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A CNT-shape memory polymer nanocomposite curling toward an infrared (IR) source. IR absorption by the CNTs is constrained to the near-surface region of a stretched ribbon. Nonradiative decay results in local heating, which leads to contraction of the near-surface region and curling of the ribbon toward the infrared source within 5 s.
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The ability to control the creation of mechanical work remotely, with high speed and spatial precision, over long distances, offers many intriguing possibilities. Recent developments in photoresponsive polymers and nanocomposite concepts are at the heart of these future devices. Whether driving direct conformational changes, initiating reversible c...
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... Composite polymer materials are widely used in many research fields [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. They are also employed in the conversion of light into mechanical work that is achieved by photoactuated films and devices based on azobenzene liquid crystals (LC) polymers [15][16][17][18][19][20][21]. Another way to convert light into work is represented by recently developed holographic photomobile polymer materials (H-PMP) where the motion can be realized by exploiting the light-induced Marangoni effect [22][23][24][25][26][27][28]. ...
We report on the photo-mobility properties of a free standing large area graphene oxide (GO) paper (GOP). The thickness of the film is ≈20 μm. GOP is made by drop casting an aqueous suspension of GO on a microscope glass slide placed on a hot plate kept at the temperature of 70 °C. The film is peeled-off from the glass substrate and irradiated under different coherent and incoherent light sources. The film bends up to ≈55° when the irradiation is made using a near infra-red (NIR) incoherent incandescent lamp and returns back to the initial position when the NIR lamp is switched-off. The bending mechanism is attributed to the asymmetry of the GOP film obtained during the film formation process. We characterize the film morphology and structure using a Scanning Electron Microscopy (SEM) imaging and X-ray Diffraction (XRD) measurements, respectively. Remarkable differences between the two surfaces of the GOP are evidenced, both on a macroscopic length scale (surface roughness) and on a microscopic one (GO interlayer distance). This asymmetry results in different (negative) thermal expansion coefficients for the two film surfaces and hence in the bending of the film when the film temperature is increased by light absorption.
... Composite polymer materials, already used in a wide variety of applications such as [10][11][12][13][14][15][16][17][18], play a fundamental role in materials science. Among them, photomobile polymers (PMP), which are materials able to convert light energy into mechanical work, represent the ideal platform for the development of a large variety of touchless devices [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In this work, we introduce a novel acousto-optic experimental setup in which small objects rotate around a single axis in space. ...
In this work, we study the light-induced changes of the rotational speed of a thin photomo-
bile film using a single-axis acoustic levitator operating at 40 kHz. In our experiments, a 50 µm thick
photomobile polymer film (PMP) is placed in one of the nodes of a stationary acoustic field. Under the
action of the field, the film remains suspended in air. By externally perturbing this stable equilibrium
condition, the film begins to rotate with its natural frequency. The rotations are detected in real
time by monitoring the light of a low power He–Ne laser impinging on and reflected by the film
itself. During the rotational motion, an external laser source is used to illuminate the PMP film; as a
consequence, the film bends and the rotational speed changes by about 20 Hz. This kind of contactless
long-distance interaction is an ideal platform for the development and study of many electro-optics
devices in microgravity and low-friction conditions. In particular, we believe that this technology
could find applications in research fields such as 3D dynamic displays and aerospace applications.
... Nowadays, composite materials are used in many application fields spanning from optical-/photonic-materials, devices, and holographic sensors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Materials responding to light-/photonic-stimuli are a novel emergent class of compounds that include azobenzene-based liquid crystal photomobile polymer films (azo-PMP) [17][18][19][20][21][22][23][24][25][26][27]. However, the most used and notable azo-PMPs are limited in their use and commercial diffusion due to two main factors: their cost and the dependence of the reversibility of their motion on two wavelengths. ...
In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape with a layer of graphene-oxide (GO) attached. Under illumination at different intensities, and with coherent and incoherent light sources, the bending of the PMP film changes considerably. In particular, we noticed a more efficient bending effect when the film is directly exposed to high light intensities or to NIR radiation in the case of incoherent light sources. For the exposure times used in our experiments, the process is completely reversible when the light source is switched off. Additionally, if we paint the side of the PVC tape exposed to light black, the film is not able to return to its starting position and the bending results are permanent. This suggests that the presence of the GO-layer is responsible for the restoration of the position of the PMP film.
