Object Transportation System Mimicking the Cilia of Paramecium aurelia Making Use of the Light‐Controllable Crystal Bending Behavior of a Photochromic Diarylethene

The design of an object transportation system exploiting the bending behavior of surface‐assembled diarylethene crystals is reported. A photoactuated smart surface based on this system can transport polystyrene beads to a desired area depending on the direction of the incident light. Two main challenges were addressed to accomplish directional motion along a surface: first, the preparation of crystals whose bending behavior depends on the direction of incident light; second, the preparation of a film on which these photochromic crystal plates are aligned. Nuclei generation and nuclear growth engineering were achieved by using a roughness‐controlled dotted microstructured substrate. This system demonstrates how to achieve a mechanical function as shown by remote‐controlled motion along a surface.     

Fabrication of Photoactuators: Macroscopic Photomechanical Responses of Metal–Organic Frameworks to Irradiation by UV Light

Photoreactive olefinic species are incorporated into a metal–organic framework (MOF), [Zn(bdc)(3‐F‐spy)] ( 1 ). Single crystals of 1 are shown to undergo three types of photomechanical macroscopic deformation upon illumination by UV light. To demonstrate the practical potential of this system, the inclusion of 1 in a PVA (polyvinyl alcohol) composite membrane, by exploiting hydrogen‐bonding interactions, is presented. Using this composite membrane, the amplification of mechanical stress to achieve macroscopic actuation behavior is demonstrated. These results pave the way for the generation of MOF‐based soft photoactuators that produce clearly defined mechanical responses upon irradiation with light. Such systems are anticipated to have considerable potential in photomechanical energy harvesting and conversion systems.