On-chip acoustic chaotic micromixer for point-of-care applications

Abstract

Micro-mixing plays an important role in the biochemical analyses using miniaturized total analysis system (µTAS) or lab-on-chips. However, the existing micromixers primarily rely on the specific medium and lack the capability of being activated on-demand, and it is rather challenging to ensure the adequate analyte capture and fluid washing on the surface of each probe particle during the assay steps. Herein, we demonstrated a novel acoustic chaotic micromixer actuated by a Lamb wave resonator (LWR) array, which integrated all steps from the initial sample pretreatment, chaotic probe particle mixing, analytes trapping, fluid washing to the ultimate signal acquisition, thereby fulfilling the “sample-in-answer-out” medical needs. The high-speed microscale acoustic streaming vortices triggered by the four LWRs in the confined micro-channel can be utilized to accelerate the particles’ velocity and enhance the collision between probe particle and target analyte. In addition, chaotic particle mixing effect was realized by on-demand controlling the direction and magnitude of the four-in-one drag force based on the programmable acoustic stimuli of each independent LWR. Besides, a compact cartridge was specifically designed to accommodate the acoustic chaotic micromixer and peripheral accessories (including RF signal source, CMOS optical sensor and mini pump), thus presenting a handheld device for point-of-care applications. Finally, the trace prostate specific antigen (PSA) derived from fingertip blood samples was effectively detected. Owning to the compact size, on-chip chaotic particle mixing, fast and sensitive detection performance, the proposed acoustofluidic system is very suitable for the on-site diagnostic applications.