Development of an amperometric alcohol sensor based on immobilized alcohol dehydrogenase and entrapped NAD

An amperometric planar alcohol sensor has been developed, which has a triple-layer enzyme-immobilized membrane. The lower layer consists of immobilized alcohol dehydrogenase (ADH), the middle layer contains entrapped mobile nicotinamide adenine dinucleotide (NAD+) molecules, and the upper layer is a denser bovine serum albumin (BSA) layer. Typical sensor response to 500 mM ethanol was 250 nA. The sensor responds sufficiently after 10 measurements and 1 month of storage at −20°C. Using this alcohol sensor, ethanol has been measured, without further addition of NAD+ or any other reactive reagent, and repeatable usage has been realized.