Hybrid Smart Fiber with Spontaneous Self-Charging for Wearable Electronic Applications

Wearable electronics have been commercialized in recent years as exemplified by smart watches and smart glasses which provide great convenience for our daily lives with advanced functions. Attributed to recent development in long-life batteries, these devices can be frequently re-charged through an external power supply with long life expectancy. The dependence on the external energy source, however, has limited implementation of the wearable electronics for advanced applications where standalone wearables are highly required, such as wearable bio-medical devices.<br/><br/>In spite of its importance, a self-charging capability in wearable devices has been its early stage of development at present. It has been a challenging issue to directly add advanced functions to wearable devices built on bulk textile platform due to lack of controllability in the bulk form. In contrast, for wearables, a bottom-up approach starting from the building block fiber/yarn allows to engineer and functionalize each layer and component with high controllability. Therefore, building wearables from fibers/yarns provides a viable solution to introduce advanced functionality, particularly, the self-charging capability for advanced wearable electronics. However, another challenge arises due to an one-dimensional (1D) nature of the fiber which makes it incompatible with conventional layer preparation methods on two-dimensional (2D) forms, such as the bulk textile. Therefore, the key to further advance wearable electronics is on (1) direct control of the building block fiber/yarn, and (2) development of the scalable method applicable to the 1D platform.<br/><br/>In light of this, we have demonstrated a template-free scalable method which enables to control key device parameters at the building block fiber scale. Our bottom-up approach using high plasma energy demonstrated an effective direct control of building block fibers, leading to an enhanced spontaneous self-charging capability. Successful implementation of the spontaneous self-charging at the building block fiber scale proves that our new method developed is a promising route to tackle the current bottlenecks that the wearable electronics confront and through this advance the future self-powered wearable electronics.