Papers by Mangirdas Malinauskas
We introduce optically clear and resilient free-form micro-optical components of pure (non-photos... more We introduce optically clear and resilient free-form micro-optical components of pure (non-photosensitized) organic-inorganic SZ2080 material made by femtosecond 3D laser lithography (3DLL). This is advantageous for rapid printing of 3D micro-/nano-optics, including their integration directly onto optical fibers. A systematic study of the fabrication peculiarities and quality of resultant structures is performed. Comparison of microlens resiliency to continuous wave (CW) and femtosecond pulsed exposure is determined. Experimental results prove that pure SZ2080 is ∼20 fold more resistant to high irradiance as compared with standard lithographic material (SU8) and can sustain up to 1.91 GW/cm 2 intensity. 3DLL is a promising manufacturing approach for high-intensity micro-optics for emerging fields in astro-photonics and atto-second pulse generation. Additionally, pyrolysis is employed to homogeneously shrink structures up to 40% by removing organic SZ2080 constituents. This opens a promising route towards downscaling photonic lattices and the creation of mechanically robust glass-ceramic microstructures.
Processing of materials by ultrashort laser pulses has evolved significantly over the last decade... more Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific, technological and industrial potential. In ultrafast laser manufacturing, optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation
on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photoionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has
been achieved. State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
A 3D printing fused filament fabrication (FFF) approach has been implemented for the creation of ... more 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 Micromachines 2014, 5 840 porosity (20%–60%) and consisted of desired volume pores (∼0.056 µm 3). 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.
We report a study of the determination of polymer cross-linking, namely the degree of conversion ... more We report a study of the determination of polymer cross-linking, namely the degree of conversion and refractive index of the microstructures created by two-photon polymerization (TPP). The influence of TPP processing parameters such as laser intensity and scanning velocity is investigated. The degree of conversion is analyzed via Raman microspectroscopy and the refractive index is measured with the interferometric technique employing a Michelson interferometer. Moreover, the relationship between these two properties is revealed and details are discussed. The largest refractive index change that we have obtained is of the order of 10^−2. Finally, we propose and demonstrate experimentally the realization of the gradient-index (GRIN) structure, resulting from a laser-induced local refractive index modification due to monomer cross-linking, i.e. degree of conversion. This work implies that the TPP technique is a valuable tool for the fabrication of GRIN microoptics for (in)homogeneous molding of light flow at the micrometer scale.
Ultrafast laser processing of materials: from science to industry
Polarization effects in laser 3D nanolithography are employed to fine-tune the feature sizes in t... more Polarization effects in laser 3D nanolithography are employed to fine-tune the feature sizes in the structuring of photoresist. The vectorial Debye theory is used for modelling and a variation of up to ≈20% in the line width of SZ2080 is shown experimentally for the identical axial extent. This proves polarization to be a variable parameter for voxel-aspect ratio control.
A tightly focused ultrafast pulsed laser beam is guided into the volume of the photosensitive mat... more A tightly focused ultrafast pulsed laser beam is guided into the volume of the photosensitive material and induces nonlinear photomodification. By translating the sample, the position of the focus is changed relatively, thus point-by-point complex 3D structures can be written inside the bulk. In this report, we present a Laser Two-Photon Polymerization (LTPP) setup for three-dimensional micro/nanostructuring for applications in photonics, microoptics, micromechanics, microfluidics and biomedicine. This system enables fabrication of functional devices over a large area (up to several cm in lateral size) with reproducible sub-micrometer resolution (up to 200 nm). In our experiments a Yb:KGW active media laser oscillator (75 fs, 200 kW, 515 nm frequency doubled, 80 MHz) was used as an irradiation source. The sample was mounted on XYZ wide range linear motor driven positioning stages having 10 nm positioning resolution. These stages enable an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support a linear scanning speed of up to 300 mm/s. Control of all the equipment was automated via custom made computer software "3D-Poli" specially designed for LTPP applications. The model of the structure can be imported as CAD file, this enables rapid and flexible structuring out of various photopolymers like ORMOCERs, ORMOSILs, acrylates and PEGDAs which are commonly used in conventional UV mask, nanoimprint and μ-stereolithographies. In this paper, we demonstrate polymeric microstructures fabricated over a large area on glass, plastic and metal substrates. This opens a way to produce functional devices like photonic crystals, microlenses, micromechanic and microfluidic components and artificial scaffolds as templates for cell growth. Additionally, results of primary myogenic stem cells expanding on microfabricated polymeric scaffolds are provided. Cell proliferation tests show the material and structure to be biocompatible for the biomedical practice.
