Electronic NOSE Seyed Farokh Atashzar Supervisor: Prof H. Taghirad Provided by : Seyed Farokh Atashzar Supervisor: Prof H. Taghirad

Table of Content INTRODUCTION WHAT IS SMELL? HUMAN OLFACTORY SYSTEM E-NOSE BASIC IDEA AND SPECIAL CONSTRUCTION GAS SENSORS HOW DOES IT WORK? PATTERN RECOGNITION AND CALIBRATION APPLICATION INTEGRATED E-NOSE( SMART E-NOSE) COMMERCIAL E-NOSE Conclusion

Electronic-Natural Olfactory Sensor Emulators INTRODUCTION Electronic-Natural Olfactory Sensor Emulators HARD WARE Sampling System Sensor array Conditioning Circuit High speed Processor Different names: ELECTRONIC NOSE ARTIFICIAL NOSE GAS DETECTOR MACHINES + Soft ware: Pattern recognition algorithms 1. Intelligent methods 2.Stochastic methods Monitoring The major differences between electronic noses and standard analytical chemistry equipment are that electronic noses Produce a qualitative output can be easier automate can be used in real-time analysis.

WHAT IS SMELL? Characteristics: Volatile Easy to dissolve in water Can be organic or inorganic like SO2 Low concentration Challenging Problems : Nonlinearity properties( that is not constant for all ) 1.Thershold 2.Saturaion There is many mixtures that have smell but the components didn’t… So it is really difficult to predict chemical structure of a gas due to its smell

HUMAN OLFACTORY SYSTEM Construction: Receptor(100,000,000) Olfactory bulb Brain

E-NOSE LEARN TO SNIF GOAL: 1.New undefined smell is similar to A or B (A and B are two gases that have learned to E-nose before.) 2.Or it’s not similar to 10 previous samples. LEARN TO SNIF

SIMILARITIES IN CONSTRUCTION

Why array?! Gas sensors selectivity are low New Idea They can no apply to complex odor There are a large number of gases that has similar response to gas sensors New Idea Odor detection can be achieved If we have a private finger print for each odor. Arrays: Monotype Multi type To create mentioned finger print Special Hardware Array sensors create a special N-dimensional coordinates Which sensors are the axis And odors are the points . Arrays can span a large group of complex odors

HOW DOSE IT WORK? Processor Gas Classification 1.Choosing the kind of input: STEP(often) Pulse Finger print 2.Choosing identifier Feature: Steady State response Transient Response Save the responses(steady state) in a matrix Here we have a 2*4 Matrix Now we have a Fingerprint Matrix Pre-Processing Learned Pattern recognition Gas Classification Processor

GAS SENSORS Important Properties Sensitivity Selectivity Threshold Saturation Lifetime Price Size Reproducibility Power Consumption Gas Sensors: Conducting polymer Sensors Metal oxide sensors Surface acoustic  wave sensor Bulk acoustic wave MOS field-effect transistor

Conducting polymer Sensors Usual type: Polymer-Carbon black solution

Advantages High discrimination in array sensors can be easily achieved different polymers give different levels of response to a given odor. Due to their construction wide range of polymeric materials available on the market Conducting polymer composites are also relatively inexpensive and easy to prepare. No heater and extra element are required Sensor can operate at room temperature. Applied in portable Battery powered e-nose systems, show highly linear responses for a wide range of gases for high sensitivity, fast response and short recovery times it is essential that the sensor geometry and all the associated properties of the polymer sensing material be highly optimized. Simple and Common signal conditioning circuit they are not easily inactivated by Contaminants

They are very sensitive to high concentration of humidity. Disadvantages They are very sensitive to high concentration of humidity.

Metal oxide sensors Principle based on change in conductance of the oxide on interaction with a gas and the change is usually proportional to the concentration of the gas. There are two types : n-type (zinc oxide, tin dioxide, titanium dioxide or iron (III) oxide) which respond to reducing gases p-type (nickel oxide, cobalt oxide) which respond to oxidizing gases n-type sensor operates as follows: oxygen in the air reacts with the surface of the sensor and traps any free electrons on the surface or at the grain boundaries of the oxide grains. This produces large resistance in these areas due to the lack of carriers if the sensor is introduced to a reducing gas like H2, CH4, CO, C2H5 or H2S the resistance drops because the gas reacts with the oxygen and releases an electron

Advantages and Disadvantages Very fast response and recovery times, depend on the temperature and the level of interaction between the sensor and gas. relatively inexpensive to fabricate, Can be integrated directly into the measurement circuitry Disadvantages: High operating, temperatures which results in increased power consumption. As a result, no handheld e-nose system has been fabricated utilizing sensors prepared from metal oxides . They also suffer from sulphur poisoning due to irreversible binding of compounds that contain sulphur to the sensor oxide .Ethanol can also blind the sensor from other volatile organic compound (VOC), gases .

