A printable liquid metal-montmorillonite ink for high-resolution stretchable bioelectronics

Abstract

Gallium-based liquid metals (LMs) are emerging as leading materials for flexible and stretchable bioelectronics due to their exceptional electrical conductivity and mechanical malleability. However, the inherently high surface tension of LMs hinders both their printability and adhesion to substrates, creating significant barriers to scalable, high-resolution patterning. Here, we present an effective strategy to overcome these challenges by formulating a printable liquid metal–montmorillonite (LM–MMT) composite ink. This LM–MMT ink demonstrates markedly improved rheological properties, facilitating reliable direct printing of high-resolution, stretchable, and highly conductive patterns on a broad range of substrates. Strain sensors fabricated from the LM–MMT ink exhibit high sensitivity, minimal hysteresis, and exceptional fatigue resistance across more than 100 cycles of deformation. These sensors enable accurate real-time monitoring of both gross human joint movements and subtle motion signals such as swallowing and neck rotation. Furthermore, we demonstrate that multi-channel strain sensing arrays based on LM–MMT ink enable real-time hand gesture recognition and robotic hand control, establishing a robust and seamless human–machine interface. This work introduces a scalable, cost-effective additive manufacturing strategy for LMs, openning new avenues for wearable sensing, continuous health monitoring, and next-generation intelligent interactive bioelectronics.