Multicomposition 3D Printing Using Tunable Ecoflex/Nanosilica Inks for Stretchable Electronics.

Additive manufacturing enables the 3D printing of various soft matter structures. Achieving the integrated printing of multicomposition 3D structures, such as ear-like structures containing both hard and soft tissue, has become a research hotspot. However, current multicomposition 3D printing technology still faces numerous challenges, including limited material selection, difficulties in achieving precise transitions between multimodulus regions, and issues with printing accuracy and stability for low-viscosity and fast-curing materials. This study modified Ecoflex by incorporating nanosilica particles and developed a series of Ecoflex/nanosilica composite (ESC) ink formulations suitable for multicomposition 3D printing. The rheological and mechanical properties of ESC inks were thoroughly evaluated, and the weight percentage of nanosilica particles in different Ecoflex types was optimized to identify the most effective formulation. Additionally, 3D printing process parameters were refined to enhance printing accuracy, facilitating the multicomposition printing of complex 3D structures such as hollow columns, nose-like structures, and ear-like structures. These inks were further utilized to print stretchable electronic substrates with strain-isolating properties, and their performance was validated through experimental studies and simulations. The results confirm that the developed ink provides robust technical support for multicomposition 3D integrated printing of stretchable electronics.