Research of biological reagent droplet formation in valve-control dispensing method

The valve-control dispensing method is one of the most common methods to dispense biological reagents in the field of life science, but it faces difficulties in control and impacts from the system parameters. Based on the two-phase volume of fluid model, a computing and simulating model of biological reagent droplet dispensing process is constructed. Through numerical simulation, the droplet formation and the influences from the parameters of driving pressure, nozzle and reagent distinction are studied. The results show that the droplet formation can be controlled by adjusting the driving pressure and valve's opening time, and the higher pressure and shorter valve's opening time can produce smaller droplets. The nozzle with a taper whose value is at 15 to 30 degrees, and a suitable large contact angle can make the droplet dispensing easy and reduce the required driving pressure, especially for the reagents with lower surface tensions and viscosities.