Reconfigurable acoustic streaming tweezers enabled portable liquid handler for nucleic acid extraction

The extraction and purification of nucleic acids (NA) play a crucial role in biomedicine, as high-purity and efficient extraction are essential prerequisites for accurate molecular diagnosis. Consequently, beads clumping and complex peripherals hinder the development of portable NA extraction apparatus. In this study, a novel reconfigurable acoustic streaming tweezer (RAST) is proposed. Two MEMS fabricated solid-mounted thin-film piezoelectric resonators (SMRs) are integrated into a compact reaction chamber. The high-frequency (>1 GHz) acoustic wave induces fast liquid flow and particle movement through the Stokes drag. By carefully designing the structure of the device and the operation program, the RAST can be switched between the chip-based centrifuge-type particle separation and the vortex-type solution mixing modes, enabling automated NA extraction without complex peripherals. Numerical simulations and micro particle image velocimetry (PIV) experiments are conducted to thoroughly investigate the particle manipulations and mixing conditions in the double SMR mode (D-SMR) and the single SMR mode (S-SMR). A portable liquid handler based on the RAST is designed and applied to NA extraction from different samples (buffers, serum, and whole blood). After optimization, the system achieves an 80 % NA recovery rate from rat whole blood. Combined with real-time quantitative PCR, the detection sensitivity for adenovirus (DNA) and COVID-19 (RNA) is as low as 10² IU/mL. When handling samples smaller than 200 μL, the sensitivity is more than 1.56 times higher than that of commercial automated liquid handling systems.