| Cell mechanics is the foreword field of modern biomechanics.More and more attention has been paid to the study of the influence of mechanical factors on cells.Mechanical stimulation,such as tension,pressure and shear stress,play an important role in regulating cell behavior.The study of cell mechanical response law can provide enlightenment for disease prevention and treatment.In this paper,a set of strain loading apparatus for adherent cells was developed,which can be used in the study of cell mechanics and biology.The instrument was maded up of cell culture system,drive control system and power transmission system.In order to study the effect of different mechanical forces on cells,a driving control system was used to load static or periodic mechanical forces of pulling and pressing on cells in cell culture chambers.The parameter setting : Tension compression strain adjustment range - 1% ～ 50%,Feed resolution — 0.01,Holding torque — 0.097 N.m,Loading frequency — 0.01 Hz ～ 4.5hz.In order to provide a suitable growth environment for cells,the cell culture system and the system of dynamic transmission were placed in the cell culture box for loading,and the drive control system was placed outside the culture box for data transmission through insulated wires.The temperature in the box was set to 36 ± 2 ℃ and the humidity was set between 45% and 65%;The control panel of the programmable controller was used to control the mechanical force action conditions(Tensile frequency,Strain size,Cycle period)and constantly monitor the strain change.The pulse was distributed to the stepping motor through the subdivision function of the driver(maximum subdivision-32)and the feed resolution was controlled.The system of dynamic transmission included two-phase stepper,ball screw,stretching platform and fixed pile.In order to adapt to the environment of cell incubator,the stretching platform was made of aluminum material,and the rest was made of stainless steel material.The cell culture system included a culture chamber and a cell nutrient solution.The culture chamber was made to a longitudinal length of 26.8mm,a transverse length of 40 mm and a height of 14.5mm and the materials for making was medical silastic solution.The bottom of the culture chamber was made into a 0.5mm thick.The chamber was transparent and bright and clean,which was convenient to observe the changes of cell morphology.In addition to the above work,the strain distribution of the chamber during uniaxial tension was also explored by using ANSYS software.The results of finite element analysis showed that the strain in the middle region of the bottom of the culture chamber was the closest to the actual strain in the range of 1% ～ 10% strain.Except for the large difference of 1% strain error(11%),the other error range is controlled between ± 3% and ±6%.Using Image J to analyze the area proportion of the middle region,the results showed that the area proportion was the largest at 1% strain,which is 77%;the minimum uniform area proportion appeared at 7% strain,which is 54%.According to the results of finite element analysis and area ratio analysis,some suggestions were put forward for sample selection after cell loading to reduce the experimental error caused by uneven cell stress.In this paper,a strain loading instrument for adherent cells was designed by combining mechanical principle with biology and mechanics.The instrument can adjust different loading modes(static stretching,static shrinkage,periodic tension and compression)accurately.It had the characteristics of high precision,small volume,wide strain range and convenient operation.In addition,three groups of cell culture substrates can be loaded simultaneously,which provided convenient conditions for the study of cell mechanics biology. |
