Provided by : Provided by : Seyed Farokh Seyed Farokh

AtashzarAtashzar

Supervisor: Supervisor: Prof H. Prof H.

TaghiradTaghirad

•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

Different names:

ELECTRONIC NOSE ARTIFICIAL NOSE GAS DETECTOR MACHINES

HARD WARE Sampling SystemSensor arrayConditioning CircuitHigh speed Processor

+Soft ware:Pattern recognition algorithms 1. Intelligent methods 2.Stochastic methodsMonitoring

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.

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

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.

Gas sensors selectivity are lowThey can no apply to complex odorThere 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.

Special Hardware To create mentioned finger print

Array sensors create a special N-dimensional coordinatesWhich sensors are the axisAnd odors are the points .

Arrays can span a large group of complex odors

2.Choosing identifier Feature:•Steady State response•Transient Response

Finger print

Important Properties

SensitivitySelectivityThresholdSaturationLifetimePriceSizeReproducibilityPower Consumption

Gas Sensors:

Conducting polymer Sensors Metal oxide sensors Surface acoustic  wave sensorBulk acoustic waveMOS field-effect transistor

Usual type:Polymer-Carbon black solution

wide range of polymeric materials available on the market

different polymers give different levels of response

to a given odor. Due to their construction

High discrimination in array sensors can be easily achieved

Conducting polymer composites are also relatively inexpensive and easy to prepare.No heater and extra element are requiredSensor can operate at room temperature.

Applied in portable Battery powered e-nose systems,

show highly linear responses for a wide range of gases

Simple and Common signal conditioning circuit

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.

they are not easily inactivated by Contaminants

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 gasesn-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: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

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

Local acoustic wave was created by an AC voltage Mechanical

wave propagates along the surface of the crystal

Probe

ANOTHER NAME:Quartz crystal microbalance (QCM)

Operating frequency:10 and 30 MHz

A MOSFET sensor comprises three layersA silicon semiconductorA silicon oxide insulator catalytic metal ,also called the gate

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

Converting time-dependent answers of the array to time independent vector

Normalizing all the answers of the sensors

Offset cancelling with a reference odor

Reference response Response in new situationFinding the linear mapping

Extend this transformation to the response of undefined gas in same situation

Now we have calibrated input vector

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

Dimension reduction

It highlights the Similarities and differences.

Step 1: Get dataStep 2: Subtract the meanStep 3: Calculate the covariance matrixStep 4: Calculate the eigenvectors and Eigen values of the covariance matrixStep 5: Choosing components and forming a feature vectorStep 6: Deriving the new data set

Real example

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

Techniques:•Multilayer feed forward neural network•Competitive neural network•Fuzzy Logic Methods

Furrier series

A supervisedmethod

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

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 detectorsground penetrating radars,optical, infrared, acoustic, X-ray analysis. Dogs!!

New approach:E-NOSE

Very low speedLow selectivity

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 fishverify 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.

Lower cost unit cost through batch production of wafersSmaller device sizeIncrease 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 signalAn 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 arrayMulti type array

Conducting polymers

Alpha M.O.S.

Lennartz Electronic

Cyrano Sciences, Inc.

FOX can be equipped with:6 sensors : FOX2000 12 sensors : FOX 3000 18 sensors : FOX 4000

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 pricedMetal Oxides or conducting polymers; as well as surface acoustic wave (SAW).It requires an external PC