ENZYME-IMMOBILIZED SH-SAW BIOSENSOR

A shear horizontal mode surface acoustic wave (SH-SAW) device has many attractions for chemical-sensing applications in liquid media. The SH -SAW that propagates on 36 degrees rotated Y-cut, X-propagating LiTaO3 is affected by a strong acoustoelectric interaction between the piezo electric potential and electric properties of the adjacent liquid. Thi s paper describes an enzyme-immobilized SH-SAW biosensor in which the detection principle is the acoustoelectric interaction due to the pH c hange in the enzyme reaction. Two kinds of enzymes, urease and choline sterase, are immobilized on the sensor surface and highly sensitive de tection of the enzyme reaction is obtained experimentally. The urease- immobilized SH-SAW biosensor is implemented in a liquid-flow system. B y using the cholinesterase-immobilized SH-SAW sensor, we have succeede d in detecting an inhibition effect of a pesticide.