Capillary force-driven reverse-Tesla valve structure for microfluidic bioassays.

Biological assays involve the lysis of biological particles, enzyme reactions, and gene amplification, and require a certain amount of time for completion. Microfluidic chips are regarded as powerful devices for biological assays and in vitro diagnostics; however, they cannot achieve a high mixing efficiency, particularly in some time-consuming biological reactions. Herein, we introduce a microfluidic reverse-Tesla (reTesla) valve structure in which the fluid is affected by vortices and branch flow convergence, resulting in flow retardation and a high degree of mixing. The reTesla is passively operated by a microfluidic capillary force without any pumping facility. Compared with our previously developed micromixers, this innovative pumpless microfluidic chip exhibited high performance, with a mixing efficiency of more than 93%. The versatility of our reTesla chip will play a pivotal role in the study of various biological and chemical reactions.