Study On Microfluidic System And Ultrasonic Vibration Micromixer For Nucleic Acid Extraction By Magnetic Beads

Nucleic acid extraction by magnetic bead method is to extract nucleic acid in biological solution by using magnetic bead in PCR nucleic acid extraction operation.Magnetic bead can adsorb nucleic acid on the surface of magnetic bead in biological solution,so as to realize the extraction of nucleic acid.Microfluidic chips have been widely used in PCR nucleic acid extraction experiments because of their integration and low consumption.In this paper,the ultrasonic vibration micromixer was used to mix the magnetic bead biological mixture on the microfluidic system of magnetic bead nucleic acid extraction.The advantages of energy concentration and high frequency of ultrasonic vibration were used to improve the efficiency of magnetic bead mixing and reduce the mixing time so as to speed up the efficiency of nucleic acid extraction.The finite element model of ultrasonic vibration propagation and attenuation in the mixing chamber of ultrasonic micromixer was established based on the mathematical model of ultrasonic wave propagation in the flow field,the finite element model of acoustic-solid coupling and the finite element model of fluid-solid coupling.The force of magnetic bead in micromixer is analyzed,and the mathematical model of acoustic radiation force on magnetic bead is established,and the main influencing factors of acoustic radiation force are analyzed.Set up 3D model of ultrasonic vibration micro mixer,movement under the action of the magnetic beads in the sound field finite element simulation analysis,get the influence of sound field distribution on the movement of magnetic beads as a result,for there is no different from acoustic field of ultrasonic vibration under the micro mixer mixing cavity dimensions of magnetic beads with the motion trajectory of finite element simulation of flow field.The finite element simulation of the acoustic field of ultrasonic vibration micromixer under the action of ultrasonic vibration of a single ultrasonic energy exchanger was carried out.The sound pressure and sound pressure level in the mixing chamber were compared under different mixing chamber size,acousto-structure interface thickness and ultrasonic vibration frequency,and the distribution of sound field was simulated and analyzed.Based on the above simulation analysis,the flow field of the mixing cavity and the motion trajectory of the magnetic beads are simulated and analyzed.The sound field in the mixing chamber was simulated and analyzed when multiple ultrasonic energy exchangers acted together in different arrangement modes,and the sound pressure and sound pressure level of the sound field were compared under different mixing chamber sizes and ultrasonic vibration frequencies.Based on the results of acoustic field simulation,the flow field of the mixing cavity and the motion trajectory of the magnetic beads are simulated and analyzed.The mixing effects of a single ultrasonic transducer and multiple transducer on magnetic beads were compared.The experimental platform of ultrasonic vibration micromixer is built.In this paper,NE555 signal generator circuit and daring tube amplifier circuit are used to generate the driving electric signal of ultrasonic transducer.The experiments of magnetic bead movement in the mixing chamber were completed when there was no formation action,when a single ultrasonic transducer acted on the magnetic bead and when multiple ultrasonic transducer acted on the magnetic bead.The experimental results are compared with the simulation results,the effect of ultrasonic vibration on the magnetic bead motion mixing in the magnetic bead biological mixture was verified.Aiming at the experimental steps of magnetic bead nucleic acid extraction,an automatic experimental platform based on the microfluidic system of magnetic bead nucleic acid extraction using ultrasonic vibration micromixer was established.