This slides will provide a bread idea about sensing mechanism involve in gas sensing operations. This slides briefly discuss the chemistry involve in sensing mechanism

1. Plan of Presentation
 Broad Research Area
 Literature survey
 Definition of the Problem
 Plan of Work

2. Broad Research Area
 Micro sensors for detection of gases/odors.
Fig 1. Gas Sensing Process

3.  Mechanism Behind Gas sensing
 Adsorption
 Absorption
Fig 2. Adsorption and Absorption
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4.  Adsorption: Change in Charge Concentration
 Physisorption
 Chemisorption
Fig 3. Physisorption and Chemisorption
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5.  Absorption: Change in Work Function
Fig 4. Absorption of Hydrogen gas in Pd Metal

6.  Parameters for Gas Sensing
 Selectivity
 Hydrogen Containing Gas Sensor
 Nitrogen Containing Gas Sensor
 Oxygen Containing Gas Sensor
 Sulphur containing gas sensor
 Sensitivity
 Response and Recovery Time
 Less Rise Time
 Less Hold Time
 Less Fall Time

7.  Fabrication Technology
 Resistor
 Capacitor
 Thick Film Technology
 Silicon Technology
 Resistor
 MIS - Capacitor
 Diode

8.  Development of Sensor Array based on silicon and Thick film
Technologies
 Development of Discrimination Techniques for identification and
quantification of gases/odors
Broad Research Area Cont…
Fig 5. Process Flow of Gas/Odor classification

9. Literature Survey
Related to Micro-sensors
 Vinode Kumar et al., 2014, observed that gridded Pt/SiO2/Si-p MOS sensor is an effective detector
for H2 gas particularly for low concentrations and inferred that fixed surface state density increases
linearly with increase in H2 concentrations which results in decrease in flat band voltage The
maximum sensitivity was found 88% at lower frequency (25 kHz) at 4000 ppm H2.
 Kihyun Kim et al.,2019, ZnO (Zinc oxide ) nano wire with single schottky contact is capable of
sensitive detection of reducing gas molecule at low concentration. he has observed that different
diameter of Zinc Oxide nano wire can detect low concentration of H2 gas unto 1000ppm.
 B. Bhowmik et al., 2019, states that The device based on p-n homojunction of TiO2 nanostructure
in which p TiO2 Nanoparticles (prepared by low temp sol-gel method) and n TiO2 nanotubes (formed
by the electrochemical anodization) is used for low concentration alcohol and acetone detection .The
maximum sensitivity is observed for ethanol at 100ppm.
Ziying Wang et al., 2019, observed that the ZnO/SnO2 n-n heterogenous structure on reduced
Graphene oxide enhance the sensing performance for NO2 gas. n type ZnO NP and n type SnO2 NP
is is constructed on RGO nano sheet by hydrothermal method and wet chemical deposition methods.
It can enhance response for NO2 unto 141% which is 3 to 4 times greater than ZnO –RG0(43.3%)
and SnO2 –RGO (34.8%).
 Preeti Panday et al., 2010, Employment of microwave in combination with RF oxygen plasma for
surface treatment of SiO2 has resulted in dramatic improvement in the hydrogen sensitivity of the
MOS gas sensor. IIT (BHU) 9

10. Literature Survey contd..
 Yuanyuan Zhu et al., 2019, observe the effect of the target gas (acetone) on the surface chemistry of
a WO3-SnO2 nanosphere (NS) composites made by hydrothermal method was investigated for
possible application of the device as a acetone sensor. WO3-SnO2 nanosphere (NS) composites show
high sensitivity, fast response and low recovery time and low detection limit for acetone gas (100
ppm).
 Eunji Lee et al., 2019, observe the Two-dimensional (2D) nanomaterials have great potential in the
field of gas sensing due to their layered structures. This type of sensor can be used for various gases
such as NO2 ,ammonia ,ethanol etc.
Andrej Paul et al., 2019, observed a composite material of copper oxide (CuO) dispersed in the
nanopores of silica (SiO2) is used as a effective sensor for the detection of hydrogen sulphide (H2S)
gas in low parts per million concentrations..
Jae-Hun Kim et al., 2019, reported gas sensing characteristics of p-reduced graphene oxide (RGO)
loaded p- CuO nanofibers (NFs) will be presented. The different amount of RGO is added to NP of
CuO and response is recorded for H2S gas .
 Myung Sik Choi et al., 2019, observed that Branched nanowires (NWs) are a novel class of
composite materials with increased surface area and enhance gas sensing. In this work a p- n, TeO2-
branched SnO2 NWs were produced by vapor-liquid-solid (VLS) growth technique for gas sensing
studies. First, SnO2 NWs were synthesized from highly pure Sn powders, and TeO2 branches were
subsequently added.
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11. Related to Pattern Recognition

Literature Survey contd..
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Definition of Problem
 Device Structure
 Improve Sensitivity
 Improve Selectivity
Improve Response Time
 Higher Temperature Range
Fig 6. Porous silicon
 Development of Sensor Array
 Development of Numerical Techniques for Pattern Recognition

13. Plan of Work
 Micro sensors based on silicon and Thick Film Technologies will
be developed for detection of gases/odours.
 Sensor array will be developed based on silicon and thick film
technologies for detection and identification of gases/odours.
 Suitable discrimination techniques will be developed for
identification.

