High‐Resolution 3D Direct Laser Writing for Liquid‐Crystalline Elastomer Microstructures

Zeng, Hao; Martella, Daniele; Wasylczyk, Piotr; Cerretti, Giacomo; Lavocat, Jean-Christophe Gomez; Ho, Chih-Hua; Parmeggiani, Camilla; Wiersma, Diederik S.

doi:10.1002/adma.201305008

Cited by 178 publications

(193 citation statements)

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“…[17], and 1 wt% of green light absorbing dye (Disperse Orange 3, Sigma Aldrich). After UV polymerization, the dyes were embedded inside the elastomeric network, without being covalently bonded to the polymeric chain.…”

Section: Methodsmentioning

confidence: 99%

“…After polymerization in the nematic state, the resulting elastomer exhibits a reversible 18% contraction in the direction parallel to the molecular orientation (director) and at the same time around 10% expansion in the perpendicular direction if the nematic order is destroyed by increasing the temperature (compare Figure 2a). [17] The monomer mixture is melted and infiltrated into a 50 μm glass cell with polyimide orienting coating on both inner surfaces (for details see Experimental Section). The top and bottom glass plates are mechanically rubbed with a pattern of 1 mm wide stripes and aligned in such a way that the rubbed areas on one glass face the nonrubbed areas on the other, as shown in Figure 2b.…”

Section: Doi: 101002/adom201600503mentioning

confidence: 99%

“…[16] With the recently developed laser lithography and molecular alignment engineering [17,18] it is now possible to pattern these soft materials in arbitrary 3D forms with a predefined actuation performance. The light-induced deformation can vary with illumination conditions, allowing one monolithic LCE structure to perform different actions, where a conventional robot would need numerous discrete actuators, each of them individually controlled.…”

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confidence: 99%

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Light‐Driven Soft Robot Mimics Caterpillar Locomotion in Natural Scale

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Section: Methodsmentioning

confidence: 99%

Section: Doi: 101002/adom201600503mentioning

confidence: 99%

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Light‐Driven Soft Robot Mimics Caterpillar Locomotion in Natural Scale

Rogóż

Zeng

Chen

et al. 2016

Advanced Optical Materials

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“…True antiplectic metachrony could be achieved by constructing the swimmer's body from an auxetic (negative Poisson's ratio) material. Passive, micro-scale auxetic metamaterials have been fabricated using technology that can be applied to LCEs 45,46 . Nevertheless, our microswimmers are capable of broader functionality than is found in nature, where any given species of ciliate exhibits only one mode of metachrony.…”

Section: Self-propulsion By Biomimetic Travelling-wave Body Deformationsmentioning

confidence: 99%

Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots

et al. 2016

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Microorganisms move in challenging environments by periodic changes in body shape. By contrast, current artificial microrobots cannot actively deform, exhibiting at best passive bending under external fields. Here, by taking advantage of the wireless, scalable and spatiotemporally selective capabilities that light allows, we show that soft microrobots consisting of photoactive liquid-crystal elastomers can be driven by structured monochromatic light to perform sophisticated biomimetic motions. We realized continuum yet selectively addressable artificial microswimmers that generate travelling-wave motions to self-propel without external forces or torques, as well as microrobots capable of versatile locomotion behaviours on demand. Both theoretical predictions and experimental results confirm that multiple gaits, mimicking either symplectic or antiplectic metachrony of ciliate protozoa, can be achieved with single microrobots. The principle of using structured light can be extended to other applications that require microscale actuation with sophisticated spatiotemporal coordination for advanced microrobotic technologies. 3Mobile micro-scale robots are envisioned to navigate within the human body to perform minimally invasive diagnostic or therapeutic tasks 1,2 . Biological microorganisms represent the natural inspiration for this vision. For instance, microorganisms successfully swim and move through a variety of fluids and tissues.Locomotion in this regime, where viscous forces dominate over inertia (low Reynolds number), is only possible through non-reciprocal motions demanding spatiotemporal coordination of multiple actuators 3 . A variety of biological propulsion mechanisms at different scales, from the peristalsis of annelids (Fig. 1a) to the metachrony of ciliates (Fig. 1b), are based on the common principle of travelling waves (Fig. 1c). These emerge from the distributed and self-coordinated action of many independent molecular motors 4,5 .Implementing travelling wave propulsion in an artificial device would require many discrete actuators, each individually addressed and powered in a coordinated fashion (Fig. 1d). The integration of actuators into microrobots that are mobile poses additional hurdles, since power and control need to be distributed without affecting the microrobots' mobility. Existing microscale actuators generally rely on applying external magnetic 6-10 , electric 11 , or optical 12,13 fields globally over the entire workspace. However, these approaches do not permit the spatial selectivity required to independently address individual actuators within a micro-device. Nevertheless, complex non-reciprocal motion patterns have been achieved by carefully engineering the response of different regions in a device to a spatially uniform external field 13,14 .The drawback is that this complicates the fabrication process, inhibits down-scaling and constrains the device to a single predefined behaviour. These challenges mean that most artificial microrobots actually have no actuators. Rather...