... The mechanical actuation demonstrated in VO 2 has been shown to lead to significant displacements in various nanostructures including nanowires, nanomembranes, and thin films [16][17][18]. Indeed the mechanical response has enabled the use of VO 2 as an actuator in various nanomechanical systems, microrobotics, and biomimetics [19][20][21][22]. In all of these applications, VO 2 is generally used as part of a bimorph system, in which VO 2 provides the actuation and a different material provides a restorative force. ...
Vanadium dioxide (VO2), a thermochromic material, undergoes an insulator-to-metal transition resulting from a thermally induced crystallographic transformation. The monoclinic insulator phase transitions to a rutile metallic phase resulting in a fast reversible transition of an array of its material properties. Here, we present the temperature-induced multi-physical transformation of a VO2 thin film grown via physical vapor deposition. Growth of the phase-changing oxide, structural characterization of the thin film, electrical transition, and the in situ thermo-mechanical response of the deposited film will be discussed. Further, we present simulation results from the investigation of these material properties in the context of actuation of VO2-bimorphs for a vertical switch and discuss how the application of this material may be extended to aerospace applications.
... Holographic structures have been recently written in photomobile polymer (PMP) films [21,22,23]. The mobility of these polymers is induced and controlled by using an external light source [24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48]. Azo-benzene based PMP thin films are processed by polarized light to generate and orient surface relief gratings [23]. ...
We recorded a permanent phase transmission grating on a thin film made by using a recently developed holographic photomobile mixture. The recorded grating pitch falls in the visible range and can be optically manipulated by using an external coherent or incoherent low power light source. When the external light source illuminates the grating the entire structure bends and, as a consequence, the optical properties of the grating change. This peculiarity makes it possible to use the recorded periodic structure as an all-optically controlled free standing thin colour selector or light switch depending on the source used to illuminate the grating itself. Additionally, it could open up new possibilities for stretchable and reconfigurable holograms controlled by light as well as thin devices for optically reconfigurable dynamic communications and displays.
... soft liquid hydrogel micro-lenses, by using light can be applied for endoscopy. [99][100][101] There are reports of the development of polypyrrole (PPy), conducting polymer (CP) trilayer actuator arrays which can be applied to other adaptive optics actuator technologies, such as piezoelectric actuators or electrostatic electrodes. 16 There are reports of the designing of an EAP-piston tilt mirror that can be used for retinal diagnostics. ...
At present, self-repairing, intelligent materials are being considered as future material. In this perspective, the electroactive materials are unique for their adaptability, sharp response time, control over the system, quick response rate, low power consumption, and compactness. The electroactive materials include electroactive polymers (EAPs), piezoelectric materials, electroactive gels, and fullerene compounds. The photonic interaction of light with the electroactive material converts light energy into mechanical energy and leads to multi-directional applications. Contemporarily with increased interest and emphasis on ‘green’ technological solutions, efforts are focussed on utilizing these electroactive materials with light energy. Corresponding to this, biomimetic and artificial intelligence are advancing to develop various optoelectronic devices, energy conversion and storage devices, photoresistors, vehicle components, sensors, robots, and medical devices. A better understanding of such light illumination with electroactive materials and prospective applications contributes to the planning of beneficial smart materials. Hence, this review article focusses on the interaction of light with different electroactive materials, their applications, and prospects of the current and future investigations.
... On the macroscopic view of this, the bilayer actuator exhibits a rapid actuation with full cycles completed within seconds ( Fig. 3.7A). Taking advantage of azobenzene dyes that cause shape deformation when included in a liquid-crystal network or liquid-crystal rubber (Camacho-Lopez et al., 2004;Finkelmann et al., 2001;Koerner et al., 2008;White et al., 2008), L. van Oosten et al. employed the dyes of A3MA and DR1A to prepare light-responsive artificial cilia by inkjet printing. These two azobenzene-containing dyes were introduced to the liquid-crystal monomers separately to form different inks with a selective absorbing wavelength of light. ...
