Electron Transfer Mediators

The evolution of Electron Transfer Mediators was the critical innovation that allowed diabetic test strips to move from clinical labs to home use. Early First Generation sensors relied on blood oxygen to facilitate the reaction, which caused inaccuracies due to oxygen fluctuations (the 'Oxygen Deficit') and required high voltages that triggered interference from drugs like Tylenol.

The industry standard shifted to Second Generation sensors using synthetic mediators—primarily Ferricyanide (LifeScan) and Ferrocene (MediSense)—which replaced oxygen as the electron shuttle. This allowed for oxygen-independent readings. Further innovation by TheraSense (Abbott) and Roche introduced Osmium and Ruthenium complexes, often tethered to polymers ('wired enzymes'). These advanced mediators operate at significantly lower electrical potentials, virtually eliminating interference from common blood substances and enabling the high accuracy required by modern ISO 15197 standards.