Light-Controlled Rotational Speed of an Acoustically Levitating Photomobile Polymer Film

Abstract

In this work, we study the light-induced changes of the rotational speed of a thin photomobile 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.

Development of a Quartz-Based Photo-Mobile Polymer Film for Controlled Motion Triggered by Light or Heat

“…Photo-mobile polymers (PMPs) are particular kinds of photo-responsive polymers having motion which can be induced without contact and controlled by an external electromagnetic field, typically in the form of a light source [10][11][12][13][14][15]. Research on PMPs is rapidly accelerating due to their potential applications in energy harvesting, light-controlled actuators, and light-induced dynamic holography [13,14,[16][17][18]. On the other hand, thermo-responsive polymers [19,20] can change their properties in response to temperature changes.…”