Ni‐GaIn Amalgams Enabled Rapid and Customizable Fabrication of Wearable and Wireless Healthcare Electronics

Abstract

Recent advances in functional low‐melting liquid metals (LMs) provide routes to quickly fabricate wearable devices, which can offer excellent mechanical compliance on human skin compared to conventional rigid wafer‐based electronics. Particularly, the Gallium‐based LM mixtures are promising materials for use as stretchable and flexible circuits in wearable healthcare electronics due to their fantastic electrical conductivity, favorable fluidity, super compliance, and benign biocompatibility. Here, the authors develop a kind of directly‐printed Ni‐GaIn functional amalgams, which can efficiently construct wearable healthcare monitors. Unlike EGaIn, Ni‐GaIn amalgam owns a tunable and enhanced adhesion, which makes it easy to directly paint on various substrate for customized circuits. A wireless power transfer coil printed with these amalgams is presented to demonstrate the electrical stability under different tensile states. Finally, the authors design a wearable healthcare monitor for pulse wave measurement via collecting pulse wave signals from the wrist steadily. With the advantages of stretchability and rapid manufacture, the functional Ni‐GaIn amalgams as currently presented shows a promising approach for individualized wearable electronics.

Liquid Metal–Based Soft Microfluidics

“…Based on this property, liquid metal also undergoes changes in properties due to the alloying with these metals. For example, alloying liquid metal with copper enhances conductivity, while alloying with nickel increases the viscosity . Alloying can be beneficial for patterning of liquid metals by a reactive wetting approach, i.e., on a gold surface .…”

“…b) Scheme of preparation of a liquid metal coil printed by employing a mask and a roller brush and corresponding optical photographs. Reproduced with permission . Copyright 2018, John Wiley and Sons.…”

One‐Step Liquid Metal Transfer Printing: Toward Fabrication of Flexible Electronics on Wide Range of Substrates

“…With the advantages of lightweight, biodegradable, easy preparation, large surface, and can be folded into 3D configurations, paper has attracted great interest and provides a highly attractive alternative to fabricate flexible electronic devices. [30] The paper sensors fabricated using conductive nanomaterials show good electrical properties, while, the electroconductivity of nonmetallic materials (carbon: 1.8 × 10 3 S m −1 , CNT: 5.03 × 10 3 S m −1 , poly (3,4ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS): 8.25 × 10 3 S m −1 ) [31] is lower than pure metal materials and the fabrication cost of nano metal ink is much higher compared to cheap paper substrate. [27] At present, various fabrications of paper electronics have been developed.…”

A Novel Strategy for Preparing Stretchable and Reliable Biphasic Liquid Metal

“…), which is enabled to slightly elongate but it is also limited. [20][21][22][23][24][25] In their methods, the liquid metal has been designed into functional conductive structure by taking advantage of own liquid characteristic. [15,16] Unlike these traditional conductive rigid materials, the emerging galliumbased liquid metals with advantages of low Young's moduli (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) and in principle infinitely deformable have attracted great attention as an ideal candidate for fabricating stretchable conductive pattern.…”

“…[14] Therefore, the traditional materials are restricted by high Young's moduli for preparing high durable conductive pattern. [22] Liu and co-workers [23] fabricated liquid metal wearable and wireless healthcare electronics. [17][18][19] Tremendous efforts have been made in liquid metal-based conductive pattern technology in the past few years, such as direct writing, masked deposition, stencil printing, 3D printing, injection, etc.…”