Porous-Architectured Composite for Fully 3D-Printed Biodegradable Soft Electronics

Biodegradable electronics offer the promise of implantable devices that disappear after use, reducing the need for surgical removal and mitigating chronic inflammatory responses. Achieving both tissue-level mechanical softness and sufficient electrical conductivity is critical for bioelectronics. Composite materials provide a versatile platform to satisfy these electrical and mechanical requirements, while 3D printing allows precise and customizable fabrication of complex and multi-material structures. However, in fully biodegradable composites, limited material options restrict simultaneous optimization of mechanical and electrical properties. Here, we introduce engineered internal porosity into a biodegradable electronic composite to achieve softer mechanical properties while maintaining electrical performance. In metal-polymer composites, a porous matrix promotes filler aggregation, forming a percolating conductive network at a lower filler loading compared to non-porous counterparts, thereby reducing stiffness. Engineered porosity within the printed structure reduces its elastic modulus by orders of magnitude and accelerates degradation. We also demonstrate multi-material 3D printing of porosity-programmed electronic inks for printed circuit boards and sensors applications. This structural strategy can be extended to other biodegradable filler-binder systems, thereby expanding the material palette for next-generation transient electronics.