Light‐Fueled Microscopic Walkers

Zeng, Hao; Wasylczyk, Piotr; Parmeggiani, Camilla; Martella, Daniele; Burresi, Matteo; Wiersma, Diederik S.

doi:10.1002/adma.201501446

Cited by 398 publications

(428 citation statements)

References 29 publications

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“…Since they can be fabricated at small length scales 35,36 and powered remotely, they are ideally suited for building mobile active robots with body sizes on the scale of hundreds of microns 32 . Instead of uniformly illuminating a complex, carefullyengineered device 13 or focusing the light onto a single spot [37][38][39] , our approach is to use structured dynamic light fields to excite sophisticated intra-body deformations within LCE microrobots with very simple and agnostic designs.…”

Section: System Conceptmentioning

confidence: 99%

“…The photoresponse arises when the covalently bound azobenzene dye in the LCE absorbs the light, driving the elastomer through the nematicto-isotropic phase transition. The mechanism consists of two different, but likely concurrent effects: the dye's trans-cis photoisomerization, and a light-induced thermal effect 32,33,37 . The axial nematic alignment of our cylinders leads, under homogeneous illumination, to axial contraction and simultaneous radial expansion (Fig.…”

Section: Selective Deformation Of Soft Continuous Micro-scale Bodiesmentioning

confidence: 99%

“…4a). The nematic LCE used for these disks exhibits typical contractions of about 20% 32 . Crucially, their axial symmetry means that, within the disk's plane, there is no preferential direction of movement.…”

Section: Versatile Microrobots Exhibit Different Behaviours On Demandmentioning

confidence: 99%

“…At the microscale, soft active materials have enriched microrobots with additional functionalities, e.g. ondemand drug release 30,31 , and LCEs have recently actuated a walking microrobot 32 .…”

Section: Introductionmentioning

confidence: 99%

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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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Section: System Conceptmentioning

confidence: 99%

Section: Selective Deformation Of Soft Continuous Micro-scale Bodiesmentioning

confidence: 99%

Section: Versatile Microrobots Exhibit Different Behaviours On Demandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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“…This technique allows us to create compound LCE elements which can support multiple functionalities. With outstanding ability to create accurate 3D microstructures and control of actuation, we expect this technique to be used for creating elastomer based microscopic robots 14 , and to open up a plethora of new strategies for the obtainment of light tunable devices 15 .…”

Section: Discussionmentioning

confidence: 99%

Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale

Zeng

Wasylczyk

Parmeggiani

et al. 2016

JoVE

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Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers' attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary threedimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

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Thermal‐ and Photo‐deformable Liquid Crystal Polymers and Bioinspired Movements

Liu

2018

Bioinspired Materials Science and Engineering

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Light‐Fueled Microscopic Walkers

Abstract: The first microscopic artificial walker equipped with liquid‐crystalline elastomer muscle is reported. The walker is fabricated by direct laser writing, is smaller than any known living terrestrial creatures, and is capable of several autonomous locomotions on different surfaces.

Cited by 398 publications

References 29 publications

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

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

Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale

Thermal‐ and Photo‐deformable Liquid Crystal Polymers and Bioinspired Movements

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Light‐Fueled Microscopic Walkers

Abstract: The first microscopic artificial walker equipped with liquid‐crystalline elastomer muscle is reported. The walker is fabricated by direct laser writing, is smaller than any known living terrestrial creatures, and is capable of several autonomous locomotions on different surfaces.

Cited by 398 publications

References 29 publications

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

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

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Thermal‐ and Photo‐deformable Liquid Crystal Polymers and Bioinspired Movements

Contact Info

Product

Resources

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Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale