The colon has a multitude of functions amongst which fermentation is an important physiological function. The production of gases as a consequence of bacterial metabolism of short chain fatty acids is critical for which diet is an important variable. Emission of gases and volatile organic compounds (VOCs) are emerging as important determinants in maintaining intestinal homeostasis in health and disease but also metabolic diseases.

Our group explores this by using an electronic nose first invented here at Warwick University. Several different technologies are applied on various biological samples from different disease groups

What’s an Electronic Nose?

An electronic nose is an instrument that attepts to replicate the biological olfactory system. Unlike many other analytical techniques, an electronic nose does not try and separate all the chemical components within a sample, but it perceives a sample as a whole, creating a global fingerprint. It contains a number of components that replicate parts of the biological system as shown below.

• For example the smells that emanate of coffee has many hundreds of different chemical components, but our biological olfactory system (and the electronic nose) simply identifies the total chemical composition as coffee.
• In an electronic nose, the headspace from a sample (i.e. the gases emanating from a sample) are delivered to an array of chemical sensors—in our case commercial metal oxide semiconductor and electrochemical sensors
• As each sensor is different in some way, (usually broadly tuned to a different chemical group) each sensors response to a sample is different. These responses can then be used to form a chemical fingerprint of a sample. The response is seen as a change in electrical properties (normally resistance) of the sensor.
• Specialised software then identifies the sample from this fingerprint.