A Printable and Conductive Yield-Stress Fluid as an Ultrastretchable Transparent Conductor

In contrast to ionically conductive liquids and gels,a new type of yield-stress fluid featuring reversible transitions between solid and liquid states is introduced in this study as a printable,ultrastretchable,and transparent conductor.The fluid is formulated by dispersing silica nanoparticles into the concentrated aqueous electrolyte.The as-printed features show solid-state appearances to allow facile encapsulation with elastomers.The transition into liquid-like behavior upon tensile deformations is the enabler for ultrahigh stretchability up to the fracture strain of the elastomer.Successful integrations of yield-stress fluid electrodes in highly stretchable strain sensors and light-emitting devices illustrate the practical suitability.The yield-stress fluid represents an attractive building block for stretchable electronic devices and systems in terms of giant deformability,high ionic conductivity,excellent optical transmittance,and compatibility with various elastomers.