Valve-based microfluidic droplet micromixer and mercury (II) ion detection

A valve-based microfluidic micromixer was developed for multiply component droplets generation, manipulation and active mixing. By integrating pneumatic valves in microfluidic device, droplets could be individually generated, merged and well mixed automatically. Moreover, droplet volume could be controlled precisely by tuning loading pressure or the flow rate of the oil phase, and certain droplets fusion conditions were also investigated by adjusting the droplet driving times and oil flow rates. In these optimized conditions, fluorescence enhancement of droplets was used to detect Hg (II) ions in droplet by mixing with probe droplets (Rhodamine B quenched by gold nanoparticle). This method would have powerful potential for tiny volume sample assay or real-time chemical reaction study.