Multi-material construction enables new approaches to lightweight production by using the right material in the right spot. In order to combine different materials suitable joining techniques are ...required, e.g., for plastics and metals. The production of plastic-metal hybrid enables reducing dead weight while maintaining and preferably boosting the components performance. Common joining techniques like adhesive joining and riveting have specific disadvantages and direct welding of these materials fails due to their different physical and chemical properties. Another promising approach is a two-staged laser-based joining process. First, a laser source generates microstructures on the metallic joining partner to increase the boundary surface and create undercut cavities. In the second step plastic and metal are thermally joined together. Both joining partners are clamped together, the metal surface is heated up with a laser, and through heat conduction, the thermoplastic polymer matrix melts and flows into the cavities. After hardening, a connection is formed. For metal surface microstructuring, ultrashort pulsed lasers can be used to create a spongy topography. These self-organizing microstructures, so-called cone-like protrusions, have previously shown to have a big influence on the wettability of the surface. For hybrid joining, it is essential to have a complete filling of the microstructures with molten polymer in order to achieve high joint strengths, which can be achieved by a good wettability of the metal surface. In this contribution, the wettability of molten plastic (PA6 and PP) on microstructured steel surfaces is evaluated to identify the correlation between wettability and joint strength.
In this work a method for fabricating functionalized preclinical devices is presented. The manufacturing process combines a laser indirect writing technique to fabricate a soda-lime glass master and ...soft-lithography methods to obtain the final structure in polydimethylsiloxane (PDMS). The roughness of the device is modified in a controlled manner by applying a post-thermal treatment to the master, and thus devices with different roughness values are created. The PDMS devices are fully covered with human umbilical vein cells in a two-step process. In order to determine the most suitable device to perform bioassays, the cell attachment to the channel is evaluated with regards to the walls roughness when flow experiments are carried out.
A laser based technique for microstructuring titanium and tantalum substrates using the Talbot effect and an array of microlenses is presented. By using this hybrid technique; we are able to generate ...different patterns and geometries on the top surfaces of the biomaterials. The Talbot effect allows us to rapidly make microstructuring, solving the common problems of using microlenses for multipatterning; where the material expelled during the ablation of biomaterials damages the microlens. The Talbot effect permits us to increase the working distance and reduce the period of the patterns. We also demonstrate that the geometries and patterns act as anchor points for cells; affecting the cell adhesion to the metallic substrates and guiding how they spread over the material.
We have produced rib waveguides by femtosecond-laser structuring of active (Yb,Nb):RbTiOPO 4 /RbTiOPO 4 epitaxial layers. The ribs were produced by the approximation scanning technique combined with ...beam multiplexing. The so-obtained waveguides are trapezoidal in shape and show propagation losses with an upper bound of ~4 dB/cm. A simulation of the rib waveguides with real geometry parameters reveals high levels of light confinement at 632 and 972 nm. The near-field patterns of the fundamental modes have been obtained by exciting the waveguides at wavelengths of 632 and 972 nm. Micro-Raman spectroscopy study reveals that the damage to the crystalline structure in the rib boundaries, showing no amorphization traces, is around 3 μm in length and depth, which is significantly shorter than the total width of the ribs.
The electric capacity of electrochemical capacitors with composite electrodes obtained by laser microstructuring was studied. The obtained electrodes allowed control of the contribution of the ...resistance of the electrode material and electrolyte to the total equivalent series resistance of the electrochemical capacitor. This allowed us to determine their effect on the resulting characteristics of the capacitors. The dependences of the specific electric capacity on the parameters of the composite structure of electrodes were studied, and the optimum parameters were found.
Writing 3D patterns of microvessels Juodkazis, Saulius
International journal of nanomedicine,
01/2012, Volume:
7, Issue:
default
Journal Article
Peer reviewed
Open access
The laser polymerization capabilities of biocompatible and cross-linkable materials using direct laser writing are discussed.
Cross-disciplinary highlight of synergy between medical applications and ...laser microfabrication.
Ti:sapphire is an attractive material for applications as a tunable or short-pulse laser and as a broadband light source in low-coherence interferometry. We investigated several methods to fabricate ...rib structures in sapphire that can induce channel waveguiding in Ti:sapphire planar waveguides. These methods include direct laser ablation, reactive ion etching, and ion beam implantation followed by wet chemical etching. With the latter two methods, we fabricated channels with depths of up to 1.5
μm. Reactive ion etching through laser-structured polyimide contact-masks has so far provided the best results in terms of definition and roughness of the etched structures.
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