Electronics nose

Paisan Doungjak

Center of Complex Systems

School of Science, Walailak University

&

Center of Nanoscience and Nanotechnology

Faculty of Science, Mahidol University

Olfactory mechanisms

What is the electronic noseHuman mimic nose

Proceedings of 2004 IEEE/RSJ international conference

Olfactory epitheium

ELECTRONIC NOSE

Conventional Olfactory laboratory relies on human nose

But human nose get tired with more samples….

ELECTRONIC NOSEHow electronic nose works:

Schematics of an electronic nose.

Scheme of the human olfactory system.

ELECTRONIC NOSE

• Types of transducer sensor

- Quartz crystal Micro Balances (QMB)

- Surface Acoustic Wave Sensors (SAW)

- Metal Oxide Semiconductor Sensors (MOS)**

- Metal Oxide Field Effect Transistors (MOSFET)

- Conducting Organic Polymers (COP)

Electronic nose system :

Optical sensor

Gravimetric Odor Sensors

Principal of QCM click!

Quartz crystal microbalance, QCM

Surface acoustic wave, SAW

Base on piezoelectric substrate;quart,LiNbO3 and ZnO

booming cellular telephones

market

Chemoresistive sensors

O2 + e- O-2

½O2 + e- O-

½O2 + 2e- O2-

O-2

O-2

O-2

O-2

O-2

O-2 O-

2

O-2

O-2

O-2

O-2

Space chargeregion

e-e- e-O-

2

O2

O2

e-

e-

e-e-e-e-

e-

e-e-

e- e-

e-e-

e-O-

2

SnO2

grainsO2O2

φb

O-2 + CO CO2 + e-

O- + CO CO2 + e-

O2- + CO CO2 + 2e-

e-

e-

e-

e-O-

2

e-e-

e-

e-

e-

e- e-e- e-e-

e-

e-

e-e-e-e-e-

e-e-

e- e-

e-e-

e-e-

φb

O2

O2

O2O2CO

CO

CO

Metal Oxide Semiconductors (MOS)

2

:

1( )

2

( ) ( ) ( )

chemical equaltion

e O O s

R g O s RO g e

−

−

+ ⎯⎯→

+ ⎯⎯→ +

Pattern Classify

Data analysis : Pattern Classification• Statistical method

- Principal component analysis (PCA)- Partial least-square (PLS)- Principal component regression (PCR)- Cluster analysis (CA) and etc.

• Biological non-parametric methodologies artificial neural network, ANNS)- Multi-layer perception (MLP)- Self-organizing map (SOM)- Neural fuzzy system (NFS) and etc.

ELECTRONIC NOSE

Classification scheme of the multivariate pattern analysis techniques in ENs

Model base

Model free

Qu

ali

tati

ve

Qu

an

titative

ELECTRONIC NOSE

PRINCIPAL COMPONENT ANALYSIS

Aim: lower dimensional representationand visualization of the data in terms of scores on (uncorrelated) principal component > score plot

Measurement on p (correlated) variances on n objects/ individuals/ experimental units

Choice to be made:-covariance or correlation matrix (raw or standardized data)-the number of PC’s to be used

ELECTRONIC NOSEData acquisitions:

Data transfer can be used

-Serial port

-Parallel port

-Infrared transfer (iR)

-Bluetooth

-Wi-Fi

And to be collected by PC

ELECTRONIC NOSE

Experimental setup• Four commercial MOS sensors (Now)

– Figaro : AF63, TGS822, TGS2600, TGS2602• Static chamber + headspace analysis

– Concentration of coffee = 0.12g/litre– 10 ml analytic odor in 125ml flask– Sensor inserted through a tight aperture on the cap– This setup eliminates cooling effects by effluent flow

• Analytic database– Operation time used in 30 min.

• Interface requirements

– LabVIEW TM

– RS-232 port

• Analysis programming

– MATLAB TM

To electronics

analyte

sensorTo electronics

analyte

sensor

VOCs and odorous gasesTGS2602

Low concentrations of air contaminates

TGS2600

organic solvent vaporsTGS 822

alcohol and gas leakAF 63

Description (by manufactory)Model

ELECTRONIC NOSE

- the transducer to be used in EN

ELECTRONIC NOSE

Superclass8

OEM-Big C7

Khao shong-red6

Khao shong-brown5

Nescafe-Gold4

Nescafe-Redcup3

Moccona-royal gold2

Moccona-select1

Type#

Odor samples:

ELECTRONIC NOSEResults : the experiment data of Thai-coffees were collected

ELECTRONIC NOSE

Feature extraction – have many methods

- Maximum value was used to statistical recognition.

- signal preconditioning : wavelet transform (to be next time)

Maximum value

ELECTRONIC NOSE

Classification scheme of the multivariate pattern analysis techniques in ENs

Model base

Model free

Qu

ali

tati

ve

Qu

an

titative

ELECTRONIC NOSE

10 degree Celsi

us

25 degree Celsi

us

40 degree Celsi

us

Results : The principal component analysis of Thai-coffees brand in 10, 25 and 40 degree Celsius

ELECTRONIC NOSE

For application works

-To use analyses of freshness of product

e.g. Beverage, food product

-Environment monitoring :

e.g Aqueous sensor Network

-Movable robot,

Bomb detector,

rescue robot ,etc…