Acoustics-driven multifunctional microreactor bioinspired by Phylum Porifera for bidirectional pumping and mixing production of silica nanofluids

The Phylum Porifera is one of the most primitive multicellular animals without a mouth, digestive cavity, or central nervous system. Its pores are strewn with flagella inside. Phylum Porifera wiggles its flagella to inhale the seawater, which brings in oxygen, bacteria, microscopic algae, and other organic debris to feed on. Inspired by this natural system, a microreactor based on sharp-edge has been developed and applied in microfluidics to achieve bidirectional pumping and mixing. Here we demonstrate a multifunctional microreactor for bidirectional pumping and mixing that mimics the internal flagella of the Phylum Porifera. The microreactor is designed based on microscale nonlinear acoustics to achieve functionalities via the acoustic streaming generated by the vibration of sharp-edge under the acoustic field. Numerical simulation is conducted to investigate the effect of sharp-edge numbers, dip angles, spreading angles, spacing of sharp-edges, and channel width on the pumping performance. And the bidirectional pumping is verified by experiments. Similarly, numerical simulation and experimental validation are conducted to investigate the effect of flow rate, amplitude, and sharp-edge density on mixing performance. Finally, to verify the application potential and good mixing performance of the developed microreactor, silica nanofluids were synthesized with excellent stability and uniform particle size distribution. These results not only provide important guidelines for the rational design of functional nanomaterials, but also shed new light on the development of efficient microreactors.