Laser micro/nano fabrication
The use of laser in manufacturing processes is rapidly growing due both to the dramatic developments in laser technology during the past 10 years (e.g., higher power and wider wavelength availability) and the innovative fabrication approaches being implemented (e.g., 3D laser based micro fabrication and laser ablation in liquid).
Two main micro/nano fabrication methods are currently investigated and implemented: 1) mask projection excimer laser stereolithography (MPExSL) for the fabrication of 3D biodegradable scaffolds; 2) pulsed laser ablation in liquid for the production of nanoparticles.
1) The newly developed MPExSL method allows the rapid fabrication of 3D polymeric scaffolds with micrometer resolution via layer-by-layer photo-polymerization using an excimer laser and the mask projection technique. The method has the advantage of being versatile and scalable, relying on relatively simple yet very effective approach, therefore providing a concrete possibility to bring 3D laser fabrication technology from the prototyping to the actual production arena. MPExSL is actually being used to fabricate 3D biodegradable scaffolds for the regeneration of nervous tissues within the EU-CHINA NEUROSCAFFOLD project. Figure 1 shows examples of 3D multichannel conduit biodegradable scaffold fabricated by MPExSL.
2) Pulsed laser ablation in liquid (PLAL) has recently emerged as a very promising method for the fabrication of nanoparticles in colloidal solutions following the twelve principles of green chemistry. In particular, for many compositions, PLAL allows the synthesis of stable crystalline nanoparticles without the use of surfactant agents, which has huge potentialities in medical applications, where the purity of particles is crucial, or in applications where the free surface of particles is utilized (e.g. for catalytic purposes).PLAL method allows the production of stable colloids in various liquids using a variety of materials. Also alloys or core-shell particles have been produced. Among the results obtained here we report: 1) ultra-small luminescent silicon nanoparticles (< 5 nm) are produced by picosecond PLAL in water and gram per hour yield is foreseen with high power lasers 2) synthesis of pure nanoparticles of precious materials (Pd, Au, Ag), useful for plasmonic or catalytic applications, has been studied in different experimental conditions; 3) feasibility of FePt nanoparticles synthesis, useful for magnetic applications, has been investigated.