Soft electrical components are highly demanded for human-machine interaction devices. “Electrofluids” (EFs), which are suspensions of electrically conductive filler particles in non-conductive solvents, are proposed as promising sensors and conductive materials since they can flow and retain electrical conductivity. As they remain liquid in working conditions, encapsulation and manufacturing of complex patterns remain as a challenge but would enable a wider variety of applications. Direct ink writing (DIW) is proposed here as a method to manufacture carbon-based EFs. Simple shear flow and Fourier-transform (FT) rheology are performed to evaluate the printability of EFs containing different concentrations of Carbon Black and Graphene Powder by DIW. Electrofluids exhibited three important characteristics to be manufactured via DIW: yield stress behavior (confirmed by flow curves), high brittleness, and a fast mechanical recovery within a range of 15 s. Printability maps are created to distinguish printable and non-printable EFs. Printable EFs are used to manufacture complex patterns. As a proof of the great potential of the EFs and DIW combination, a comparison between simple and multiline strain gauges showed an enhancement in the sensitivity of EFs as strain sensors by almost 800%.
Advanced Materials Technologies , 2025, xxx (xxx), xxx.