Portable Detection System For Magnetostrictive Sensor Based On Pulse Excitation

The magnetostrictive sensor is a resonant sensor that uses an amorphous ferromagnetic alloy as the sensor sensing unit.The resonant frequency of the sensing unit is extremely sensitive to the quality of the surface adsorption.Accurate and real-time measurement of immune-adsorbing microorganisms and biomarkers can be achieved by measuring the change of the resonant frequency.The resonant frequency is measured by the way of magnetic field coupling between the sensing unit and the coil.There is no connection between the sensing unit and the detection device in the detection process.Magnetostrictive sensors have the advantages of wireless passive,high sensitivity and real-time performance,and are suitable for measuring in liquids in situ.They have wide application prospects in fields such as physical and biochemical detection,especially in medical sensors.Traditional magnetostrictive sensor detection systems rely on large-scale analytical instruments such as network analyzers or spectrum analyzers,which have high detection accuracy.However,The wide application of such magnetostrictive sensors is restricted by factors such expensive instruments,large power consumption,and large volume.At present,the integrated magnetostrictive sensor detection systems using microcontrollers are mostly developed based on the sweep frequency method,and there are many peripheral circuit modules.Most systems can only detect large-size sensors with low sensitivity,and they cannot implement simultaneous measurement of multiple sensors.To solve the above problems,this paper presents a portable magnetostrictive sensor detection system based on pulse excitation single coil structure.The detection system takes the DSP chip which has strong signal processing capability as the core and supplemented with fewer peripheral circuits to realize the miniaturization and integration of the magnetostrictive sensor.The system uses planar coil drive and detection magnetostrictive sensor,and develops portable detection system for plane coil for the first time.Compared with the traditional spiral coil,the planar coil manufactured by MEMS technology has many advantages,such as small volume,integration,easy to micro machining,and so on.Through the simulation,the influence of the different design parameters of the plane coil is analyzed from the aspects of excitation and detection,which provides a theoretical basis for the design of the excitation signal.In terms of signal processing,the resonant frequency of the sensing unit is calculated by combining Fast Fourier Transform(FFT)and Linear Frequency Modulation Z Transform(CZT)algorithms,which effectively improves the detection accuracy of the millimeter-level magnetostrictive sensor.On the basis of theoretical analysis,a portable magnetostrictive sensor detection system has been prepared.This detection system has a certain generality,which can be detected with a spiral coil or a plane coil.A suitable planar coil was used to build the detection system,which realized the simultaneous detection of two different size(2mm,3mm)sensors and the real-time detection of the liquid volatilization process is realized.A portable system based on a spiral coil is used to detect two different sizes(4mm,5mm)sensors at the same time.The experimental results showed that the sensitivity of the sensor with length of 4mm was 0.3841(kHz/?g)and the sensitivity of the sensor with length of 5mm was 0.2198(kHz/?g).The experimental results verify that this portable system has wide applications in rapid,on-site biochemical detection.