Study Of Cell Mechanical Property Based On Piezoresistive Cantilever Sensor

The mechanical property of cell has a relationship with the growth of celland the regulating function of itself. The correlation between deformability of cells and diseases is well-known, and has been evaluated in and cell ‘poking’ experiments. The piezoresistive micro cantilever probe makes it possible to detect the property of single cell via the mechanical method. And the piezoresistive micro cantilever probe is also popular in the Nanobiology on account of its high precisionand can do the measurement in the biological environment etc. It can do the nanoindentation experiment to explore the mechanical property of the sample because of the load on the sample can be detected by the deformation of cantilever.In this article we study the mechanical property of yeast cells by the piezoresistive micro cantilever sensor. The piezoresistive micro cantilever sensor has not only advantages of AFM applied in the field of nano biomechanics, but also the characteristics of low cost, external simple circuit, high sensitivity. The experimental results obtained in this paper will provide more references for the study of the mechanical properties of yeast cells, and the application of the equipment and methods will provide new tools and techniques for the research of nano biomechanics. The main research contents include:In the first part, based on the study of biological cells at home and abroad, the methods of measuring the elastic modulus, elastic modulus and adhesion properties of biological cells were analyzed. In view of the existing research methods, we put forward the method of measuring the mechanical properties of yeast cells based on the piezoresistive micro cantilever sensor.In the second part, the principle of nano indentation is introduced in detail, and analyzes the factors that may affect the measurement results, such as the shape of the indenter, the surface morphology of the material tested, and the location of the zero point.In the third part, force measuring device based on piezoresistive cantilever sensor has been designed. According to the characteristic of the weak output signal of the sensor, the excitation bridge of DC voltage,instrumentation amplifier, the Butterworth low pass filter and the fine tuning offset voltage circuit are applied. For force calibration of the sensor, the AFM probe is indented with the piezoresistive cantilever sensor by the accurate control of the nano-driven platform under the scanning electron microscope.In the fourth part, the nanoindentation simulation is carried out on yeast cells and measurement ofyeast cells Young’s Modulushave been completed in the experiment. Finiteelement analysis software ABAQUS is used to simulate the nanoindentation experimenton the basis of references and experiment data. Yeast cells are indented by the indenter with different tilt angle and mechanical curveswith different tilt angles have been obtained. In the experiment of measuring yeast cells mechanics, the experimental data obtained are fitted by quadratic polynomial through MATLAB. Combining Hertz model to YoungModulus of the yeast cells is calculate by Hertz mechanical model. The data of finite element method and nanoindentation experiment are analyzed and compared.Both are consistent.In the last part, the adhesion force between cell and substrate was measured based on the piezoresistive cantilever sensor. In the experiment of measuring cell and tip of the adhesion, the single variable method is adopted to analyses the influence of the magnitude of load and the loading time respectively on the adhesion force.In yeast cells and substrate adhesion experiment, the influence of contact time and different substrates are analyzedon yeast cell adhesion force. We have drawn Conclusion: loading time and load can make the adhesion force increase and adhesion force of positively charged glassslide is larger than ordinary glassslide.