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An active mixing printhead for PDMS-based functionally gradient material substrate using variable stiffness electric-field-driven jet deposition 3D printing

Functionally gradient materials (FGM) can be customized according to their required function because the multi-material components can change continuously in space. They have the potential for wide-ranging application in the fields of embedded sensors/actuators, microelectromechanical systems (MEMS), porous structures, and composite materials. In this paper, an active mixing printhead using electric field-driven jet deposition (EFD) 3D printing is proposed to fabricate a PDMS-based functionally gradient material substrate with variable stiffness. Theoretical analysis of the mechanical characteristics of nanoparticles in fluid was performed, and COMSOL simulation software was used to analyze the effects of premix inlet velocity, impeller blade speed, and base liquid viscosity on nanoparticle dispersion. The analysis and simulation results were validated by printing examples of a variable hardness substrate model, flexible conductor, and flexible electrode. This study provides theoretical support and directional guidance for the development of 3D printing equipment for FGM and the formation and application of flexible electronic substrates.