Flexible three-dimensional integrated circuits (3D ICs) based on liquid metal

The rapid advancement of flexible electronics has unlocked opportunities across diverse fields, including medical science and device engineering. Developing flexible three-dimensional integrated circuits (3D ICs) is a key strategy for driving the miniaturisation, wearability and multifunctionality of flexible devices. Among these innovations, liquid metal-based flexible electronics have elicited significant attention due to their exceptional conductivity, high stretchability and low toxicity. This review highlights recent research breakthroughs in the application of liquid metal for flexible 3D ICs, providing a detailed discussion of the design concepts and strategies for patterning and interconnection structures that harness the unique properties of liquid metal. Using 3D printing technology to fabricate high-resolution, durable 3D ICs from liquid metal represents a major research direction. Moreover, advanced fabrication methods diverging from conventional 3D printing systems are explored. Finally, we examine persistent challenges and offer a forward-looking perspective on the potential of liquid metal-based flexible 3D ICs to revolutionise human–machine interactions and enable intelligent living. KEYWORDS • Comparison between traditional 3D integrated circuits (3D-IC) and flexible 3D integrated circuits, and introduction to liquid metal-based flexible 3D-IC. • Methods for 3D printing liquid metal-based flexible 3D-IC. • Advanced methods for constructing liquid metal-based flexible 3D-IC. • Application prospects of liquid metal-based flexible 3D-IC.