| Micro nano operation usually refers to the use of ultra-high precision robot systems to measure,manipulate and characterize micron scale targets.Because it can make new discoveries in life science,material science,instrument science and other fields possible,it is currently a research hotspot in many disciplines.Due to the complexity of micro nano operation tools and the size of the operated object,material properties and forces in the operation process,it is very challenging to design high-performance sensors that can be integrated with micro nano operation tools.Due to the advantages of high resolution,easy integration with micro nano operation tools,high sensitivity and strong anti electromagnetic interference ability,optical fiber force sensor has great application potential in the field of micro nano operation.In order to explore the fiber-optic micro force sensor suitable for micro nano operation,this paper has carried out the following research from the theoretical and experimental aspects:(1)Study on the model of optical fiber micro force sensor with light intensity modulation.Aiming at the difficulty of micro force sensing of compliant micro nano operating mechanism with large deformation,based on the transmission theory of light wave electromagnetic field in optical fiber,the relationship between the output light intensity of bent optical fiber and the radius of curvature is deduced and obtained.Further,combined with the finite-difference time-domain method,the variation of light intensity energy distribution with the radius of curvature is given through simulation,which provides a theoretical basis for the subsequent sensor design.Finally,the relationship between deformation and force of large deformation beam element is derived by using Mohr integral method.Combined with the above relationship between light intensity and radius of curvature,a light intensity modulated micro force sensing model is es-tablished.(2)Based on the light intensity modulated optical fiber sensing model,a force sensing con-figuration with corrugated beam structure is proposed,and a new bending optical fiber force sensor is designed.Through theoretical analysis,the relationship between the output light in-tensity and the radius of curvature of the bent fiber is obtained,and the correctness of the results is verified by experiments.The characteristics of the sensor under different working conditions are studied,and its main parameters such as sensitivity,range and error are discussed.A new bending optical fiber force sensor with the advantages of simple structure,stability and reli-ability is obtained,and the force measurement of large deformation compliant mechanism is realized.(3)Study on the micro force sensing model of optical wavelength modulated high-resolution fiber Bragg grating.Firstly,based on the propagation principle of light in finite space,the influence of the structural parameters of the grating on its output spectrum is simulated and analyzed? According to the mode theory of light wave,the relationship between the grating pe-riod,the refractive index and the peak value of the output spectrum is obtained by using the finite time domain difference method.Based on the small bending deformation theory and elas-tic theory of thin plate,the relationship between external force and the stress and strain at the fiber core is analyzed.Using the structural deformation and the photoelastic effect of materials,the effects of stress and strain on the grating period and refractive index are obtained.Based on this,the sensing mapping relationship between optical wavelength signal deformation / stress stress signal is obtained,and the optical wavelength modulated fiber grating micro force sensing model is established.(4)Based on the optical wavelength modulation optical fiber sensing model,a new can-tilever optical fiber force sensor is designed with a cantilever beam as the force sensor config-uration.Considering the processing constraints and other conditions,the sensitivity coefficient optimization model is established based on the optical wavelength modulation force sensing model.Further,the parameter optimization of cantilever optical fiber micro force sensor is re-alized through numerical simulation.By analyzing the sensitivity curve of the sensor obtained from the experiment,the sensor is divided into two working modes.The main parameters such as sensitivity,measuring range and error are discussed.A cantilever optical fiber micro force sensor with high sensitivity,good linearity and compact structure is obtained,which realizes the high-precision measurement of the contact force of micro samples in the micro nano operation system.(5)Research on the application of two new force sensors in the scene of part microassem-bly and cell micromanipulation.The bending force sensor is applied to the bending moment test platform in the micro assembly system to realize the real-time torque measurement in the pre tightening process of micro thread assembly,which further proves the excellent characteristics of the new sensor and provides a guarantee for the stability of the micro assembly process of pre-cision parts.The cantilever micro force sensor is applied to the cell micromanipulation system as an end effector,which realizes the measurement of the mechanical properties of embryonic cells,verifies the high sensitivity and high linearity of the cantilever micro force sensor,and lays a foundation for the design of force feedback end effector and the realization of accurate clamping force feedback.The research work of this paper provides theoretical support and experimental verification for the micro force sensor in the micro nano operating system,promotes the development of the design theory of the optical fiber principle micro force sensor,and provides a new idea for the force measurement in the micro scale. |
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