Laser Induced Periodic Surface Structures: from physical ... LIMS2018 sito/3_1 Orazi... · potenza...

Laser Induced Periodic Surface Structures: from physical phenomena to industrial

applications

Prof. Leonardo Orazi

Department of Sciences and Methods for Engineering Manufacturing and Technology Group

Department of Sciences and Methods for Engineering Campus San Lazzaro - Reggio Emilia

Manufacturing and Technology Group @ DISMI

2Department of Sciences and Methods for Engineering Manufacturing and Technology Group

LIMS2018 - ENEA Frascati 17-18 May 2018L. Orazi

Department of Sciences and Methods for Engineering

• Management and Production Engineering

• Mechatronics

Laser texturing as a tool to improve surface characteristics

‣Wear‣Wettability ‣Tribology‣Biomedical‣Photovoltaic‣Microfluidics



The diffraction limit is a physical constrain in obtaining small features

‣Wavelengths-CO2 → 10 microns-Nd::YAG, Yb::glass → 10## nm-Ti::Sapphire→ 850 nm



Tecnologie Speciali Lavorazioni Laser

Θ0

"2x0 "x0 x0 2x0x

"2R0

"R0

R0

2R0

R!x"

Figura 5.27: Geometria del fascio gaussiano

!2x0 !x0 x0 2x0x

0.250.50.75

1

I!0,Ρ"#I0

Figura 5.28: Intensita sull’asse del fascio gaussiano

La potenza totale viene calcolata con la solita

P =

! ∞

0

! 2π

0I (x, ρ, θ) ρ dθ dρ = 2π

! ∞

0I (x, ρ) ρ dρ

ovvero

P =1

2I0πR

20

In pratica la potenza totale e pari a meta dell’ampiezza massima moltiplicata per l’area delfascio nella zona di focalizzazione. Pua essere interessante esprimere la l’irradianza in funzionedella potenza totale che e la grandezza nota della sorgente

I(x, ρ) =2P

πR2(x)e−2( ρ

R(x) )2

La frazione di potenza emessa da un fascio di raggo ρ0 si ottiene dalla seguente:

Pρ0

P=

2π

P

! ρ0

0I(x, ρ)ρdρ = 1− e−2( ρ0

R(x) )2

da cui si evince che la potenza racchiusa in un cerchio di raggio R(x) racchiude l’86% dellapotenza totale mentre il 99% della potenza e all’interno di un cerchio di raggio pari a 1.5R(x). Alladistanza pari a R(x) dall’asse l’intensita si attenua di un fattore pari 1/e2 = 0.135 rispetto al valoresull’asse. Come gia visto convenzionalmente il diametro del fascio e fissato convenzionalmente inR(x).

L’ampiezza del fascio varia lungo l’asse secondo la formula gia vista in Eqn. 5.4. Alla distanzadi Rayleigh il diametro del fascio e aumentato di un fattore

√2 da cui il raddoppio dell’area e il

dimezzamento dell’irradianza.Per distanze elevate lungo l’asse del fascio (|x| ≫ x0) l’andamento dell’ampiezza puo aprossi-

marsi con la seguente:

R(x) ≈ R0

x0x = θ0x

file:Dispense TS 118 Ing. Leonardo Orazi

dmin =4

⇡�f

D

‣ In industrial applications the minimum focus is always > 10 µm, normally 20 µm

Laser Induced Periodic Surface Structures ( LIPPS )‣ First observed in dielectric in 1965‣ Role of self-organized dynamics has always

drawn interest.‣ LIPSS observed in metals, dielectrics,

semiconductors. Basic mechanism uncovered in 1980’s.

‣ Persistent difficulties with achieving fine control over the structures has limited impact of the field.

‣ Active field, with >1000 papers published, but few applications demonstrated so far.

•  First observation in 1965.

•  Role of self-organized dynamics has always drawn interest.

•  LIPSS observed in metals, dielectrics, semiconductors.

•  Basic mechanism uncovered in 1980’s.

•  Persistent difficulties with achieving fine control over the

structures has limited impact of the field.

•  Active field, with >1000 papers published, but few applicants

demonstrated so far.

Laser-Induced Periodic Surface Structures (LIPSS) �

Young, et al., 1982 !

Bonse, Resonfeld, !Krüger, 2009!

Audouard, et al., 2010 !Guo, et al., 2005 !












Audouard, et al., 2010!Guo, et al., 2005!












