Tailorable liquid metal composite inks: Formulations, properties, and applications

Abstract

Advanced liquid metal (LM) inks, which combine the metallic properties with processability, are revolutionizing flexible electronics, bio-integrated devices, and intelligent sensing. However, single-component LM inks often fall short of the demands imposed by modern 3D/4D printing technologies, making the development of high-performance LM composite inks increasingly important. To systematically survey the characteristics and recent progress of emerging LM inks, this review provides a comprehensive overview of their formulation and preparation—spanning ink design, performance tuning, and functional applications. We categorize inks modified with polymers, metals, inorganic materials, and gels, detailing how these composites enhance key properties (e.g, rheology, viscosity: 10⁻¹–10³ Pa·s, sheet resistance: 0.01–10 Ω/sq, printability). Furthermore, the application efficiency of composites in stretchable sensors, skin bioelectronics, and reconfigurable circuits is discussed. The structure-activity relationship of over 28 kinds of LM ink formulations was systematically evaluated, and the core challenges along with future research directions in this field are outlined.