| YSI biosensor technology is the key to
fast, accurate measurement. An enzyme specific for the substrate of
interest (glucose oxidase or L-lactate oxidase) is immobilized between two membrane
layers, polycarbonate and cellulose acetate. The substrate is oxidized as it enters the
enzyme layer, producing hydrogen peroxide, which passes through cellulose acetate to a
platinum electrode where the hydrogen peroxide is oxidized. The
resulting current is proportional to the concentration of the substrate. YSI membranes contain three layers. The first layer, porous polycarbonate, limits the diffusion of the substrate into the second layer (enzyme), preventing the reaction from becoming enzyme-limited. The third layer, cellulose acetate, permits only small molecules, such as hydrogen peroxide, to reach the electrode, eliminating many electrochemically-active compounds that could interfere with the measurement. |
