Microfabrication and surface functionalization of soda lime glass through direct laser interference patterning

All-purpose glasses are common in many established and emerging industries, such as microelectronics, photovoltaics, optical components, and biomedical devices due to their outstanding combination of mechanical, optical, thermal, and chemical properties. Surface functionalization through nano/micropatterning can further enhance glasses’ surface properties, expanding their applicability into new fields. Although laser structuring methods have been successfully employed on many absorbing materials, the processability of transparent materials with visible laser radiation has not been intensively studied, especially for producing structures smaller than 10 µm. Here, interference-based optical setups are used to directly pattern soda lime substrates through non-lineal absorption with ps-pulsed laser radiation in the visible spectrum. Line-and dot-like patterns are fabricated with spatial periods between 2.3 and 9.0 µm and aspect ratios up to 0.29. Furthermore, laserinduced periodic surface structures (LIPSS) with a feature size of approximately 300 nm are visible within these microstructures. The textured surfaces show significantly modified properties. Namely, the treated surfaces have an increased hydrophilic behavior, even reaching a super-hydrophilic state for some cases. In addition, the micropatterns act as relief diffraction gratings, which split incident light into diffraction modes. The process parameters were optimized to produce high-quality textures with super-hydrophilic properties and diffraction efficiencies above 30%.Fil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Alamri, Sabri. Fraunhofer Institute For Material And Beam Technology Iws; AlemaniaFil: Sürmann, Paul Alexander. Fraunhofer Institute For Material And Beam Technology Iws; AlemaniaFil: Kunze, Tim. Fraunhofer Institute For Material And Beam Technology Iws; AlemaniaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemani

Label-free detection of C-Reactive protein using bioresponsive hydrogel-based surface relief diffraction gratings

[EN] Responsive hydrogel-based surface relief gratings have demonstrated great performances as transducers in optical sensing. However, novel and smart designs of hydrogels are needed for the appropriate detection of analytes and biomolecules since the existing materials are very limited to specific molecules. In this work, a biosensing system based on surface relief gratings made of bioresponsive hydrogels has been developed. In particular, the hydrogel contains phosphocholine moieties to specifically recognize C-Reactive protein (CRP). The CRP-Sensing hydrogel capacity to selectively detect CRP was fully demonstrated. Using Direct Laser Interference Patterning, micro-gratings were created on CRP-Sensing hydrogel substrates and applied for the label-free sensing of CRP using a simple laser-based homemade optical setup. Limits of detection (LOD) and quantification (LOQ) in human serum dilutions of 1.07 and 8.92 mg L-1, respectively, were reached. These results demonstrate that the biosensing system allows the selective label-free detection of CRP within concentration ranges around those related to risks of cardiovascular diseases and sepsis. Besides, amplification strategies have been carried out improving the sensitivity, widening the linear range, and reaching better LOD and LOQ (0.30 mg L-1 and 4.36 mg L-1). Finally, all the approaches were tested for the quantification of CRP in certified human serum with recoveries of around 100%.This work was financially supported by the E.U. FEDER, the Spanish Ministry of Economy and Competitiveness MINECO (BiHolog-CTQ2016- 75749-R and AdBiHol-PID2019-110713RB-I00) and Generalitat Valenciana (PROMETEO/2020/094). M. I. Lucío acknowledges MINECO for her Juan de la Cierva Formacion and Incorporacion grants (FJCI-2016-29593, IJC 2018-035355-I). The authors acknowledge the assistance and advice of the Electron Microscopy Service of the Universitat Politècnica de València.Lucío, MI.; Hernández-Montoto, A.; Fernández-Sánchez, ME.; Alamri, S.; Kunze, T.; Bañuls Polo, M.; Maquieira Catala, Á. (2021). Label-free detection of C-Reactive protein using bioresponsive hydrogel-based surface relief diffraction gratings. Biosensors and Bioelectronics. 193:1-10. https://doi.org/10.1016/j.bios.2021.11356111019

Direct laser interference patterning of transparent and colored polymer substrates: Ablation, swelling and the development of a simulation model

It is well known that micro and sub-micrometer periodical structures play a significant role on the properties of a surface. Ranging from friction reduction to the bacterial adhesion control, the modification of the material surface is the key for improving the performance of a device or even creating a completely new function. Among different laser processing techniques, Direct Laser Interference Patterning (DLIP) relies on the local surface modification process induced when two or more beams interfere and produce periodic surface structures. Although the produced features have controllable pitch and geometry, identical experimental conditions applied to different polymers can result on totally different topologies. In this frame, observations from pigmented and transparent polycarbonate treated with ultraviolet (263 nm) and infrared (1053 nm) laser radiation permitted to identify different phenomena related with the optical and chemical properties of the polymers. As a result from the experimental data analysis, a set of material-dependent constants can be obtained and both profile and surface simulations can be retrieved, reproducing the material surface topography after the surface patterning process

Development of a general model for direct laser interference patterning of polymers

This study investigates the general mechanism of Direct Laser Interference Patterning (DLIP) involved in the structuring process of polymer materials. An empirical model is developed taking into account experimental observations of DLIP-treated pigmented and transparent polycarbonate substrates with UV (263 nm) and IR (1053 nm) laser radiation. Depending on the used laser processing conditions, the type of material as well as the spatial period of the interference pattern, four different structuring mechanisms can be identified. The treated surfaces are investigated using confocal microscopy, scanning electron microscopy and focus ion beam and as a result from the experimental data analysis, the developed model predicts the material surface topography after the patterning process, by means of a set of material-dependent coefficients