Processing of materials by ultrashort laser pulses has evolved significantly over the last
decade... more Processing of materials by ultrashort laser pulses has evolved significantly over the last
decade and is starting to reveal its scientific, technological, and industrial potential. In
ultrafast laser manufacturing, optical energy of tightly focused femtosecond or
picosecond laser pulses can be delivered to precisely defined positions in the bulk of
materials via two-/multi-photon excitation on a timescale much faster than thermal
energy exchange between photoexcited electrons and lattice ions. Control of photoionization
and thermal processes with the highest precision, inducing local
photomodification in sub- 100-nm sized regions has been achieved.
State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial
resolution and almost unrestricted three-dimensional structuring capability. Adjustable
pulse duration, spatiotemporal chirp, phase front tilt, and polarization allow control of
photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical
technologies have enabled laser processing speeds approaching meters-per-second,
leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed
with an emphasis on the fundamental relation between spatial resolution and total
fabrication throughput. Emerging biomedical applications implementing micrometer
feature precision over centimeter-scale scaffolds and photonic wire bonding in
telecommunications are highlighted.
The Angle Orthodontist, 2015
To find a correlation between the severity of enamel microcracks (EMCs) and their increase duri... more To find a correlation between the severity of enamel microcracks (EMCs) and their increase during debonding and residual adhesive removal (RAR). Following their examination with scanning electron microscopy (SEM), 90 extracted human premolars were divided into three groups of 30: group 1, teeth having pronounced EMCs (visible with the naked eye under normal room illumination); group 2, teeth showing weak EMCs (not apparent under normal room illumination but visible by SEM); and group 3, a control group. EMCs have been classified into weak and pronounced, based on their visibility. Metal brackets (MB) and ceramic brackets (CB), 15 of each type, were bonded to all the teeth from groups 1 and 2. Debonding was performed with pliers, followed by RAR. The location, length, and width of the longest EMCs were measured using SEM before and after debonding. The mean overall width (Woverall) was higher for pronounced EMCs before and after debonding CB (P < .05), and after the removal of MB. Pronounced EMCs showed greater length values using both types of brackets. After debonding, the increase in Woverall of pronounced EMCs was 0.57 µm with MB (P < .05) and 0.30 µm with CB; for weak EMCs, - 0.32 µm with MB and 0.30 µm with CB. Although the teeth having pronounced EMCs showed higher width and length values, this did not predispose to greater EMCs increase after debonding MB and CB followed by RAR.
2011 13th International Conference on Transparent Optical Networks, 2011
Three-dimensional photonic crystals with woodpile structure are demonstrated to exhibit collimati... more Three-dimensional photonic crystals with woodpile structure are demonstrated to exhibit collimation of light beams behind the photonic structure. Woodpile structure photonic crystals with longitudinal modulation periods in a range of 7.4 - 7.8 μm, and transverse periods of 1 μm were fabricated using laser multi-photon polymerization technique in a negative-tone photoresist. As expected from theoretical predictions, the beams propagating along
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
2007 Quantum Electronics and Laser Science Conference, 2007
ABSTRACT
Optics letters, Jan 15, 2014
We experimentally demonstrate the recently predicted effect of near-field focusing for light beam... more We experimentally demonstrate the recently predicted effect of near-field focusing for light beams from flat dielectric subwavelength gratings (SWGs). This SWGs were designed for visible light 532 nm and fabricated by direct laser writing in a negative photoresist, with the refractive index n=1.5 and the period d=314 nm. The laterally invariant gratings can focus light beams without any optical axis to achieve the transversal invariance. We show that focal distances can be obtained up to 13 μm at normal reflection for TE polarization.
