Search for: All records

Microbial fuel cells (MFCs) that generate electricity generation from a broad diversity of biomass and organic substrates through microbial metabolism have attracted considerable research interest as an alternative clean energy technology and energy‐efficient wastewater treatment method. Despite encouraging successes and auspicious pilot‐scale experiments of the MFCs, increasing doubts about their viability for practical large‐scale applications are being raised. Low performance, expensive core parts and materials, energy‐intensive operation, and scaling bottlenecks question a sustainable development. Instead, special MFCs for low‐power battery‐reliant devices might be more applicable and potentially realizable. Such bacteria‐powered biobatteries would enable i) a truly stand‐alone device platform suitable for use in resource‐limited and remote regions, ii) simple, on‐demand power generation within a programmed period of time, and iii) a tracelessly biodegradable battery due to the use of the bacteria used for power generation. The biobattery would be an excellent power solution for small‐scale, on‐demand, single‐use, and disposable electronics. Recent progress of small‐scale MFC‐based biobatteries is critically reviewed with specific attention toward various device platforms. Furthermore, comments and outlook related to the potential directions and challenges of the biobatteries are discussed to offer inspiration to the community and induce fruitful future research.

 

Paper‐based electronics (papertronics) are recently considered as one of the most exciting device platforms because of their flexibility, sustainability, eco‐friendliness, and low cost as well as their excellent mechanical, dielectrical, and fluidic properties. Now, innovative structure engineering techniques can manipulate diameters of the cellulose fibers of paper, smoothing the roughness and controlling the transparency for numerous device applications. Novel functionalization techniques of paper with organic, inorganic, and biological entities enable many engineering possibilities, revolutionizing papertronics for the next generation of electronics. Among those techniques for new functionalities, integrating electric bacteria into paper has attracted considerable interest as a new energy technique for papertronics. Paper has unique synergistic characteristics including a porous and hydrophilic environment for bacterial viability, a high surface area for bacterial accumulation, and sustainability even in resource‐limited settings. In this work, comprehensive analytical and experimental approaches to provide a novel but realistic and accessible power source from bacteria loaded into paper are pursued. This report provides new approaches to revolutionarily activate the biobattery and significantly improve its shelf life. Furthermore, for the first time the practical efficacy of the explored technique is ensured, generating on‐demand energy even in resource‐limited environments.

 

We developed an innovative paper-based platform for high-throughput culturing, trapping, and monitoring of C. elegans. A 96-well array was readily fabricated by placing a nutrient-replenished paper substrate on a micromachined 96-well plastic frame, providing high-throughput 3D culturing environments and in situ analysis of the worms. The paper allows C. elegans to pass through the porous and aquatic paper matrix until the worms grow and reach the next developmental stages with the increased body size comparable to the paper pores. When the diameter of C. elegans becomes larger than the pore size of the paper substrate, the worms are trapped and immobilized for further high-throughput imaging and analysis. This work will offer a simple yet powerful technique for high-throughput sorting and monitoring of C. elegans at a different larval stage by controlling and choosing different pore sizes of paper. Furthermore, we developed another type of 3D culturing system by using paper-like transparent polycarbonate substrates for higher resolution imaging. The device used the multi-laminate structure of the polycarbonate layers as a scaffold to mimic the worm’s 3D natural habitats. Since the substrate is thin, mechanically strong, and largely porous, the layered structure allowed C. elegans to move and behave freely in 3D and promoted the efficient growth of both C. elegans and their primary food, E. coli. The transparency of the structure facilitated visualization of the worms under a microscope. Development, fertility, and dynamic behavior of C. elegans in the 3D culture platform outperformed those of the standard 2D cultivation technique.