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Photogated humidity-driven motility.

Zhang L, Liang H, Jacob J, Naumov P - Nat Commun (2015)

Bottom Line: Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light.A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min(-1).The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself.

View Article: PubMed Central - PubMed

Affiliation: New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.

ABSTRACT
Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min(-1). The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

No MeSH data available.


Mechanism of hygroinduced locomotion of PCAD@AG films.(a) Square-shaped film, (b) rectangular film and (c) film strip. For each aspect ratio and stage of locomotion, both cartoons and snapshots of the real film are shown.
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f3: Mechanism of hygroinduced locomotion of PCAD@AG films.(a) Square-shaped film, (b) rectangular film and (c) film strip. For each aspect ratio and stage of locomotion, both cartoons and snapshots of the real film are shown.

Mentions: The kinematics and mechanism of locomotion depend on the aspect ratio of the film. A film cut into a square undergoes a locomotive cycle composed of nine stages (Fig. 3a; Supplementary Movie 6). When the film is placed on a moist substrate, the expansion of the surface of the film facing the substrate due to adsorption of water exceeds that of the opposite (upper) surface, whereby the film curls up (I). As the gravity centre rises, the film becomes mechanically unstable and slumps to one side (II). The film then curls up from one corner and rolls over horizontally (III). The upper face of the film turns over the lower face and comes into contact with the moist substrate (IV). As the film unfolds, one corner starts rolling up again (V). The continual water adsorption and desorption eventually drives the film to curl up into a tubular shape (VI). Mechanical instability then causes the tube to roll and slide (VII). The upper face of the film slides down again (VIII), and due to asymmetric swelling, the unfolded film continues to curl up to start a new cycle (IX). A PCAD@AG film cut into a rectangular shape undergoes a series of sequential locomotive processes similar to those observed with a square-shaped film (Fig. 3b; Supplementary Movie 6). Briefly, the film curls up (I) to form a short tube (II) and topples over (III). It then unfolds, whereby the upper face turns down (IV). The film then rolls up from one corner (V) and shapes up into a long tube (VI), which unfolds (VII), cocks up from one corner (VIII) and rolls from one side to start a new cycle (IX).


Photogated humidity-driven motility.

Zhang L, Liang H, Jacob J, Naumov P - Nat Commun (2015)

Mechanism of hygroinduced locomotion of PCAD@AG films.(a) Square-shaped film, (b) rectangular film and (c) film strip. For each aspect ratio and stage of locomotion, both cartoons and snapshots of the real film are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490392&req=5

f3: Mechanism of hygroinduced locomotion of PCAD@AG films.(a) Square-shaped film, (b) rectangular film and (c) film strip. For each aspect ratio and stage of locomotion, both cartoons and snapshots of the real film are shown.
Mentions: The kinematics and mechanism of locomotion depend on the aspect ratio of the film. A film cut into a square undergoes a locomotive cycle composed of nine stages (Fig. 3a; Supplementary Movie 6). When the film is placed on a moist substrate, the expansion of the surface of the film facing the substrate due to adsorption of water exceeds that of the opposite (upper) surface, whereby the film curls up (I). As the gravity centre rises, the film becomes mechanically unstable and slumps to one side (II). The film then curls up from one corner and rolls over horizontally (III). The upper face of the film turns over the lower face and comes into contact with the moist substrate (IV). As the film unfolds, one corner starts rolling up again (V). The continual water adsorption and desorption eventually drives the film to curl up into a tubular shape (VI). Mechanical instability then causes the tube to roll and slide (VII). The upper face of the film slides down again (VIII), and due to asymmetric swelling, the unfolded film continues to curl up to start a new cycle (IX). A PCAD@AG film cut into a rectangular shape undergoes a series of sequential locomotive processes similar to those observed with a square-shaped film (Fig. 3b; Supplementary Movie 6). Briefly, the film curls up (I) to form a short tube (II) and topples over (III). It then unfolds, whereby the upper face turns down (IV). The film then rolls up from one corner (V) and shapes up into a long tube (VI), which unfolds (VII), cocks up from one corner (VIII) and rolls from one side to start a new cycle (IX).

Bottom Line: Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light.A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min(-1).The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself.

View Article: PubMed Central - PubMed

Affiliation: New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.

ABSTRACT
Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min(-1). The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

No MeSH data available.