Audouard, et al., 2010!Guo, et al., 2005!

Young et al. 1982Birnbaum, 1965



Audoard et al, 2010Guo et al, 2005

High Regular HR-LIPSS: electrodynamic theory

6Dipartimento di Scienze e Metodi dell’Ingegneria Tecnologia e Sistemi di Lavorazioni


Incoming high intensity laser pulse

Surface Plasmon-Polariton Wave:

modulation of the electron density

Electric field of the incident wave

interferes with the plasmonic field

Higher electric field ↓

stronger the electron heating

forming metal oxide (TiO2) of an amount that is proportional to thelaser-activated metal (titanium) or available O2 at that point, which-ever is smaller. Here, we simply refer to this controlled transformationas ablation, because similar physical processes underlie it, eventhough the metal is not removed, but is chemically transformed. Asa result of the ablation threshold, no processing of the surfaceshould occur between the nanolines, where partially destructive inter-ference leads to the total intensity being below the ablation threshold.The presence of this threshold, which was confirmed experimentally(Fig. 3; Supplementary Section ‘Experimental evidence for thethreshold for intensity’), is the main source of nonlinearity.

When scanning a small-diameter beam, the nanostructures arecreated sequentially, with existing structures creating new structures,similar to the toppling of dominoes. This enables the formation ofextremely uniform nanostructures (experimental and simulatedresults are shown in Fig. 3e and f, respectively). Moreover, it ispossible to tile indefinitely large areas with nanostructures,without a discernible reduction in long-range uniformity whenusing a small laser beam. We scan the beam along a line, thenshift the beam laterally while still preserving a partial overlap withthe previous point, and then scan again parallel to the line of thescan (with partial overlap being maintained all along the way withthe first line of the scan). This can be visually observed inSupplementary Movie S1, where the red disk represents the beamlocation and verified experimentally (Supplementary Movie S2).Further evidence of the role of nonlocal feedback lies in the factthat the new structures form a tilted front and the nanolinesbecome distorted into a wavy pattern at the end of each scan linedue to incomplete nonlocal feedback.

The nanostructure formation mechanism exhibits a significantdegree of robustness against distinct types of perturbations. First,the resultant field at any point is formed collectively by the entiresurrounding area, so the contributions of isolated defects or roughpatches on the surface are easily overwhelmed. When a defect isplaced along the beam path (under conditions otherwise the sameas in Fig. 3f), the nanolines suffer only minor distortions(Fig. 3g). Defects encountered in Supplementary Movie S2provide experimental confirmation. Second, Supplementary MovieS2 shows that the beam focus was not maintained well during scan-ning due to the poor mechanical stability of our set-up. However,key features, such as nanoline period and width, are independentof laser power (see Supplementary Section ‘Insensitivity of thenanostructure features to laser power and exposure time’ for directexperimental confirmation). Because of this insensitivity, a partialloss of focus during scanning is inconsequential. In fact, we foundthe standard and Allan deviations of the nanoline period of thisstructure to be 0.9 nm and 0.14 nm, respectively (for details seeSupplementary Section ‘Characterization of the uniformity of thenanostructures’). Third, as a result of the negative feedbackmechanism, the growth of the nanostructures saturates at a givenheight. Even minutes-long exposure to a stationary beam or multiplescans of the laser over the same area have no discernible effect(Supplementary Movie S4). Robustness against a range of pertur-bations is a coveted feature of nonlinear systems5 that is extremelydifficult to achieve in strictly linear systems.

A diverse range of nanostructures have been fabricated using thisapproach. A photograph of nanostructures covering a 3 mm2 area,fabricated on a thin and flexible glass slide, is presented in Fig. 4a.

0

10

0 200

10

0 50 100 150 200 250

40

0

10

0 50 100 150 200

x (µm)

0 20 40x (µm)

0 20 40x (µm)

y (µ

m)

e

f

g

0 40

4

8

0 100 200 300

8 0 40

4

8

0 50 100 150

8

a

b

c

d

Figure 3 | Nanostructure formation dynamics. a,b, SEM image of the experimental results (a) and numerical simulation results (b) of nanostructures formedaround an isolated scatterer by a few, high-energy pulses with linear polarization. c,d, SEM image of the experimental results (c) and numerical simulationresults (d) of nanostructures obtained with a large and stationary laser beam. e, SEM image of uniform nanostructures obtained by scanning a small laserbeam. f, Numerical simulation results of nanostructures obtained by scanning a small laser beam. g, Numerical simulation results showing robustness of thenanostructure formation against a defect, showing minor distortion and quick subsequent recovery. Colour bars indicate height in nanometres.

