General description of biosensors
Biosensors implantable in vivo

In 1962, Clark developed the first model of a glucose biosensor. (figure ). For the first time, an analytical detection method combined an electrochemical device (an oxygen electrode) with a component of biological origin, an enzyme (glucose oxidase). The glucose present around the electrode was degraded by glucose oxidase into gluconolactone, in a reaction that consumed a molecule of molecular oxygen O₂. Clark then used an electrochemical cell to reduce the O₂, which provided a current directly proportional to the O₂ concentration and therefore inversely proportional to the glucose...