Directly Printable, Non‐Smearable and Stretchable Conductive Ink Enabled by Liquid Metal Microparticles Interstitially Engineered in Highly Entangled Elastomeric Matrix

Abstract Liquid metal or liquid metal microparticles (LMP) based conductive inks, though promising for fabrication of circuits for use in soft and stretchable electronics, are constrained by a few drawbacks such as need for encapsulation, need for sintering to induce conductivity, and smearing. To address these issues, herein, a stretchable conductive composite ink is developed by combining LMPs with carbon black (CB) in highly entangled polysiloxane elastomer. LMP‐dispersed elastomer lacks conductivity because of its non‐percolated network, however, the CB can interconnect LMPs to act as a bridge, thereby imparting conductivity to the elastomer. Due to presence of fluidic LMPs, the LMPs‐dispersed elastomer lies in soft regime with initial conductivity of 5.6 S m⁻¹, aided by the presence of CB in the interstitial spaces between the LMPs. The highly entangled molecular network of the encapsulating elastomer endows the resulting composite with high stretchability (≈286%) and softness (0.648 MPa) and its long pot life enables rheological modulation of the ink to achieve pressure‐driven direct printed non‐smearing traces. The LMPs‐based conductive ink developed in this work is expected to be further utilized in the fabrication of soft robotics and electronic skin and integrated into electronic modules by facile direct 3D printing.