The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optic... more The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optical responses to various vapours. However, the mechanism behind this phenomenon is not fully quantitatively understood. This work reports on process developments in the micro-fabrication of a Morpho-inspired photonic structure in atomic layer deposited (ALD) materials in order to investigate the vapour optical sensitivity of such artificial nanostructures. By developing recipes for dry and wet etching of ALD oxides, we micro-fabricated two structures: one combining Al2O3 and TiO2, and the other combining Al2O3 and HfO2. For the first time, we report the optical response of such ALD Morpho-like structures measured under a controlled flow of either ethanol or isopropyl alcohol (IPA) vapour. In spite of the small magnitude of the effect, the results show a selective vapour response (depending on the materials used).
Based on micro-Raman spectroscopy (μRS) and X-ray photoelectron spectroscopy (XPS), we study the ... more Based on micro-Raman spectroscopy (μRS) and X-ray photoelectron spectroscopy (XPS), we study the structural damage incurred in monolayer (1L) and few-layer (FL) graphene subjected to atomic-layer deposition of HfO2 and Al2O3 upon different oxygen plasma power levels. We evaluate the damage level and the influence of the HfO2 thickness on graphene. The results indicate that in the case of Al2O3/graphene, whether 1L or FL graphene is strongly damaged under our process conditions. For the case of HfO2/graphene, μRS analysis clearly shows that FL graphene is less disordered than 1L graphene. In addition, the damage levels in FL graphene decrease with the number of layers. Moreover, the FL graphene damage is inversely proportional to the thickness of HfO2 film. Particularly, the bottom layer of twisted bilayer (t-2L) has the salient features of 1L graphene. Therefore, FL graphene allows for controlling/limiting the degree of defect during the PE-ALD HfO2 of dielectrics and could be a goo...
Achieving fast, sensitive and selective detection of bacteria in liquid samples is a major challe... more Achieving fast, sensitive and selective detection of bacteria in liquid samples is a major challenge for public healthcare. Unlike conventional methods, CMOS chips with sensing parts provide tremendous benefits in term of portability, system integration and reduced cost. CMOS-compatible microelectrodes were shown to selectively detect whole-cell Staphylococci after drying the sensor surface1. Here, we extend the use of these microelectrodes to bacteria detection in continuous flow for microfluidic applications.
Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization e... more Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization effects on light such as color contrast or geometrical polarization rotation by reflection on their wing scales. The photonic structures found on these species that show these properties are multilayered spherical cavities or triangular grooves which polarize the light due to multiple inner reflections. These polarization effects, in addition to the intrinsic color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves s...
In this work, we investigate a new way to secure anti-counterfeiting using light polarization ef... more In this work, we investigate a new way to secure anti-counterfeiting using light polarization effects inspired from natural photonic structures found on the scales of Papilio butterflies (blumei, ulyss) and on cuticles of Cicendela (chinensis). Polarization effects is only observed by the human eye helped by a polarizer. Thus it can insure two of the three levels of security in banknotes and passports [1]. The first level is a pattern easily recognized by anyone as a colorized symbol. The second level is a pattern that requires a simple device, i.e. a UV lamp or a polarizer, to be observed. The optical structure of papilio and cicendela consists in multilayered cavities. It allows back-‐reflections by multiple reflections near Brewster angle which result in polarized spectrum [2]. Moreover, geometrical effect induces rotation of the polarization state [3] so that the light is not blocked by cross-polarizer (Fig. 1.a). These effects are canceled from the macroscopic point of view due to spherical symmetry of the structure. Breaking the symmetry is thus mandatory. For this purpose, we reproduce the photonic crystal using microfabrication techniques in cylindrical symmetry with two orthogonal directions. Bragg mirror was obtained by atomic layer deposition (ALD). Theoretical reflection spectrum was computed by multiscale simulations (ray-tracing and transfert matrix) and compared with FDTD. Characterizations made by optical microscope and in situ polarizer show that the performed structure enhances polarization effects even at macroscopic point of view (fig. 1.b). Polarization effects have never been used so far in anti-‐counterfeiting industry. This work shows promising results on this way.
Biomimicry or bio-inspiration refers to the approach of reproducing or imitating natural structur... more Biomimicry or bio-inspiration refers to the approach of reproducing or imitating natural structures using artificial materials in order to achieve high structural and material complexity (Figure 1). In the case of insects, natural photonic crystals (PCs) are responsible for the bright iridescent colors found on some species of butterflies and beetles [1]. Such colors are due to light interference thanks to PCs and are called physical color. The large structural diversity of these PCs makes them a valuable source of inspiration, not only for the color they exhibit but also for their properties [2].
