Abstract
This paper reviews the material properties, fabrication and functionalities of liquid metal-based devices. In modern wireless communication technology, adaptability and versatility have become attractive features of any communication device. Compared with traditional conductors such as copper, the flow characteristics and lack of elastic limit of conductive fluids make them ideal alternatives for applications such as flexible circuits, soft electronic devices, wearable stretch sensors, and reconfigurable antennas. These fluid properties also allow for innovative manufacturing techniques such as 3-D printing, injecting or spraying conductive fluids on rigid/flexible substrates. Compared with traditional high-frequency switching methods, liquid metal (LM) can easily use micropumps or an electrochemically controlled capillary method to achieve reconfigurability of the device. The movement of LM over a large physical dimension enhances the reconfigurable state of the antenna, without depending on nonlinear materials or mechanisms. When LM is applied to wearable devices and sensors such as electronic skins (e-skins) and strain sensors, it consistently exhibits mechanical fatigue resistance and can maintain good electrical stability under a certain degree of stretching. When LM is used in microwave devices and paired with elastic linings such as polydimethylsiloxane (PDMS), the shape and size of the devices can be changed according to actual needs to meet the requirements of flexibility and a multistate frequency band. In this work, we discuss the material properties, fabrication and functionalities of LM.
Highlights
In the EGaIn thin line pattern production method based on soft lithography technology, the size of the produced thin lines can be scalable, uniform and without residue, and the line width on the same soft substrate can be from a single micron to a few millimeters [3]
liquid metal (LM) droplets can be sprayed on the cloth substrate and the oxide film can be removed by immersing in a NaOH solution
The LM used in the method was a semi-LM material (Cu-EGaIn) with high viscosity and flexibility prepared by mixing gallium-based alloy and solid metal particles (Cu) at room temperature
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. LM has been integrated with micro/nano technology, so that LM has significantly diversified properties These innovative functional materials have the softness of classic liquid metals, and have many outstanding properties, including self-healing ability and stimulus-response deformation ability. In liquid metal-based reconfigurable antennas, alterations in the length and position of the LM in a large amplitude greatly enhance the reconfigurable state of the devices, and with an extensive frequency adjustment range. The realization of these reconfigurable states does not depend on nonlinear materials or mechanisms, compared to antennas using semiconductor switches, and these antennas have higher linearity.
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