scholarly journals Picosecond Laser Ablation of Polyhydroxyalkanoates (PHAs): Comparative Study of Neat and Blended Material Response

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 127 ◽  
Author(s):  
Rocío Ortiz ◽  
Pooja Basnett ◽  
Ipsita Roy ◽  
Iban Quintana
Keyword(s):  
Tissue Engineering ◽  
Laser Ablation ◽  
Food Packaging ◽  
Laser Energy ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Ablation Efficiency ◽  
Medium Chain Length ◽  
Micro Structuring ◽  
Convenient Technique

Polyhydroxyalkanoates (PHAs) have emerged as a promising biodegradable and biocompatible material for scaffold manufacturing in the tissue engineering field and food packaging. Surface modification is usually required to improve cell biocompatibility and/or reduce bacteria proliferation. Picosecond laser ablation was applied for surface micro structuring of short- and medium-chain length-PHAs and its blend. The response of each material as a function of laser energy and wavelength was analyzed. Picosecond pulsed laser modified the surface topography without affecting the material properties. UV wavelength irradiation showed halved ablation thresholds compared to visible (VIS) wavelength, revealing a greater photochemical nature of the ablation process at ultraviolet (UV) wavelength. Nevertheless, the ablation rate and, therefore, ablation efficiency did not show a clear dependence on beam wavelength. The different mechanical behavior of the considered PHAs did not lead to different ablation thresholds on each polymer at a constant wavelength, suggesting the interplay of the material mechanical parameters to equalize ablation thresholds. Blended-PHA showed a significant reduction in the ablation threshold under VIS irradiation respect to the neat PHAs. Picosecond ablation was proved to be a convenient technique for micro structuring of PHAs to generate surface microfeatures appropriate to influence cell behavior and improve the biocompatibility of scaffolds in tissue engineering.

Micromachining of Metals, Alloys and Ceramics by Picosecond Laser Ablation

2008 ◽  
Author(s):  
Wenqian Hu ◽  
Galen B. King ◽  
Yung C. Shin
Keyword(s):  
Electron Microscope ◽  
Laser Ablation ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Optical Microscope ◽  
Recast Layer ◽  
Laser Machining ◽  
Percussion Drilling ◽  
Scanning Electron

Microhole drilling and microstructure machining with a picosecond (ps) Nd:YVO4 laser (pulse duration of 10 ps) in metals, alloys and ceramics are reported. Blind and through microholes were drilled by percussion drilling as well as trepanning drilling. The diameters of the holes were in the range from 20 μm to 1000 μm. Microfeatures were machined and the flexibility of ps laser machining was demonstrated. The quality of drilled holes, e.g., recast layer, microcrack and conicity, and that of the microstructures, were investigated by optical microscope, surface profilometer, or scanning electron microscope (SEM). Ps laser ablation rate was investigated by experiments as well as a simplified laser ablation model.

scholarly journals Scanning electron microscope studies on laser ablation of solids

2019 ◽  
Vol 37 (01) ◽  
pp. 101-109 ◽  
Author(s):  
Mohamed E. Shaheen ◽  
Joel E. Gagnon ◽  
Brian J. Fryer
Keyword(s):  
Pulse Width ◽  
Laser Energy ◽  
Laser System ◽  
Picosecond Laser ◽  
Laser Pulses ◽  
Ablation Rate ◽  
Laser Wavelength ◽  
High Laser Fluence ◽  
Electron Imaging ◽  
Scanning Electron

AbstractThis study investigates the interaction of picosecond laser pulses with sapphire and brass in air using scanning electron microscopy. A picosecond laser system operating at a wavelength of 785 nm, pulse width of 110 ps, and variable repetition rate (1–1000 Hz) was used in this study. The pulse width applied in this work was not widely investigated as it lies in the gap between ultrashort (femtosecond) and long (nanosecond) pulse width lasers. Different surface morphologies were identified using secondary electron and backscattered electron imaging of the ablated material. Thermal ablation effects were more dominant in brass than in sapphire. Exfoliation and fractures of sapphire were observed at high laser fluence. Compared with brass, multiple laser pulses were necessary to initiate ablation in sapphire due to its poor absorption to the incident laser wavelength. Ablation rate of sapphire was lower than that of brass due to the dissipation of a portion of the laser energy due to heating and fracturing of the surface.

Picosecond Laser Ablation of Polydimethylsiloxane (PDMS)

2009 ◽  
Author(s):  
Hansong Zeng ◽  
Yi Zhao ◽  
Benxin Wu ◽  
Chris Taylor ◽  
Ronald L. Jacobsen ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Laser Fluence ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Pulse Number ◽  
Hole Diameter ◽  
Replica Molding

Picosecond laser ablation of Polydimethylsiloxane (PDMS) has been studied experimentally. The measurements show that laser ablation rate per pulse increases with laser fluence and pulse number. The laser-drilled hole diameter increases with pulse number, and it saturates above certain pulse number for low fluence. The study shows that picosecond laser ablation may provide a good solution for micromachining PDMS, which is more flexible and versatile than the replica molding technique.