NATURE PHOTONICS DOI: 10.1038/NPHOTON.2013.272 LETTERS

NATURE PHOTONICS | VOL 7 | NOVEMBER 2013 | www.nature.com/naturephotonics 899

4

vector along the x ' ( y ' ) axis, θ is the angle between r�

and y ' , and r�

is the displacement vector

between (x, y) and (x ', y ') . In order to find the total local field at an arbitrary point (x, y) on the

surface, we integrate over the contributions from all points on the surface,

E��surf ,n =

�En (x, y)+

�Escat (x ', y ')dx 'dy '∫∫ . (7)

Here, normalization of this result to ensure that the sum of the total power scattered over the

surface and that of the reflected light equals the incoming power is implicit.

In order to clarify the underlying physics, let us consider the special case of linearly polarised light

along the y axis. As such, φ = 0 , Ex ' = 0 and Ey ' = E0 . Then, our result reduces to

�Escat (x ', y ') = E0 sinθ cosθ( fr + gθ )x '+ ( fr cos

2θ + gθ sin2θ )y '{ }× e−

x '−x '0 ,n( )2+ y '−y '0 ,n( )22w2 .

For large r , further simplification is in order,

�Escat (x ', y ') = Ey ' e

iφ gθ sinθ cosθ x '+ Ey eiφ gθ sin

2θ y '{ }× e−x '−x '0 ,n( )2+ y '−y '0 ,n( )2

2w2

=E0 exp −x '− x '0,n( )2 + y '− y '0,n( )2

2w2

⎛

⎝⎜⎜

⎞

⎠⎟⎟ξh(x ', y ') k

r⎛⎝⎜

⎞⎠⎟ sin

2θei(ωt−kr )y '. (8)

Thus, the total electric field and intensity formed on the surface during the nth pulse reduce to

Esurf ,n (x, y) = Enn is

the pulsenumber

� (x, y)+ ξ E0 h(x ', y ')effect of the surface point

�� kr

⎛⎝⎜

⎞⎠⎟

sets the finite range of influence

�sin2θdeterminesdirection of

nanostructures

� ei(ωt−kr )

phase term, where k

determines the period

�� e−

(x '−x '0 ,n )2+(y '−y '0 ,n )2

2w2

imposes the finite-sizeof the laser beam

� �� dx 'dy '∫∫

integration over the entire (x,y) plane� ��

, (9)

Isurf ,n (x, y) = Esurf ,n (x, y)2, (10)

where we have ignored the component along x ' , since it does not interfere with the incoming light,

which is along y ' and the implicit normalisation operation suppresses its influence.

Interpretation of this result is straightforward. The total field is a surface integral with the product

of the surface height and the incident field at each point contributing. The form of the integral is

4 NATURE PHOTONICS | www.nature.com/naturephotonics

SUPPLEMENTARY INFORMATION DOI: 10.1038/NPHOTON.2013.272

Nonlinear Laser Lithography: surface roughness and spot diameter are the key factors

7Dipartimento di Scienze e Metodi dell’Ingegneria Tecnologia e Sistemi di Lavorazioni


forming metal oxide (TiO2) of an amount that is proportional to thelaser-activated metal (titanium) or available O2 at that point, which-ever is smaller. Here, we simply refer to this controlled transformationas ablation, because similar physical processes underlie it, eventhough the metal is not removed, but is chemically transformed. Asa result of the ablation threshold, no processing of the surfaceshould occur between the nanolines, where partially destructive inter-ference leads to the total intensity being below the ablation threshold.The presence of this threshold, which was confirmed experimentally(Fig. 3; Supplementary Section ‘Experimental evidence for thethreshold for intensity’), is the main source of nonlinearity.

