Light-Triggered Core Coalescence of Double-Emulsion Droplets for High-Throughput Microreaction on a LiNbO3 Platform

Optically triggering the core coalescence of double-emulsion droplets remains challenging. Herein, we utilize a photovoltaic field generated by laser illumination on LiNbO3 crystals to trigger the core coalescence in a high-throughput manner. The synergy between the interfacial pressure of the shell droplet and the internal flow induced by the photovoltaic field facilitates the core coalescence. With an increase in the core number, the illumination intensity required for the core coalescence is found to increase initially, whereas it tends to saturate at 5 × 107 W/m2, an intensity that does not cause a large temperature increase (<4 °C). The effective mixing of the substances contained in two core droplets after their coalescence is also verified. The proposed technique provides a precise, non-thermal and electrodeless strategy for high-throughput biochemical microreactions.