Biosensors

A biosensor is an instrument for the measurement of biological or chemical parameters. They usually combine biological and physical-chemical components.

Generally, they consist of three parts:

• The biological sensor: It may be a tissue, a culture of microorganisms, enzymes, antibodies, nucleic acid chains, etc. The sensor can be taken from the wild or be a product of synthetic biology.
• The transducer: Its function is to bind the other two elements and translate the signal emitted by the sensor.
• The detector: It can be optical, piezoelectric, thermal, magnetic, etc.

The most common example is a biosensor that measures blood glucose. It uses an enzyme that processes glucose molecules, releasing an electron for each molecule. Said electron is collected at one electrode and the electron flow is used as a measure of the glucose concentration.

The caged canaries used by miners to detect the presence of lethal gases can be seen as an early example of biosensors (Wikipedia, 2014)

By using modified bacteria E. coli for this, we will try to find a cheaper, easier, and faster way to detect the problem of anoxia and heavy metals in some aquifers of Mexico City. We will have to analyze samples of water at different depths to know where the problem is worse and what probable native species could be more affected.

Some of the benefits of using biosensors instead of other sensing methods, as observed by Ajit Sadana and AzoSensors, are:

• A fast response in time.
• Fast and continuous measurement.
• High specificity because of its shape-specific recognition.
• Simplicity in its use.
• Capability of measuring concentrations ranging from 10^-18 to 10^-19 M, so we need low sample requirements.
• Capability of real time measurements.