When scanning a small-diameter beam, the nanostructures arecreated sequentially, with existing structures creating new structures,similar to the toppling of dominoes. This enables the formation ofextremely uniform nanostructures (experimental and simulatedresults are shown in Fig. 3e and f, respectively). Moreover, it ispossible to tile indefinitely large areas with nanostructures,without a discernible reduction in long-range uniformity whenusing a small laser beam. We scan the beam along a line, thenshift the beam laterally while still preserving a partial overlap withthe previous point, and then scan again parallel to the line of thescan (with partial overlap being maintained all along the way withthe first line of the scan). This can be visually observed inSupplementary Movie S1, where the red disk represents the beamlocation and verified experimentally (Supplementary Movie S2).Further evidence of the role of nonlocal feedback lies in the factthat the new structures form a tilted front and the nanolinesbecome distorted into a wavy pattern at the end of each scan linedue to incomplete nonlocal feedback.

The nanostructure formation mechanism exhibits a significantdegree of robustness against distinct types of perturbations. First,the resultant field at any point is formed collectively by the entiresurrounding area, so the contributions of isolated defects or roughpatches on the surface are easily overwhelmed. When a defect isplaced along the beam path (under conditions otherwise the sameas in Fig. 3f), the nanolines suffer only minor distortions(Fig. 3g). Defects encountered in Supplementary Movie S2provide experimental confirmation. Second, Supplementary MovieS2 shows that the beam focus was not maintained well during scan-ning due to the poor mechanical stability of our set-up. However,key features, such as nanoline period and width, are independentof laser power (see Supplementary Section ‘Insensitivity of thenanostructure features to laser power and exposure time’ for directexperimental confirmation). Because of this insensitivity, a partialloss of focus during scanning is inconsequential. In fact, we foundthe standard and Allan deviations of the nanoline period of thisstructure to be 0.9 nm and 0.14 nm, respectively (for details seeSupplementary Section ‘Characterization of the uniformity of thenanostructures’). Third, as a result of the negative feedbackmechanism, the growth of the nanostructures saturates at a givenheight. Even minutes-long exposure to a stationary beam or multiplescans of the laser over the same area have no discernible effect(Supplementary Movie S4). Robustness against a range of pertur-bations is a coveted feature of nonlinear systems5 that is extremelydifficult to achieve in strictly linear systems.

A diverse range of nanostructures have been fabricated using thisapproach. A photograph of nanostructures covering a 3 mm2 area,fabricated on a thin and flexible glass slide, is presented in Fig. 4a.

0

10

0 200

10

0 50 100 150 200 250

40

0

10

0 50 100 150 200

x (µm)

0 20 40x (µm)

0 20 40x (µm)

y (µ

m)

e

f

g

0 40

4

8

0 100 200 300

8 0 40

4

8

0 50 100 150

8

a

b

c

d

Figure 3 | Nanostructure formation dynamics. a,b, SEM image of the experimental results (a) and numerical simulation results (b) of nanostructures formedaround an isolated scatterer by a few, high-energy pulses with linear polarization. c,d, SEM image of the experimental results (c) and numerical simulationresults (d) of nanostructures obtained with a large and stationary laser beam. e, SEM image of uniform nanostructures obtained by scanning a small laserbeam. f, Numerical simulation results of nanostructures obtained by scanning a small laser beam. g, Numerical simulation results showing robustness of thenanostructure formation against a defect, showing minor distortion and quick subsequent recovery. Colour bars indicate height in nanometres.

NATURE PHOTONICS DOI: 10.1038/NPHOTON.2013.272 LETTERS

NATURE PHOTONICS | VOL 7 | NOVEMBER 2013 | www.nature.com/naturephotonics 899

Öktem et al., Nature Photonics 7, 897–901 (2013)

HR-LIPSS obtained by Laser nanopatterning

‣Periods ∼ (0.2 - 0.8) λ/2 ‣Large Areas → 2500 mm2

‣Stable and robust process‣Conductors, Dielectric and Organic materials‣Productivity ∼ 400 mm2/min and scalable to

higher value‣No vacuum condition requested



Laser source cost decreasing → applications in more traditional sectors

Emerging/advanced applications

Possible applications



‣ Wear resistant surfaces ‣ Super hydrophobic surfaces ‣ Friction force reduction ‣ …

‣Nano filters ‣Diffraction gratings ‣Micro nano/fluidics ‣MEMS ‣Biologic applications ‣Lithography ?

