Human nose is one of the most amazing human organ which is able to detect more than 10,000 chemicals in air or simply able to detect many ‘smells’.For years scientists were on research to find an artificial nose better known as ‘electronic nose ‘to replace a natural one which could find a lot of applications in food industries,explosive industries and other industries where human intake of a chemical become harmful.
Lawrence Livermore scientists were the leading ones in the field of miniature electronic tools to detect various magnetic,acoustic,seismic,electrical,nuclear signal etc.Now in favour of Departments of Defense and Homeland Security planners they are in research of miniaturized electronic nose that could be used to detect nuclear,toxic and explosive materials which finds a lot of application in the security field.
They are close to the finishing line and the Livermore sensor that they developed is able to detect many airborne chemicals from a mixture,with the help of minuscule diving boards called microcantilevers.Once the sensor is trained for a particular smell or vapour its able to detect that chemical at any instant.It proved it reliability by detecting 11 different chemical vapours, including chemical warfare agents VX and sulfur mustard,along with any warfare chemicals used for destruction.
Design of an electronic nose
The the design by the Livermore scientist is mainly based on the differential blending of microcantilivers made of silicon which is covered with silicon nitride a chemically inert material.Then it is covered with a film of plastic to safeguard from moisture.The more the chemical is absorbed the more the cantiliver bends.
How an electronic nose works ?
The device works on the principle of microelectromechanicalsystems(MEMS),it generally uses a chemical sensor ,usually a specialized polymer which has got an affinity for chemical vapours and simultaneously undergo reaction with interaction.In the Livermore design it will produce a volumetric strain on contact with the vapours and hence the chemical signal is converted into a mechanical one.The mechanical distortion could be calculated by the principle of ‘piezo electricity’.the mechanical cantiliver is made of piezo resistive material that the pressure produced by distortion give rise to electric signals or may cause the change in resistivity of the material there by causing a variation in flowing electric signal which could be calibrated and compared with onboard signals and the smell could be identified.
Advantages of Livermore Design
- small size
- small power consumption
- high sensitivity
- low cost
Could be used for industrial as well as environmental monitoring,detection of toxic materials in warfares,for disease diagnostic since some disease are related with the over production of certain chemicals,detection of nuclear materials or weapons etc.A multicantiliver sensor is shown below