Study And Exploration Of Thin Film Bulk Acoustic Resonator (FBAR) In Biological Detection Field

Biosensors have been widely employed as an important tool for biology and biochemical applications where precise and selective detection of target molecules is required.High sensitivity,label-free,real-time response and continuing miniaturization are the key driver of biosensor for the wide spread usage.At the same time,the thin film technology has raised increasing interest for new biosensors.Specifically the electro-acoustic technology employing piezoelectric thin films has made tremendous advance for biosensor fields.The main electro-acoustic conversion devices used at present are quartz crystal microbalance(QCM),surface acoustic wave sensor(SAW)and thin film bulk acoustic resonator(FBAR).According to its higher resonant frequency,better chemical stability and compatibility with semiconductor technology,FBAR has been more used for preparing biosensor.With the development of integrated circuit technology,the number of transducers fabricated on a single wafer has increased and the size of sensor device has minimized.So,the biosensor based on FBAR will play a more important role and been more widely employed in more fields.On account of the characteristics and development trend of biosensor,this thesis focuses on the fabrication of AIN FBAR and its detection of Mucin 1(MUC1).The main content of this thesis includes the following three parts:1.Fabrication of AIN FBAR.FBAR component was prepared on double sided polished silicon wafer mainly through magnetron sputtering and lift-off photolithography process.Firstly,a Bragg reflector consisted of 6 alternating layers of Ti and Mo was sputtered on the silicon wafer using DC magnetron sputtering.Secondly,a highly c-axis oriented AIN film was sputtered on the Bragg reflector through RF reactive magnetron sputtering.Finally,the top electrode on the surface of AlN film was prepared using sputtering and a lift-off photolithography process.The structure and performance of resonator was characterized by SEM,XRD,and vector network analyzer.2.Fabrication of MUC1 aptamers-AuNP conjugates.Firstly,AuNPs solution was prepared by sol-gel method using the HAuCl4 solution and trisodium citrate.Then the AuNPs solution was mixed with MUC1 aptamers buffer which was modified with thiol and biotin.In virtue of the combination between AuNPs and thiol producing Au-S bond,the MUC1 aptamers-AuNP conjugates which was used for detecting MUC1 were finally fabricated.3.Modified FBAR with streptavidin for detecting MUC1.At first,streptavidin was fabricated onto the surface of the resonator using mercaptopropionic acid as medium.Then,different concentrations of tested MUC1 solution were mixed with previously fabricated MUC1 aptamers-AuNP conjugates according to certain proportion,followed by adding the mixture onto the streptavidin modified surface of resonator.Through the detection of resonance frequency shift,it could be concluded the relationship between the resonance frequency shift and the concentrations of MUC1 solution.Finally,the detection of MUC1 was finished,followed by detecting of different biological molecules to illustrate the good selectivity of the FBAR biosensor.