AISI 316L: primary structures 450-500 nm ( LSFL: Low Spatial Frequency LIPSS )



LSFL and HSFL: High Spatial Frequency LIPSS < 100 nm in AISI 316L



Quasi-hexagonal nanostructures with single pass treatments on AISI 316



AISI 316L: aspect ratio



Dry sliding – Mean friction coefficient Slider on Cylinder test

BENDING LOAD CELL

SLIDER

CYLINDER

LVDT

Slider: 316L + LIPSS, 316L LTC + LIPSS

Cylinder: 316L, 100Cr6

‣Testing conditions:- Dry sliding - Load (5 N)- Speed (0.3 m/s)- Sliding distance (100 m)

‣Measurements:- Friction coefficient- System wear



(COF)

0.2

0.3

0.5

0.7

0.8

1.0

0.3232

0.190.0

0.2

0.4

0.6

0.8

1.0

0.6985

0.4824

Dry sliding – Mean Friction coefficient after 10 m



0.0

0.2

0.4

0.6

0.8

1.0

0.4049

0.5332

0.2655

0.0860.0776

AISI 316L LIPPS AISI 316L AISI 316L LIPPS 100 Cr6AISI 316L LTC

LIPPS AISI 316L

Tribological tests 2 – Lubricated sliding

‣Reciprocating mode‣Lubricant: MOBIL UNIVIS

N46‣Load (F): 1 N‣100Cr6 steel ball, r: 3 mm‣Pit radius (R): 7.2 mm‣Cycles: 1000 ‣Stroke distance (S): 2 mm



R

S,v

Fr

Lubricated test – Friction coefficient

DISMI - UNIMORE - Manufacturing & Technology Group

Untreated AISI 316L AISI 316L LIPSS



Fric

tion

coe

ffic

ient

Lubricated tests – Friction coefficients

DISMI - UNIMORE - Manufacturing & Technology Group

0.00

0.13

0.25

0.38

0.50

AISI 316L Untreated Big LIPSS LIPSS 3 LIPSS 11 LIPSS 19

0.22

0.32

0.220.20

0.220.18

0.22

0.380.39

0.200.210.200.230.24

0.20

0.26

0.430.38

Min COF (absolute value)Max COF



Round specimens, radial and circunferential treatments



High uniform LIPSS in Molybdenum



High uniform LIPSS in Molybdenum on large area…



Wettability tuning

‣v parallel = 36.6 mm/s‣v perpendicular = 5.23 mm/s

‣v parallel = 38.9 mm/s‣v perpendicular = v = 37.4 mm/s



Micro

Nano

Wettability tuning: complex track



Ti/Zr alloys for bio-medical applications



Huang et al. - The construction of hierarchical structure on Ti substrate with superior osteogenic activity and

intrinsic antibacterial capability. Nature - Scientific Reports 4 -

6172. (2014)

www.futuremedicine.com 727

Figure 1. Laser-textured surfaces. Scanning electron microscopy micrographs and roughness profiles of laser-induced periodic surface structures (A–C), nanopillar- (D–F) and microcolumn- (G–I) textured surfaces. The arrows in (A, D & G) indicate the polarization direction of the laser beam. The micrographs in (B & E) were taken at a tilting angle of 45°. The scale bar is 5 μm (A & D), 10 μm (G) and 2 μm (B, E & H). LIPSS: Laser-induced periodic surface structure. For color figures, please see online at www.futuremedicine.com/doi/full/10.2217/NNM.15.19

future science group

Human mesenchymal stem cell behavior on femtosecond laser-textured Ti-6Al-4V surfaces Research Article

1–20 mm/s by means of a computer-controlled XYZ stage (PI miCos; Eschbach-Germany) while pulsing the laser at 1 kHz. To achieve complete surface cover-age, consecutive laser tracks were partially overlapped by a lateral displacement of about 30% of the track width. The polarization direction was controlled by a half-wave plate introduced in the optical path. The laser treatment was carried out in air.

Surface characterizationQuantitative assessment of the surface topography was carried out using stereoscopic pairs of scanning elec-tron microscopy (SEM) micrographs obtained at 0 and 10° tilting angle using a JEOL JSM-7001F field emis-sion gun scanning electron microscope (FEG-SEM) and Alicona-MeX© software 2.0 (Alicona Imag-ing; Graz-Austria) [21]. The surface roughness was expressed by the parameters arithmetic mean height

(Ra) and maximum height (Rz), defined according to ISO 4287 standard and calculated from at least ten measurements taken from each stereoscopic pair in a direction perpendicular to the laser beam scanning direction.

