Design And Application Of Rapid Microdroplets System

Microfluidic chip which possesses a number of advantages:small volume, high efficiency, less reagent consumption, high resolution, high sensitivity, short time consuming, and low cost has been widely used in many fields. And droplet-based microfluidic chip, one most important branch of microfluidic chip, has given rise to a large number of scientific and technological developments over the last few years. The driving and control technology is the base of microfluidic chip operation. The classical microfluidic driving source is syringe pumps, but the syringe pumps have large ripple, the scope of flow velocity is small and the core rod of syringe is easy to deformation.Fortunately, the pneumatic driving which has small ripple, fast respond and h wide control range can well solve those disadvantages of syringe pumps. Therefore, a new rapid microdroplets driving system which based on pneumatic drive is necessary. The rapid microdroplets system which was designed in this paper has four modular:the hardware circuit modular, human-computer interaction graphical interface modular, the mechanical structure of the pump's shell, the accessories of the system. This system has the following advantages:1) Small size, light weight and two independent chambers which can drive two channels liquid flow at the same time; 2) The pressure of the system range from 0 bar to 10 bar, the resolution is 0.001 bar and the precision is 0.001 bar; 3) This system can easily generate micro-nano litres droplets.In the later of this paper, the rapid microdroplets system was used to study the droplets stability of different distribution of Hydrophile-Lipophile Balance (HLB) value and different distribution of surfactant content. By large experiments we find that when the HLB value is 5.5 and the concentrations of surfactants (v/v) is 5%, the stability of the droplets which diameter below 100 ?m is relatively high.Finally, the rapid microdroplets system was used to study the relationship between pneumatic pressure and the shape and size of droplets. Experiments show that different water phase pressure and oil phase pressure will affect the "shrink neck" size of water phase in the intersection, which affecting the size of the droplets. When the oil pressure is greater than the water pressure, with the increasing of oil phase pressure, droplets diameter will decrease. The relationship between the absolute slope value of droplets diameter change and the pressure ratio of oil phase and water phase is reciprocal relationship. And in the same pressure ratio of oil phase with water phase, droplet size decreases with the increase of water phase pressure.Rapid Microdroplets System is very suitable for working as driving source of droplet microfluidic or other microfluidic. And in the near future, it will be more and more popular, even completely replace syringer pump in some ways.