Electric Field-Driven Liquid Metal Droplet Generation and Direction Manipulation

Abstract

A gallium-based liquid metal got high attention recently, due to the excellent material properties that are useful in various research areas. We report here on electric field-induced liquid metal droplet generation and falling direction manipulation. The well-analyzed electro-hydrodynamic method is a selectable way to control the liquid metal, as the liquid metal is conductive. The electric field-induced liquid metal manipulation can be affected by the flow rate (0.05~0.2 mL/min), voltage (0~7 kV), and distance (15 and 30 mm) between electrodes, which changes the volume of the electric field-induced generated liquid metal droplet and the number of the generated droplets. When the electric field intensity increases or the flow rate increases, the generated droplet volume decreases, and the number of droplets increases. With the highest voltage of 7 kV with 15 mm between electrodes at the 0.2 mL/min flow rate, the lowest volume and the largest number of the generated droplets for 10 s were ~10 nL and 541, respectively. Additionally, we controlled the direction of the generated droplet by changing the electric field. The direction of the liquid metal droplet was controlled with the maximum angle of ~12°. Moreover, we exhibited a short circuit demonstration by controlling the volume or falling direction of the generated liquid metal droplet with an applied electric field.

Controllable Flow and Manipulation of Liquid Metals

“…[ 210 ] f) Electric field‐driven the controllable formation of LMDs. [ 211 ] g) LMs transported over long distances via electromigration. [ 214 ] a) Reproduced with permission.…”

“…Additionally, the direction of the LMD is controlled with the maximum angle of ≈12 o by changing the symmetry of electric field. [ 211 ] By combining the electric field with a spinning disk, a new technique called eletrodispersion is established for LMDs formation. The spinning disk induces a flow of oil phase to prevent the coalescence of the LMDs, leading to the monodisperse of generated droplets with uniform size.…”

“…e) Dielectrophoresis aligning LMDs along electric field direction for self-healing electronics [210]. f) Electric field-driven the controllable formation of LMDs [211]. g) LMs transported over long distances via electromigration [214].…”

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

“…Such a thin layer of semisolid surface oxide forms rapidly and does not grow thicker in air, even at a very low oxygen concentration (∼1 ppm) [2], providing the mechanical strength to produce different functional patterns and structures [4,14]. In contrast, the presence of oxide reduces the surface tension of the bulk metal [15,16], and because of that, the electrohydrodynamic methods [17] of tuning the thickness of the oxide have gained significant research interest over the last few years [18][19][20][21][22][23].…”

Electrically Induced Liquid Metal Droplet Bouncing

“…The electrically induced liquid oscillations for conductive and dielectric nonmetallic liquid droplets have been researched for multiple decades; − however, effective electrical manipulation of liquid metals originated with the discovery of continuous electrowetting (CEW) . Electrowetting has been explored with various liquid metals, including aluminum, gallium, and mercury . Eutectic gallium–indium alloy (EGaIn) has emerged as one of the most viable liquid metals because of its extraordinary properties such as excellent fluidity, low melting point, high conductivity, and low toxicity, marking it a promising candidate for applications such as flexible electronics, microfluidic acoustic metamaterials, , and conductive printing .…”