Development And Application Of Digital Microfluidic Chip

Droplet microfluidic also called digital microfluidic, as a popular direction of microfluidic technology, it has many advantages, such as low sample consumption, rapid response, good heat and mass transfer effects, and no pollution etc. Its application has expanded from analysis and testing, biological engineering, medical analysis to organic synthesis and other cutting-edge technology field. Micro-droplet generation device as the foundation of this technique, is regarded as the key of generating a large number of stable and uniform droplet. In view of the high price of existing device on the market, thus advancing the related research of this technique and developing a set of economic and efficient micro-droplet generation device has important significance.Firstly, research actuality and development trend of micro-droplet’s formation and manipulation are reviewed. Research objective is established which aims at developing microfluidic chip and ancillary equipment.The principle and related theory of micro-droplet are proposed, including the non-dimensional parameters in droplet dynamics, wall wetting properties, contact angle, marangoni effect, flow resistance and interface dynamics etc.The similarities and differences between the two methods of generating micro-droplets are described, which includes active and passive method. Passive method is used by this paper as it is used to generating large quantities of micro-droplet quickly. Microfluidic chip is designed and fabricated on these foundations, including common-cross, serpentine-cross and division-cross channel structure. In addition, in order to ensure good air tightness in the experiment process, the existing fixture was improved by machining holes to insert tube on the upper cover and machining through groove to observe on the base to match the chips.Secondly, a micro-droplet generation device which has two kinds of control schemes is developed. The two schemes respectively based on PC and single chip microcomputer. The hardware of first scheme includes plunger pump, solenoid valve, stepper motor drives,optocoupler isolation protection circuit, serial port, parallel port, power, computer and microfluidic chip. The software is compiled with VB.NET, including serial communication program and parallel port control program. A set of portable device is created in the second scheme, which takes STC89C52 RC MCU as core and out of serial port and parallel port.Finally, an experimental system is set up by chips, fixtures, micro-droplet generation device and improved inverted microscope and micro-droplet is generated on this platform.The formation process and affecting factors of micro-droplet is simulated by usingCOMSOL software and compared with the experimental results. In addition, the relevant application of micro-droplet is explored, such as single cell wraps, protein crystallization,particle synthesis, drug delivery, PCR and disease detection.