| As the demand of biomedical detection for multi parameter holographic analysis has surged,biosensor combine technology has attracted increasing attention.Piezoelectric biosensors and electrochemical biosensors have been extensively applied in biological detection owing to the simple structure,high sensitivity,portability,and the ability thereof to realize real-time detection and label free detection.The piezoelectric sensor has the characteristics of high sensitivity,low power consumption and fast label-free detection,and is highly sensitive to quality,viscoelasticity,conductivity,density and others.Because of the higher sensitivity thereof than mass based piezoelectric biosensors,focus has shifted towards thin film based piezoelectric biosensors.Electrochemical sensors are widely used in biomedical detection due to the significant selectivity,wide detection range and reliable detection system thereof.The traditional electrochemical selective electrode is composed of an ion selective membrane,electrolytic solution and reference electrode,and is too large to maintain because of the electrolyte.The potentiometric sensor using solid ion selective electrode instead of charging solution is easily miniaturized.The combination technology of piezoelectricity and electrochemistry requires high sensitivity,holographic information acquisition and multi parameter expression for biosensors.The focus of the present thesis is on the research on high sensitivity sensors and multi detection methods in combination with technology,for which the following work was conducted:(1)For the purpose of studying the piezo-electrochemical method,a thin film piezoelectric biosensor with high sensitivity and stability was designed.The hydrophobic material Parylene-C was investigated as the waveguide layer of the Lamb wave sensor,and the sensor was employed to measure liquid parameters.The stability of the P-Lamb wave sensor based on Parylene-C waveguide layer was improved,the surface roughness was reduced by 33%±1.25%,the acoustic leakage was reduced,the energy loss was reduced,and the signal was increased by 2.75%±0.15%.Compared with the traditional piezoelectric sensor,the frequency shift of P-Lamb wave sensor was 200 times that of the shear QCM,which could capture the phase transition from liquid to solid.The experimental results reveal the feasibility of the thin film piezoelectric sensor in biological liquid phase detection,the improved sensitivity of piezo-electrochemical sensor detection,and lay the foundation for the development of piezo-electrochemical technology.(2)In order to meet the demand of piezo-electrochemical technology for all solid state electrochemical sensors with high sensitivity and high stability,an all solid state ion selective electrode was explored in the present thesis.The conductivity of the screen printed electrode was improved by adding graphene paste into carbon paste.Compared with the redox reaction PEDOT solid-state contact layer,the electric double-layer capacitor with WCNT as the solid-state contact layer had better conductivity and better electrode stability.The gel potassium chloride layer was fixed on the reference electrode to form a quasi reference electrode,and the stability of the electrode was improved,with the potential drift of 30 min being less than 4 mV.The Nernst response sensitivity was 63.567 mV/pH,and the correlation coefficient of the calibration curve was R2=0.998.An observation could be made that the high performance solid-state ion selective electrode can provide significant technical support for piezo-electrochemical technology.(3)A nucleic acid detection method based on the all solid state hydrogen ion selective electrode was constructed,so as to further verify the detection performance of the all solid state ion selective electrode in piezo-electrochemical technology.The gradient and stability of the hydrogen ion selective electrode were tested,and the packaging of the ion selective electrode(ISE)was designed and optimized.Meanwhile,a solid-state hydrogen ion selective electrode was developed for direct measurement of isothermal amplification products,and the concentration of HIV-1 template RNA was detected from 100 copies/μL to 105 copies/μL.Compared with the detection results of the fluorescent PCR instrument,the detection limit of all solid-state hydrogen ion selective electrode was lower,and the detection time was shorter.After the detection of 57 clinical samples,96.5%of the results were found to be consistent with those of Roche’s related instruments.The minimum detection limit of clinical samples was 10 copies/tube,and the detection time was 10-25 minutes.The portable detection experimental verification system was integrated,and the dual channel detection was designed to display the detection curve in real time.The rapid detection of nucleic acid by ion selective electrode in emergency was realized,which further verified the high sensitivity and stability of all solid state ion selective electrode biological detection.(4)A preliminary study on the integration of the thin film piezoelectric sensor and the all solid state ion selective electrode was conducted.The buffer solutions with different pH values were detected by a thin film piezo-electrochemical device.The experimental results exhibit that the thin film piezoelectric sensor had high sensitivity to the density of the measured object,and the frequency moved 68 Hz per 1 kg/m3 change.For different buffer solutions with the same pH,the thin film piezoelectric sensor gave a different frequency response,but based on the potential of the all solid state ion selective electrode remaining unchanged,the reliability of ISE was also verified.The aforementioned preliminary findings verify the multi-dimensional expression of piezo-electrochemical technology on the same sample under test,and that the measurement of physical and chemical parameters could be realized. |
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