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 iezTube) 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 iezTube 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.

Skin-Interfaced Wearable Sweat Sensors for Precision Medicine

“…The stretchable textile BFC could output up to 250 μW cm –2 with 20 mM lactate and maintain a stable power output after 100 cycles of 100% stretching. In addition, a self-contained laser-induced graphene-based wearable BFC-in-a-tube was recently reported for energy generation from untreated human sweat to power a wearable digital watch …”

“…In addition, a self-contained laser-induced graphene-based wearable BFC-in-a-tube was recently reported for energy generation from untreated human sweat to power a wearable digital watch. 418 BFCs capable of outputting milliwatt levels of power are highly desired for Bluetooth-based wireless sensing applications. "Island-bridge" configuration epidermal BFCs have been reported with high power output, stretchability, and durability.…”

Integrated multimodal microfluidic E-skin powered by synergistic tandem nanogenerators for sweat-based health monitoring and skin-temperature analysis

“…42 Traditional wearable electronics use rigid batteries, which have the disadvantages of being inconvenient to wear and having poor deformability. 43 In contrast to conventional batteries, energy supply using renewable green energy sources can solve the above problems and provide a continuous power source, such as biofuel cells, [44][45][46] ion-selective batteries 29 and hydrovoltaic electricity generation, 28 which holds great potential for power supply in exible wearable electronics. Among so many renewable green energy sources, benetting from easy-utilization and sustainability, hydrovoltaic electricity generation and/or moisture electricity generation for energy supply are excellent candidates for exible wearable electronic devices, especially for sweat monitoring.…”

Universal Fully Integrated Wearable Sensor Arrays for the Multiple Electrolyte and Metabolite Monitoring in Raw Sweat, Saliva, or Urine

“…Fully integrated wearable devices are one of the most coveted and ultimate aims of modern technology design and development that offer complete functioning but do not need additional peripherals. − The incorporation of fully integrated wearables into the process of analyzing raw noninvasive biofluids results in the development of fully integrated wearable sensors, which makes it possible to perform in situ, noninvasive, dynamic, and wireless monitoring of molecular-level biomarkers in raw noninvasive biofluids for the purpose of improving the management of health conditions. − Since Javey’s group pioneered the first fully integrated wearable sensor arrays (FIWSAs) for the analysis of multiple electrolytes and metabolites in sweat in 2016, extensive efforts have been made to further the study of developing FIWSAs for multiple electrolyte and metabolite monitoring in noninvasive biofluids. ,,,, In addition to sweat, Wang’s group demonstrated the first fully integrated wearable saliva sensor for assessing saliva metabolite (i.e., uric acid, UA) . Lately, in addition to sweat and saliva, Chen’s group proposed the first fully integrated wearable urine sensor within a diaper for simultaneously measuring urinary metabolite (i.e., UA) and electrolyte (i.e., Na + ) .…”