Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

Hendrikx, Matthew; Sırma, Burcu; Schenning, Albertus P. H. J.; Liu, Danqing; Broer, Dirk J.

doi:10.1002/admi.201800810

Cited by 15 publications

(20 citation statements)

References 19 publications

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“…13 Later, the use of (reactive) azobenzene-containing dopants allowed for the LCN to be addressed and actuated with light. 1,5,6,[22][23][24][25][26][27][28] Compared to this earlier work the tapered films show an increasingly smaller r C over their length, allowing them to effectively roll into themselves.…”

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confidence: 54%

Butterfly proboscis-inspired tight rolling tapered soft actuators

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confidence: 54%

Butterfly proboscis-inspired tight rolling tapered soft actuators

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“…This phenomenon becomes even clearer when the substrate allows deformations. This has been demonstrated by Hendrikx et al with a bilayer coating configuration, in which an LCN coating with orthogonal planar director patterns adheres to a soft compliant layer in between the LCN and the glass substrate. The compliant layer (≈60 MPa) exhibits a substantially lower modulus compared with that of the hard glassy LCN top coating (≈ 2 GPa at room temperature).…”

Section: Light‐responsive Liquid Crystal Networkmentioning

confidence: 87%

Surface Dynamics at Photoactive Liquid Crystal Polymer Networks

Liu

2019

Advanced Optical Materials

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creating insulation under cold conditions and emitting evaporable liquid when it is warm. [1][2][3] Peacock feathers, wings of certain butterflies, and plants exhibit color by means of structural color to communicate attraction or, inversely, repulsion. Often, the colors originate from periodic structures on or under a surface, thus benefiting from the interplay of light and diffractive effects.A surface is the outermost layer of matter and therefore is primarily perceived by humans upon touch or vision. Surfaces provide perceptible information by not only shape, color, and/or reflective properties but also how the matter feels upon touch, e.g., smooth or rough. Welldocumented static structures have been reported for haptic applications. [4] Studies have suggested that humans can distinguish changes in topographical dimensions down to nanometers. [5] Additionally, a surface is the first contact between objects of matter, either of the same object or that of another origin. Surfaces facilitate man-machine interactions, [6] either by touch (smooth, rough, heat conductive, etc.) or by vision (scattering, specular reflection, printed information, etc.). [7][8][9] In relation to this function, tribological properties such as friction, stick, and adhesion coefficients also find application in the field of haptics, where robotic manipulation is of importance. In contrast to nature, the surface structures in modern man-made technology are often still static. Mimicking the lotus flower, surfaces with artificially formed micrometer-sized structures that are produced by lithography or micromachining have been made, and they indeed show improved cleaning under rainy conditions. However, one expands the surface function when these structures are made dynamic, rather than static, for example, the surface would be able to remove dirt under dry conditions, as well. In the case of topographies for haptic use, man's sensitivity could be enhanced when the corrugations are moving with a frequency tuned to the maximum sensitivity of humans. However, only a few publications have described dynamic structures to enhance human-surface interactions, which could even help visually disabled people. Moreover, in an advanced technology such as microfluidics, the low Reynolds number prohibits turbulent mixing of fluid components. Mixing can be induced by surface topographical structures in the microchannels to increase the contact area and the contact time between the reagents. The microfluidic functionality would be enhanced if the topography of its inner walls could be switched in a dynamic way, e.g., to decide on the exact location and time that switching The field of advanced and responsive soft materials is at the edge of a new era. After several decades during which liquid crystals generated new functions for information displays and could solve many problems in emerging fields such as (tele)communications, this material system is being utilized to reach out to completely new application fields with functions that can take over biologica...

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Section: Polymeric Photoactuators: Moving Toward Artificial Musclesmentioning

confidence: 99%

“…This effect is most interesting for applications in self‐cleaning surfaces, soft robotics, haptics, and cell culturing. A recent approach developed by Hendrikx et al exploits a compliant intermediate layer between a glass support slide and an LCN coating with a patterned director for further enhancing the oscillation amplitude of the topography from roughly 70–100 nm to 1 µm (Figure d) . All of these initial developments in light‐driven actuation paved the way for various separate motions to be combined on the same engineering platform, for higher‐order composite motions, that are necessary to create functioning simple actuation devices that can perform complex prescribed tasks, such as “artificial muscles” powered only by light.…”

Section: Polymeric Photoactuators: Moving Toward Artificial Musclesmentioning

confidence: 99%

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

Chang

Fedele

Priimägi

et al. 2019

Advanced Optical Materials

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systems interact with artificial materials, researchers have now assembled a versatile toolkit of materials and processes that allows one to fine-tune interactions at the interface, tailoring specific biological responses on demand. These strategies for biocontrol can be broadly categorized as chemical (charge, ligand presence, surface groups), material changes (moisture content, stiffness), or morphological changes (molecular orientation, surface topography, or mechanical actuation). Rational design of materials for biological interface applications has a unique set of challenges due to the unique requirements of a wide range of biological systems, since different tissues present specific compositions, with their own elasticity, structural organization, and triggering mechanisms. Even within a single organ or tissue, mechanical properties can vary widely depending on the region. A recent study of viscoelasticity in live mouse brain tissue for example found a tenfold difference within the brain depending on the region and morphological structure studied. [2] However, most biological tissues are far less stiff, and far more viscoelastic than typical artificial materials employed at their interface, especially early artificial cell culture materials, which can be much stiffer than in vivo extracellular matrix by many orders of magnitude. [3] In vivo, cells interface with a surrounding microenvironment consisting of an intricate macromolecular network of proteins and sugars swollen in an aqueous media gel. Therefore, the interaction between cells and the extracellular matrix (ECM) in the body is complex and involves a variety of cues related to topography, chemical markers, protein composition, solubility factors, and mechanical properties such as stiffness and elasticity (Figure 1a). [4] Yet much research over the past decades was focused on studying in vitro the effects of each of these signals on cell behavior, with a particular interest on the chemical factors, whereas only recently more advanced biomaterials with controlled physicomechanical properties have been developed, such as those with tunable and variable stiffness, alignment and orientation of key functional groups, and mechanical actuation. There is a large range of stiffness in human tissue, where bone (≈100 GPa) is nine orders of magnitude harder than brain tissue (≈0.1 kPa). [4] Therefore, biomaterial researchers assume a complex task of providing materials and processing technologies for controlling stiffness and micro-and nanostructures in Photoreversible optically switchable azo dye molecules in polymer-based materials can be harnessed to control a wide range of physical, chemical, and mechanical material properties in response to light, that can be exploited for optical control over the bio-interface. As a stimulus for reversibly influencing adjacent biological cells or tissue, light is an ideal triggering mechanism, since it can be highly localized (in time and space) for precise and dynamic control over a biosystem, and low-power visible light...

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Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

Cited by 15 publications

References 19 publications

Butterfly proboscis-inspired tight rolling tapered soft actuators

Butterfly proboscis-inspired tight rolling tapered soft actuators

Surface Dynamics at Photoactive Liquid Crystal Polymer Networks

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

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