The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) using a XSAM800 (KRATOS) spectrometer operated in the fixed analyzer transmission mode, with a pass energy of 20 eV, nonmonochromatized AlKα radiation (hν = 1486.6 eV), 120 W power (10 mA × 12 kV) and a take-off angle relative to the surface holder of 45°. The samples were analyzed in ultra-high vacuum (∼10-7 Pa) at room temperature. The spectra were collected and stored in 300 channels with a step of 0.1 eV and 60 s of acquisition time by sweep, using Vision (KRA-TOS) software. The areas of the peaks components were evaluated after fitting with Gaussian-Lorentzian

Length (µm)Length (µm)Length (µm)

Laser beam scanning direction

Hei

ght (

µm)

40302010011-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

22 33 44 5 5

-1.5-2.0

-1.0-0.5

0.00.5

1.00.20.20.10.1

-0.1-0.1-0.2

0.0

C IF

A

E

S

H

GD

B

730 Nanomedicine (Lond.) (2015) 10(5)

Table 3. X-ray photoelectron spectroscopy atomic ratios.

Ratios Surfaces (%)

Polished LIPSSs NPs MC-LIPSSs

Ti(0)/Ti(total) × 100 8.1 – 4.8 –

Ti(III)/Ti(total) × 100 5.9 4.6 2.9 2.9

Ti(IV)/Ti(total) × 100 86.0 95.4 92.3 97.1

Al/(Al+Ti) × 100 44 55 52 47

,)033��,ASER INDUCED�PERIODIC�SURFACE�STRUCTURE��-# ,)033��-ICROCOLUMNS�COVERED�WITH�,)033��.0��.ANOPILLAR��

Figure 3. Cell spreading. Low-magnification fluorescence images of human mesenchymal stem cells cultured on polished (A), laser-induced periodic surface structures (B), NPs (C) and microcolumn (D) surfaces 24 h after cell seeding. F-actin fibers (green) and cell nucleus (blue). The scale bar is 200 μm. Quantification of the cell area (E). *Statistically significant differences between the average values; p < 0.05. LIPSS: Laser-induced periodic surface structure; MC-LIPSS: Microcolumns covered with LIPSS; NP: Nanopillar.

70,000

56,000

42,000

28,000

14,000

0Polished LIPSSs MC-LIPSSsNPs

Culture substrates

Cel

l are

a (µ

m2 )

**

*

A B

C D

E

future science group

Research Article Cunha, Zouani, Plawinski et al.

the processing methods and parameters indicated in Table 1. The texture depicted in Figure 1A–C consists of nanoripples known as LIPSSs. The average period and the peak-to-valley distance are 715 ± 86 and 296 ± 58 nm, respectively. The second type of texture consists of an array of NPs (Figure 1D–F). The rounded tops of the NPs are due to resolidification of molten

material. The third type of texture consists of micro-columns with roughly elliptical cross-section covered with LIPSSs (Figure 1G–I), forming a bimodal surface roughness distribution. The length of the major and minor axis of the columns and their maximum height are 8 ± 2, 6 ± 1 and 4 ± 1 μm, respectively. These textures are not commensurate with the grain size of the material and bear no relationship with the mate-rial microstructure. The values of Ra and Rz for all the laser-textured surfaces are given in Table 2.

XPS survey spectra of the laser-treated surfaces are presented in Supplementary Figure 1 (see online at www.futuremedicine.com/doi/suppl/10.2217/nnm.15.19). They present peaks corresponding to titanium, alumi-num, oxygen and carbon, as well as Auger electrons peaks of Ti, O and C. The vanadium peaks are par-tially overlapped with the oxygen satellite peaks and cannot be distinguished. The Ti 2p, O 1s and Al 2p peaks are presented in Figure 2. The Ti 2p peak con-sists of three doublets with a spin-orbit split of 5.7 ± 0.1 eV. The main component (Ti 2p3/2) of the major dou-blet is centered at 458.3 ± 0.1 eV and can be assigned to Ti (IV) in TiO2. A less intense doublet with a Ti 2p3/2 component centered at 455.6 ± 0.2 eV can be assigned to Ti (III) in Ti2O3. In addition, for polished and nano-pillar textured specimens a third doublet with the Ti 2p3/2 component centered at 453.8 ± 0.2 eV is observed, which can be attributed to metallic titanium. The O 1s peak consists of three components at 529.9 ± 0.2, 531.5 ± 0.1 and 532.7 ± 0.3 eV. They can be attributed to O-2, a mixture of hydroxyl (OH-) and carbonyl groups (C = O) and oxygen singly bound to carbon (C – O), respectively. The presence of C – O and C = O groups was also confirmed by the analysis of the C 1s peak (not shown). The Al 2p peak consists of three doublets with a spin-orbit split of 0.4 eV. The most intense has its main component, Al 2p3/2, centered at 74.3 ± 0.1 eV and can be assigned to Al (III) in Al2O3. Another dou-blet, with the Al 2p3/2 component centered at 71.6 ± 0.1 eV, is observed for the polished surface and is due to metallic aluminum. Finally, a low-intensity doublet with the Al 2p3/2 component centered at 76.5 ± 0.1 eV is observed for microcolumn-textured surfaces, which

