Electronic Nose, the name looks funny as it sounds like how could be a nose made of electronics. But the advancement in electronics has developed an E-Nose which can sense the Odors or Flavors. This electronic nose senses the odors or flavors based on the sensing technology named as “Electronic Sensing” or “e-Sensing”. Electronic-Nose uses two mechanisms one is the electronic sensors and another one is pattern recognition. The electronic sensors are used for chemical detection and neural network mechanism is used for pattern recognition. Electronic sensing has the capacity to reproduce human nose senses by the use of sensor arrays and pattern recognition mechanisms.
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How Electronic Nose or E-Nose works?
E-Nose has undergone various important developments especially in technical and commercial point of view. It is basically developed to function similar to Human Nose. The array of sensors generates electrical signals when it is subjected to flavors or odors present in a gaseous sample.
It consists of three major parts:
1. Sample Delivery System – This system generates a sample for analysis and then injected to detection system.
2. Detection System – The group of sensors in a detection system reacts to the flavor or odor present in a compound and generated an electrical signal based on the flavor. This electrical signal is then recorded by an electronic interface to get transformed into a digital signal.
3. Computing System – The responses from all the sensors are combined to produce a final result. There will be a database collection of samples which are already processed and the result is analyzed based on that database. The computing system recognizes the pattern and gives us a desired result.
In an Electronic nose, a sample is applied to a small chamber consists group of arrays making the sample to pass through these arrays. When the sample passes through the arrays they produce some responses and these responses are recorded and injected to the signal-processing unit. Responses are nothing but the electrical signals. The Signal-Processing unit converts the electrical signals into machine understandable language i.e. digital signal and forwards that digital signal to a computing system. The computing system recognizes the pattern based on the database of predefined results of samples and finally gives us the result.
Different types of Sensors that can be used in Electronic nose or E-Nose:
1. Conductivity Sensors:
These sensors are used to sense volatile organic compounds and provide a result on change in conductance.
2. Polymer Sensors:
To find the changes in conductivity of the polymers like Polypyrroles, indoles, furans etc. when they are exposed to different types of chemicals the Polymer Sensors are used. Here the change in size gives us the result.
3. Piezo Electric Sensors:
This sensor uses piezoelectric effect to measure any physical change of the sample that is used to test. The results are based on the change of mass of sensor.
4. FET (Field-Effect Transistor) Gas Sensors:
These sensors act as a chemical sensor to find a change in chemical process of molecules, atoms and ions of samples like liquids and gases.
5. Optical Sensors:
These sensors are coated with chemical active material either on their sides or ends and when a light source is used to interact with the samples. As the sample interact with the sensors the color changes as they are made up of fluorescent dye and hence giving us the result.
It is an example of handheld “Electronic Nose” developed by Cyrano Sciences of Pasadena in 2000. The main applications of Cyranose are to detect COPD and other medical conditions as well as industrial applications generally related to quality control or contamination detection.
Applications of Electronic Nose:
• Environmental Monitoring: Identifies volatile organic compounds in air, water and soil samples for protecting Environment.
• Quality Control Laboratories: Detects the contamination, spoilage and adulteration and monitors storage conditions.
• Medical Diagnosis: It examines the odors from the body and identifies the problem.
• Food Industry: Checks the quality assessment and monitors various food items based on their odor.
Features of Electronic Nose:
• High Sensitivity and Specialty.
• Improved Compliance
• No health risk
Future of Electronic Nose:
• It has the ability to detect drug odors and also airborne odors which can confuse well trained police dogs and prevent crime.
• Even it can be used in Bomb Detection by installing several electronic noses and effective computer systems.
Although of its many advantages it’s still far from the selectivity provided by Human Nose.