An artificial organic skin that can secrete liquid and wet its surface is demonstrated. The secretion is triggered by an alternating electric field at radio frequency. The polymer skin is constructed of a porous liquid crystal polymer network with the embedded dielectric liquid. The electric field accumulates the liquid in between the electrodes. By network contraction, the liquid is ejected at the surface of the polymer skin.
In analogy with developments in soft robotics it is anticipated that soft robotic functions at surfaces of objects may have a large impact on human life with respect to comfort, health, medical care and energy. In this review, we demonstrate the possibilities and versatilities of liquid crystal networks and elastomers being explored for soft robotics, with an emphasis on motile surface properties, such as topographical dynamics. Typically the surfaces reversibly transfer from a flat state to a pre-designed corrugated state under various stimuli. But also reversible conversion between different corrugated states is feasible. Generally, the driving triggers are heat, light, electricity or contact with pH changing media. Also, the macroscopic effects of those dynamic topographies, such as altering the friction, wettability and/or performing work are illustrated. The review concludes with the existing challenges as well as outlook opportunities.
This work describes a method to create dynamic pre-programmed surface textures by an alternating electric field on coatings that consist of a silicon oxide reinforced viscoelastic siloxane network. Finite element...
Coatings with dynamic surface structures are appealing to many applications like haptics and soft robotics. Restrictively, the speed of the surface dynamics in these coatings is often limited to frequencies below 1 kHz, which makes them unsuitable for applications like acoustics and communication optics. This work describes a method to create high‐frequency surface dynamics controlled by alternating electric fields on a substrate‐contact‐modulated coating that consists of an elastic poly(dimethyl siloxane) network supported by SU‐8 microstructures. The principle is based on the global application of Maxwell stress that is locally resisted by the supporting SU‐8 microstructures. In‐between the microstructures the elastic material is stretched, causing a large deformation of the surface topography, which is supported by the authors’ finite element method models. By applying a high‐frequency alternating field, they discovered resonance effects at frequencies up to 230 kHz, where the surface of the coating vibrates at high speeds and large amplitudes. At these high frequencies, the coatings can produce and detect ultrasound waves underwater, indicating their potential for ultrasound transducers in the future.
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