A Flexible Loudspeaker Using the Movement of Liquid Metal Induced by Electrochemically Controlled Interfacial Tension

Sang Woo Jin, Yu Ra Jeong, Heun Park, Kayeon Keum, Geumbee Lee, Yong Hui Lee, Hanchan Lee, Min Su Kim, Jeong Sook Ha

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

A flexible liquid metal loudspeaker (LML) is demonstrated consisting of a gallium-based eutectic liquid metal (Galinstan) and basic aqueous electrolyte (NaOH(aq)). The LML is driven by liquid metal motion induced by the electrochemically controlled interfacial tension of the Galinstan in NaOH(aq) electrolyte under an applied alternating current (AC) voltage. The fabricated LML produces sound waves in the human audible frequency band with a sound pressure level of ≈40–50 dB at 1 cm from the device and exhibits mechanical stability under bending deformation with a bending radius of 3 mm. Various sounds can be generated with the LML from a single tone to piano notes and human voices. To understand the underlying mechanism of sound generation by the LML, motion analyses, sound measurements, and electrical characterization are conducted at various frequencies. For the first time, this work suggests a new type of liquid metal-based electrochemically driven sound generator in the field of flexible acoustic devices that can be applied to future wearable electronics.

Original languageEnglish
Article number1905263
JournalSmall
Volume15
Issue number51
DOIs
Publication statusPublished - 2019 Dec 1

Bibliographical note

Funding Information:
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (Grant No. NRF-2019R1A2B5B03069545). The authors also thank the KU-KIST graduate school program of Korea University.

Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • acoustic device
  • electrochemical wetting
  • flexible loudspeaker
  • interfacial tension
  • liquid metal

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • General Chemistry
  • General Materials Science
  • Biotechnology
  • Biomaterials

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