Beyond sintering: design strategies for initially conductive liquid metal particle inks in stretchable and printable...

Liquid metal particles (LMPs) have emerged as promising candidates for stretchable printable electronics, leveraging their high conductivity and intrinsic fluidity, as well as enhanced wettability compared to bulk LMs. However, a major limitation of conventional LMP-based inks lies in their electrically insulating oxide shell, which necessitates post-printing activation (e.g., mechanical sintering) that may introduce complexity, impair reproducibility, and compromise device integrity. In this context, the development of LMP-based inks with initial conductivity represents a transformative advancement, enabling direct formation of conductive pathways during printing and subsequent drying/curing processes without additional sintering. This article provides a timely overview of recent advances in such intrinsically conductive LMP inks. We begin by outlining their fundamental advantages over post-print-activated systems. Next, a series of key design strategies including surface engineering, biphasic networks, and hybrid fillers are discussed, emphasizing the underlying mechanisms that permit immediate electrical conduction. Finally, we discuss ongoing challenges and future directions for these advanced systems. By circumventing the need for external activation, initially conductive LMP inks are expected to unlock robust, scalable, and high-performance stretchable electronics.