Abstract:The functional surface features of living creatures are driven by the complex morphology of periodically arranged micro/nanoscale structures. Various fabrication processes have been devised mimic the performance of natural features; these methods morph hierarchical and multi-leveled pillar arrays, such as top-down, bottom-up, and a hybrid of top-down and bottom-up processes.Different methodologies are employed depending on the materials, such as polymeric composites, metal oxides, metals, and carbon nanotubes.… Show more
“…We also observed that the assembly of arrays occurred despite small contact areas among pillar tops, unlike in the case of capillary-collapsed nanopillar arrays . The polymeric solutes are localized at the interspace of self-assembled micropillars. − The original upright states of the micropillars were retrieved with regular spacings by simply rinsing out the water-soluble polymers. Therefore, micropillar arrays can be subjected to magnetic actuation or the evaporation of a polymeric solution for reversible chirality selection or capillary-assisted self-assembly.…”
Chiral morphology has been intensively studied in various
fields
including biology, organic chemistry, pharmaceuticals, and optics.
On-demand and dynamic chiral inversion not only cannot be realized
in most intrinsically chiral materials but also has mostly been limited
to chemical or light-induced methods. Herein, we report reversible
real-time magneto-mechanical chiral inversion of a three-dimensional
(3D) micropillar array between achiral, clockwise, and counterclockwise
chiral arrangements. Inspired by the flower corolla, achiral arrays
of five and six radially arranged semicylindrical micropillars were
employed as model systems to investigate the dynamic symmetry properties
of arrays consisting of odd and even numbers of micropillars, respectively.
Each micropillar underwent twisting actuation with a different twisting
angle depending on the angle with the magnetic field direction and
magnetic flux density, thereby collectively changing the chirality
from the achiral to chiral state. Importantly, the morphological handedness
of the micropillars was inverted within a few seconds by manipulating
the direction of the magnetic field. A chiral morphology consisting
of magnetically twisted micropillars was shape-fixed by the introduction
of a polymeric binder. This binder could be simply washed off to return
the shape-fixed twisted micropillars to their initial straight state.
Magnetically programmable and reproducible 3D flower corolla-like
micropillar arrays are expected to expand the potential of shape-reconfigurable
devices that require real-time chiral manipulation in ambient environments.
“…We also observed that the assembly of arrays occurred despite small contact areas among pillar tops, unlike in the case of capillary-collapsed nanopillar arrays . The polymeric solutes are localized at the interspace of self-assembled micropillars. − The original upright states of the micropillars were retrieved with regular spacings by simply rinsing out the water-soluble polymers. Therefore, micropillar arrays can be subjected to magnetic actuation or the evaporation of a polymeric solution for reversible chirality selection or capillary-assisted self-assembly.…”
Chiral morphology has been intensively studied in various
fields
including biology, organic chemistry, pharmaceuticals, and optics.
On-demand and dynamic chiral inversion not only cannot be realized
in most intrinsically chiral materials but also has mostly been limited
to chemical or light-induced methods. Herein, we report reversible
real-time magneto-mechanical chiral inversion of a three-dimensional
(3D) micropillar array between achiral, clockwise, and counterclockwise
chiral arrangements. Inspired by the flower corolla, achiral arrays
of five and six radially arranged semicylindrical micropillars were
employed as model systems to investigate the dynamic symmetry properties
of arrays consisting of odd and even numbers of micropillars, respectively.
Each micropillar underwent twisting actuation with a different twisting
angle depending on the angle with the magnetic field direction and
magnetic flux density, thereby collectively changing the chirality
from the achiral to chiral state. Importantly, the morphological handedness
of the micropillars was inverted within a few seconds by manipulating
the direction of the magnetic field. A chiral morphology consisting
of magnetically twisted micropillars was shape-fixed by the introduction
of a polymeric binder. This binder could be simply washed off to return
the shape-fixed twisted micropillars to their initial straight state.
Magnetically programmable and reproducible 3D flower corolla-like
micropillar arrays are expected to expand the potential of shape-reconfigurable
devices that require real-time chiral manipulation in ambient environments.
“…These well-defined nanostructures with high freedom of structural designability could result in some unique properties. Furthermore, external stimuli (e.g., capillary force, light, magnetic field, and heat) will further adjust these properties in a dynamic way 7 . Such promising features should be in favor of device utilization.…”
Section: Resultsmentioning
confidence: 99%
“…Due to the compelling requirement of device miniaturization, synthesis of nanoscopic structures and their macroscopic integration into a large-scale array are fundamental to modern and future devices in the fields of optics 1 , electronics 2 , telecommunication 3 , biology 4 , energy conversion/storage 5 , 6 , and stimuli-responsive materials 7 , etc. It is known that nanostructures are subject to physical and chemical property variation as a function of their geometry and composition; 8 and arrayed assemblies of these nanostructures exhibit collective behaviors of their responses in terms of coupling in the same set and synergy between different sets 9 , 10 , .…”
Well-defined nanostructuring over size, shape, spatial configuration, and multi-combination is a feasible concept to reach unique properties of nanostructure arrays, while satisfying such broad and stringent requirements with conventional techniques is challenging. Here, we report designable anodic aluminium oxide templates to address this challenge by achieving well-defined pore features within templates in terms of in-plane and out-of-plane shape, size, spatial configuration, and pore combination. The structural designability of template pores arises from designing of unequal aluminium anodization rates at different anodization voltages, and further relies on a systematic blueprint guiding pore diversification. Starting from the designable templates, we realize a series of nanostructures that inherit equal structural controllability relative to their template counterparts. Proof-of-concept applications based on such nanostructures demonstrate boosted performance. In light of the broad selectivity and high controllability, designable templates will provide a useful platform for well-defined nanostructuring.
“…An example of small scale devices is micro-and nanopillars assembled into arrays on the flat substrates [2]. Areas of applications of small-scale pillar arrays include e.g.…”
This paper deals with multicomponent systems subjected to suddenly applied loads. Such multicomponent systems consist of functionally identical elements, but the elements differ in their ability to sustain the applied load. Specifically, arrays of pillars are an example of the multicomponent systems. The capability of the array to sustain the applied load depends not only on the strength of the pillars but also on how the load coming from failed pillars is redistributed to the intact ones. We employ a Fiber Bundle Model with load transfer restricted within a rectangular region generated dynamically after each pillar's destruction. We investigate strength of the array and its survivability.
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