We investigate the structural damage of graphene underlying dielectrics (HfO2 and Al2O3) by remot... more We investigate the structural damage of graphene underlying dielectrics (HfO2 and Al2O3) by remote plasma-enhanced atomic layer deposition (PE-ALD). Dielectric film is grown on bilayer graphene without inducing significant damage to the bottom graphene layer. Based on Raman spectra, we demonstrate that the bottom graphene layer has the salient features of single layer graphene. During the initial half-cycle PE-ALD, the upper graphene layer reacts with the metal precursor, forming uniform nucleation islands or an active metallic carbide layer. After monolayer dielectric coverage, the bottom graphene layer has additional protection. The upper graphene layer serves as a sacrificial layer, which not only promotes the adhesion of dielectric on graphene, but also protects the lattice symmetry of the bottom graphene layer. Our results indicate that bilayer graphene allows for controlling/limiting the degree of defect during the ALD of dielectrics and could be a good starting material for b...
Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization e... more Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization effects on light such as color contrast or geometrical polarization rotation by reflection on their wing scales. The photonic structures found on these species that show these properties are multilayered spherical cavities or triangular grooves which polarize the light due to multiple inner reflections. These polarization effects, in addition to the intrinsic color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves show greater polarization contrast than the C-grooves, but the spectrum is specular. The C-grooves exhibit lower polarization effects but have a dispersive spectrum. In both cases, the structures show additional optical properties, such as diffraction, macroscopic color contrast under a polarizer, and contrast inversion due to geometries which contribute to their uniqueness.
The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optic... more The unique architecture of iridescent Morpho butterfly scales is known to exhibit different optical responses to various vapours. However, the mechanism behind this phenomenon is not fully quantitatively understood. This work reports on process developments in the micro-fabrication of a Morpho-inspired photonic structure in atomic layer deposited (ALD) materials in order to investigate the vapour optical sensitivity of such artificial nanostructures. By developing recipes for dry and wet etching of ALD oxides, we micro-fabricated two structures: one combining Al2O3 and TiO2, and the other combining Al2O3 and HfO2. For the first time, we report the optical response of such ALD Morpho-like structures measured under a controlled flow of either ethanol or isopropyl alcohol (IPA) vapour. In spite of the small magnitude of the effect, the results show a selective vapour response (depending on the materials used).
Based on micro-Raman spectroscopy (μRS) and X-ray photoelectron spectroscopy (XPS), we study the ... more Based on micro-Raman spectroscopy (μRS) and X-ray photoelectron spectroscopy (XPS), we study the structural damage incurred in monolayer (1L) and few-layer (FL) graphene subjected to atomic-layer deposition of HfO2 and Al2O3 upon different oxygen plasma power levels. We evaluate the damage level and the influence of the HfO2 thickness on graphene. The results indicate that in the case of Al2O3/graphene, whether 1L or FL graphene is strongly damaged under our process conditions. For the case of HfO2/graphene, μRS analysis clearly shows that FL graphene is less disordered than 1L graphene. In addition, the damage levels in FL graphene decrease with the number of layers. Moreover, the FL graphene damage is inversely proportional to the thickness of HfO2 film. Particularly, the bottom layer of twisted bilayer (t-2L) has the salient features of 1L graphene. Therefore, FL graphene allows for controlling/limiting the degree of defect during the PE-ALD HfO2 of dielectrics and could be a goo...
Achieving fast, sensitive and selective detection of bacteria in liquid samples is a major challe... more Achieving fast, sensitive and selective detection of bacteria in liquid samples is a major challenge for public healthcare. Unlike conventional methods, CMOS chips with sensing parts provide tremendous benefits in term of portability, system integration and reduced cost. CMOS-compatible microelectrodes were shown to selectively detect whole-cell Staphylococci after drying the sensor surface1. Here, we extend the use of these microelectrodes to bacteria detection in continuous flow for microfluidic applications.
Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization e... more Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization effects on light such as color contrast or geometrical polarization rotation by reflection on their wing scales. The photonic structures found on these species that show these properties are multilayered spherical cavities or triangular grooves which polarize the light due to multiple inner reflections. These polarization effects, in addition to the intrinsic color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves s...
