incorporated into the blend matrix of cellulose Acetate (CA) and ε-polycaprolactone (PCL) nano?brous scaffold. The compositional, microstructural and morphological behaviors for the obtained nano?bers were investigated using X-ray diffraction (XRD), Fourier Transformed Infrared, Transmission Electron Microscope (TEM) and Field Emission-Scanning Electron Microscope (FESEM). The cell viability and antibacterial activity were investigated against Staphylococcus aureus (S. aureus) and Escherichia coli (E-coli). TEM micrographs refer that while CuONPs were involved in the middle of CA/PCL ?brous scaffold with diameters around 160 nm. The morphological investigations indicated the scaffolds were con?gured in a non-oriented form with diameters 0.45–0.9 μm in the case of ZnONPs involved in blend matrix ?bers. The ratio of viable cells displays that compositions are biocompatible, while the antibacterial activity of both AgNPs and CuONPs showed an inhibition zone around 11.2.3 ± 2.2 mm and 9.4 ± 1.2 mm respectively. Bio-blend polymers matrices carrying nanoparticles could be tailored for a plethora of biomedical applications upon their compositions.
关键词： Laser ablation,CuO,Antibacterial,Ag nanoparticles,Wound healing,Blend polymer
更新于2025-09-19 17:13:59
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Dynamic Multifocus Laser Writing with Acousto‐Optofluidics
摘要： Laser writing of materials is normally performed by the sequential scanning of a single focused beam across a sample. This process is time-consuming and it can severely limit the throughput of laser systems in key applications such as surgery, microelectronics, or manufacturing. A parallelization strategy based on ultrasound waves in a liquid to diffract light into multiple beamlets is reported. Adjusting amplitude, frequency, or phase of ultrasound allows tunable multifocus distributions with sub-microsecond control. When combined with sample translation, the dynamic splitting of light leads to high-throughput laser processing, as demonstrated by locally modifying the morphological and wettability properties of metals, polymers, and ceramics. The results illustrate how acousto-optofluidic systems are universal tools for fast multifocus generation, with potential impact in fields such as imaging or optical trapping.
关键词： complex patterning,laser ablation,high throughput processing,wettability
更新于2025-09-19 17:13:59