Research On Particle Motion And Sensing Based On Dielectrophoresis Mechanism And Fabry-perot Cavity Structure

Cells are one of the basic units of biological metabolism and function.Cell concentration is considered to be an important indicator of the physiological state.The development of high-resolution cell concentration detection methods has aroused widespread research interest.The bulk refractive index sensing based on Fabry Perot(FP)resonant cavity can be applied to the detection of cell concentration so that the light wave can completely penetrate into the bulky sample solution,and the interaction between light and matter is very strong.There are good application prospects in the detection of analyte concentration.However,in order to achieve high-resolution ultra-low cell concentration detection,the cavity length of the FP resonant cavity needs to be increased to obtain stronger light-analyte interaction,but it also increases the difficulty of collimation and the required sample volume.In order to solve the above problems,the study applied dielectrophoresis(DEP)technology to FP cavity sensing.While performing concentration sensing,DEP technology enriched the uniformly suspended yeast cells in the sensing area to achieve low Concentration solution detection,thereby improving the sensitivity of the sensor.Firstly,the concentration detection based on refractive index sensor,research progress,and the advantages and limitations of these sensing methods is described.At the same time,the research progress of DEP enhanced concentration sensor is investigated,which shows that DEP technology is superior to FP resonant cavity structure for refractive index sensing.Based on the theory of DEP,a star-shaped microelectrode was designed and fabricated by lift-off process.The experimental device was built with this electrode as the core,and polystyrene microspheres were selected as the experimental analyte.The optimal parameters of PS microsphere enrichment were determined by experiments.Then,the enrichment effect of different concentrations of PS microsphere was explored under the condition of constant experimental parameters.Secondly,the DEP-FP sensing device is designed based on the Fabry-Perot resonator,and the specific test scheme is determined.After the DEP-FP structure was successfully fabricated,a test platform was built based on this device.Before the in vivo refractive sensing experiment,yeast cells were used as the experimental analyte to carry out enrichment experiments on the ring electrode,and the optimal parameters of frequency and voltage were determined to realize the aggregation of yeast cells in the enrichment area.It lays a foundation for the application of DEP technology in bulk refractive sensing,the realization of low concentration cell clusters,and concentration detection.Finally,based on the test platform of the DEP-FP sensing structure,the bulk refractive sensing experiment of yeast cell concentration was carried out.The performance of the sensor was characterized,the influence of laser thermal effect on the experiment was monitored,and the error was eliminated in subsequent experiments.The refractive index sensing experiment was used to verify the dielectrophoretic manipulation of yeast cells.The reflectance spectra at different time points were recorded and the concentration difference before and after enrichment was compared.Five different concentrations of yeast cell solutions were prepared to evaluate the performance of the DEP-FP sensing system.The results show that the DEP-FP structure has a lower detection limit and wider detection range.