Biosensors are analytical devices that utilise biological responses to create electrical signals and ultimately an analysis of a substance. Biological systems such as antibodies or enzymes are attached to carbon nanotubes or nanowires that act as transistors. When a protein binds, it interacts with the electrons traveling through the nanotube or nanowire, altering its conductivity. This principle can used to detect biological molecules or viruses in the air, water or blood. The nanowires or nanotubes can be placed in arrays, each with a different antibody to detect multiple molecules at once.

The unique properties of nanowires and carbon nanotubes mean that these sensors can detect smaller molecules and molecules that are present in smaller quantities. Biosensors have many potential benefits including earlier detection of diseases, monitoring blood glucose more accurately and monitoring particles in the air and water to create safer working environments and products.