The Study Of Surface Acoustic Wave Immunosensor

Surface Acoustic Wave(SAW) sensor is a newly developed sensor, which offers a great advantage of rapid, sensitive and real-time detection without high cost. This research reports on the development of SAW sensor and develops a 36°-YX LiTaO₃ Shear-Horizontal Surface Acoustic Wave (SH-SAW) Liquid Detecting System based on monocrystalline silicon substrate, which consists of a SAW immunosensor. The SH-SAW immunosensor consists two delay lines,which operates at a frequency of 104 MHz. One channel is a reference one, another is coated with antibody By applying silicon sealed rubber-ring and resin liquid cell, the sensor is able to detect the corresponding antigen in liquid and protect the IDT electrode. Several immubilization methods are focused on. Self-assembled monolayer and Protein A immobilization method are used to immubilize DDT antibody and AFP antibody on the surface of SAW sensor.Modern microelectronic and instrumental fabrication tecnique is used in the whole detecting system. The measurements utilize a droplet method to detect the relevant frequency shift. In antigen detection experiments, the results show that the relation between frequency shift and concentration of the corresponding antigen is linear in the range between several ppb to dozens of ppb. This surface acoustic wave immunosensor has good repeatability, high sensibility and a low detection limit.