Energy-harvesting bioreactors: toward self-powered microfluidic devices, a mini-review

The past decades have witnessed tremendous progress in microfluidics in terms of functionalities and applications. To realize various functions such as actuation and sensing, a source of energy is often needed. Batteries, as a common energy source for portable devices, are not always preferred in situations such as remote sensing and in vivo applications. Nature has provided us with microorganisms and biomolecules capable of converting biomass into useful form of energy via complex chemical pathways. It would be extremely useful if microdevices can be self-powered by consuming “foods” around them. Recently, various types of microfluidic bioreactors have been developed to harness energy by intending to replicate natural processes. Most of them were used to generate electricity in a biofuel cell configuration. Others were used to produce mechanical actuation based on processes such as fermentation. Here, we summarize recent progresses made in this area. Specifically, we compare various applications and their performance metrics. We also discuss critical problems in this technology and highlight future opportunities for self-powered microfluidics.