Multifunctional Centrifugal Microfluidic System And Its Application In Nucleic Acid Extraction And Detection

Microfluidics is the science of manipulating and controlling fluids,usually in the range of microliters to picoliters,in networks of channels with dimensions from tens to hundreds of micrometers.It can integrate common biological and chemical analyses into chips to realize miniaturization,integration and automation of traditional biochemical analyses.The microfluidic chips have the advantages of high throughput,low sample consumption,fast response,and portability.They have been widely used in biochemical analysis,point of care test,molecular diagnosis,biopharmaceuticals,environmental detection and other fields.However,with the deepening of the study,the functions of microfluidic chips are becoming more and more complex,and the driving mode of traditional microfluidic technology limits the large-scale integration of chips.As the important branch of microfluidics,centrifugal microfluidics can solve this problem very well.Centrifugal microfluidics uses the centrifugal force generated by the rotation of the motor as the driving force.It integrates the biochemical detection and analysis process on a disc,and because of the simple driving method,low cost,and high integration,centrifugal microfluidics has attracted more and more attention in the industry and academic field,and has been used in many areas.This paper proposes a multi-functional centrifugal microfluidic system,which is modularized and separated.First,the detection chip is separated from the system,and different detections can be performed in the system only need to replace different microfluidic chips.Secondly,the functional modules of the system are also separated,including the main control board,detection board,power board,control board,passive board,etc.The modules are relatively independent,which is convenient for maintenance and upgrade of the system.The system integrates the detection function,which can be used for real-time detection of fluorescence and chemiluminescence,so that the system can realize the sample-to-answer detection.The system integrates the wireless power supply function,and the rotating part of the system can introduce the control of the micro-chips and the paraffin valve,etc.,which increases the flexibility of the chip design.The system implements an intelligent control platform on the mobile phone.On the platform,various components used in the chip can be defined,the components can be controlled separately,or a series of control command can be written in one process to realize the automation of the detection process.This paper also explored the integrated design of the system,designed the prototype,printed it with 3D printing technology,and successfully installed the system into the prototype.Based on the multi-function centrifugal microfluidic system,a droplet generation chip and whole blood DNA extraction chip were designed based on the two-state model.On conventional centrifugal microfluidic chips,liquids can only flow radially outward under the action of centrifugal force,which limits the functions that the chip can achieve.By introducing an additional shaft on the centrifugal force chip,the Euler force generated by the rotational acceleration can be used to make the chip have two states of "left state"and "right state”,so more complex operations can be realized on chipo。In this paper,a multi-parallel two-state chip is realized,and liquid metering and droplet generation chips are designed based on the two-state model.The experimental results show that the droplet generation based on the two-state model produces good droplet uniformity,and by switching between "left state" and "right state",the timing of droplet generation is controllable.Based on the two-state model,this paper designed a DNA extraction chip for whole blood,and biological experiments were carried out.Compared with the results of standard spin column experiments,the results showed that the DNA purity obtained based on the two-state extraction chip was very small difference compared with the standard spin column,the extracted DNA can be used in nucleic acid amplification reactions.Following the DNA extraction chip,a chip for PCR was designed.Using the two-state characteristics,two reaction chambers of different temperatures are designed to make the liquid flow back and forth between the two reaction chambers to achieve thermal cycling.In this paper,another DNA extraction and RAA amplification chip was designed based on paraffin valve and spiral channel structure.The paraffin valve ensures that the reagents can be loaded sequentially,and the spiral distribution structure can realize multi-parameter detection on a single chip.The final experimental results show that the chip can achieve RAA amplification very well.