| Detecting the mechanical and electrical properties of cells is an important means of studying cell physics,medicine,and basic biology.It can reveal the internal physical and chemical mechanisms of cells,as well as their response and adaptability to the external environment.The combination of the two can provide a more comprehensive study of cell characteristics.Traditional single-cell mechanical property detection methods mainly include atomic force microscopy,micro-pipette aspiration,and optical tweezers.However,they have shortcomings such as low detection throughput and complex operation,which limit their practical applications.With the development of microfluidic technology,detection methods based on microfluidic technology continue to emerge.The contraction channel-induced deformation method is a representative method.By combining contraction channels and impedance cytometry technology,it can achieve continuous measurement of the strain ability and impedance characteristics of single cells.This method has the characteristics of high detection accuracy,small equipment volume,and simple data processing,and can perform high-speed,real-time,and accurate single-cell analysis.It has broad application prospects in the fields of cell analysis and single-cell detection.Based on these advantages,our research group proposed a method that can simultaneously detect the mechanical and electrical properties of single cells in contraction channels,and conducted the following research:(1)A glass capillary with a contraction structure was fabricated using a homemade microelectrode puller.Three microfluidic detection chips with different electrode structures were designed and fabricated on this basis.The ITO coplanar electrode was made using photolithography;A rod shaped platinum electrode was selected and electrode channels were made using a model replication method;The silver electrode is directly processed on both sides of the inner wall of the glass capillary through chemical plating,achieving integration between the electrode and the channel.The detection performance of three electrodes was tested and compared.The results indicate that the platinum electrode has the best sensitivity when an uncharged ball passes through the detection area.The ITO coplanar electrodes had weaker detection performance than platinum electrodes due to their higher internal resistance.The performance of silver electrodes made by chemical plating is weaker than that of platinum electrodes,which may be due to the thinner coating.Based on the electrode detection performance and chip fabrication difficulty,a microfluidic chip based on platinum electrodes was selected for subsequent research.(2)A detailed explanation of the Coulter principle and cell impedance principle was given.Clarifying the electrical properties of cells under low-frequency and high-frequency signals.Based on theoretical analysis and the characteristics of the signals in the detection channel,hardware circuits were designed and developed.Developed upper computer software that facilitates signal acquisition and analysis.Combined with microfluidic detection chips,a microfluidic cell mechanical and electrical properties detection system was established,and experiments were conducted on zebrafish embryo cells.The results showed that the insulation of healthy zebrafish embryonic cells under low-frequency signals resulted in voltage and time changes mainly depending on the cell volume.The voltage changes of dead zebrafish embryonic cells are very weak,proving that the selective permeability of cell membranes is related to cell activity.Track and detect zebrafish embryonic cells under high-frequency signals.The results indicate that there are significant differences in voltage changes under three different growth stages.Based on this law,the growth stage can be inferred using electrical signals(3)The electrical relationship between the inner diameter and resistance of the glass micro-needle tip in a small aperture was established.Optimized the tip resistance formula and detection method.A system for detecting the inner radius of glass micro-needles was established.Glass micro-needles with equal tip length but different inner diameters were prepared using a homemade needle-pulling apparatus.The tip resistance of the micro-needles was measured using a detection device,and the results were fitted to the inner diameter measured by optical microscopy with a fitting degree of 0.9723.Using detection device to detect glass microneedles with different tip lengths,inner diameters,and handle inner diameters.The average relative error between the detection results and the optical microscope detection results is only 0.914%.The accuracy,effectiveness,and reliability of this device have been verified... |