Surface acoustic wave sensor Local acoustic wave was created by an AC voltage Mechanical wave propagates along the surface of the crystal Probe The mass of the gas sensitive membrane of the SAW device is changed on interaction with gas and causes the frequency of the wave to be altered

Quartz crystal microbalance (QCM) Bulk acoustic wave Operating frequency: 10 and 30 MHz ANOTHER NAME: Quartz crystal microbalance (QCM)

Metal oxide semiconductor field-effect transistor sensors The selectivity and sensitivity of MOSFET sensors may be influenced by the operating temperature (50–200 °C), the composition of the metal gate, the microstructure of the catalytic metal A MOSFET sensor comprises three layers A silicon semiconductor A silicon oxide insulator catalytic metal ,also called the gate

CALIBRATION and Pre-processing Converting time-dependent answers of the array to time independent vector

CALIBRATION and Pre-processing Normalizing all the answers of the sensors Offset cancelling with a reference odor Finding the linear mapping Reference response Response in new situation Extend this transformation to the response of undefined gas in same situation Now we have calibrated input vector

PATTERN RECOGNITION Parametric(Statistical) Non-Parametric(Intelligent techniques ) Supervises Unsupervised

Statistical techniques EXP. Principal Components Analysis PCA Dimension reduction It is a linear unsupervised method that It highlights the Similarities and differences. Step 1: Get data Step 2: Subtract the mean Step 3: Calculate the covariance matrix Step 4: Calculate the eigenvectors and Eigen values of the covariance matrix Step 5: Choosing components and forming a feature vector Step 6: Deriving the new data set Real example

Intelligent techniques Multilayer feed forward neural network Competitive neural network Fuzzy Logic Methods The number of detectable chemicals is generally increased less selective sensors which are generally less expensive can be Used Unknown chemicals can be rapidly learned and identified learning capabilities, self-organizing, generalization and noise tolerance

Multilayer feed forward neural network A supervised method Furrier series

Multilayer feed forward neural network

Application Automotive Applications AEROSPACE APPLICATIONS APPLICATION IN  MEDICINE Detection of Explosives ELECTRONIC NOSES FOR ENVIRONMENTAL MONITORING ELECTRONIC NOSES FOR THE FOOD INDUSTRY TELE MEDIA

AUTOMOTIVE APPLICATIONS Monitoring the exhaust for combustion efficiency Monitoring the cabin air for passenger safety Monitoring the engine compartment for other conditions such as leaking oil or other fluids Can be used in a system which the exhaust is monitored for the presence of compounds indicative of incomplete combustion, and feedback to the engine will adjust engine settings to improve combustion efficiency.

AEROSPACE APPLICATIONS planetary atmospheric studies on landers In the search for evidence of life on other planets  application is monitoring air quality in human habitats Specially for Ammonia surrounding the cabin

APPLICATION IN MEDICINE Odors in the breath can be indicative of gastrointestinal problems, sinus problems, diabetes, and liver problems. Infected wounds and tissues emit distinctive odors that can be detected by an e- nose. Odors coming from body fluids can indicate liver and bladder problems.  tele-surgery

Detection of Explosives Around the world land mines claim the life of a victim or maim one victim every 22 minutes. There are about 120 million unexploded landmines lurking in . With the current technology, 4.6 square miles of landmine infested area can be cleared per year. For every mine that is cleared, 20 new mines are laid. The cost of a mine ranges from $3–$5, whereas clearing it costs between $100-$1000. On average, for every 5000 mines removed, one mine-clearer is killed and two others are injured. It would cost about $120 billion and take a thousand years to clear all the mines in the world with the current technology.!!!!!!!!!!!!! Traditional detection techniques:   magnetic metal detectors ground penetrating radars, optical, infrared, acoustic, X-ray analysis. Dogs!! New approach: E-NOSE Very low speed Low selectivity

ELECTRONIC NOSES FOR ENVIRONMENTAL MONITORING WATER AIR

ELECTRONIC NOSES FOR THE FOOD INDUSTRY quality control tool to check raw materials, to check product deterioration to monitor product during transport to retailers a tool for process control to monitor food odors during critical stages of production to ensure that optimum processing conditions are being maintained grading the freshness of fish verify the authenticity of cheese. In coffee industry. It can use the EN to precisely control the roasting and blending process and final products. checking the freshness of fruit when it is harvested, during shipment, and at the point of sale. (Tea and Tea taster )Flavor and Aroma are important quality attributes of tea.

Integrated E-nose

Advantages Mono type array Multi type array Conducting polymers Lower cost unit cost through batch production of wafers Smaller device size Increase in sensor reproducibility by the integration of arrays of sensors onto the same substrate. Superior signal conditioning by less noise generated in the transmission of signal An improved limit of detection for the whole sensing system. The full integration of gas micro sensors and signal processing circuitry can causes: improvements in sensor sensitivity through advances in individual micro sensor technologies The development of novel gas-sensitive materials, Mono type array Multi type array Conducting polymers

Multi type

Micro Chanel

Micro check valve

Micro pump

Commercial E-nose Alpha M.O.S. Lennartz Electronic Cyrano Sciences, Inc. Alpha M.O.S. Lennartz Electronic

Cyranose 320 32-polymer composite (polymers filled with the conductive particles carbon black real-time, portable device  $9,000- priced handheld device It requires a one-time training lightweight

Alpha M.O.S.& FOX series FOX can be equipped with: 6 sensors : FOX2000 Easy sensor array upgrade from 6 to 24 sensors for any type of application High sensitivity It allows techniques like principal component analysis (PCA), projection to latent structure (PLS), and artificial neural networks (ANNs), as well as a transferability utility to convert data from different systems $50,000 priced Metal Oxides or conducting polymers; as well as surface acoustic wave (SAW). It requires an external PC  

Conclusion Important topics that was nod mentioned in this Presentation: Conditioning circuit Classical methods KNTU & E-NOSE

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