Design, Fabrication, and Performance Study of 3D‐Printed Multi‐Tooth Interlocking Discrete Functionally Gradient Stretchable Substrates

Flexible hybrid electronics (FHE), which integrate the deformation capability of flexible substrates with the functional stability of rigid components, show broad application prospects in wearable devices and aerospace fields. Among these, functionally graded substrates have gained significant attention due to their ability to mitigate the separation issues between electronic components and flexible substrates. However, continuous functionally graded substrates face challenges in manufacturing processes and precise dimensional control, while discrete functionally graded substrates exhibit issues like interlayer separation and poor tensile performance. This paper proposes a multi‐tooth interlocking large‐tensile discrete functionally graded substrate interface structure that combines high tensile strength with excellent durability. This innovative design effectively enhances interfacial bonding strength, thereby improving the tensile modulus and fatigue life of functionally graded substrates. Under large strain, failure occurs through fracture at the “tooth bridge” rather than delamination along the weak interface. The fabricated substrate achieved an elongation at break of up to 145%. The interlocking interface remained intact after 1000 cycles of 60% tensile strain and combined torsion‐tensile cycles, demonstrating excellent durability. This study realizes highly stretchable and reliable flexible substrates through structural design and multi‐material integrated 3D‐printing, providing an effective solution for the application of flexible electronics in high‐stretch environments.