Research On Two-dimensional Phononic Crystal Biosensor

As a lethal chronic disease with no effective cure for the time being,the accuracy of testing blood glucose concentration as the main method to diagnose diabetes is crucial to the process of diabetes prevention and treatment.To circumvent the problems of easy inactivation,difficult fixation and poor repeatability of oxidase in existing enzyme glucose sensors,it is of great practical importance to explore the method of direct detection of human blood glucose concentration in the diagnosis and treatment of diabetes.Phononic crystals are periodic composite materials,and localized modes are generated when defects are introduced periodically by disrupting the phononic crystal(changing the acoustic properties of the scatterer),and resonant cavities with high quality factors can be formed at the defective structure due to the energy localization effect,providing a new way for the design of novel biosensors.To achieve accurate measurement of diabetic biomarkers,a biosensor sensitive to changes in glucose concentration is designed in this paper by combining a two-dimensional phononic crystal with surface acoustic wave device with high frequency,high sensitivity,and small size,and the performance of the biosensor is investigated in terms of sensor detection mechanism,mode recognition,and performance parameters on how to improve the performance of the biosensor.(1)A two-dimensional phononic crystal biosensor with resonant modes was developed to realize the sensing function by the frequency shift of defective state resonance peak caused by the change of analyte concentration.The results showed that the sensitivity of the sensor reached 66891 Hz when the glucose concentration was 54.6%,corresponding to a quality factor of 2235;The sensitivity and quality factor of the sensor were 51486 Hz and 1852 when the hydrogen peroxide concentration was 43.3%,respectively.(2)The interaction between hole type two-dimensional phononic crystals and love wave is investigated,and a method of accurately screening love wave modes from mixed modes by SH polarization ratio and normalized energy depth is proposed;After the introduction of the line defect structure,the love wave defect state characteristics(NED value)are used to directly determine the acoustic energy aggregation effect,and an optimized structure of love wave defect-type phononic crystals with sharp resonance peaks is obtained(hole radius of 0.8 μm,cavity width of 16 μm,and number of phononic crystals of 7).(3)Innovative proposal of hole type two-dimensional phononic crystal love wave biosensor.The results show that the sensitivity of the sensor reaches 1.967 MHz at 10%glucose concentration and the corresponding quality factor is 5497 when the radius of the circular hole is 0.6 μm and the height is 2.5 μm;The sensitivity and quality factor of the sensor are 1.7 MHz and 5274 at 4% hydrogen peroxide concentration,respectively,which is about 30 times more sensitive than the two-dimensional phononic crystal biosensor,allowing accurate detection of diabetic biomarker concentrations without the use of glucose oxidase to produce catalysis.