Biofabrication, 2015
Over the last decade DLW employing ultrafast pulsed lasers has become a well-established techniqu... more Over the last decade DLW employing ultrafast pulsed lasers has become a well-established technique for the creation of custom-made free-form three-dimensional (3D) microscaffolds out of a variety of materials ranging from proteins to biocompatible glasses. Its potential applications for manufacturing a patient's specific scaffold seem unlimited in terms of spatial resolution and geometry complexity. However, despite few exceptions in which live cells or primitive organisms were encapsulated into a polymer matrix, no demonstration of an in vivo study case of scaffolds generated with the use of such a method was performed. Here, we report a preclinical study of 3D artificial microstructured scaffolds out of hybrid organic-inorganic (HOI) material SZ2080 fabricated using the DLW technique. The created 2.1 × 2.1 × 0.21 mm(3) membrane constructs are tested both in vitro by growing isolated allogeneic rabbit chondrocytes (Cho) and in vivo by implanting them into rabbit organisms for one, three and six months. An ex vivo histological examination shows that certain pore geometry and the pre-growing of Cho prior to implantation significantly improves the performance of the created 3D scaffolds. The achieved biocompatibility is comparable to the commercially available collagen membranes. The successful outcome of this study supports the idea that hexagonal-pore-shaped HOI microstructured scaffolds in combination with Cho seeding may be successfully implemented for cartilage tissue engineering.
Journal of Materials Science: Materials in Medicine, 2015
The biocompatibility of dental implant abutment materials depends on numerous factors including t... more The biocompatibility of dental implant abutment materials depends on numerous factors including the nature of the material, its chemical composition, roughness, texture, hydrophilicity and surface charge. The aim of the present study was to compare the viability and adhesion strength of human gingival fibroblasts (HGFs) grown on several dental materials used in implant prosthodontics. Surfaces of the tested materials were assessed using an optical imaging profiler. For material toxicity and cellular adhesion evaluation, primary human gingival fibroblast cells were used. To evaluate the strength of cellular adhesion, gingival fibroblasts were cultured on the tested materials and subjected to lateral shear forces by applying 300 and 500 rpm shaking intensities. Focal adhesion kinase (FAK) expression and phosphorylation in cells grown on the specimens were registered by cell-based ELISA. There was a tendency of fibroblast adhesion strength to decrease in the following order: sandblasted titanium, polished titanium, sandblasted zirconium oxide, polished zirconium oxide, gold-alloy, chrome-cobalt alloy. Higher levels of total as well as phospho-FAK protein were registered in HGFs grown on roughened titanium. Material type and surface processing technique have an impact on gingival fibroblast interaction with dental implant abutment materials.
Springer Series in Materials Science, 2014
ABSTRACT We overview principles and developments of three-dimensional (3D) direct laser writing i... more ABSTRACT We overview principles and developments of three-dimensional (3D) direct laser writing in polymers. Challenges to reach efficient structuring with sub-100 nm spatial resolution are presented. Research into the structuring by ultrashort laser pulses has seen an immense growth over the last decade due to its flexibility, easy handling and variety of applications. Here, a discussion regarding the mechanisms of the linear and nonlinear light absorption at tight focusing conditions and typical writing parameters are provided. The traditional and novel polymers together with their photosensitization and sample developing strategies are reviewed. Sub-1 ps pulses are capable to create cross-linkable species by direct absorption and bond breaking at \(\sim \)TW/cm\(^2\) irradiance. Confined thermal and linear absorption via avalanche ionization is an efficient use of light energy for localized polymerization. This is a unique feature of ultrashort laser. Applications in microoptics, photonics, microfluidics and cell scaffolds are presented. Directions of up-scaling the fabrication throughput for industrial demands are introduced. 3D laser writing is becoming a part of wider field of additive manufacturing techniques which is innovating for creation of microdevices.