EFFECT OF LASER WAVELENGTH AND ABLATION TIME ON PULSED LASER ABLATION SYNTHESIS OF AL NANOPARTICLES IN ETHANOL

2012 ◽  
Vol 05 ◽  
pp. 58-65 ◽  
Author(s):  
A. BALADI ◽  
R. SARRAF MAMOORY
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Ablation Rate ◽  
Laser Wavelength ◽  
Aluminum Nanoparticles ◽  
Ablation Efficiency ◽  
Ablation Time ◽  
Al Nanoparticles ◽  
Ablated Mass

Aluminum nanoparticles were synthesized by pulsed laser ablation of Al targets in ethanol for 5-15 minutes using the 1064 and 533 nm wavelengths of a Nd:YAG laser with energies of 280-320 mJ per pulse. It has been found that higher wavelength leads to significantly higher ablation efficiency, and finer spherical nanoparticles are also synthesized. Besides, it was obvious that higher ablation time resulted in higher ablated mass, while lower ablation rate was observed. Finer nanoparticles, moreover, are synthesized in higher ablation times.

High Intensity Laser Ablation of Titanium Target

2011 ◽  
Vol 227 ◽  
pp. 57-61 ◽  
Author(s):  
Kenza Yahiaoui ◽  
Tahar Kerdja ◽  
Smail Malek
Keyword(s):  
Laser Ablation ◽  
Laser Energy ◽  
Thin Film Deposition ◽  
Ablation Rate ◽  
Film Deposition ◽  
Laser Irradiance ◽  
Phase Explosion ◽  
Sem Images ◽  
Laser Breakdown ◽  
The Impact

In thin film deposition by pulsed laser ablation (PLD), the mass ablation rate depends on laser energy, on the pulse duration and on the thermodynamic properties of the ablated materials. In order to optimize the PLD technique and the films quality, the evolution of the amount of the ejected materials with laser irradiance, the SEM images of the laser impacts on the target and the ion yield in the vapour plume, were used. This allows us to predict the different mechanisms that are responsible to mass ablation according to laser irradiance which was ranging from 1.5108W/cm2 to 5.51010 W/cm2. Three diagnostics devices have been used: A quartz microbalance placed in front of the target, where the maximum of materials ejection occurs, a Scanning Electron Microscope (SEM) was used to show the impact morphology evolution with the laser irradiance and a charge collector, biased at negative voltage, was used to measure the ions yield and ions kinetic energy. The results show the evolution from normal evaporation mechanism at moderate laser irradiance to phase explosion mechanism at higher laser irradiance. Laser irradiance threshold for phase explosion onset is well determined by microbalance measurement, SEM micrographic pictures and the laser breakdown in the vapour plume was determined by the charge collector.

Surface Processing: An Elegant Way to Enhance the Femtosecond Laser Ablation Rate and Ablation Efficiency on Human Teeth

2019 ◽  
Vol 51 (9) ◽  
pp. 797-807 ◽  
Author(s):  
Sarathkumar Loganathan ◽  
Soundarapandian Santhanakrishnan ◽  
Ravi Bathe ◽  
Muthukumaraswamy Arunachalam
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Femtosecond Laser Ablation ◽  
Ablation Rate ◽  
Surface Processing ◽  
Human Teeth ◽  
Ablation Efficiency

Micromachining of Metals, Alloys, and Ceramics by Picosecond Laser Ablation

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Wenqian Hu ◽  
Yung C. Shin ◽  
Galen B. King
Keyword(s):  
Electron Microscope ◽  
Laser Ablation ◽  
Picosecond Laser ◽  
Ablation Rate ◽  
Optical Microscope ◽  
Recast Layer ◽  
Laser Machining ◽  
Percussion Drilling ◽  
Scanning Electron

Microhole drilling and microstructure machining with a picosecond (ps) Nd:YVO4 laser (pulse duration of 10 ps) in metals, alloys, and ceramics are reported. Blind and through microholes are drilled by percussion drilling as well as trepanning drilling, where the diameters of the holes are in the range of 20–1000 μm. Microfeatures are also machined and the flexibility of ps laser machining is demonstrated. The quality of drilled holes, e.g., recast layer, microcrack, and conicity, and that of the microstructures, are investigated by an optical microscope, a surface profilometer, or a scanning electron microscope. Ps laser ablation rate is studied by experiments and a simplified laser ablation model.

scholarly journals Gum Tragacanth (GT): A Versatile Biocompatible Material beyond Borders

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1510 ◽  
Author(s):  
Mohammad Ehsan Taghavizadeh Yazdi ◽  
Simin Nazarnezhad ◽  
Seyed Hadi Mousavi ◽  
Mohammad Sadegh Amiri ◽  
Majid Darroudi ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Food Packaging ◽  
Three Dimensional ◽  
Great Promise ◽  
Anionic Polymer ◽  
Gum Tragacanth ◽  
New Horizons ◽  
Tissue Healing ◽  
The Stability ◽  
Therapeutic Substance

The use of naturally occurring materials in biomedicine has been increasingly attracting the researchers’ interest and, in this regard, gum tragacanth (GT) is recently showing great promise as a therapeutic substance in tissue engineering and regenerative medicine. As a polysaccharide, GT can be easily extracted from the stems and branches of various species of Astragalus. This anionic polymer is known to be a biodegradable, non-allergenic, non-toxic, and non-carcinogenic material. The stability against microbial, heat and acid degradation has made GT an attractive material not only in industrial settings (e.g., food packaging) but also in biomedical approaches (e.g., drug delivery). Over time, GT has been shown to be a useful reagent in the formation and stabilization of metal nanoparticles in the context of green chemistry. With the advent of tissue engineering, GT has also been utilized for the fabrication of three-dimensional (3D) scaffolds applied for both hard and soft tissue healing strategies. However, more research is needed for defining GT applicability in the future of biomedical engineering. On this object, the present review aims to provide a state-of-the-art overview of GT in biomedicine and tries to open new horizons in the field based on its inherent characteristics.

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