Point-of-care SH-SAW biosensor

This paper describes a two-channel liquid-phase shear horizontal surface acoustic wave (SH-SAW) immunoassay biosensor. The sensor device was designed using a 250MHz SH-SAW delay-line on Quartz substrates, which is composed of a transmitting and receiving transducers and a biochemical reaction area in between them. Those transducers are protected from liquids by a glass lid and epoxy walls which are constructed using a photo-lithography technique. So the sensor devices can be directly dipped into a liquid and a liquid can be directly applied onto the surface of the sensor device. A two-channel delay-line design technique can effectively suppress unwanted bulk wave spurious signals. On the other hand, in order to detect the mass and viscosity changes of the antigen-antibody reactions on the surface of the sensor device, a prototype electric reader having measurement circuits was realized with 14 × 10 × 4 cm³ in size. The reader has a burst circuit to eliminate unwanted electro magnetic feed through signals. A model immunoassay based upon human serum albumin detection was used to assess suitability of point-of-care testing applications.