Electronics nose - Nano Mahidol - Mahidol University

Chemoresistive sensors
Metal Oxide Semiconductors (MOS)
SnO 2
O
O
grains
2
2
O -
O - O -
2 O - 2 O - 2
O - 2
2 e - e - e
2 e e - e-
O - 2 O - e - ē -
2
O ē - 2 e - e -
e -
Space charge
region
O - 2
eē- O - 2
O - 2
O 2
e -
e -
e - O - 2
O - 2
O 2
+ e - O - 2
½O 2
+ e - O -
½O 2
+ 2e - O 2-
φ b
chemical equaltion :
1
−
e+ O2
⎯⎯→ O()
s
2
−
Rg ( ) + Os ( ) ⎯⎯→ ROg ( ) + e
O 2
CO O 2
CO
eē- e - e -
O - e -
e - e - 2
e - e
e e - e-
e - e-e- O e - e - e - e - e - e - e -
2
e - e -
O 2
O - 2 + CO CO 2 + e-
CO
O - + CO CO 2
+ e -
O 2- + CO CO 2
+ 2e -
φ b
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.