Organic-inorganic heterostructures for stretchable electronics

As new technologies arise such as wearable electronics, soft-robotics, Internet-of-Things (IoT), among others, mechanical compliance to diverse shapes has become an important new requirement for conventional electronics. Unfortunately, both conventional silicon-based electronic devices and printed circuit boards (PCBs) are characteristically rigid. Nonetheless, several strategies have been demonstrated to transform conventional electronics into more compliant platforms that can satisfy the new mechanical needs of the fore-mentioned novel technologies. In this paper, the use of organic-inorganic heterostructures will be discussed as an effective scheme to integrate diverse materials and simple techniques to achieve flexibility and even stretchability from the device level to system level. First, a novel approach will be described to develop silicon-based, highly-stretchable structures, through the optimized integration of different shapes and geometries, such as serpentines, horseshoes and spirals. Additionally, it will be shown that the incorporation of soft organic encapsulation can work synergistically to further improve the mechanical characteristics of the inorganic structures. On the other hand, a simple kirigami-based strategy will be described to show how to manufacture flexible and stretchable copper-onpolyimide- based PCBs. Once again, soft polymer encapsulation is demonstrated to improve the mechanical robustness of the implementation. Finally, the presented manufacturing strategies can offer an interesting and versatile approach to build ultra-conformal electronics from devices to system-on-board implementations.