Recent Progress of Direct Ink Writing of Electronic Components for Advanced Wearable Devices

Three-dimensional (3D) printing technology has been recognized as an emerging advanced fabrication technology in both industry and academia. Direct ink writing (DIW), a type of 3D printing technology, can build 3D structures through the deposition of custom-made inks, printing devices with complex architectures, excellent mechanical properties, and enhanced functionalities. DIW can greatly facilitate the fabrication of miniaturized or flexible electronic components. These components are potentially useful for their applications in advanced wearable devices. This article highlights recent advancements in 3D direct ink written electronic components with an emphasis on their potential applications for wearable devices. The relationship among ink formulations, DIW techniques, and printed devices is highlighted. In particular, the DIW-assisted fabrication of key components in wearable electronics, including power generation (nanogenerators), energy storage (e.g., lithium ion batteries), and energy consuming products (e.g., strain sensors) are reviewed in terms of performance metrics and fabrication strategies. Optimized ink preparations, evolving DIW techniques, and device designs can work synergistically to enhance the development of printed advanced wearable devices.