Simas Butkus

3D microporous scaffolds manufactured via combination of fused filament fabrication and direct laser writing ablation

A 3D printing fused filament fabrication (FFF) approach has been implemented for the creation of microstructures having an internal 3D microstructure geometry. These objects were produced without any sacrificial structures or additional support materials, just by precisely tuning the nozzle heating, fan cooling and translation velocity parameters. The manufactured microporous structures out of polylactic acid (PLA) had fully controllable porosity (20%–60%) and consisted of desired volume pores (~0.056 μm3). The prepared scaffolds showed biocompatibility and were suitable for the primary stem cell growth. In addition, direct laser writing (DLW) ablation was employed to modify the surfaces of the PLA structures, drill holes, as well as shape the outer geometries of the created objects. The proposed combination of FFF printing with DLW offers successful fabrication of 3D microporous structures with functionalization capabilities, such as the modification of surfaces, the generation of grooves and microholes and cutting out precisely shaped structures (micro-arrows, micro-gears). The produced structures could serve as biomedical templates for cell culturing, as well as biodegradable implants for tissue engineering. The additional micro-architecture is important in connection with the cell types used for the intention of cell growing. Moreover, we show that surface roughness can be modified at the nanoscale by immersion into an acetone bath, thus increasing the hydrophilicity. The approach is not limited to biomedical applications, it could be employed for the manufacturing of bioresorbable 3D microfluidic and micromechanic structures.

Hybrid subtractive-additive-welding microfabrication for lab-on-chip applications via single amplified femtosecond laser source

Abstract. An approach employing ultrafast laser hybrid subtractive-additive microfabrication, which combines ablation, three-dimensional nanolithography, and welding, is proposed for the realization of a lab-on-chip (LOC) device. A single amplified Yb:KGW femtosecond (fs)-pulsed laser source is shown to be suitable for fabricating microgrooves in glass slabs, polymerization of fine-meshes microfilter out of hybrid organic–inorganic photopolymer SZ2080 inside them, and, finally, sealing the whole chip with cover glass into a single monolithic piece. The created microfluidic device proved its particle sorting function by separating 1- and 10-μm polystyrene spheres in an aqueous mixture. All together, this proves that laser microfabrication based on a single amplified fs laser source is a flexible and versatile approach for the hybrid subtractive-additive manufacturing of functional mesoscale multimaterial LOC devices.

Analysis of the Micromachining Process of Dielectric and Metallic Substrates Immersed in Water with Femtosecond Pulses

Micromachining of 1 mm thick dielectric and metallic substrates was conducted using femtosecond pulse generated filaments in water. Several hundred microjoule energy pulses were focused within a water layer covering the samples. Within this water layer, non-linear self-action mechanisms transform the beam, which enables higher quality and throughput micromachining results compared to focusing in air. Evidence of beam transformation into multiple light filaments is presented along with theoretical modeling results. In addition, multiparametric optimization of the fabrication process was performed using statistical methods and certain acquired dependencies are further explained and tested using laser shadowgraphy. We demonstrate that this micromachining process exhibits complicated dynamics within the water layer, which are influenced by the chosen parameters.

Rapid microfabrication of transparent materials using a filamented beam of the IR femtosecond laser

Glass drilling and welding applications realized with the help of femtosecond lasers attract industrial attention , however, desired tasks may require systems employing high numerical aperture (NA) focusing conditions, low repetition rate lasers and complex fast motion translation stages. Due to the sensitivity of such systems, slight instabilities in parameter values can lead to crack formations, severe fabrication rate decrement and poor quality overall results. A microfabrication system lacking the stated disadvantages was constructed and demonstrated in this report. An f-theta lens was used in combination with a galvanometric scanner, in addition, a water pumping system that enables formation of water films of variable thickness in real time on the samples. Water acts as a medium for filament formation, which in turn decreases the focal spot diameter and increases fluence and axial focal length . This article demonstrates the application of a femtosecond (280fs) laser towards two different micromachining techniques: rapid cutting and welding of transparent materials. Filament formation in water gives rise to strong ablation at the surface of the sample, moreover, the water, surrounding the ablated area, adds increased cooling and protection from cracking. The constructed microfabrication system is capable of drilling holes in thick soda-lime and hardened glasses. The fabrication time varies depending on the diameter of the hole and spans from a few to several hundred seconds. Moreover, complex-shape fabrication was demonstrated. Filament formation at the interface of two glass samples was also used for welding applications. By varying repetition rate, scanning speed and focal position optimal conditions for strong glass welding via filamentation were determined.

Combination of additive and subtractive laser microprocessing in glass/polymer microsystems for chemical sensing applications

The fabrication of a novel 3D polymer/glass micromechanical sensor concept is demonstrated by combining two femtosecond laser direct writing processes: laser exposure and chemical etching of glass combined with two-photon polymerization.

Laser subtractive-additive-welding microfabrication for Lab-On-Chip (LOC) applications

An approach employing ultrafast laser hybrid microfabrication combining ablation, 3D nanolithography and welding is proposed for the realization of Lab-On-Chip (LOC) device. The same laser setup is shown to be suitable for fabricating microgrooves in glass slabs, polymerization of fine meshes inside them, and, lastly, sealing the whole chip with cover glass into one monolithic piece. The created micro fluidic device proved its particle sorting function by separating 1 μm and 10 μm polystyrene spheres from a mixture. Next, a lens adapter for a cell phones camera was manufactured via thermal extrusion 3D printing technique which allowed to achieve sufficient magnification to clearly resolve <10 μm features. All together shows fs-laser microfabrication technology as a flexible and versatile tool for study and manufacturing of Lab-On-Chip devices.

Microfabrication of transparent materials using filamented femtosecond laser beams

Glass drilling realized with the help of femtosecond lasers attract industrial attention, however, desired tasks may require systems employing high numerical aperture (NA) focusing conditions, low repetition rate lasers and complex fast motion translation stages. Due to the sensitivity of such systems, slight instabilities in parameter values can lead to crack formations, severe fabrication rate decrement and poor quality overall results. A microfabrication system lacking the stated disadvantages was constructed and demonstrated in this report. An f-theta lens was used in combination with a galvanometric scanner, in addition, a water pumping system that enables formation of water films of variable thickness in real time on the samples. Water acts as a medium for filament formation, which in turn decreases the focal spot diameter and increases fluence and axial focal length. This article demonstrates the application of a femtosecond (280fs) laser towards rapid cutting of different transparent materials. Filament formation in water gives rise to strong ablation at the surface of the sample, moreover, the water, surrounding the ablated area, adds increased cooling and protection from cracking. The constructed microfabrication system is capable of drilling holes in thick soda-lime, hardened glasses and sapphire. The fabrication time varies depending on the diameter of the hole and spans from a few to several hundred seconds. Moreover, complex-shape fabrication was demonstrated.