The idea for biosensors \u2014 using some part of an organism to generate a signal to measure or monitor the presence of a substance \u2014 has been around for more than a century. The classic example is the use of canaries in coal mines to detect toxic gasses. Because these tiny birds are so sensitive to these gases that they would sicken long before the miners felt the effects, they served as a warning system.<\/p>\n
Most modern biosensors are at the cutting edge of innovation, some using nanotechnology to detect substances in concentrations as small as a few parts per billion. Today, 85 percent of commercial biosensors are glucose sensors used by millions of diabetics to measure their blood sugar, according to Professor Anthony Turner, director of the Biosensors and Bioelectronics Centre at Link\u00f6ping University, in Sweden. However, there are also many applications in such fields as safety, security, and environmental monitoring. For example, Portland International Airport, in Oregon, uses biosensors to monitor the effluent from its deicing facilities, before discharging it. While biosensors are very effective for certain applications, they are expensive to purchase and maintain. For many applications, industry is shifting to TOC (total organic carbon) meters.<\/p>\n