Journal of Laser Micro/Nanoengineering, 2014
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIV, 2014
ABSTRACT We report direct laser fabrication of free-standing 3D structures in a sol-gel photo-pol... more ABSTRACT We report direct laser fabrication of free-standing 3D structures in a sol-gel photo-polymer SZ2080, poly(ethylene glycol) diacrylate (PEG-DA-700) and thermo-polymer polydimethylsiloxane (PDMS) without use of two-photon absorbing photo-sensitizers. By estimating the multi-photon and avalanche ionization rates in the focal volume it is shown that bulk structuring of pure materials was achieved via a controlled avalanche. It is shown that several non-photosesitized materials can be combined for fabrication of composite material structures evoking a possibility to create non-toxic biocompatible scaffolds for tissue engineering, transparent microoptical elements and higher damage threshold photonic devices.
Laser 3D Manufacturing, 2014
ABSTRACT We present a developed method based on direct laser writing (DLW) and chemical metalliza... more ABSTRACT We present a developed method based on direct laser writing (DLW) and chemical metallization (CM) for microfabrication of three-dimensional (3D) metallic structures. Such approach enables manufacturing of free-form electro conductive interconnects which can be used in integrated electric circuits such micro-opto-electro mechanical systems (MOEMS). The proposed technique employing ultrafast high repetition rate laser enables efficient fabrication of 3D microstructures on dielectric as well as conductive substrates. The produced polymer links out of organic-inorganic composite matrix after CM serve as interconnects of separate metallic contacts, their dimensions are: height 15μm, width 5μm, length 35-45 μm and could provide 300 nΩm resistivity measured in a macroscopic way. This proves the techniques potential for creating integrated 3D electric circuits at microscale.
Journal of Laser Micro/Nanoengineering, 2014
ABSTRACT form only given. We present direct laser fabrication of 3D microstructured scaffolds con... more ABSTRACT form only given. We present direct laser fabrication of 3D microstructured scaffolds consisting out of a few polymeric materials owning different biological properties. Direct laser writing in photo/thermo-sensitive materials using ultra short light pulses of high repetition laser provides unmatched flexibility in controllable 3D microstructuring in a variety of bio-materials [1], as well as manufacturing throughput empowers overall structure size of more than 1 mm3, making it an attractive method to fabricate scaffolds for cell studies and tissue engineering applications [2, 3]. In this work, a femtosecond direct laser writing system was supplemented by a machine vision [4] to relocate the sample between different fabrication steps.
Lithuanian Journal of Physics, 2014
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Papers by Mangirdas Malinauskas
on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photoionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has
been achieved. State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
decade and is starting to reveal its scientific, technological, and industrial potential. In
ultrafast laser manufacturing, optical energy of tightly focused femtosecond or
picosecond laser pulses can be delivered to precisely defined positions in the bulk of
materials via two-/multi-photon excitation on a timescale much faster than thermal
energy exchange between photoexcited electrons and lattice ions. Control of photoionization
and thermal processes with the highest precision, inducing local
photomodification in sub- 100-nm sized regions has been achieved.
State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial
resolution and almost unrestricted three-dimensional structuring capability. Adjustable
pulse duration, spatiotemporal chirp, phase front tilt, and polarization allow control of
photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical
technologies have enabled laser processing speeds approaching meters-per-second,
leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed
with an emphasis on the fundamental relation between spatial resolution and total
fabrication throughput. Emerging biomedical applications implementing micrometer
feature precision over centimeter-scale scaffolds and photonic wire bonding in
telecommunications are highlighted.
on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photoionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has
been achieved. State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
decade and is starting to reveal its scientific, technological, and industrial potential. In
ultrafast laser manufacturing, optical energy of tightly focused femtosecond or
picosecond laser pulses can be delivered to precisely defined positions in the bulk of
materials via two-/multi-photon excitation on a timescale much faster than thermal
energy exchange between photoexcited electrons and lattice ions. Control of photoionization
and thermal processes with the highest precision, inducing local
photomodification in sub- 100-nm sized regions has been achieved.
State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial
resolution and almost unrestricted three-dimensional structuring capability. Adjustable
pulse duration, spatiotemporal chirp, phase front tilt, and polarization allow control of
photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical
technologies have enabled laser processing speeds approaching meters-per-second,
leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed
with an emphasis on the fundamental relation between spatial resolution and total
fabrication throughput. Emerging biomedical applications implementing micrometer
feature precision over centimeter-scale scaffolds and photonic wire bonding in
telecommunications are highlighted.