Droplet microfluidics for energy and bioelectrochemical applications
Abstract
Droplet microfluidics has become a modern technology for chemical, biological, electrochemical and energy applications, which helps in the manipulation of a discrete droplet in a size range from 10 pL to 100 nL. Compared to conventional techniques, the droplet-based platform provides a 10–100-fold faster mass-transfer rate, reduces reagent usage by up to 95%, decreases reaction time from hours to minutes, and enables ultra-efficient screening of 10 3 –10 4 droplets s -1 . The capabilities have greatly advanced the discovery and optimization of advanced materials, catalysts, and bioelectrochemical systems. This review covers all aspects of droplet generation, manipulation, detection methods and the latest progress in device manufacturing for energy and bioelectrochemical applications. Representative studies show that the droplet-assisted microfluidic platforms can be used to screen electrocatalysts within minutes, can be used for membrane-less electrochemical systems with current densities over 100–500 mA cm -2 , and can be used to reduce material consumption by over 80% with enhanced catalyst utilization. Droplet microfluidics has enabled rapid microbial screening, improved control of biofilms, removal of up to 95% chemical oxygen demand (COD), and microbial electrolysis system with hydrogen production rates up to 314 ± 17 m 3 H 2 m -3 reactor per day with optimized electrode configuration in bioelectrochemical applications. The review also emphasizes the use of AI, machine learning, digital microfluidics and automation for autonomous experimentation and optimization based on data. Finally, the current challenges regarding scalability and standardization of devices, long-term operational stability and commercialization of devices are critically discussed. Overall, droplet microfluidics is a versatile and scalable platform that has the potential to speed up the next-generation of sustainable energy technologies and to bioelectrochemical systems by providing more precise control of reactions, high throughput experimentation, and more efficient use of resources.