Flexible Biofuel Cell‐In‐A‐Tube (iezTube): An Entirely Self‐Contained Biofuel Cell for Wearable Green Bio‐energy Harvesting

Abstract Wearable biofuel cells (BFCs) technologies have the potential to address the challenge of on‐body energy supply of wearable electronics. However, previous wearable BFCs primarily focus on “worn‐on‐skin” sweat ones, which can hardly directly generate steady and nonintermittent electricity under certain but almost ineluctable wearable circumstances (e.g., intermittent sweating, perspiration biofuel concentration fluctuation, and dynamic contact between wearable BFCs and epidermal sweat). Here, in an alternative “worn‐close to‐skin” manner, the first example of a flexible BFC‐in‐a‐tube (named i ez Tube) as an entirely self‐contained wearable BFC (ESW‐BFC) for wearable energy generation by integrating a single‐layer fluff pulp (FP)‐based microfluidic module for the efficient sampling/utilization of biofuel fluids and the steady contact between biofuel fluids and wearable BFC with a flexible nano‐engineered BFC‐based BFC module for real‐time bio‐energy generation, along with an air‐breathing module that is based on a breathable and waterproof non‐woven tapes covered centrifuge tube‐based for continuous oxidizer supply, is reported. Through the seamless system integration, effective series‐connection pattern, and diverse readily accessible biofuel fluids pre‐collection, the i ez Tube demonstrates an exceptional capability to steadily and nonintermittently power wearable electronics under some certain but nearly ineluctable wearable circumstances and holds considerable and inimitable prospects as an ESW‐BFC for wearable electronics.