Polarization-dependent deformation in light responsive polymers doped by dichroic dyes

Martella, Daniele; Nocentini, Sara; Micheletti, Filippo; Wiersma, Diederik S.; Parmeggiani, Camilla

doi:10.1039/c8sm01954a

Cited by 39 publications

(45 citation statements)

References 32 publications

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“…Both laser and incoherent light irradiation (by an LED lamp) can be used to drive the deformation [38]. Within the selected formulations, the mechanism of the material reshaping has to be ascribed to thermal heating (where light energy is dissipated inside the network as heat) [39], rather than an optical effect, due to the trans-to-cis isomerization that, on the other hand, affords a photo-softening effect at low light power [27]. As the laser power increase, the material temperature gradually increases, disordering the molecular arrangement and thus leading to different curvature radii [27].…”

Section: Resultsmentioning

confidence: 99%

“…Even if modulation of the light-dose response can also be achieved by other strategies (such as by variation of the dye content [42]), the proposed approach focuses on the improvement of shape-deformation at lower temperatures, which is required for the use of reduced energy in photothermal effects. An additional degree of freedom should be introduced by means of dichroic dyes controlled by polarized light [39].…”

Section: Resultsmentioning

confidence: 99%

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Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach

Martella¹,

Nocentini²,

Antonioli

et al. 2019

Polymers

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The ability to obtain 3D polymeric objects by a 2D-to-3D shape-shifting method is very appealing for polymer integration with different materials, from metals in electronic devices to cells in biological studies. Such functional reshaping can be achieved through self-folding driven by a strain pattern designed into the molecular network. Among polymeric materials, liquid crystalline networks (LCNs) present an anisotropic molecular structure that can be exploited to tailor internal strain, resulting in a natural non-planar geometry when prepared in the form of flat films. In this article, we analyze the influence of different molecular parameters of the monomers on the spontaneous shape of the polymeric films and their deformation under different stimuli, such as heating or light irradiation. Modifying the alkilic chains of the crosslinkers is a simple and highly effective way to increase the temperature sensitivity of the final actuator, while modifying ester orientation on the aromatic core interestingly acts on the bending direction. Combining such effects, we have demonstrated that LCN stripes made of different monomeric mixtures originate complex non-symmetric deformation under light activation, thus opening up new applications in photonic and robotics.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach

Martella¹,

Nocentini²,

Antonioli

et al. 2019

Polymers

View full text Add to dashboard Cite

show abstract

“…Optical control works differently and makes use of different properties of the light field. Robots can be made to respond differently to different parts of the optical spectrum,73 with, in principle, a large degree of freedom in “spectral fingerprint.” The polarization of light is the second control mechanism,74,75 and the third is spatial patterning of the light 12. Control light can be either scanned (e.g., with micromirrors) or projected with the desired pattern.…”

Section: Pros and Cons Discussionmentioning

confidence: 99%

Pros and Cons: Magnetic versus Optical Microrobots

2020

Self Cite

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Mobile microrobotics has emerged as a new robotics field within the last decade to create untethered tiny robots that can access and operate in unprecedented, dangerous, or hard‐to‐reach small spaces noninvasively toward disruptive medical, biotechnology, desktop manufacturing, environmental remediation, and other potential applications. Magnetic and optical actuation methods are the most widely used actuation methods in mobile microrobotics currently, in addition to acoustic and biological (cell‐driven) actuation approaches. The pros and cons of these actuation methods are reported here, depending on the given context. They can both enable long‐range, fast, and precise actuation of single or a large number of microrobots in diverse environments. Magnetic actuation has unique potential for medical applications of microrobots inside nontransparent tissues at high penetration depths, while optical actuation is suitable for more biotechnology, lab‐/organ‐on‐a‐chip, and desktop manufacturing types of applications with much less surface penetration depth requirements or with transparent environments. Combining both methods in new robot designs can have a strong potential of combining the pros of both methods. There is still much progress needed in both actuation methods to realize the potential disruptive applications of mobile microrobots in real‐world conditions.

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“…If the design of new machines based on photo-responsive elastomers is to go beyond single contracting or bending strips of a stimulus-responsive material, towards more complex modes of operation, better understanding of the photo-mechanical response of LCE actuators is needed. The light-induced deformation of liquid crystal elastomers can be sensitive to the light spectrum [40] or polarization [41]. This offers more degrees of freedom much needed for the realization of the non-reciprocal motion and other advanced functionalities.…”

Section: Discussionmentioning

confidence: 99%

Photo-Mechanical Response Dynamics of Liquid Crystal Elastomer Linear Actuators

2020

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With continuous miniaturization of many technologies, robotics seems to be lagging behind. While the semiconductor technologies operate confidently at the nanometer scale and micro-mechanics of simple structures (MEMS) in micrometers, autonomous devices are struggling to break the centimeter barrier and have hardly colonized smaller scales. One way towards miniaturization of robots involves remotely powered, light-driven soft mechanisms based on photo-responsive materials, such as liquid crystal elastomers (LCEs). While several simple devices have been demonstrated with contracting, bending, twisting, or other, more complex LCE actuators, only their simple behavior in response to light has been studied. Here we characterize the photo-mechanical response of a linear light-driven LCE actuator by measuring its response to laser beams with varying power, pulse duration, pulse energy, and the energy spatial distribution. Light absorption decrease in the actuator over time is also measured. These results are at the foundation of further development of soft, light-driven miniature mechanisms and micro-robots.

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Polarization-dependent deformation in light responsive polymers doped by dichroic dyes

Abstract: A polarization-dependence of the deformation in light-responsive materials can be induced through optimizing the dye dopant alignment.

Cited by 39 publications

References 32 publications

Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach

Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach

Pros and Cons: Magnetic versus Optical Microrobots

Photo-Mechanical Response Dynamics of Liquid Crystal Elastomer Linear Actuators

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