Research On Key Techniques Of Highly Sensitive Surface Acoustic Wave Biosensor

Surface acoustic wave(SAW)biosensor has shown a great potential towards wide application in various areas such as molecular biology,analytical chemistry,material science and medical science owing to its merits of integration,miniaturization,low-cost and easy operation for mass production.Highly sensitive and label-free early tumor diagnosis is expected to be achieved by utilizing SAW biosensors.To achieve this goal,sensitivity and specificity of SAW biosensors still require to be improved.In this dissertation,some issues were thus studied,such as theoretical models,mass sensitivity,insertion loss,bio-detection strategies and non-specific bindings towards improving the performance of SAW biosensors.Firstly,SAW device theoretical models were analyzed.The velocity,particle motion and energy distribution in Love wave device were described.The relationships between mass sensitivity and device materials and waveguide layer thickness were discussed.And the optimal structures and metials were selected.Secondly,SAW sensors with filled microcavities and waveguide were presented.Various structures were simulated and optimized by using finite element analysis.It was demonstrated that the filled microcavities and waveguide structures can significantly lower the power consumption and increase the mass sensitivity.Then,the SAW devices were fabricated and measured to verify the validy of theoretical results.It was indicated that the filled microcavities and waveguide can decrease the insertion loss by approximately 5 dB and increase the mass sensitivity up to 9 times.Thirdly,the strategy of detecting the specific tumor marker[carcino embryonic antigen(CEA)]was discussed.Gold nanoparticles were used to amplify the bio-signals to increase the sensitivity.The synthesis,assembly of gold nanoparticles and the surface modification and assembly were described.Fourthly,the strategy of using Rayleigh wave to increase the specificity.of SAW biosensors was presented.The non-specific bindings adsorbing on the sensor surface could be removed by using Rayleigh wave,and the specificity of SAW biosensors was enhanced.The heating effect of Rayleigh wave was studied and tested,and its influence on biotesting was discussed.Eventually,the noval orthogonal SAW biosensor was designed and tested,and the effect of removing non-specific bindings was tested.Finally,the bio-testing performance of the SAW biosensor was tested.Using gold nanoparticles to amplify the signal,the sensor's sensitivity was effectively increased.The limit of detection of SAW biosensor was lowered to 37 pg/mL,and the detection of CEA in low concentration was achieved.