| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 103 === There are two main kinds of traditional strain gauges which are the metallic type and the semiconductor type. The gauge factor of the strain gauges sensitivity is approximately 2-120, lacking of sensitivity and is more susceptible to temperature, which gives an inaccuracy in stability and repeatability. Moreover, the price of the semiconductor type of the strain gauge is expensive. In this study, the cobalt-based material is used as the sensing element, because it can resist a larger magnetic impedance change for the sake of high sensitivity, the good stability and the lower price of the strain gauges. The material is excited by the alternating current or the alternating electromagnetic field, which produces the skin effect in the material surface. The magnetic moment revolving and the magnetic domain wall movement are created by the deformation of the soft material from the external force which is affecting magnetic permeability change influence skin depth to cause the material impedance large change, called giant stress-impedance (GSI). This effect is made of thin-film strain gauges gauge factor usually 1500 or more, the GSI stain gauges is developed by utilizing high gauge factor feature.
In this study, the depositions of the Co60Fe20B20 target have been made on polyimide substrate by self-sputtering as a magnetic sensing element. Using a negative photoresist SU-8 with UV exposure, and finally by reactive ion etching achieve the expected profile of the thin-film strain gauges. The magnetic thin film strain gauges excite the excitation source of the signal processing electric circuit, which in the inverting amplifier circuit architecture match a signal generator architecture afford the magnetic thin-film strain gauges excitation current source and impedance measured. To match root-mean-square value electric circuit, the signal will exchange the direct-current to conveniently observation. Moreover, in repeated bending strain experimental test sensitivity and stability, and with semiconductor strain gauges to verification. The commercialization of high sensitivity magnetic thin-film strain gauges will be developed.
In this paper, the magnetic thin film strain gauge voltage sensitivity is 0.0358mV/με, which strain formulate to the coefficient gauge factor only 26. To compare with the results is not as good as previous works in our lab. The experiment sputtered film saturation magnetization of about 0.267T, the coercive force of about 17.13Oe, the maximum thickness of 200nm, and the material formulations are similar to the 2714A saturation magnetization which are about 0.57T. Furthermore, the coercive force is less than 0.2Oe and the thickness of 15μm. However, it has chance for future improvement, which is expected to further enhance the sensitivity of the magnetic strain gauges.
|
|---|
