Howard P. Isermann Department of Chemical and Biological Engineering
An Introduction to Biosensors
Biosensor is the term used for a whole class of sensors that utilize a biochemical reaction to determine a specific compound.
Continual measurements of raw materials and products are important for the control of Biochemical processes.
Monitoring of important organic pollutants is also required for environmental control. Recently, many biosensors have been developed and provided methods of rapid and continuous measurements of various compounds.
A biosensor is generally an immobilized enzyme or cell that is combined with a transducer to monitor a specific change in the microenvironment.
The probe tip is immersed in the liquid phase and is in contact with the process either directly or through a membrane.
To date, these instruments have not seen wide spread use because as a class they exibit many disadvantages. These include:
Microbial sensors are suitable for the industrial process because they are stable for a long time. Two different types of microbial sensors were developed for measurement of organic compounds.
An inability to be steam sterilized
- They react with the product
- And are oversensitive
1.) Microbial sensors consisting of immobilized whole cells and an oxygen probe when used for determination of substrates and products.
The concentration of compounds was determined from microbial respiration activity which could be directly measured by an oxygen probe.
2.) Microbial sensor consisting of immobilized microorganisms and an electrode was used for determination of organic compounds.
The concentraion of compounds was indirectly determined from electroactive metabolites such as proton, carbon dioxide, hydrogen, formic acid, and reduced co-factors which can be measure by the electrode.
Examples of Biosensors
Biosensors for Nutrients:
Biosensors for Cell Population:
Biosensors for Products:
Biosensors for Environmental Control:
This text was written by Craig Pohan and Matt Armstrong at Rensselaer Polytechnic Institute (c) 1995