Liquid-metal capillary switch for electrical power application

Liquid-metal (LM) electrical switches have been desired for decades to overcome intrinsic shortcomings of traditional mechanical switches equipped with solid contacts. Existing LM electrical switches, functioning via solid-liquid wetting or liquid droplet actuation, mostly focus on low current and s...

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Veröffentlicht in:Applied physics letters 2020-12, Vol.117 (26), Article 263701
Hauptverfasser: Zhu, Xiaonan, Yang, Fei, Zhao, Siyuan, Wang, Haoran, Niu, Chunping, Rong, Mingzhe
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Sprache:eng
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Zusammenfassung:Liquid-metal (LM) electrical switches have been desired for decades to overcome intrinsic shortcomings of traditional mechanical switches equipped with solid contacts. Existing LM electrical switches, functioning via solid-liquid wetting or liquid droplet actuation, mostly focus on low current and small signal switches. In this Letter, a LM switch aiming at a power-level current switch has been proposed. A proof-of-concept prototype was fabricated via encapsulating Galinstan droplets into a silicone matrix. The device switches on a circuit when LM droplets are squeezed into a capillary channel to coalesce. The switch-off process with arc burning is realized by capillary breakup of the LM bridge and high-speed contact separation driven by a pressure difference contributed by Laplace pressure, electrical arc pressure, and atmospheric pressure. Switching off 0.5 A–5 A current under DC 220 V within 0.13–1.69 ms, the device demonstrates a high-speed current interruption ability compared to two kinds of commercial push-button switches. A high-speed camera is utilized to visualize the LM switch's current interruption process. In such a situation, the LM contacts exhibit a separation speed up to 3.85 m/s. Apart from the pressure difference, a slip layer between the LM and capillary wall also plays an important role in driving LM contacts. The LM switch has potential for applications in communication and control equipment acquiring a fast switch of the electrical power signal. This paper offers a framework for designing the LM switch dealing with intense electrical discharge.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0028685