The Flying Carpet and Other Tales

Abstract

In this thesis we demonstrate propulsion of a thin plastic piezoelectric sheet using controlled traveling wave deformations. This is achieved in air, without touching the ground, thus confirming the physical basis for a "flying" carpet near a horizontal surface. The device developed in this work demonstrates a novel form of propulsion, which operates without separate moving parts, since all actuation elements are formed from the same thin sheet of material. Potential advantages of this include low manufacturing costs and long lifetime. This work also demonstrates the advantages, in general, of using integrated sensors to control the vibrations of thin plastic sheets. Although we focus here on traveling waves, the same techniques could be used to produce a wide variety of time-varying deformations. The device could be used to model biological organisms, for example, for fluid dynamics studies. In addition, sensor arrays, for example chemical or biological, could be integrated onto the sheet.

We discuss the fundamental and experimental conditions for realizing such a device, and describe the experimental approach to produce the traveling waves and demonstrate propulsion. The propulsive forces qualitatively agree with previous theoretical predictions. Theory predicts that such a sheet needs to reach speeds of ~20 cm/s to produce its own lift (the so-called "flying carpet" effect). Currently, the sheet is not free, so the observed velocity is ~1-2 cm/s. We present preliminary work to free the sheet from its tethers by providing on-board power using a boost-converter circuit, and, alternatively, using a cart that carries the tethering wires and follows the sheet. In addition, to enable the sheet to begin moving without external lift, methods to reduce friction and static electricity are presented. Experiments with passive test samples show indications of lift beginning at ~20-30 cm/s.

Two aspects related to the integration of improved functionality on the sheet are also described. The first is preliminary work on room-temperature printing of silicon nanoparticles. This might be useful for integrating circuits directly on the "flying carpet", as it can't be heated above ~60º C. The second is PZT nanoribbons transferred to rubber, which could lead to reduced voltage requirements for the "flying carpet".

Eight videos are included as supplemental online material, and are referenced throughout the thesis. Descriptions/captions for these videos are included in the supplemental file "Jafferis_Thesis_Supplement.pdf"