Study On Separation And Processing Technology Of Microalgae Cells On Microfluidic Chip

As an important tool for ocean transportation,the ship's smooth navigation mainly relies on ballast water to maintain balance.It is worth noting that the harmful microorganisms carried in the ballast water will seriously damage the marine ecological environment.Therefore,the Ballast Water Convention stipulates that each ship needs to detect microorganisms before discharging the ballast water.When it exceeds the discharge standard,the ballast water needs to be further processed.However,various algae and impurities in the ballast water are doped with each other,which causes great troubles for the detection process and subsequent further processing.Therefore,the study of high-throughput microalgae separation methods,efficient microalgae inactivation and rapid feedback methods are urgent problems in the current research of ballast water.In view of the above problems,this paper studies the separation of algae and the rapid and efficient treatment of microalgae based on microfluidic chip.The content mainly includes the following two aspects:(1)Separation of microalgae cells in ballast water based on deterministic lateral displacement chipIn this paper,a passive separation chip based on deterministic lateral displacement was proposed,according to the different characteristics in size and hardness between different microalgae.Firstly,by designing triangular and circular microcolumn arrays with specific parameters in the microfluidic chip,the microalgae of different sizes could be manipulated to move along different trajectories.Secondly,through the simulation of the velocity field and the pressure field between the microcolumns,the influence of various parameters between the microcolumns on the trajectories of the microalgae cells was analyzed,and then the separation parameters were determined.Finally,the triangular and circular separation chips were fabricated by soft lithography.The separation system design was completed and the microalgae cells were separated by manipulating the sample flow rate,which provides a basis for the subsequent microalgae property detection and microalgae treatment.(2)Detection and activity detection of microalgae cells based on microfluidic chipIn this technical study,microalgae cells in ballast water were chemically treated using various concentrations of treatment liquid.Firstly,a concentration gradient generation chip based on microfluidic was proposed,which could generate the treatment liquid of any concentration.This chip used a highly efficient serpentine channel,based on the Hagen-Poiseuille's law,the equivalent circuit of the microfluidic loop was obtained.The Kirchhoff current and voltage law were used to analyze and determine the parameters of the chip to complete the chip design.Secondly,based on the characteristics of laser-induced microalgae chlorophyll fluorescence,the whole fluorescence of microalgae cells treated with NaClO solution was collected in real time,and the fluorescence intensity of quantitative cells was used to characterize the survival rate of microalgae cells.Finally,a high-flux concentration gradient chip and microalgae fluorescence detection were combined to design a microalgae treatment detection system,and the optimum concentration of treatment solution and treatment time for inactivation of microalgae were quickly screened,which provided an important reference for the screening of ballast water treatment parameters.