Strain tunable optics of elastomeric microlens array

Li, Zhengwei; Xiao, Jianliang

doi:10.1016/j.eml.2015.05.005

Cited by 17 publications

(8 citation statements)

References 24 publications

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“…In our experiment, the compressive strain ε pre is caused by Poisson's effect when a tensile strain ε applied is applied along the horizontal direction in Figure a. Since PDMS is nearly incompressible, the compressive strain ε pre in Equation can be related to the tensile strain ε applied as

ε_{pre} = 1 - \frac{1}{\sqrt{1 + ε_{applied}}}

…”

Section: Resultsmentioning

confidence: 97%

“…Micro‐ and nanostructured soft surfaces offer a new strategy to dynamically tune optical properties by changing the surface topography without affecting the bulk properties . Recently, surface wrinkling has become a very cost‐effective, facile technology to reversibly control the surface topography, which inspired a wide range of applications such as thin‐film properties measurement, tunable adhesion and wettability, stretchable electronics, and optical materials/devices . Some more recently studies have demonstrated that surface wrinkling can also be used to prepare large‐area smart windows capable of controlling the light transmittance by means of micro‐ and nanopillar arrays on wrinkled elastomers, crumpling of metallic nanofilms, graphene films, and graphene oxide films on elastomeric substrates and silica nanoparticle‐embedded elastomer composite .…”

Section: Introductionmentioning

confidence: 99%

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Harnessing Surface Wrinkling–Cracking Patterns for Tunable Optical Transmittance

Zhai

Wang

et al. 2017

Advanced Optical Materials

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to prepare, and some of them are chemically unstable during optical switching. [11] Furthermore, the assembly of these smart windows often suffers from complicated processes, high cost, and low efficiency. [1,3] Therefore, a convenient, cheap, and highly effective method is desirable for the fabrication of large-area smart windows with advanced functional features, such as large transmittance modulation, fast response time, and chemical stability suitable for long-term use without deteriorating optical performance.Micro-and nanostructured soft surfaces offer a new strategy to dynamically tune optical properties by changing the surface topography without affecting the bulk properties. [12][13][14][15][16][17][18][19] Recently, surface wrinkling [20][21][22] has become a very cost-effective, facile technology to reversibly control the surface topography, which inspired a wide range of applications such as thinfilm properties measurement, [23] tunable adhesion and wettability, [24] stretchable electronics, [25][26][27][28] and optical materials/ devices. [29][30][31][32][33][34][35][36][37][38] Some more recently studies have demonstrated that surface wrinkling can also be used to prepare large-area smart windows capable of controlling the light transmittance by means of micro-and nanopillar arrays on wrinkled elastomers, [12,13] crumpling of metallic nanofilms, [14] graphene films, [15] and graphene oxide films [16] on elastomeric substrates and silica nanoparticle-embedded elastomer composite. [17] It should be made clear that the light transmittance change mentioned in these studies is actually normal transmittance change, which was usually achieved by scattering the light rather than absorbing the light. Despite the clear advantages in material fabrication and stability, these methods still suffer from complicated fabrication processes, high cost, small transmittance modulation range, or potential material degradation. For example, smart windows achieved by micro-and nanopillar arrays on wrinkled elastomers [12,13] usually require multistep fabrication processes including template preparation, replica modeling, and surface wrinkling. Furthermore, these pillar arrays cannot be completely eliminated during the mechanical actuation which limits the achievable transmittance modulation range. For thin film/elastomer systems, [14][15][16] extremely large and more complicated biaxial prestrains (e.g., 400% for graphene oxide film/silicone rubber system [16] ) are usually required to realize very large surface topography change to enable large optical transmittance tuning. And also, the thin film materials are Optical devices with tunable specular optical transmittance have recently attracted great interest due to their wide range of applications. However, the reported methods of realizing tunable optical transmittance suffer from complex fabrication processes, high cost, unstable materials, or low tuning range. In this study, a simple, cheap, and highly effective approach to achieve large tuning range of optical transm...

