Surface acoustic wave biosensors: a review

Abstract

This review presents an overview of 20 years of worldwide development in the field of biosensors based on special types of surface acoustic wave (SAW) devices that permit the highly sensitive detection of biorelevant molecules in liquid media (such as water or aqueous buffer solutions). 1987 saw the first approaches, which used either horizontally polarized shear waves (HPSW) in a delay line configuration on lithium tantalate (LiTaO(3)) substrates or SAW resonator structures on quartz or LiTaO(3) with periodic mass gratings. The latter are termed "surface transverse waves" (STW), and they have comparatively low attenuation values when operated in liquids. Later Love wave devices were developed, which used a film resonance effect to significantly reduce attenuation. All of these sensor approaches were accompanied by the development of appropriate sensing films. First attempts used simple layers of adsorbed antibodies. Later approaches used various types of covalently bound layers, for example those utilizing intermediate hydrogel layers. Recent approaches involve SAW biosensor devices inserted into compact systems with integrated fluidics for sample handling. To achieve this, the SAW biosensors can be embedded into micromachined polymer housings. Combining these two features will extend the system to create versatile biosensor arrays for generic lab use or for diagnostic purposes.

Detection of coatings within liquid-filled tubes and containers by mode conversion of leaky Lamb waves

“…Before, only non-leaky Lamb wave (Lohr and Rose, 2003) on non-piezoelectric substrates or shear horizontal waves on piezoelectric substrates (Balantine et al, 1997;Thomson and Stone, 1997) were investigated, because it was thought that bulk acoustic waves or surface acoustic waves with a dominant vertical displacement would be inapplicable for coating detection in a liquid environment (Länge et al, 2008;Calabrese et al, 1987).…”

Wave propagation and acoustic band gaps of two-dimensional liquid crystal/solid phononic crystals

“…Some of the technological applications of this well-suited material include: bulk acoustic wave devices, acoustic transducers, piezoelectric transducers and piezoelectric sensors [28]. Its good mechanical stability and chemical stability make LTA already widely used as a substrate in surface acoustic wave (SAW) devices [29]. LiTaO 3 has twelve independent acoustic physical constants.…”

Portable SAW Impedance Sensor Using a 1-Port Resonator Approach

“…SAW signal generating and receiving elements, called interdigital transducers (IDTs), are realized by interdigitated microelectrodes. This standard electrode configuration has been successfully optimized towards high-sensitive SAW sensors and is highly sensitive to a number of physical parameters, e.g., humidity, temperature, and mass [1]. It has been recently shown that the conventional 2-port transmission approach can be significantly simplified by utilizing only one single IDT for SAW generation and simultaneously as sensing element.…”