36 research outputs found
Surface plasmon resonance assisted rapid laser joining of glass
Rapid and strong joining of clear glass to glass containing randomly distributed embedded spherical silver nanoparticles upon nanosecond pulsed laser irradiation (∼40 ns and repetition rate of 100 kHz) at 532 nm is demonstrated. The embedded silver nanoparticles were ∼30–40 nm in diameter, contained in a thin surface layer of ∼10 μm. A joint strength of 12.5 MPa was achieved for a laser fluence of only ∼0.13 J/cm2 and scanning speed of 10 mm/s. The bonding mechanism is discussed in terms of absorption of the laser energy by nanoparticles and the transfer of the accumulated localised heat to the surrounding glass leading to the local melting and formation of a strong bond. The presented technique is scalable and overcomes a number of serious challenges for a widespread adoption of laser-assisted rapid joining of glass substrates, enabling applications in the manufacture of microelectronic devices, sensors, micro-fluidic, and medical devices
High-performance thermal emitters based on laser engineered metal surfaces
Effective thermal management is of paramount importance for all high-temperature
systems operating under vacuum. Cooling of such systems relies mainly on radiative heat transfer
requiring high spectral emissivity of surfaces, which is strongly affected by the surface condition.
Pulsed laser structuring of stainless steel in air resulted in the spectral hemispherical emissivity
values exceeding 0.95 in the 2.5–15 µm spectral region. The effects of surface oxidation and
topography on spectral emissivity as well as high temperature stability of the surface structures
were examined. High performance stability of the laser textured surfaces was confirmed after
thermal aging studies at 320°C for 96 hour
Hybrid Antibacterial Surfaces:Combining Laser-Induced Periodic Surface Structures with Polydopamine-Chitosan-Silver Nanoparticle Nanocomposite Coating
Bacterial biofilm-associated infections are a persistent and growing problem, further exacerbated by the rapid development of antibiotic-resistant bacterial strains. Antibacterial surfaces hold great potential for controlling the survival, growth, and transmission of bacterial pathogens. This study demonstrates the synergetic integration of laser-assisted topographical surface modification with coating solutions to simultaneously engage both chemical and nano-/micro-topography-sensitive bacterial attachment mechanisms. The developed mechano-chemo bactericidal surface combines laser-induced periodic surface structures (LIPSS) on titanium (Ti) with a polydopamine-chitosan-silver nanoparticles (PCA) composite coating. The antibacterial performance of this hybrid surface against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) exceeds the benchmark performance achieved by either surface modification approach alone. The hybrid surface demonstrates superior resistance to biofilm formation, offering a viable route for large-scale production of antimicrobial surfaces with enhanced functionality and superior long-term performance
Low secondary electron yield engineered surface for electron cloud mitigation
Secondary electron yield (SEY or δ) limits the performance of a number of devices. Particularly, in high-energy charged particle accelerators, the beam-induced electron multipacting is one of the main sources of electron cloud (e-cloud) build up on the beam path; in radio frequency wave guides, the electron multipacting limits their lifetime and causes power loss; and in detectors, the secondary electrons define the signal background and reduce the sensitivity. The best solution would be a material with a low SEY coating and for many applications δ < 1 would be sufficient. We report on an alternative surface preparation to the ones that are currently advocated. Three commonly used materials in accelerator vacuum chambers (stainless steel, copper, and aluminium) were laser processed to create a highly regular surface topography. It is shown that this treatment reduces the SEY of the copper, aluminium, and stainless steel from δmax of 1.90, 2.55, and 2.25 to 1.12, 1.45, and 1.12, respectively. The δmax further reduced to 0.76-0.78 for all three treated metals after bombardment with 500 eV electrons to a dose between 3.5 × 10-3 and 2.0 × 10-2 C·mm-2