A. Cunha et al. - Human mesenchymal stem cell behavior on femtosecond laser-textured Ti-6Al-4V

surfaces. Nature - Nanomedicine. (2015)Can LIPSS improve the

osteointegration?

Ti/Zr alloys for bio-medical applications



30 lab rats divided in 4 groups

Laser nanopatterning

Dulbecco’s Modified Eagle Medium; Fetal Bovine Serum; L-glutamine; Mercaptoethanol24 h incubation 37 °C

Human Dermal Fibroblasts Adult

seeding

Metabolic Alamar Blue Assay

In Vitro

As is

Ti As is

Zr As is

Ti LIPSS

Zr LIPSS SEM Analysis

In Vivo

30 samples - 9 mm discs• Ti6Al4V ( commercial grade 1 )• Zr ( 99.7% purity )

Cells viability: in-vitro results analysis



0

200

400

600

800

1000

1200

1400

D3 D7 D10

Fluo

resc

ence

Time [days]

Ti6Al4V in vitro analysis

control

textured

0

200

400

600

800

1000

1200

1400

D3 D7 D10

Fluo

resc

ence

Time [days]

Zr in vitro analysis

control

textured

Cells viability: in vivo results analysis



Fb

Fb Le

Fi

Fi

Fi

Fi

Fb

Er

Ti6

Al4

VZ

r

Connective fibres (Fi)Erythrocytes (Er)Leucocytes (Le) Fibroblasts (Fb)

Control the plastic flow in micro injection moulding

‣Local treatments of mould surfaces in order to improve and control the plastic flow during injection.



21

+ -0,01

0,01

3 -00,01 7

-00,02

10

+ 0,04

0

A

A

superficial treatment

SEZIONE A-A

B

C

D

1 2

A

321 4

B

A

5 6

Codice disegno:

Titolo disegno: 37.COATED.FIXED.INSERTUniversità di PadovaDIMEG

Via Venezia, 135131 PADOVA

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Disegnato Controllato

Smussi non quotati: Racc. non quotati:

Materiale:A4

06/11/14

43 5 6

C

D

Control the plastic flow in micro injection moulding



Adhesive joint on Ti6Al4V alloy: improving of the shear maximum stress



E

Vs

F

E

Vs

F

Cutting Tools: generation of patterns for MoS2 deposits.



