Emerging Role of Liquid Metals in Sensing

Abstract

Low melting point metals and alloys are the group of materials that combine metallic and liquid properties, simultaneously. The fascinating characteristics of liquid metals (LMs) including softness and high electrical and thermal conductivity, as well as their unique interfacial chemistry, have started to dominate various research disciplines. Utilization of LMs as responsive interfaces, enabling sensing in a flexible and versatile manner, is one of the most promising traits demonstrated for LMs. In the context of LMs-enabled sensors, gallium (Ga) and its alloys have emerged as multipurpose functional materials with many compelling physical and chemical properties. Responsiveness to different stimuli and easy-to-functionalize interfaces of Ga-based LMs make them ideal candidates for a variety of sensing applications. However, despite the vast capabilities of Ga-based LMs in sensing, applications of these materials for developing different sensors have not been fully explored. In the present review, we provide a comprehensive overview regarding the applications of Ga-based LMs in a wide range of sensing approaches that cover different physical and chemical sensors. The unique features of Ga-based LMs, which make them promising materials for sensing, are discussed in subsections followed by relevant case studies. Finally, challenges as well as the prospected future and developing motifs are highlighted for each type of LM-based sensors.

Multi‐Electrode Printed Bioelectronic Patches for Long‐Term Electrophysiological Monitoring

“…Materials and fabrication techniques for advancement of this field have been a major focus of investigation in the past few years. [28,29] This includes techniques for implementation of deterministic structures, [30] conductive composites, [31][32][33][34][35][36] and liquid metals, [37][38][39] which include soft lithography, [40][41][42][43][44] laser patterning, [45][46][47][48][49] stencil printing, [12,34,44,50] or direct deposition. [16,31,32,46,49] Another requirement is the integration of skin-interfacing electrodes to collect biopotentials from the epidermis for EMG/ECG/EEG monitoring, which include the traditional Ag/AgCl electrodes, novel wet hydrogel electrodes [51,52] as well as printed dry electrodes based on carbon, [12] silver [2,12,20,53,54] or polymers such as PEDOT:PSS.…”

Liquid-Metal-Coated Magnetic Particles toward Writable, Nonwettable, Stretchable Circuit Boards, and Directly Assembled Liquid Metal-Elastomer Conductors

“…Figure f shows that the fabricated circuit responds to the magnet due to the iron particles in the core. Circuit boards having this ability could be useful for magnetic actuators ,,, and proximity sensors …”

“…Circuit boards having this ability could be useful for magnetic actuators 38,45,56,57 and proximity sensors. 58 2.4. Directly Assembled Microwires by Applying External Magnetic Fields.…”

Emerging Liquid Metal Biomaterials: From Design to Application

“…LMs with electrical conductivity, softness, and deformability have the ability to contact skin conformally, leading to the sensitive collection of electrophysiological signals (e.g., ECG). [ 132 ] A multifunctional EGaIn electrode was fabricated by vertical stacking three layers LM‐patterned electrospun elastomeric fiber mats to monitor diverse physiological signals of human bodies (Figure 9c). [ 131 ] The LM‐patterned fiber mats have ultrahigh conductivity (up to 1 800 000 S m −1 ), ultrahigh strain (over 1800%), and high permeability to air and moisture.…”