SH-SAW biosensor based on pH change

Abstract

This paper describes an enzyme-immobilized biosensor using a surface acoustic wave (SAW) device fabricated on 36° rotated Y-cut, X-propagating LiTaO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . The sensing wave on the substrate is a predominantly shear-horizontal-mode SAW (SH-SAW) and is affected by a strong acoustoelectric interaction between the electric field and electric properties of the materials in the adjacent liquid. As an example of an electric property, the pH change associated with an enzyme reaction leads to measurable perturbation in the wave-propagation characteristics. Taking advantage of this phenomenon, we realized a SAW biosensor which consists of an immobilized urease film on the surface. Also, highly sensitive detection for the urea solution was obtained in our preliminary experiments