Silicon: PV applications



Sapphire: first results known in literature

‣Some first results on Sapphire



Diffraction effects: gratings with periodicity near the visible wavelength



Nickel

AISI 316 LTC

Diffraction effects: aesthetic and anti-counterfeiting applications



AISI 316 polishedAISI 316 unpolished

LIPSS@DISMI new set-up

‣3 harmonics laser‣Two concurrent

beamlines at 1030 and 343 nm with galvoscanner and laser spot ≈ 10!.‣XYZ stage +

polarization direction rotation



Bibliografia

[1] M. Sorgato, D. Masato, G. Lucchetta, and L. Orazi, “Effect of different laser-induced periodic surface structures on polymer slip in PET injection moulding,” CIRP Journal of Manufacturing Science and Technology, 2018.[2] I. Gnilitskyi, T. J.-Y. Derrien, Y. Levy, N. M. Bulgakova, T. Mocek, and L. Orazi, “High-speed manufacturing of highly regular femtosecond laser- induced periodic surface structures: physical origin of regularity,” Scientific Reports, vol. 7, p. 8485, Aug. 2017.[3] I. Gnilitskyi, A. Rota, R. Ctvrtlik, A. P. Serro, A. P. Serro, E. Gualtieri, and L. Orazi, “Multifunctional Properties of High-speed Highly Uniform Femtosecond Laser Patterning on Stainless steel,” in Conference on Lasers and Electro-Optics (2017), paper ATu1C.5, p. ATu1C.5, Optical Society of America, May 2017.[4] L. Orazi, I. Gnilitskyi, and A. P. Serro, “Laser Nanopatterning for Wet- tability Applications,” Journal of Micro and Nano-Manufacturing, vol. 5, pp. 021008–021008–8, Mar. 2017.[5] G. Rotella, L. Orazi, M. Alfano, S. Candamano, and I. Gnilitskyi, “Inno- vative high-speed femtosecond laser nano-patterning for improved adhesive bonding of Ti6al4v titanium alloy,” CIRP Journal of Manufacturing Sci- ence and Technology, 2017.[6] I. Gnilitskyi, V. Gruzdev, N. M. Bulgakova, T. Mocek, and L. Orazi, “Mechanisms of high-regularity periodic structuring of silicon surface by sub-MHz repetition rate ultrashort laser pulses,” Applied Physics Letters, vol. 109, p. 143101, Oct. 2016.[7] I. Gnilitskyi, S. Mamykin, M. Dusheyko, T. Borodinova, N. Maksimchuk, and L. Orazi, “Diffraction Gratings Prepared by HR-LIPSS for New Surface Plasmon-Polariton Photodetectors & Sensors,” in Frontiers in Optics 2016 (2016), paper JW4A.88, p. JW4A.88, Optical Society of America, Oct. 2016.[8] I. Gnilitskyi, L. Orazi, N. Bulgakova, and V. Gruzdev, “Formation and Application of highly-regular LIPSS on Surface of Silicon Crystals,” in Frontiers in Optics 2016 (2016), paper JTh2A.113, p. JTh2A.113, Optical Society of America, Oct. 2016.

[9] I. Gnilitskyi, F. Rotundo, C. Martini, I. Pavlov, S. Ilday, E. Vovk, F. O . Ilday, and L. Orazi, “Nano patterning of AISI 316l stainless steel with Non- linear Laser Lithography: Sliding under dry and oil-lubricated conditions,” Tribology International, vol. 99, pp. 67–76, July 2016.[10] I. Gnilitskyi, L. Orazi, N. Bulgakova, and V. Gruzdev, “Highly Regular Nanostructuring of Si Surface by Ultrashort Laser Pulses,” in Conferenceon Lasers and Electro-Optics (2016), paper STh1Q.4, p. STh1Q.4, Optical Society of America, June 2016.[11] I. Gnilitskyi, M. Pogorielov, D. Dobrota, R. Viter, L. Orazi, and O. Mis- chenko, “Cell and Tissue Response to Modified by Laser-induced Periodic Surface Structures Biocompatible Materials for Dental Implants,” in Con- ference on Lasers and Electro-Optics (2016), paper AW4O.6, p. AW4O.6, Optical Society of America, June 2016.[12] I. Gnilitskyi, M. Dusheyko, T. Borodinova, S. Mamykin, N. Maksim- chuk, A. Ivaschuk, Y. Yakymenko, and L. Orazi, “Self-assembling of Gold Nanoparticles on Si-based Laser Nanotextured 1d Surface for Plasmonic Application,” in Conference on Lasers and Electro-Optics (2016), paper STh4K.3, p. STh4K.3, Optical Society of America, June 2016.[13] L. Orazi, I. Gnilitskyi, I. Pavlov, A. P. Serro, S. Ilday, and F. O. Ilday, “Nonlinear laser lithography to control surface properties of stainless steel,” CIRP Annals - Manufacturing Technology, vol. 64, no. 1, pp. 193–196, 2015.[14] I. Gnilitskyi, I. Pavlov, F. Rotundo, L. Orazi, C. Martini, and F. Ilday, “Nonlinear laser lithography for enhanced tribological properties,” in Con- ference on Lasers and Electro-Optics Europe - Technical Digest, vol. 2015- August, Institute of Electrical and Electronics Engineers Inc., 2015.[15] I. Gnilitskyi, I. Pavlov, F. Rotundo, L. Orazi, S. Ilday, C. Martini, and F. Ilday, “Laser-patterning stainless steel with nonlinear laser lithography for enhanced tribological properties,” vol. Part F4-CLEO 2015, 2015.



Laser Induced Periodic Surface Structures: from physical phenomena to

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Department of Sciences and Methods for Engineering Manufacturing and Technology Group

Department of Sciences and Methods for Engineering Campus San Lazzaro - Reggio Emilia

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