Team F TANU JINDAL(200601014) SANIKA JOSHI(200601017 )
What is e-nose and e-tongue? An electronic nose (e-nose) is a device that identifies the specific components of an odor and analyzes its chemical makeup to identify it. The electronic tongue (e-tongue) is an instrument that measures and compares tastes. These can be used for a wide range of applications including quality control, product matching, origin identification, spoilage detection and flavor quantification.
General Working of E-sensors
Similarity with human tongue E-tongue is structurally similar to the human tongue, which has different kinds of receptors that respond to distinct tastes. Like human receptors, each sensor has a spectrum of reactions different from the other. In the biological mechanism, taste signals are transmitted by nerves in the brain into electric signals. Similarly,e-tongue sensors process generate electric signals as potentiometric variations. Taste quality perception and recognition is based on building or recognition of activated sensory nerve patterns by the brain and on the taste fingerprint of the product. This step is achieved by the e- tongue’s statistical software which interprets the sensor data into taste pattern
Working of E-Tongue(1) The e-tongue is based on an array of tiny synthetic membranes built on a single silicon chip called a multisensor. Liquid and solid samples are analyzed differently. A potentiometric difference between each sensor and a reference electrode is measured and recorded by the E-Tongue software. The information given by each sensor is complementary and the combination of all sensors results generates a unique fingerprint.
Working of E-Tongue(2) A completely different idea for an electronic tongue realization was presented in 1997 In this method 10 to 100 polymer micro-beads are positioned on a silicon chip of about one centimeter square. Beads are arranged in tiny pits to represent taste buds and each pit is marked with dye to create a red, green, and blue (RGB) color bar. The colors change when chemicals are introduced to the e-tongue.
Array of tiny pits
Working of E-Tongue(3) Simple RGB analysis is performed by a camera on a chip connected to a computer. NOTE : E-tongue can detect an electronic change of 10 part per billion
Applications Electronic Tongues has several applications in various industrial areas: the pharmaceutical industry, food and beverage sector. It can be used to: Analyze flavor ageing in beverages Quantify bitterness or “spicy level” of drinks or dissolved compounds Analyze medicines stability in terms of taste
Comparison with human nose
Functional Blocks It primarily consists of four functional blocks, Odour Handling and Delivery System Sensors and Interface Electronics Signal Processing Intelligent Pattern Analysis and Recognition.
Details of working (1) Odour handling and delivery system ensures constant exposure rate of volatile odour vapour to sensor array chamber. Discrimination among complex odours is done using array of sensors which consists of a number of broadly tuned sensors that are treated with a variety of odour- sensitive biological or chemical materials.
Details of working (2) The chemical sensors (Metal Oxide Sensors) are a set of electrodes which are coated with different polymer films that are specially designed to conduct electricity . Because each film is made of a different polymer, each one reacts in a slightly different way upon contact with different volatile chemical compounds.
Each polymer changes its size, and therefore its resistance, by a different amount, making a pattern of the change .
Details of working (3) The response signals of sensor array are conditioned and processed through suitable circuitry and fed to an intelligent pattern recognition engine for classification, analysis and declaration.
Applications of E-Nose Used for quality control applications in the food, beverage and cosmetics industries. Detection of odors specific to diseases for medical diagnosis Detection of pollutants and gas leaks for environmental protection. Water and wastewater analysis.
Problems Faced The machines are large and expensive Have limited sensitivity Frequent need of re-calibration Therefore current research is focused on making the devices smaller, less expensive, and more sensitive.
Conclusion Excellent tools for sensory measurements. Both quantitative and qualitative results can be obtained. Detection thresholds are similar or better than those of human receptors. Simplicity , objectivity and speed of analyses make E- sensors very advantageous.
References Alpha-MOS_Articles_0308_Soft_Drinks.pdf Alpha-MOS_Articles_0310_AAPS.pdf Artificial electronic tongue in comparison to the electronic nose - state of the art and trends [ Peter Hauptmann, Ralf Borngraeber, Jens Schroeder, Otto- von-Guericke-University ]
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