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“…For this reason the absorption maximum of the azo-dye is tuned to around 530 nm by changing the substituent on the aromatic rings. 29 This also coincides with the pump wavelength of PM 597-doped laser cavities.…”

Section: Sample Fabricationmentioning

confidence: 99%

Optically controlled elastic microcavities

et al. 2015

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Whispering gallery mode (WGM) resonators made from dielectrics like glass or polymers have outstanding optical properties like huge cavity quality (Q) factors which can be achieved on scales compatible with on-chip integration. However, tunability of these resonances is typically difficult to achieve or not suitable for robust device applications. We report here on the fabrication of polymeric micro-goblet WGM resonators with an optically controlled and stable reversible tunability over a large spectral range. This tunability is achieved by integration of photo-responsive liquid crystalline elastomers (LCEs) into micro-goblet cavities. The optical response of the elastomer allows reshaping the goblet by employing low pump power, leading to a fully reversible tuning of the modes. The structure can be realistically implemented in on-chip devices, combining the ultra-high Q factors, typical of WGM resonators, with reliable, optical tunability. This result serves as an example of how light can control light, by invoking a physical reshaping of the structure. This way of optical tuning creates interesting possibilities for all-optical control in circuits, enabling interaction between signal and control beams and the realization of self-tuning cavities. Keywords: liquid crystal elastomers; polymeric cavities; tunable micro-resonators; whispering gallery modes INTRODUCTION Solid-state optical microcavities are versatile photonic devices which come in a large variety of appearances. 1 Of particular interest are whispering gallery mode (WGM) resonators which feature small modal volume and large quality (Q) factors. 2 They are highly attractive for fundamental physics studies like cavity quantum electrodynamics, 3 as well as for applications like single photon sources, 4 optical sensing 5 or communication technology. 6,7 A key feature of WGM microcavities is the occurrence of ultra-narrow optical resonances and the functionality of the cavity often relies on the shift of the resonance frequency. This is the case, e.g., for optical sensors where the modal shift indicates the presence of attached bio-molecules or a change in the composition of the surrounding medium. 5 Essential features of such resonators are thus a large free spectral range and a narrow linewidth of the resonances but for many applications additionally an active manipulation of the cavity resonances is required. Examples are the tuning of the cavity into resonance with a quantum emitter 8,9 or utilization of the cavity in optical filters and light modulators. 10 In the last decade, a new class of WGM resonators has emerged featuring ultra-high Q factors. These resonators have spherical, cylindrical, toroidal, disk or goblet shapes 1,9,11 and are made of silica, polymers or liquids. Besides their excellent sensing capabilities they can also be turned into micro-lasers when incorporating laser dyes 12 or quantum dots 13 or be coupled to form photonic molecules. 14 But an obstacle effectively hindering some applications of these cavities is the limited tunab...

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High‐Resolution 3D Direct Laser Writing for Liquid‐Crystalline Elastomer Microstructures

Cited by 178 publications

References 18 publications

Light‐Driven Soft Robot Mimics Caterpillar Locomotion in Natural Scale

Light‐Driven Soft Robot Mimics Caterpillar Locomotion in Natural Scale

Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots

Optically controlled elastic microcavities

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