Influence of the Geometric Parameters of Raised Islands on the Performance of Flexible Wearable Electronic Systems

The flexible wearable electronic systems have great potential in medical treatment, electronic skin, energy storage and other applications. A successful flexible wearable electronic system not only has to fulfill its functionality and adapt to the complex environments of human skin, but also needs to consider the comfortability during wearing. However, the normal structured flexible wearable systems would always make discomforts to human skin, owing to relatively large local stress caused by these rigid devices. The island-bridge structures with raised islands have proven advantages in the improvement of stretchability and alleviation of skin's local stress. To further exploit this advantage, the influence of the geometric parameters (e. g. shape, size and thickness) on stretchability and comfortability have been analyzed, thereby providing guidance to the further optimization. Both the simulation and experiment results indicate that smaller size and larger thickness of the raised islands can decrease the surface deformation of the raised island and reduce the mismatch between rigid devices and largely-deformed human skin. This finding is exemplified by optimizing the geometric parameters on an island-bridge structured temperature detection patch. The testing results show that the optimized island-bridge structure is available to reduce the skin stress and improve the comfort of the human skin compared with the normal structure. This work provides design guidelines for the island-bridge structured flexible wearable electronic systems, which can substantially improve the comfortability and stretchability.