Generation of Nonspherical Liquid Metal Microparticles with Tunable Shapes Exhibiting an Electrostatic-Responsive Performance

Abstract

Nonspherical liquid metal microparticles (NLMs) show extraordinary potential in various applications due to their multifunctional and structural advantages. To one-step-produce shaped NLMs with high efficiency, high controllability, and free of template, a facile microfluidic strategy named rotary flow shearing (RFS) is reported. A high-speed viscous shearing flow is provided by two counter-rotating rotors in the carrier fluid, inducing continuous pinch-off of liquid metal flowing from a capillary tube positioned in face of the slit between two rotors. The real-time oxidation realizes the rapid solidification of the pinching neck and the liquid metal surface during the RFS process, resulting in massive NLMs. Different from other microfluidic methods, the RFS enables tunable shapes of NLMs, especially for working materials at high viscosities. The collected NLMs exhibit special electrostatic-responsive performances including translation, rotation, reciprocation, and lining up under the manipulation of an external electric field. Such NLMs can be promisingly used for the construction of novel micromotors and soft electronics.

Microfluidic Methods for Generation of Submicron Droplets: A Review

“…The thread can be reduced to submicron thickness by increasing the flow rate of the focusing fluid and decreasing that of the focused fluid, without transition to the dripping mode, since the continuous phase flow issued from the opposed direction does not provide a focusing effect ( Figure 3 c). Recently, a rotary-flow-shearing strategy was realized with two counter-rotational cylinders, which provide strong shear force to the disperse fluid issued from a capillary [ 46 ] ( Figure 3 d). Non-spherical liquid metal particles can be generated.…”

“…( c ) Continuous phase back-flow induces tipstreaming with very thin jet without transition to the dripping mode, by avoiding the focusing effect, reproduced from [ 45 ], copyright 2018, Royal Society of Chemistry. ( d ) Rotary-flow-shearing method providing strong shear and elongational stress to the disperse fluid, reproduced from [ 46 ], copyright 2021, American Chemical Society.…”

Emerging Liquid Metal Biomaterials: From Design to Application

“…Based on their deformability, LMs can be processed into different scales and various shapes. [40] The intrinsic morphological control of LM at the micro-/nanoscale can be achieved mainly by sonication and templating methods to transform bulk LM into micro-/nanodroplets with diverse shapes. [7,38,39,41,42] Various shapes of LM nanoparticles including sphere, rod, and rice can be obtained via sonication with surfactants, which can be tuned by changing parameters.…”

Liquid metals as soft electromechanical actuators

“…Electrostatic forces have also been used to successfully actuate non-spherical LM particles electrophoretically. 91 The particles were created using shear forces to pinch off LM flow out of a capillary tube. The silicone oil used as the fluid was saturated with oxygen to ensure rapid oxidation of the LM.…”