Resolving Thermal Accumulation and Rigid-Soft Interface Mismatch in Stretchable Electronics with Cubic Boron Nitride Composite Islands.

Integrated stretchable electronic systems for soft robotics and wearable devices require effective thermal management to mitigate heat accumulation around functional components. Here, we propose an island-bridge architecture with localized thermally conductive composite islands for enhanced heat dissipation. By incorporating cubic boron nitride (c-BN) into selected regions of the soft substrate, we construct thermally conductive composite islands with in-plane and through-plane thermal conductivities of 2.327 and 2.596 Wm1-K-1, respectively. Compared with the substrate without composite islands, the peak temperature is reduced by 12.8 °C. Furthermore, a stretchable computing platform based on this design maintains an operating temperature below 40 °C during practical operation, demonstrating an important thermal safety advantage for human-contact applications. In addition, the local modulus gradient created by the composite islands near the chip mitigates rigid-soft interfacial mismatch, thereby alleviating stress concentration and increasing stretchability from 70.41% to 122.67%. The proposed design further demonstrates long-term stability in soft robotic end-effectors and wearable systems, providing an effective strategy for achieving both thermal safety and mechanical reliability in highly integrated stretchable electronics.