Structure Optimization And Performance Study Of Magnetostrictive Biosensor

Magnetostrictive biosensor is a resonant sensor based on magnetostrictive materials.The excitation and transmission of its signals are carried out by magnetic field coupling.It has the characteristics of wireless,passive,small volume and high sensitivity.At present,there are more and more researches on the detection and theory of magnetostrictive biosensors,but most of them focus on the detection of bacteria,vibration characteristics and application characteristics of the sensor.The influence of material size and external magnetic field on the impedance response of the sensor is seldom considered,but these factors have a great influence on the sensor in practical application.In addition,in the literature reports on magnetostrictive biosensor,amorphous soft magnetic alloy Metglas 2826MB is mostly used as the material of the transducer,and Cr/Au coating is mostly used as the functional coating,which has disadvantages such as high price and difficulty in preparation,and is not conducive to marketization.In view of this,this paper focuses on the thermal stability of the transducer,the corrosion resistance of the functional coating,the influence of external magnetic field on resonance parameters and the detection of bacteria in the following three aspects:(1)The development of a new magnetostrictive biosensor:through the analysis of the magnetic properties and thermal stability of three grades of iron-based amorphous soft magnetic alloy,the appropriate material is selected as the transducer;In comparison of the corrosion resistance of PVA coating and Au coating,the material with high corrosion resistance and high density was selected as the functional coating.(2)Analyze the influence of external magnetic field on the resonance parameters of magnetostrictive biosensor:carry out experimental research from three aspects:DC bias magnetic field,AC excitation magnetic field and size.The experimental results show that the impedance response and energy conversion rate of the sensor can be improved by setting the bias magnetic field.The excitation magnetic field is set to avoid sensor distortion and improve the impedance response.Impedance response can be improved by setting reasonable length and width of sensor.(3)Detection of Escherichia coli by magnetostrictive biosensor:a sensor with the size of 5mm×1.4mm×25?m was used to detect the concentration of10~1-10~8CFU/m L Escherichia coli suspension for control experiment,and scanning electron microscope(SEM)was used to observe the bacteria adsorption.The experimental results showed that both the surface of the transducer and the PVA coating showed certain nonspecific binding ability to E.coli,but the resonance frequency offset of the transducer was smaller than that of the sensor loaded with antibody at the same bacterial concentration,and the difference of the resonance frequency offset was larger with the increase of the concentration.Antibody-loaded sensors have a good ability to detect E.coli.