Fabricating Laser-Induced Periodic Surface Structures on Medical Grade Cobalt–Chrome–Molybdenum: Tribological, Wetting and Leaching Properties

Results of the work in the Laser4Fun project has been published as:

van der Poel, S.H., Mezera, M., Römer, G.R.B.E., de Vries, E.G., Matthews, D.T.A., Fabricating Laser-Induced Periodic Surface Structures on Medical Grade Cobalt–Chrome–Molybdenum: Tribological, Wetting and Leaching Properties. Lubricants  2019, 7(8), 70. 

Abstract

Hip-implants structured with anti-bacterial textures should show a low-friction coefficient and should not leach hazardous substances into the human body. The surface of a typical material used for hip-implants, namely Cobalt–Chrome–Molybdenum (CoCrMo) was textured with different types of laser-induced periodic surface structures (LIPSS)—i.e., low spatial frequency LIPSS (LSFL), hierarchical structures consisting of grooves superimposed with high spatial frequency LIPSS (HSFL) and Triangular shaped Nanopillars (TNP)—using a picosecond pulsed laser source. The effect of LIPSS on the wettability, friction, as well as wear of the structures, when slid against a polyethylene (PE) counter surface and biocompatibility was analyzed. Surfaces covered with LSFL show superhydrophobicity and grooves with superimposed HSFL, as well as TNP, show hydrophobic behavior. The coefficient of friction (CoF) of LIPSS against a polyethylene (PE) counter surface was found to be higher (ranging from 0.40 to 0.66) than the CoF of (polished) CoCrMo, which was found to equal 0.22. It was found that the samples release cobalt within biocompatible limits. Compared to polished reference surfaces, LIPSS cause higher friction of CoCrMo against PE contact. However, the wear of the PE counter surface only increased significantly for the LSFL textures. For these reasons, it is concluded that LIPSS are not suitable for a heavily loaded metal-on-plastic bearing contact.

Link

https://doi.org/10.3390/lubricants7080070

Upscaling laser-induced periodic surface structures (LIPSS) manufacturing by defocused laser processing

Results of the work in the Laser4Fun project has been published as:

Marek Mezera and G.R.B.E. Römer. Upscaling laser-induced periodic surface structures (LIPSS) manufacturing by defocused laser processing, Proc. SPIE 10906, Laser-based Micro- and Nanoprocessing XIII, 109060U (4 March 2019); doi: 10.1117/12.2510004

Abstract

Low spatial frequency Laser-induced Periodic Surface Structures (LSFL) have been created on single crystal silicon with picosecond laser pulses with a wavelength of λ =1030nm with varying laser spot diameters obtained by a defocused laser beam. The laser processing parameters have been adjusted theoretically and experimentally to obtain similar LSFL for all studied laser spot diameters. The periodicity and amplitude of the LSFL were measured by SEM and AFM analysis. It has been found that the periodicities of the LSFL do not change when LSFL were created with larger laser spot diameters. The amplitudes of the LSFL decrease with increasing laser spot diameters, although this correlation is not strong.

Links:

DOI: 10.1117/12.2510004

Model based optimization of process parameters to produce large homogeneous areas of laser-induced periodic surface structures

Results of the work in the Laser4Fun project has been published as:

Marek Mezera and G.R.B.E. Römer. Model based optimization of process parameters to produce large homogeneous areas of laser-induced periodic surface structures, Opt. Express 27, 6012-6029 (2019); doi: 10.1364/OE.27.006012

Abstract

A model is presented, which allows to predict the (in)homogeneity of large areas covered with Laser-induced Periodic Surface Structures (LIPSS), based on the laser processing parameters (peak laser fluence and geometrical pulse-to-pulse overlap) and experimentally determined material properties. As such, the model allows to establish optimal processing conditions, given the material properties of the substrate to be processed. The model is experimentally validated over a large range of geometrical pulse-to-pulse overlap values and fluence levels on silicon using a picosecond laser source.

Links:

DOI: 10.1364/OE.27.006012

Laser-Induced Periodic Surface Structures (LIPSS) on Polymers Processed with Picosecond Laser Pulses

Results of the work in the Laser4Fun project has been published as:

Marek Mezera, Martin van Drongelen and G.R.B.E. Römer. Laser-Induced Periodic Surface Structures (LIPSS) on Polymers Processed with Picosecond Laser Pulses, Journal of Laser Micro/Nanoengineering  Vol. 13, No. 2, 2018; doi: 10.2961/jlmn.2018.02.0010

Abstract

Based on a literature review, it was concluded that Laser-induced Periodic Surface Structures (LIPSS) on polymers are produced when applying laser sources operating either in the ultraviolet wavelength and nanosecond pulse duration, or radiation of wavelengths ranging from 265nm to 1045nm and pulse durations in the femtosecond regime. LIPSS were not reported when using pico-second laser sources. The purpose of this paper is to study whether (and if so which) LIPSS form on polymers when picosecond pulsed laser source is applied. Low Spatial Frequency LIPSS (LSFL) and High Spatial Frequency LIPSS (HSFL) have been obtained on polycarbonate and on polystyrene when applying picosecond laser pulses at a wavelength of 343nm on single spots and on processed lines. When using a wavelength of 515nm, LSFL and HSFL have been produced only on polycar-bonate, but also led to porosity of the structured area.

Links:

DOI: 10.2961/jlmn.2018.02.0010