Research On Wireless Passive Measurement Method Based On Resistive Strain Sensor

In today's various modern industries,strain monitoring technology has a wide range of application requirements.For example,in the field of structural health monitoring,strain monitoring technology is required to ensure that the structure is used within the allowable range.However,most of the current strain sensors use wired active technical solutions,which are difficult to apply to harsh measurement occasions such as closed spaces,high temperature and high pressure,and mechanical power rotating parts.For the strain measurement in the above situations,only wireless passive strain sensors can be used.Therefore,the research on wireless passive strain sensors is very meaningful.Common capacitive wireless passive strain sensors have complex structures and high process requirements,which limit their use occasions and are not suitable for the measurement of large strains(several millimeters or even tens of millimeters).To this end,this paper studies a resistive wireless passive strain sensor composed of planar inductance,ceramic capacitor and strain resistance,which can not only realize the wireless passive measurement of larger strain under the premise of ensuring higher sensitivity,but also has a simple structure,reliable performance,convenient processing,low cost and other advantages.The main research contents and work of this article include:(1)Aiming at the wireless demand of strain sensors,a wireless passive strain sensor circuit with strain resistance as the sensitive element is designed by utilizing the near-field coupling characteristics of the inductive coil.Using the equivalent impedance analysis method,the correlation between the strain resistance value and the equivalent input impedance phase of the circuit is derived.It can be seen from the circuit simulation results that the deviation between the obtained correlation and the simulation results is about 1%,and the strain sensor circuit experiment is carried out based on the above correlation.The experimental results show that the strain test error does not exceed 5%.(2)For the resistive wireless passive strain sensor circuit designed in this paper,the problem of insensitivity of impedance phase change caused by strain change,a circuit design method for comprehensive optimization of readout inductance and sensor inductance is proposed,which improves the sensitivity of the sensor to enhance the readout performance of the sensor circuit.From the circuit simulation results,it can be seen that the circuit designed by this optimization method under the same strain effect has an impedance phase increase of about 50%and a sensitivity increase of 0.012°/? at the resonance frequency compared to the unoptimized circuit,and is designed using comprehensive optimized parameters Strain sensor circuit,the results of the strain test experiment show that under the same strain effect,the circuit designed with the optimized parameters has a significantly larger phase change at the resonant frequency than before the optimization,with an increment of about 47%and a sensitivity increase of 0.011°/?.(3)According to the multi-target strain measurement requirements of wireless passive sensor circuits in practical applications,the principle of the existing multi-target measurement scheme is analyzed.Using the matching design idea of the inner and outer diameter of the inductor,a specially wound laminated inductor structure is improved.It can be seen from the simulation results that the sensor circuit with the improved laminated inductance structure can realize the strain measurement of three target points,and the improved laminated inductance structure is used to realize the multi-target strain measurement experiment.It can be seen from the actual measurement results that the improved laminated inductor structure can achieve strain measurement at three target points.