High-throughput and Multimodal Separation of Microbeads Using Cyclical Induced-charge Electro-osmotic Vortices and Its Application in Size Fractionation of Crumpled Graphene Oxide Balls

Abstract Crumpled graphene oxide (CGO) balls are new 3D applied materials, which present good potential in the development of energy storage and conversion devices for the advantages of high surface areas and resistant to aggregation. Utilizing ready-made CGO balls with defined sizes to synthesize desired materials or modify existing components, if achieved, we may make the functions and properties of the final products more controllable and programmable. However, acquiring uniform-size CGO particles still remains under challenge now, because uniform-size pristine graphene oxide is difficult to obtain and the size of CGO balls is sensitive to many parameters during the synthesis. An alternative potential solution, classifying the synthetized CGO balls to obtain uniform-size CGO balls may ingeniously circumvent above tricky issue. Here we designed tilted-angle ridge floating electrode sequence (TARFES) to actuate cyclical asymmetrical ICEO (AICEO) vortices to achieve particle separation and augment the throughput capability (105 particles/h), overcoming the limitation of existing vortex-based separation criteria. We firstly conducted simulations to identify the optimum configuration of TARFES. According to spatial features of cyclic AICEO vortices, two separation modes were developed. We separated silica and polymethyl methacrylate (PMMA) microbeads to validate the capability of the first separation mode, and studied the effects of voltage and flow speed on the separation results, obtaining 97.3% separation efficiency. We then separated PMMA microbeads and yeast cells with 93.1% separation efficiency to evidence the second separation mode. Also, we accomplished the simultaneous separation of multiple particles. Depending on characterization of CGO balls, the second separation mode was successfully engineered to realize size fractionation of CGO balls in continuous flow, yielding clear separation. Finally, we also modulated the voltage input to isolate nanoscale CGO balls from the background. This operative separation technique offers a unique route to acquire uniform-size CGO balls with potential applications in the fabrications of batteries and ultracapacitors.