Biosensors

A device that combines a biomolecule, such as an enzyme, with a tranducer to produce an electrical signal which measures the concentration of a chemical

• uses immobilised enzymes
• rapidly and accurately detects, identifies and measures concentration of important molecules
• works on principle that enzymes are SPECIFIC and are able to select one type of molecule from a mixture

Allows people with diabetes to check their blood to see how well they are controlling their blood glucose concentration

1) enzyme electrode placed in small sample of their blood

2) glucose and O₂ diffuse into immobilised enzyme layer (rate of O₂ uptake proportional to rate of glucose uptake)

3) glucose oxidase (enzyme) catalyses the reaction of glucose and oxygen which causes a chemical change

4) tranducer converts these chemical changes into electrical signals

5) electrical signals sent to amplifier, which produces a reading for blood glucose concentration

6) reading shows up on enzyme electrode (more glucose present = greater singal = greater reading)