Study On Microalgae Separation Chip In Ship Ballast Water Based On Dielectrophoresis

The bacteria,microalgae and other organisms carried in the ballast water of ships are discharged into the new sea area,which seriously threaten the ecological environment of the ocean.In order to protect the marine ecological environment,microalgae cells in ballast water should be detected in the process of ballast water treatment.However,the samples in the actual testing process are not pure samples,so the pre-processing work is very important.The target sample can be separated from impurities before testing.On the one hand,it is not only related to the accuracy of microalgae detection,but also related to the efficiency of ballast water detection.On the other hand,when ship ballast water needs high accuracy detection or high concentration detection,it is very important for detecting and separating the target and concentrating it into high concentration sample.To solve the above problems,we designed microalgae separation chip based on dielectrophoresis for ship ballast water,and embedded 3D micro electrode into microfluidic chip to achieve high-throughput,automatic and continuous separation of microalgal cells and similar size impurities(polystyrene particles).The first is the dielectrophoretic force of neutral particle in a non uniform field formula from the analysis of dielectrophoresis theory,analysis of polystyrene particle frequency response curve,and draw the algae cells and polystyrene particles by dielectrophoresis based on difference,stress analysis of the particle position and velocity equation of particle.Secondly,a separate chip model with three layers of structure is designed,and the separation chip is simplified as a two dimensional simulation model.The distribution of electric potential,electric field intensity and dielectrophoresis force in the channel is simulated,and the separation of particles with different sizes is simulated.Then the ITO(Indium Tin Oxide)glass substrate is produced by the lithography and etching process in the semiconductor fabrication process.Microelectrodes and PDMS(Polydimethylsiloxane)microchannels were fabricated by soft photolithography,and the three layer structure was encapsulated into a well sealed separation chip.Finally,the separation system is set up,and the experimental samples are allocated.The reference ranges of the amplitude and frequency of the AC voltage of the separation experiments are determined before the chip is encapsulated.the movement of single particles,separation of two different sizes of particles,and separation of microalgae from particles were carried out after the chip is encapsulated.In the above separation system,the separation experiments of microalgae cells with similar dimensions(polystyrene particles)were carried out.It lays the foundation for the ship's ballast water to separate the target samples from the more complex samples in the actual pre-test.