Study On The Bulk Wave Resonant Liquid-phase Sensor Integrated With Microchannel

Microfluidics have a great potential in the application of modern biological and chemical detection.As a powerful tool to manipulate the tiny sample liquid,microfluidics devices can achieve a low cost,fast,and efficient detection.In addition,since the fabrication process of microfluidics devices is compatible with that of MEMS,it can be integrated with sensing elements to accomplish the Lab-on-a-chip application.As a piezoelectric mass sensor,film bulk acoustic resonator(FBAR)works at giga hertz and has a high quality factor(Q),leading to a very high mass sensitivity.Based on the MEMS fabrication process,FBAR can be utilized as a powerful tool to realize low cost and high sensitivity detection.It is convenient for FBAR to be integrated with signal process element due to the fabrication of MEMS is compatible with that of integrated circuit(IC).FBAR suffers a severe decline of performance in the liquid environment,which hinders the wide application of FBAR in the field of biological and chemical detections.To address the sensing problem of FBAR in the liquid environment,this thesis presents the solution of the integration of microchannel and FBAR sensor by combining the microfluidics technology.This method can avoid the large scale contact between the FBAR sensing surface and the liquid,which greatly improves the Q.We designed the layout,fabricated the device,and then set up the measurement platform.The practicability of this platform was proved by the successful detections of glucose and glycerol.The main achievements of this thesis are listed as follow:1.The solution of the integrated microchannel and FBAR sensor system was proposed.The Al N microchannel was designed based on microfluidics theory.We developed a method to integrate the microchannel and FBAR by using the sacrificial layer releasing process.We explored the fabrication process and solved the critical problems.2.The performance of the device in the air and liquid was tested by the measurement platform.The result indicated that an order of improvement of the Q factor was realized in the liquid environment.Moreover,the applicationin detecting the concentration of glucose and glycerol were demonstrated by the platform.3.The reason of the improved performance of the sensor was explained by the simulation and theoretical derivation.The mechanism of the resonant frequency rising with the increasing concentration was further discussed.