Digital holographic microscopy for real-time observation of surface-relief grating formation on azobenzene-containing films

Rekola, Heikki; Berdin, Alex; Fedele, Chiara; Virkki, Matti; Priimägi, Arri

doi:10.1038/s41598-020-76573-6

Cited by 50 publications

(61 citation statements)

References 48 publications

(55 reference statements)

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“…The sinusoidal profile of the photoinscribed SRG was measured by digital holographic microscopy (DHM), a quantitative phase imaging technique. 57 , 58 DHM measures both the amplitude and the phase of the light reflected from the sample. It reconstructs the surface modulation from the hologram created by a reference beam and a beam reflected by the sample surface.…”

Section: Results and Discussionmentioning

confidence: 99%

Multiscale Hierarchical Surface Patterns by Coupling Optical Patterning and Thermal Shrinkage

Shirazi

Dong

Niskanen

et al. 2021

ACS Appl. Mater. Interfaces

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Herein, a simple hierarchical surface patterning method is presented by effectively combining buckling instability and azopolymer-based surface relief grating inscription. In this technique, submicron patterns are achieved using azopolymers, whereas the microscale patterns are fabricated by subsequent thermal shrinkage. The wetting characterization of various topographically patterned surfaces confirms that the method permits tuning of contact angles and choosing between isotropic and anisotropic wetting. Altogether, this method allows efficient fabrication of hierarchical surfaces over several length scales in relatively large areas, overcoming some limitations of fabricating multiscale roughness in lithography and also methods of creating merely random patterns, such as black silicon processing or wet etching of metals. The demonstrated fine-tuning of the surface patterns may be useful in optimizing surface-related material properties, such as wetting and adhesion, producing substrates that are of potential interest in mechanobiology and tissue engineering.

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Section: Results and Discussionmentioning

confidence: 99%

Multiscale Hierarchical Surface Patterns by Coupling Optical Patterning and Thermal Shrinkage

Shirazi

Dong

Niskanen

et al. 2021

ACS Appl. Mater. Interfaces

Self Cite

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“…Holographic inscription, which is based on the directional mass migration of soft matter along a grating vector ( G ), provides the highest compatibility with the texturing of a sinusoidally modulated surface. [ 9–20 ] A specific soft material, in which azobenzene molecules are incorporated into a polymeric chain or supramolecule, can migrate along the polarization ( P ) direction of light, while this migration is proportional to the light intensity ( I ). [ 15,18,21–38 ] The mixing of two or more types of beams can result in a sinusoidally modulated P or I along G ; this ideally formulated optical potential can be applied to the directional mass migration of azomaterials.…”

Section: Introductionmentioning

confidence: 99%

A Field Guide to Azopolymeric Optical Fourier Surfaces and Augmented Reality

Lim

Kang

Hong

et al. 2021

Adv Funct Materials

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Optical Fourier surfaces (OFSs) are used for various applications, from diffractive optics to augmented reality (AR). However, the current methods of fabricating OFSs primarily rely on lithographic photochemical reactions and etching. These methods are likely to fabricate digitalized binary reliefs, which cannot match the ideal surface profile of OFSs. Such a profile is the sum of sinusoidal surfaces with various spatial frequencies. As an exception, scanning probe lithography (SPL) is found to be compatible with OFSs. However, the accessible pattern area of the OFSs created via SPL is relatively small owing to the serial feature of the fabrication, which in turn results in an undesired and complicated Fourier spectrum. In this article, the holographic inscription is redesigned for the low‐cost, large‐area, and rapid prototyping of customized OFSs. To this end, an integrative pipeline is established across numerical design, material optimization, and the pragmatic considerations of optical processing. Then, a soft molding strategy is suggested for optically transparent and flexible OFSs and its use for easy‐to‐craft AR devices. Overall, this intuitive framework not only expands the scope of Fourier optics but also acts as a field guide to azopolymeric OFSs and AR technology for experts and newcomers alike.

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“…There are several ways to create dynamic photocontrollable surfaces based on amorphous azobenzene-containing polymer systems 11 , 12 and LC networks, which are mainly multistep and require lithography, masks, or exposure to interference patterns. 13 − 21 However, dynamic surfaces can be fabricated by homogeneous photopolymerization of cholesteric layers with fingerprint texture.…”

Section: Introductionmentioning

confidence: 99%

Light-Fueled Nanoscale Surface Waving in Chiral Liquid Crystal Networks

Ryabchun

Lancia

Katsonis

2021

ACS Appl. Mater. Interfaces

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Nano-and micro-actuating systems are promising for application in microfluidics, haptics, tunable optics, and soft robotics. Surfaces capable to change their topography at the nano-and microscale on demand would allow control over wettability, friction, and surface-driven particle motility. Here, we show that light-responsive cholesteric liquid crystal (LC) networks undergo a waving motion of their surface topography upon irradiation with light. These dynamic surfaces are fabricated with a maskless one-step procedure, relying on the liquid crystal alignment in periodic structures upon application of a weak electric field. The geometrical features of the surfaces are controlled by tuning the pitch of the liquid crystal. Pitch control by confinement allows engineering one-dimensional (1D) and two-dimensional (2D) structures that wave upon light exposure. This work demonstrates the potential that self-organizing systems might have for engineering dynamic materials, and harnessing the functionality of molecules to form dynamic surfaces, with nanoscale precision over their waving motion.

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Digital holographic microscopy for real-time observation of surface-relief grating formation on azobenzene-containing films

Cited by 50 publications

References 48 publications

Multiscale Hierarchical Surface Patterns by Coupling Optical Patterning and Thermal Shrinkage

Multiscale Hierarchical Surface Patterns by Coupling Optical Patterning and Thermal Shrinkage

A Field Guide to Azopolymeric Optical Fourier Surfaces and Augmented Reality

Light-Fueled Nanoscale Surface Waving in Chiral Liquid Crystal Networks

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