One-step fabrication of asymmetric saw-tooth-like surface structures on stainless steel using direct laser interference patterning

We report about the fabrication of asymmetrical periodic arrays on stainless steel by means of Direct Laser Interference Patterning. The fabrication strategy consists in irradiating the surface of the material under a certain inclination angle using a two-beam interference setup equipped with a pulsed picosecond laser system (70 ps) operating at a wavelength of 1064 nm. In particular, for tilting angles higher than 30°, well-defined saw-tooth like geometries could be produced. Due to the ultra-short duration of the laser pulses, also Laser Induced Periodic Surfaces Structures are fabricated, which create hierarchical morphologies similar to the one present in nature

Micro-fabrication of high aspect ratio periodic structures on stainless steel by picosecond direct laser interference patterning

We have studied the fabrication of line-like and pillar-like periodic microstructures on stainless steel by means of direct laser interference patterning. A picosecond (10 ps) pulsed Nd:YAG laser operating at 1064 nm wavelength was used to produce the microstructures with spatial periods ranging from 2.6 μm to 5.2 μm. By varying the laser parameters (laser fluence, pulse-to-pulse overlap) structure depths ranging from 500 nm to nearly 11.5 μm could be obtained. Furthermore, low and high frequency laser induced periodic surface structures (LIPSS) have been generated, resulting in three-level multi-scaled patterns. The orientation of the laser induced periodic structures with respect to the interference patterns could be adjusted by controlling the laser beam polarization. Finally, static water contact angle measurements are performed to investigate its correlation with the surface morphology. The treated surfaces are characterized using confocal and scanning electron microscopy

Controlling the wettability of polycarbonate substrates by producing hierarchical structures using Direct Laser Interference Patterning

New strategies for the fabrication of surface structures using Direct Laser Interference Patterning are presented in this work, aiming to fabricate hierarchical structures with selective wetting properties. Polycarbonate sheets have been structured employing a two-beam interference arrangement using an ultraviolet (263 nm) nanosecond-pulsed laser, creating line- and pillar-like structures with simple and hierarchical geometries. Two different methods for producing hierarchical structures are here provided, both relying on a pixel-wise structuring technique and able to achieve high structure depths. The produced surface patterns are characterized by confocal microscopy, scanning electron microscopy and the influence of the surface topography on the water contact angle is investigated. The correlation between structure geometry and wettability response, in terms of structure height and directionality of the droplet shape is reported

Interference-based laser-induced micro-plasma ablation of glass

Glass is one of the most important technical surfaces for numerous applications in automotive, optical, and consumer industries. In addition, by producing textured surfaces with periodic features in the micrometre range, new functions can be created. Although laser-based methods have shown to be capable to produce structured materials in a wide amount of materials, due to its transparency large bandgap dielectrics can be only processed in a controlled manner by employing high-power ultra-short pulsed lasers, thus limiting the employable laser sources. In this article, an interference-based method for the texturing of soda-lime glass using a 15 ns pulsed (1 kHz repetition rate) infrared (1053 nm) laser is proposed, which allows fabricating different periodic patterns with micrometre resolution. This method consists on irradiating a metallic absorber (stainless steel) put in direct contact with the glass sample and inducing locally an etching process on the backside of the glass. Then, the produced plasma at the interference maxima positions leads to the local fabrication of well-defined periodic line-like and dot-like surface patterns. The produced patterns are characterised using white light interferometry and scanning electron microscopy

Maximizing the efficiency of laser-fabricated diffraction gratings on PET using direct laser interference patterning

Recently, product protection and tracking became increasingly important due to the spread of piracy and counterfeiting. A common anti-counterfeiting procedure is embedding holographic motives or logos onto the good. If the motive is engraved directly onto the material surface, these features are inseparable from the good adding a higher degree of security. Holographic coloring is achieved by fabricating periodic surface structures, where the dimensions of the spatial periods lie in the order of the wavelengths contained in the visible spectrum. However, the fabrication of such periodic features directly on the product surface at high resolution and manufacturing speed is still challenging. Direct Laser Interference Patterning (DLIP) is an industrial compatible method with high processing flexibility which allows the structuring of holographic motives with high resolution and throughput. In this work, DLIP is employed to produce diffraction gratings with variable spatial periods and feature heights on a transparent PET substrate, which is a polymer commonly used for mass consumer goods and packaging. A numerical model based on the finite element method was used to restrict the gratings’ geometrical parameters that maximize the diffraction efficiency in reflection mode before their fabrication. Then, using the design of experiment approach, the laser processing parameters (laser power, pulse-overlap, spatial period) were selected in order to maximize the experimental first-order diffraction intensity, measured with a photospectrometer. The results allow to find the optimum set of parameters to fabricate homogeneous gratings with a first-order reflected intensity up to 4 % of the light source intensity

Design of perfectly ordered periodic structures on polymers using direct laser interference patterning

Frontal polymerization (FP) or vitrification consists in the generation of a reaction front, in a localized sector of the material, that travels in a particular direction. Their remarkable flexibility permits to controllably polymerize materials with different molecular weights and variable chemical nature. One of the advantages of FP is that it is possible to generate thin layers of a polymerized material over an unpolymerized composite, being suitable for creating wrinkled patterns in homogenous polymeric materials. In this chapter, the main types of frontal polymerization are described, as well as several examples and applications which take advantage of this methodology to form wrinkled patterns of variable materials