Study On Surface Optimization Design Of The Magnetoelastic Sensor And Its Application In Biochemical Detection

Biochemical sensing technology develops rapidly and plays an indispensable role in environmental monitoring,clinical medicine and animal husbandry.Traditional sensors can not meet the needs of modern biochemical detection.It puts forward higher standards and requirements on the design of biochemical sensors:high sensitivity,low cost,miniature portability,multi-functionality and so on.As a new-type biochemical sensor,the magnetoelastic sensor has attracted much attention due to its excellent characteristics such as wireless passive,low cost and good portability.It is of great research significance and practical value to design high-performance magnetoelastic sensors and apply them to the health and environmental protection fields which are highly concerned by human beings.However,at present,magnetoelastic sensors still have problems including relatively low sensitivity,large volume,unsatisfactory performance of specificity and stability,and have certain application limitations.Therefore,this work aims to develop new magnetoelastic sensing technology.Based on the current demand for the biochemical detection,the dissertation is devoted to surface optimization design research,and has constructed various magnetoelastic sensors that can be applied to environmental detection,classical swine fever prevention,and carcinoembryonic antigen detection.Its sensitive characteristics were systematically studied,which verified its excellent sensing performance.The specific research contents are as follows:1.The processing method for the optimization of the magnetoelastic sensor surface was studied.The size of the sensor was optimized to be 5 mm×1 mm×28?m through the simulation calculation using the software COMSOL Multiphysics.Magnetoelastic sensing chip was prepared by sputtering chromium nanoparticles with a thickness of 100 nm and gold nanoparticles with a thickness of 100 nm on the surface of magnetoelastic iron-based amorphous alloy film Metglas 2826 MB in order to improve its corrosion resistance and biological compatibility,and its surface morphology and chemical composition were characterized.The methods of amplifying the response signal were proposed to optimize the surface functional structure,further improving the sensitivity and reducing the detection limit,which provids an effective method for the fabrication and function expansion of high-performance magnetoelastic sensors.By reducing the coil diameter and the design of resonance frequency test system,the key problem of signal measurement for small-size magnetoelastic sensor was solved.2.For the environmental detection,the new methods based on magnetoelastic sensors for detection of heavy metal ions and atrazine as small-molecule pesticide were proposed.The detection mechanisms were explored and the sensitive characteristics were studied.The key common problem in the application of magnetoelastic sensors for detection of heavy metal ions and small-molecule pesticides was solved.?1?The magnetoelastic sensor surface was optimized by BSA functional modification to realize real-time detection of trace heavy metal ions.The experimental results showed that the sensor has linear response to Pb²⁺,Cd²⁺and Cu²⁺.The detection limits for Pb²⁺,Cd²⁺and Cu²⁺are respectively 3.3×10^-7 mol/L,2.4×10^-7 mol/L,2.3×10^-7 mol/L,which are superior to the national standard.The detection sensitivity is respectively 9.4×10⁷ Hz/mol?L^-1,7.1×10⁷ Hz/mol?L^-1,4.7×10⁷ Hz/mol?L^-1,regularly ordered as Pb²⁺>Cd²⁺>Cu²⁺.The sensor is more sensitive to the heavy metal with larger relative atomic mass.Compared with the method based on displacement reaction,the detection sensitivity of the sensor for Pb²⁺is improved by about 4 orders of magnitude,and the detection limit is reduced by about 5 orders of magnitude.?2?A magnetoelastic sensing method based on competitive immunoassay was proposed to achieve trace,real-time and specific detection of atrazine.The competition immunoassay was used to optimize the functional structure of the sensor surface,and the protein A was used to achieve the orientation immobilization of the atrazine antibody.The experimental results showed that the optimal concentration of the antibody and ATZ–BSA was 50?g/mL and 40?g/mL,respectively.The resonance frequency shift is inversely and linearly proportional to the logarithm of atrazine concentrations ranging from 1 ng/mL to100?g/mL,with the sensitivity of 3.43 Hz/?g?mL^-1 and the detection limit of1 ng/mL,which is significantly lower than the standard established by US Environmental Protection Agency?EPA?and is below the detection limit of the published methods.3.For the classical swine fever?CSF?prevention,the new methods based on magnetoelastic sensors for detection of classical swine fever virus?CSFV?and CSFV E2 antibody were proposed.The detection mechanisms were explored and the sensitive characteristics were studied.The application of magnetoelastic sensors to the prevention and control of CSF was developed.?1?A portable magnetoelastic test paper was designed to achieve high-sensitivity and real-time detection of CSFV.The magnetoelastic sensor surface was optimized by anti-CSFV IgG functional modification,and a portable magnetoelastic test paper was designed.The test results showed that the magnetoelastic test paper had better sensitivity and selectivity for CSFV detection.The resonance frequency shift is linearly proportional to the concentrations in the range from 0 to 2.5?g/mL,and becomes sub-linear at higher concentrations.The test paper for CSFV detection has the sensitivity about 95 Hz/?g?mL^-1,and the detection limit of 0.6?g/mL.?2?A magnetoelastic sensing method based on enzymatic catalysis generating precipitation for signal amplification was proposed to realize high-sensitivity,rapid and real-time detection of CSFV E2 antibody.The indirect method?sandwich immune sequence?was used to optimize the functional structure of the sensor surface.The immobilization concentration of CSFV E2was optimized to be 50?g/mL.The test results showed that the sensor has good response characteristics and specific selectivity for CSFV E2 antibody compared with the existing detection methods.The sensor shows a linear response to the logarithm of CSFV E2 antibody concentrations ranging from 5 ng/mL to 10?g/mL,with a detection limit of 2.466 ng/mL and the sensitivity of 56.2 Hz/?g?mL^-1.4.Using carcinoembryonic antigen antibody?CEA-Ab?to modify and optimize the surface of magnetoelastic sensor,a novel magnetoelastic sensor was developed for CEA detection.The modification concentration of CEA-Ab was optimized to be 50?g/mL,and BSA blocking was used to reduce non-specific binding and steric hindrance effect.The experimental results showed that the sensor has excellent response characteristics and specificity for CEA detection.The linear response range is from 0.1 ng/mL to 100 ng/mL,and the detection limit is as low as 2.5 pg/mL,which is far lower than the upper limit of CEA concentration in healthy adult serum,meeting the standard requirements.Its comprehensive performance is better than other CEA detection methods reported in the current literatures.