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Biofuel cells have been in the spotlight for the past century because of their potential and promise as a unique platform for sustainable energy harvesting from the human body and the environment. Because biofuel cells are typically developed in a small platform serving as a primary battery with limited fuel or as a rechargeable battery with repeated refueling, they have been interchangeably named biobatteries. Despite continuous advancements and creative proof-of-concept, however, the technique has been mired in its infancy for the past 100 years, which has provoked increasing doubts about its commercial viability. Low performance, instability, difficulties in operation, and unreliable and inconsistent power generation question the sustainable development of biofuel cells. However, the advancement in bioelectrocatalysis revolutionizes the electricity-producing capability of biofuel cells, promising an attractive, practical technique for specific applications. This perspective article will identify the misconceptions about biofuel cells that have led us in the wrong development direction and revisit their potential applications that can be realizable soon. Then, it will discuss the critical challenges that need to be immediately addressed for the commercialization of the selected applications. Finally, potential solutions will be provided. The article is intended to inspire the community so that fruitful commercial products can be developed soon. 

Bioelectrochemical technologies have attracted significant scientific interest because the effective bacterial electron exchange with external electrodes can provide a sustainable solution that joins environmental remediation and energy recovery. Multispecies electroactive bacterial biofilms are catalysts that will drive the operation of bioelectrochemical devices. Unfortunately, there is a lack of understanding of key mechanisms determining their electron-generating capabilities and syntrophic relations within microbial communities in biofilms. This is because there are no universally standardized models for simple, rapid, reliable, and cost-effective fabrication and characterization of electroactive multispecies biofilms. The heterogeneous and long-term nature of biofilm formation has hampered the development of those models. This work develops novel biofabrication and analysis platforms by creating innovative, paper-based 3-D systems that accurately recapitulate the structure, function, and physiology of living multispecies biofilms. Multiple layers of paper containing bacterial cells were stacked to simulate different layered 3-D biofilm models with defined cellular compositions and microenvironments. Overall bacterial electrogenic capabilities through the biofilm structures were characterized by thoroughly monitoring collective electron flows through different external resistors. Changes in the type of species and order of stacking created biofilm modeling which allowed for the study of their electrogenic performance via variation in electron flow rate output. Furthermore, multi-laminate structures allowed for straightforward de-stacking and layer-by-layer separation for analyses of pH distribution and cellular viability. Our multi-laminate structures provide a new strategy for (i) controlling the biofilm geometry of 3-D bacterial cultures, (ii) monitoring the microbial electoral properties, and (iii) constructing an artificial biofilm layer by layer. 

Traditional hydrophilic wound dressings, while common, fail to effectively drain wound exudate, creating conditions favorable for bacterial growth. Similarly, newer Janus‐type dressings with hydrophobic‐hydrophilic properties also fall short, as their hydrophobic side causes excessive dryness by pulling biofluids from the wound, disrupting moisture balance. Additionally, embedding antibiotics in dressings at fixed concentrations, regardless of the infection type, reduces effectiveness and contributes to the growing problem of antibiotic resistance. In response, a single‐layered Janus paper wound dressing, designed for efficient exudate absorption and precise antibiotic delivery, is developed. The approach differs from traditional Janus‐type dressings; a hydrophilic layer is placed directly against the wound for better moisture management, while antibiotics are applied through the hydrophobic layer. To further enhance exudate management, the hydrophilic section with four extra absorbent pads is extended. The dressing's antibiotic efficacy and dosage are tailored based on antibiotic susceptibility testing, ensuring targeted treatment. The selected antibiotic is manually added but automatically delivered directly to the wound bed. The in vitro and ex vivo evaluations, using bacterial cultures on agar and porcine skin assays, respectively, confirm the dressing's superior exudate drainage and its ability to inhibit pathogen growth and reproduction, marking a significant advancement in wound care.

 

An intimate and direct interface between inorganic electronics and living organisms will revolutionize the next generation of bioelectronics by bridging the signal and material gap between these two different fields. In this work, a redox-active microbial electrode is constructed as the novel interface by simultaneously 3-D printing and electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in a liquid containing electrochemically active bacteria. A custom-made 3-D printer with a concurrent electrochemical control allows a scalable, template-free deposition of electrochemically active organic electrodes in a single printing. Electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) acts as redox-active bridges by exploiting extracellularly transferred electrons generated from the bacterial respiration, constructing a seamless contact between the biological processes and the external abiotic systems. 

We demonstrate the first example of a wearable self-charging power system that offers (i) the high-energy harvesting function of a microbial fuel cell (MFC) and (ii) the high-power operation of a supercapacitor through charging and discharging. The MFC uses human skin bacteria as a biocatalyst to transform the chemical energy of human sweat into electrical power through bacterial metabolism, while the integrated supercapacitor stores the generated electricity for constant and high-pulse power generation even with the irregular perspiration of individuals. The all-printed paper-based power system integrates the horizontally structured MFC and the planar supercapacitor, representing the most favorable platform for wearable applications because of its lightweight and easy integrability into other wearable devices. The self-charging wearable system attains higher electrical power and longer-term operational capability, demonstrating considerable potential as a power source for wearable electronics.