Rayleigh SAW assisted SH-SAW immunosensor on X-cut 148-Y LiTaO3

This paper describes a shear horizontal surface acoustic wave (SH-SAW) immunosensor which utilizes an agitation using Rayleigh surface acoustic wave (R-SAW) on the substrate. On an X-cut 148-Y LiTaO3 substrate, SH-SAWs and R-SAWs can be effectively generated at an interdigital transducers (IDT) with different frequencies. SH-SAWs can be suitable for liquid phase sensors such as immunosensors. On the other hand, since R-SAWs can agitate the liquid solution due to longitudinal wave radiations to the liquid, R-SAWs might improve the immunoreactions. In this paper, an SH-SAW delay-line which has a propagation area covered with antigens of human serum albumin (HSA) between transmitting and receiving IDTs was designed on the substrate. After a solution with antibodies applied to the surface, the SH-SAW velocity can be changed due to an antibody-antigen binding event. Some experimental results of an R-SAW assisted SH-SAW immunosensor using HSA immunoreactions are described.