Liquid Metal-Based Microfluidic Metasurface for Controllable Electromagnetic Wave Reflection Attenuation

Abstract

We demonstrated a liquid metal based microfluidic chip that enabled consistent, continuous and large liquid metal unit structure array reconfiguration. The chips were assembled into a metasurface, which preliminary achieved controllable electromagnetic wave reflection attenuation. The chip contained a 5 × 6 Galinstan split-ring resonator (SRR) array, and the SRRs could be reconfigured continuously by NaOH solution pressure driven. A fin shaped microvalve was designed and integrated onto the chip, which could withstand a high fluid driving pressure (over 210 kPa), so the SRRs could be reconfigured with a large split angle. The flow resistance of each SRR chamber was analyzed for consistent and robust SRRs deformation. The SRRs enabled more than 250° reconfiguration and showed consistent deformation with a standard derivation less than 8.5°. The metasurface showed 7.5 dB and 13.5 dB attenuation at 3 GHz and 4 GHz respectively. Also, with the different split angles, there could be three attenuation peaks that reach -10 dB when the frequency ranged from 2.9-3.1 GHz, 3.7-4.2 GHz and 4.8-5.0 GHz, respectively. The metasurface we proposed can be potentially used in multiband controllable electromagnetic wave absorption.

Gallium‐Based Liquid Metals: Optical Properties, Applications, and Challenges

“…As shown in Figure a, by adjusting the angle of the circular meta structure, the reflection attenuation coefficient of the metamaterial to electromagnetic waves can be changed, giving the metamaterial the potential for multiband controllable electromagnetic wave absorption. [ 103 ] Additionally, annular structures have been used to design lenses with tunable focal lengths based on LM mercury. [ 104 ] Given the similarity between Ga‐based LMs and mercury, this study also provides a new idea for designing lenses with tunable focal lengths.…”

“…Reproduced under terms of the CC‐BY license. [ 103 ] Copyright 2022, The Authors, published by IEEE. b) Schematic of multifunctional polarization converter using galinstan LM.…”

Machine learning (ML)-assisted surface tension and oscillation-induced elastic modulus studies of oxide-coated liquid metal (LM) alloys

“…Numerous techniques are currently available in the literature to study the elastic modulus and surface tension of gallium alloys; however, the utility of pendant droplets (symmetric and asymmetric) for (a) machine-learning (ML) assisted surface tension and (b) oscillation-induced elastic modulus studies have remained unexplored. Gallium and its alloys at low melting points [1][2][3] have emerged as the most promising soft conductor for sensors, actuators, pumps, flexible electronics, and other microfluidics applications [3][4][5][6][7][8][9][10]. High electrical conductivity, low toxicity, low vapor pressure, biocompatibility, and tunable surface tension (∼600 mN m −1 -100 mN m −1 ) are some of the notable properties at room temperature [11,12]of these alloys; however, the unique behavior of these alloys arise from their native 1-5 nm thick, and passivating Ga 2 O 3 layer [13].…”

Photoacoustic property of Gallium-based liquid metals measured with intensity modulated high repetition supercontinuum laser

“…Additionally, the naturally formed oxidation layer on the surface of gallium-based liquid metals acts as a protective barrier, preventing further oxidation and ensuring long-term stability of their optical response. Utilizing the optical properties of gallium-based liquid metals, researchers have found applications in optical sensors [9], controlled metamaterials [10], photoacoustic imaging [11] and so on. Due to the easy surface combination of gallium-based liquid metals with other substances, surface functional modifications can be made.…”