The Characteristic Of Giant Magnetostrictive Thin Film With Gas Sensitive Layer And Its Application

Giant magnetostrictive thin film (GMF) is a new functional material. It indicates the wide prospect in the field of micro-manufacturing equipments relying on its remarkable advantages of giant magnetostriction, high coupling coefficient and fast response. The scientists from all over the world gradually pay attention to researches on micro-sensing devices comprising of GMF. But they rarely study on the combination of GMF and special gas sensitive material, and make them a new micro-gas sensor with their performance characteristics. Based on the combination of this new functional material and gas sensitive layer, one kind of mass micro-gas sensor is designed in this thesis. Through analyzing the static and dynamic characteristics of GMF with gas sensitive layer in low magnetic field, some new principles and methods are provided to study magnetomechanical coupling relations of GMF and micro-sensor.According to the magnetostrictive characteristic of GMF and its requirement of drive magnetic field, an experiment system for the static and dynamic characteristics of GMF with gas sensitive layer is established, which consists of a Hehnholtz coil and a laser tnangulation sensor. The magnetic field amplitude and uniformity produced by the coil are high enough, which are simulated by ANSYS software and testified by experiment data. According to the nonlinear elastic theory, a static magnetomechanical model of bimorph cantilever GMF with gas sensitive layer is established and its end displacement equation is deduced. Experiment results indicate that the model curve has better predictability with the magnetostriction hysteresis, and the GMF with gas sensitive layer exhibits lower hysteresis and higher sensitivity.In the dynamic vibration characteristics experiment, the GMF with gas sensitive layer exhibits n order super harmonic resonance, and the third order effects are comparable with the main resonance. Using its main resonance effects, the cantilever GMF is applied to design the ethanol gas micro-sensor, and the sensitivity test platform of ethanol gas is established. The experiment indicates that the vibration response of micro-cantilever has better linearity and sensitivity when the ethanol gas is in range of 100～600ppm.Above all, high amplitude and uniformity drive magnetic field endow GMF with gas sensitive layer fine static and dynamic magnetomechanical coupling property. The mass micro-gas sensor is well responded to the ethanol gas concentration. The research results have certain value of reference in the micro-sensor application of GMF.