Voltage Modulated SAW Microtrap System: Smart Assaying of Biomaterials

This paper details the development of a novel analytical microsystem for the rapid screening of biological materials. The novel design employs a dual shear horizontal surface acoustic wave (SR-SAW) sensing device and multivariate signal processing. The device comprises a voltage-modulated shorted SR-SAW delay-line device together with a free delay-line designed for better sensitivity and selectivity, together with a parylene coated SU8 liquid reservoir with an embedded microparticle filter, all assembled within an automated testing station. The basic sensing principle is that the polarized metal electrode attracts statically or electrokinetically bioparticles in the liquid, which perturb the acoustic waves; thus changing their phase velocity and attenuation. In theory the voltage/frequency is set according to the properties of the bioparticles, e.g. charge/size, dielectric constant. Ideally, the SAW sensors have no bio-chemical layers although a functionalized biocoating may be added for more specific protein-based biological applications