4D -printed functional materials with animated architectures that have the ability to change their shape, properties, and functions in response to light have had a dramatic growth in interest in recent decades because light, as an excellent stimulus, enables remote control, rapidly switching on and off, easy tunability, precisely local area projection, and other advantageous features. This chapter focuses on the growing research on 4D-printed light-responsive structures, including their basic design principles and actuation mechanisms, the advanced material, and the light-responsive behaviors. Special attention is devoted to the complex shape deformation, the soft robots, and others. Potential emerging applications in encryption, anticounterfeiting, self-healing, and photo-controlled microfluidics are further illustrated. Finally, the current challenges and outlook toward 4D-printed light-responsive structures are also pointed out to leave open a significant space for future innovation.
... On the macroscopic view of this, the bilayer actuator exhibits a rapid actuation with full cycles completed within seconds ( Fig. 3.7A). Taking advantage of azobenzene dyes that cause shape deformation when included in a liquid-crystal network or liquid-crystal rubber (Camacho-Lopez et al., 2004;Finkelmann et al., 2001;Koerner et al., 2008;White et al., 2008), L. van Oosten et al. employed the dyes of A3MA and DR1A to prepare light-responsive artificial cilia by inkjet printing. These two azobenzene-containing dyes were introduced to the liquid-crystal monomers separately to form different inks with a selective absorbing wavelength of light. ...
Additive manufacturing technologies such as screen, inkjet, and three-dimensional (3D) printing of various conductive, nonconductive, and specifically engineered materials can be beneficially employed to fabricate diverse electronic systems such as sensors, actuators, and batteries. By employing these technologies, such systems can be fabricated highly specialized and individualized while still being comparably inexpensive. The high degree of specialization has recently led to an increased aim to reduce system complexity while still achieving the desired functionality. To this end, 4D-printing is an advantageous approach since it results in systems that can be externally controlled through specific environmental stimuli (temperature, humidity, light, etc.) without the necessity of solid-state circuitry and control algorithms. This chapter deals with functionalized sensor systems based on additive fabrication technologies and their combinations. An outline of how these can be beneficially applied to robotics and wearable medical applications for human-device interfaces is given together with an outlook into the developments toward 4D-printing and promising future applications.
... It is embedded into supramolecular assemblies [2][3][4] and proteins [5] to modify the structure of materials and influence biological processes. Polymers incorporating azo moieties can be patterned by irradiation [6][7][8][9][10][11] and azo-based LC-polymers generate strong opto-mechanical responses that can be harnessed for light-controllable actuators [12][13][14], to name only a few examples. ...
This computational study investigates the influence of light on supramolecular aggregates of three-arm azobenzene stars. Every star contains three azobenzene (azo) moieties, each able to undergo reversible photoisomerization. In solution, the azo stars build column-shaped supramolecular aggregates. Previous experimental works report severe morphological changes of these aggregates under UV–Vis light. However, the underlying molecular mechanisms are still debated. Here we aim to elucidate how light affects the structure and stability of the columnar stacks on the molecular scale. The system is investigated using fully atomistic molecular dynamics (MD) simulations. To implement the effects of light, we first developed a stochastic model of the cyclic photoisomerization of azobenzene. This model reproduces the collective photoisomerization kinetics of the azo stars in good agreement with theory and previous experiments. We then apply light of various intensities and wavelengths on an equilibrated columnar stack of azo stars in water. The simulations indicate that the aggregate does not break into separate fragments upon light irradiation. Instead, the stack develops defects in the form of molecular shifts and reorientations and, as a result, it eventually loses its columnar shape. The mechanism and driving forces behind this order–disorder structural transition are clarified based on the simulations. In the end, we provide a new interpretation of the experimentally observed morphological changes.
... The layers can be overlaid and designed to be water soluble to disintegrate the outer layers. [95][96][97][98][99][100]. Again, this work is focused on actuators with flexible and soft-engineered materials, thus many intensely studied opto-mechanisms are not included, such as optical tweezers [101,102], micro optomechanical systems (MOMS) by photo coupling [103,104] and optical forces (radiant pressure and gradient forces) [105,106], and photostrictive actuators [107,108], among others. ...
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