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.
Damage initiation and propagation in composite shells subjected to impact
Abstract The paper investigates the impact-induced damage initiation and propagation for laminated composite shells under low-velocity impact. A three-dimensional eight-node non-conforming element is described to analyze interlaminar stress distribution, and progressive failure. The damage analysis is performed by using Tsai–Wu quadratic failure criterion, Tsai’s damage modes and an additional delamination formula at all Gaussian points. The damage modes considered are matrix cracking, fiber breakage and delamination. The progressive failure is expressed by reducing stiffness of the material at all failed Gaussian points. Special attention is centered on curved laminates. Impact energy threshold for the onset of damage and transient damage size are predicted for composite shells. The analyses of the flat and curved laminates are compared for discussing their different damage mechanism. In addition, the influence of the stacking sequence, the thickness and the radius of curvature on damage behavior of composite shells are studied.