Preparation Of Femtoliter Droplets And Hydraulic Analysis Of Microfluidic Chip

Droplet based microfluidics has the advantage of tiny volume as well as high precision.It has been widely used in many applications ranging from single cell analysis to droplet digital PCR.Here,some work is done as follows.Fistly,a dual temperature working mode is set up to simplify the complex thermal process for solidifying the coating of optical sensitive resin.The soft baking is finished at 65 ? for several minutes,while the hard barking is complete at 95 ? for 5-45 minutes.The post exposure baking is finished at 65 ? for several minutes,while the hard barking is complete at 95 ? for 5-15 minutes.On the basic of dual temperature mode,microchannels of high side wall,as well as,two layers of lithography,are successfully made.Secondly,we develop a new method to produce droplets downsize to femtoliter.With capillary-based parts in tubing systems of biological detecting machines,the exiting tube is inserted into the feeding tube and a funnel-shaped meniscus is formed before droplet formation.In this way,one can create droplets of same sizes with less flow rates of continuous phase than usual.In other words,with the same flow rates of continuous phase,one can make small droplets as opposed to the conventional methods.Finally,the pressure drops of channel connection with three branches are modeled theoretically in the form of the Ohm's law of circuit,where the pressure drop stands for the voltage drop and the flow rate of fluid is equivalent to the current.The obtained formula are verified numerically.The results show that the local resistances of branches to flow rate cannot be neglected as usual,in particular in the case of the branch by the outmost side.