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ε_{pre} = 1 - \frac{1}{\sqrt{1 + ε_{applied}}}

…”

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Harnessing Surface Wrinkling–Cracking Patterns for Tunable Optical Transmittance

Zhai

Wang

et al. 2017

Advanced Optical Materials

Self Cite

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show abstract

“…In the current bilayer film, the compressive strain ε pre is caused by Poisson's effect when a mechanical strain ε applied is applied on the film. Since PDMS is nearly incompressible, the ε pre can be related to mechanical strain ε applied as

ε_{pre} = 1 - \frac{1}{\sqrt{1 + ε_{applied}}}

…”

Section: Resultsmentioning

confidence: 99%

A General and Robust Strategy for Fabricating Mechanoresponsive Surface Wrinkles with Dynamic Switchable Transmittance

Jiang

Liu

Gao

et al. 2018

Advanced Optical Materials

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including the use of liquid crystals, [7] suspended particles, [8] photonic crystals, [9] and chromogenic materials driven by temperature, [10] light, [11] mechanical force, [6,12] magnetic field, [13] and electrical field. [14] However, it still faces great challenges in practical uses of the smart optical materials, especially in smart windows, for example, due to the complicated process, high cost, and low efficiency for the preparation and fabrication of such smart windows. Therefore, it is highly desirable to develop simple and effective strategies to design new smart optical materials with rapid responsive time, large transmittance modulation, and good repeatability, which may open up new opportunities for applications in large-area smart windows.Wrinkling (or buckling) is a ubiquitous phenomenon that occurs in both natural [15] and artificial systems, [12a,16] with dimensions across a wide range of length scale from meters down to nanometers. Artificial wrinkles can be generated by introducing compressive stresses to a skin layer/elastomer substrate bilayer film through various approaches, such as thermal stress, [17] mechanical stress, [18] capillary force, [19] light-driven photoisomerization, [20] and osmotic pressure. [21] Owing to their spontaneous nature, versatility, and tunability or even total reversibility in response to external stimuli, surface wrinkling has provided an effective platform to create smart, controllable, and responsive surface topography and subsequently to dynamically tune functionality, which inspired various important applications including flexible electronic devices, [22] tunable diffraction gratings, [23] microlens arrays, [24] dry adhesives, [25] dynamic scaffolds, [26] and optical devices. [27] Since mechanical force as an external stimuli has many advantages such as simple and independent control of the amount, direction, and timing of strain, [28] some recent studies have demonstrated that mechanoresponsive surface wrinkles offer an effective and repeatable strategy to dynamically tune optical properties on-demand by changing the surface topography in responsive to mechanical force. For example, the light transmittance of mechanoresponsive surface wrinkles for smart windows has been dynamically tuned by means of micro-and nanopillar arrays on wrinkled elastomers, [28,29] harnessing Preparation of surface wrinkles on a skin layer/elastomer substrate bilayer film has attracted extensive attention because of their unique and broad applications in flexible electronic devices, tunable diffraction gratings, and smart windows. However, it still remains a great challenge to develop a general strategy for fabricating mechanoresponsive surface wrinkles using various skin layer materials with wide tunability of wrinkles' wavelength and amplitude, large optical modulation range, rapid optical switching rate, and high stability. Here, a general, simple, and cost-effective strategy is reported, through uniaxially stretching and subsequently releasing skin layer/elastomer substrate...

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“…Other researchers have built systems with deformable lens arrays to tune the focal length. Li et al [16] conducted a finite element analysis of a lens array placed in tension and studied the corresponding increase in focal length of the lenses in the lens array. Chandra et al [7] built concave and convex elastic microlens arrays whose focal lengths are tunable by stretching.…”

Section: Related Workmentioning

confidence: 99%

“…However, the lens array is attached to the mechanism such that its thickness will be unconstrained. As explored in the literature [12,11,16,7], when a lens array is stretched the shape of the individual lenses in the array will change. This change in shape will impact the imaging properties of the lenses.…”

Section: The Mechanical Principles Of Stretch Imagingmentioning

confidence: 99%

Stretchcam: Zooming Using Thin, Elastic Optics

Sims¹,

Cossairt²,

Yu³

et al. 2018

Preprint

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Stretchcam is a thin camera with a lens capable of zooming with small actuations. In our design, an elastic lens array is placed on top of a sparse, rigid array of pixels. This lens array is then stretched using a small mechanical motion in order to change the field of view of the system. We present in this paper the characterization of such a system and simulations which demonstrate the capabilities of stretchcam. We follow this with the presentation of images captured from a prototype device of the proposed design. Our prototype system is able to achieve 1.5 times zoom when the scene is only 300 mm away with only a 3% change of the lens array's original length.

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Strain tunable optics of elastomeric microlens array

Cited by 17 publications

References 24 publications

Harnessing Surface Wrinkling–Cracking Patterns for Tunable Optical Transmittance

Harnessing Surface Wrinkling–Cracking Patterns for Tunable Optical Transmittance

A General and Robust Strategy for Fabricating Mechanoresponsive Surface Wrinkles with Dynamic Switchable Transmittance

Stretchcam: Zooming Using Thin, Elastic Optics

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