Microfluidic plasmas: Novel technique for chemistry and chemical engineering

As an emerging technology that features the integration of microfluidics and non-equilibrium plasmas, microfluidic plasmas not only allow the precise and effective matter and heat transport via the microfluidic system, but also provide an extremely reactive medium full of high energy plasma-generated species. Therefore, they could open new pathways for chemical synthesis or chemical engineering processes that are hardly achievable by conventional methods. In this review, three main microfluidic plasma configurations are reviewed, including plasmas confined within microchannels, plasma jets beyond microchannels and microfluidic plasma arrays. The state-of-the-art diagnostic techniques for characterizing the microfluidic plasma are also examined. A broad range of applications of microfluidic plasmas of particular interest to chemistry and chemical engineering, such as nanomaterials fabrication, surface modification, chemical synthesis, environmental application, and micro total analysis systems, are discussed. The research gaps, bottlenecks and future perspectives of this novel technology are presented.