Novel energy harvesting using acoustically oscillating microbubbles

Abstract

When a bubble hanging on a piezocantilever is excited by an acoustic wave around its resonant frequency, it oscillates and simultaneously generates cavitational microstreaming around it. The microstreaming bends the piezocantilever with fine vibration, resulting in electric power generation from the piezocantilever. In this study, we explore the dynamic behaviors of an acoustically oscillating bubble on the flexible substrate as well as demonstrate applicability of the proposed system to practical applications such as energy harvesting and acoustic wave sensors. First, the effects of an applied frequency and bubble size on the dynamic characteristics of an acoustically oscillating bubble, such as maximum amplitude and resonant frequency, are experimentally investigated. The amplitude of an oscillating bubble is maximized at its resonant frequency, which is inversely proportional to its size. In addition, electrical voltage generated by a piezocantilever attaching with an oscillating bubble is measured at different applied frequencies, bubble sizes, and distances between the bubble and piezoactuator. The results show that the generated voltage is strongly affected by the applied frequency and is inversely proportional to the bubble size and the distance between the bubble and piezoactuator. Finally, the output voltage is almost linearly proportional to the number of bubbles.

Review of Bubble Applications in Microrobotics: Propulsion, Manipulation, and Assembly

“…Bubbles actuated by acoustic waves can be used as a source of mechanical energy for “generators.” Jeon et al [ 178 ] suspended a bubble on a flexible piezocantilever. When the bubble was excited by acoustic waves near its resonance frequency, it oscillated and generated cavitation microstreaming around it.…”

“…Lower: still images of the oscillating bubble. Adapted from Jeon et al [ 178 ] with permission from Springer Nature, Copyright 2021. ( c ) Upper: fabrication of micro-tools for material transport.…”

Recent Development of Liquid Metal‐Based Functional Materials Combined with Common Transition Metals

“…During the preparation and application process, the surface oxide layer of LMs is removed or prevented through the hydrocarbon group, [82] surfactant, [87] plastic materials, [88] and the acid or alkaline solution environment, [22,89] which allows magnetic LMs to be more widely used in fields such as drug loading, [34,72] controllable machines, [8,38,40] and electrical switches. [42,80]…”

“…A layer of iron powder is coated on the oxide layer of the LMs surface to make a magnetic marble. [79][80][81] Magnetic LM fluid can be prepared by internalizing iron powder or mechanical alloying. [82] In the study by Kim et al [79] and Jeon et al, [42] Fe powder was adhered to the oxide skin on the surface of LMs, producing a LM marble with magnetism.…”

“…A layer of iron powder is coated on the oxide layer of the LMs surface to make a magnetic marble. [ 79–81 ] Magnetic LM fluid can be prepared by internalizing iron powder or mechanical alloying. [ 82 ] In the study by Kim et al.…”