Research On Influence Of Nanoparticles On The Dynamic Characteristics Of Micro Mass Sensor

In recent years,mechanical sensors have the advantages of small size,high sensitivity,and the ability to adjust to nanoscale sizes,therefore they are widely used in the fields of biology,medicine,and chemistry to perform quality detection of micro-nano particles.The principle of the micro-nanometer mass sensor is that the effective mass of the sensor changes due to the adhesion of the measured material to the sensor surface,thus changing the resonance frequency of the sensor.By measuring the motion of the sensor frequency,the quality and position information of the particles to be measured can be obtained.At the same time,because the micro-nanometer mass sensor can be scaled down in structure size,it can achieve the high frequency vibration of the sensor.The small size sensor loading has a higher frequency movement after absorbing the particle load,so it has a higher detection sensitivity.In the application of sensors,the previous scholars generally set the ideal conditions for the detection of particles,that is,ignoring the influence of stress and stiffness on the sensor modes.At the same time,it is generally assumed that the mass of the particles to be measured is much smaller than the mass of the sensor.Therefore,the sensor mode before and after adsorption of the particles does not change.In fact,in practical applications,the mass ratio between the object to be measured and the sensor is relatively large.Through the previous calculation and simulation,it is concluded that with the increasing of the quality of adsorbed particles,the modal changes of sensor also show an increasing trend.When the quality of particles increases to a certain extent,the modal changes will cause the detection quality.Large error.Due to the extremely high sensitivity of the micro-nano structure,even the smaller mass load will affect the sensor's mode,which will affect the accuracy of the anti-particle quality process and eventually affect its detection accuracy.Based on the previous research,the resonance frequency and mode of nanometer mechanical sensor with particle adsorption at any position are deduced in detail.Taking the micro-cantilever beam and bridge structure as the research objects,the exact modal and resonant frequency closed expressions of the sensor with load particles were obtained by using the Rayleigh Ritz theorem.The relationship between the adsorption quality and the frequency movement of sensor particles before and after adsorption is obtained.For a given cantilever bridge and cantilever beam sensor,the curve can be drawn by calculating the relationship between the frequency movement and the load,and then the measured frequency is moved,and the corresponding can be obtained in the curve.The mass ratio between the load and the sensor,so that the mass of the particles is finally obtained.At the same time,the resonance frequency and mode of the sensor after disturbance are defined by perturbation method.The first-order perturbation expression of the sensor is obtained by using the boundary conditions and orthogonal properties of the cantilever bridge and beam.The results of both methods show that the modal shape changes caused by the relatively large particle adsorption after loading the particles have a great influence on the performance of the nanometer mechanical resonator.At the same time,on the basis of the previous two research methods,the stress of the sensor itself is taken into account,and the more accurate modes of the sensor under the action of stress are obtained by using the Rayleigh Ritz theorem.The results show that with the increase of stress,the modal influence on the sensor is greater,and the stress will increase the mode of the sensor.Under the stress effect of the sensor,the mode of adsorbing particles is decreasing.The above three parts of the theoretical calculation are all verified by the finite element simulation method to prove the correctness of the theoretical derivation.