In this work, we investigate a new way to secure anti-counterfeiting using light polarization ef... more In this work, we investigate a new way to secure anti-counterfeiting using light polarization effects inspired from natural photonic structures found on the scales of Papilio butterflies (blumei, ulyss) and on cuticles of Cicendela (chinensis). Polarization effects is only observed by the human eye helped by a polarizer. Thus it can insure two of the three levels of security in banknotes and passports [1]. The first level is a pattern easily recognized by anyone as a colorized symbol. The second level is a pattern that requires a simple device, i.e. a UV lamp or a polarizer, to be observed. The optical structure of papilio and cicendela consists in multilayered cavities. It allows back-‐reflections by multiple reflections near Brewster angle which result in polarized spectrum [2]. Moreover, geometrical effect induces rotation of the polarization state [3] so that the light is not blocked by cross-polarizer (Fig. 1.a). These effects are canceled from the macroscopic point of view due to spherical symmetry of the structure. Breaking the symmetry is thus mandatory. For this purpose, we reproduce the photonic crystal using microfabrication techniques in cylindrical symmetry with two orthogonal directions. Bragg mirror was obtained by atomic layer deposition (ALD). Theoretical reflection spectrum was computed by multiscale simulations (ray-tracing and transfert matrix) and compared with FDTD. Characterizations made by optical microscope and in situ polarizer show that the performed structure enhances polarization effects even at macroscopic point of view (fig. 1.b). Polarization effects have never been used so far in anti-‐counterfeiting industry. This work shows promising results on this way.
Biomimicry or bio-inspiration refers to the approach of reproducing or imitating natural structur... more Biomimicry or bio-inspiration refers to the approach of reproducing or imitating natural structures using artificial materials in order to achieve high structural and material complexity (Figure 1). In the case of insects, natural photonic crystals (PCs) are responsible for the bright iridescent colors found on some species of butterflies and beetles [1]. Such colors are due to light interference thanks to PCs and are called physical color. The large structural diversity of these PCs makes them a valuable source of inspiration, not only for the color they exhibit but also for their properties [2].
We investigate the structural damage of graphene underlying dielectrics (HfO2 and Al2O3) by remot... more We investigate the structural damage of graphene underlying dielectrics (HfO2 and Al2O3) by remote plasma-enhanced atomic layer deposition (PE-ALD). Dielectric film is grown on bilayer graphene without inducing significant damage to the bottom graphene layer. Based on Raman spectra, we demonstrate that the bottom graphene layer has the salient features of single layer graphene. During the initial half-cycle PE-ALD, the upper graphene layer reacts with the metal precursor, forming uniform nucleation islands or an active metallic carbide layer. After monolayer dielectric coverage, the bottom graphene layer has additional protection. The upper graphene layer serves as a sacrificial layer, which not only promotes the adhesion of dielectric on graphene, but also protects the lattice symmetry of the bottom graphene layer. Our results indicate that bilayer graphene allows for controlling/limiting the degree of defect during the ALD of dielectrics and could be a good starting material for b...
Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization e... more Some insects, such as Papilio blumei and Suneve coronata, are known for exhibiting polarization effects on light such as color contrast or geometrical polarization rotation by reflection on their wing scales. The photonic structures found on these species that show these properties are multilayered spherical cavities or triangular grooves which polarize the light due to multiple inner reflections. These polarization effects, in addition to the intrinsic color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves show greater polarization contrast than the C-grooves, but the spectrum is specular. The C-grooves exhibit lower polarization effects but have a dispersive spectrum. In both cases, the structures show additional optical properties, such as diffraction, macroscopic color contrast under a polarizer, and contrast inversion due to geometries which contribute to their uniqueness.
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Papers by Olivier Poncelet
color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves show greater polarization contrast than the C-grooves, but the spectrum is specular. The C-grooves
exhibit lower polarization effects but have a dispersive spectrum. In both cases, the structures show additional optical properties, such as diffraction, macroscopic color contrast under a polarizer, and contrast inversion due to geometries which contribute to their
uniqueness.
color-mixing properties of these photonic structures, are of interest in the anti-counterfeiting field due to their invisibility to the naked eye. In this paper, we report micro-fabrication techniques to produce bio-inspired cylindrical grooves (C-grooves) and triangular grooves (V-grooves) that demonstrate the same properties. Theoretical analyses were carried out by using multi-scale simulation (MS) as well as by finite-difference time-domain (FDTD) in order to compare the polarization capability of both structures. The V-grooves show greater polarization contrast than the C-grooves, but the spectrum is specular. The C-grooves
exhibit lower polarization effects but have a dispersive spectrum. In both cases, the structures show additional optical properties, such as diffraction, macroscopic color contrast under a polarizer, and contrast inversion due to geometries which contribute to their
uniqueness.