SH-SAW biosensor on quartz
This paper describes a shear horizontal surface acoustic wave (SH-SAW) immunoassay biosensor on a quartz substrate. The SH-SAW biosensor is a 250MHz SH-SAW delay-line which has a gold surface covered with antibodies. It is important to discuss the detection mechanism of SH-SAW biosensors on quartz. In this paper, the detection mechanism of SH-SAW biosensors are investigated, using three methods of numerical analysis. The first method is a mass loading model analysis. The second method is a viscosity model analysis. The third method is a viscoelasticity model analyasis. A numerical calculation method for SH-SAW propagation characteristics, which is a modified Campbell and Jones method involving the effect of liquid viscosity is applied to quartz. In order to confirm the proposed numerical analysis models, 250MHz SH-SAW biosensors on quartz substrates were tested. The mass, viscosity, and viscoelastic behavior of fluids on SH-SAW biosensors were theoretically and experimentally discussed.
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 electromagnetic feed through signals. A model immunoassay based upon human serum albumin detection was used to assess suitability of point-of-care testing applications.
New low-loss SAW filter using internal floating electrode reflection types of single-phase unidirectional transducer
A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the floating electrodes of open and short metal strips inserted into the interdigital transducer within a half wavelength is described.