Surface skimming bulk waves: a novel approach to acoustic biosensors

Mass loading of the SSBW (surface skimming bulk wave) device results in a composite acoustic device, known as a Love plate, with a shear-horizontal wave guided at the interface of the deposited layer (overlayer) and the SSBW substrate. Two different Love plate composite structures were investigated, one with a silica and one with a poly(methyl)methacrylate overlayer. Insertion loss and phase measurements were used to assess the optimum thickness of each overlayer and the sensitivity of the device to mass loading and viscosity changes. The potential of the device as a liquid-based immunosensor was also demonstrated by following the adsorption of human-immunoglobulin-G (IgG) on the polymer surface and the subsequent binding of anti-human IgG and protein A.<>