14. [1] Sung Min Kim, Hye Ju Kim, Hae Jun Jung, Ji-Yong Park, Tae Jun Seok, Yong-Ho Choa, Tae Joo
Park, and Sang Woon Lee “High-Performance, Transparent Thin Film Hydrogen Gas Sensor Using
2D Electron Gas at Interface of Oxide Thin Film Heterostructure Grown by Atomic Layer
Deposition” Journal of Advanced Functional Materials 29, 1807760 ,2019.
[2] Lintu Rajan,C.Periasamy , and Vineet Sahula , “An In-Depth Study on Electrical and Hydrogen
Sensing Characteristics of ZnO Thin Film With Radio Frequency Sputtered Gold Schottky
Contacts” IEEE SENSORS JOURNAL, VOL. 19, NO. 9, MAY 1, 2019.
[3]. Deepak Punetha and Saurabh Kumar Pandey, “CO Gas Sensor Based on E-Beam Evaporated
ZnO, MgZnO, and CdZnO Thin Films: A Comparative Study, IEEE SENSORS JOURNAL, VOL. 19,
NO. 7, APRIL 1, 2019.
[4]. K.V. Gurava, M.G. Ganga, S.W. Shina, U.M. Patilb, P.R. Deshmukhb, G.L. Agawanea, M.P.
Suryawanshia, S.M. Pawara, P.S. Patila, C.D. Lokhandeb, J.H. Kim, “Gas sensing properties of
hydrothermally grown ZnO nanorods with different aspect ratios”, Sensors and Actuators B 190 ,
439– 445 ,(2014).
[5]. Tzu-Chieh Chou , Ching-Hong Chang, Cheng Lee, and Wen-Chau Liu, “Ammonia Sensing
Characteristics of a Tungsten Trioxide Thin-Film-Based Sensor”, IEEE TRANSACTIONS ON
ELECTRON DEVICES, VOL. 66, NO. 1, JANUARY 2019.
[6]. Feng-Renn Juang., “Ag Additive and Nanorod Structure Enhanced Gas Sensing Properties of
Metal Oxide-Based CO2 Sensor”, IEEE SENSORS JOURNAL, VOL. 19, NO. 12, JUNE 15, 2019.
References
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15. [7] Ting-ting Yu, Xian-Fa Zhang, Ying-Ming Xu, Xiao-Li Cheng, Shan Gao, Hui Zhao, Li-Hua Huo.,
“Low concentration H2S detection of CdO-decorated hierarchically mesoporous NiO nanofilm with
wrinkle structure”, Sensors and Actuators B 230, 706–713 ,2016.
[8] Preeti Pandey, J.K. Srivastava, V.N. Mishra, R. Dwivedi Center, “Pd gate MOS sensor for
hydrogen detection”, Solid State Sciences 11 ,1370–1374 ,2009.
[9]. Andrej Paul, Christian Weinberger, Michael Tiemann, and Thorsten Wagner.,“Copper
Oxide/Silica Nanocomposites for Selective and Stable H2S Gas Detection”, ACS Appl. Nano Mater
2, 3335−3338 Letter,2019.
[10] Eunji Lee, Young Soo Yoon, and Dong-Joo Kim, “Two-Dimensional Transition Metal
Dichalcogenides and Metal Oxide Hybrids for Gas Sensing” : ACS Sens. 3, 2045−2060,2019.
[11] Yuanyuan Zhu , Hongjun Wang , Jianke Liu , Mingli Yin , Lingmin Yu , High-performance gas
sensors based on the WO3-SnO2 nanosphere composites”, Journal of Alloys and Compounds 782
,789-795,2019.
[12] Hui-Bing Na, Xian-Fa Zhang, Zhao-Peng Deng, Ying-Ming Xu, Li-Hua Huo, and Shan Gao,
“Large-Scale Synthesis of Hierarchically Porous ZnO Hollow Tubule for Fast Response to ppb-Level
H2S Gas”, ACS Appl. Mater. Interfaces 11, 11627−11635,2019.
References contd..
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16. IIT (BHU)
References contd..
[13] Vinod Kumar , Sunny , Ishpal Rawal b, V.N. Mishra, R. Dwivedi , R.R. Das” Fabrication and
characterization of gridded Pt/SiO2/Si MOS structure for hydrogen and hydrogen sulphide sensing”,
Materials Chemistry and Physics 146, 418-424,2019.
[14] Ziying Wang, Shang Gao, Teng Fei, Sen Liu, and Tong Zhang., “Construction of ZnO/SnO2
Heterostructure on Reduced Graphene Oxide for Enhanced Nitrogen Dioxide Sensitive Performances
at Room Temperature”, ACS Sens. 4, 2048−2057,2019.
[15] B. Bhowmik, K.Dutta, Member and P. Bhattacharyya, ” An Efficient Room Temperature
Ethanol Sensor Device Based on p-n Homojunction of TiO2 Nanostructures”, IEEE
TRANSACTIONS ON ELECTRON DEVICES, VOL. 66, NO. 2, FEBRUARY 2019.
[16] Kihyun Kim , Hyeon-Tak Kwak , Hyeonsu Cho, M. Meyyappan, and Chang-Ki Baek, “Design
Guidelines for High Sensitivity ZnO Nanowire Gas Sensors With Schottky Contact,” IEEE
SENSORS JOURNAL, VOL. 19, NO. 3, FEBRUARY 1, 2019.
[17] J. Kanungo, H. Saha, S. Basu,” Room temperature metal–insulator–semiconductor (MIS)
hydrogen sensors based on chemically surface modified porous silicon”, journal of Sensors and
Actuators B 140 (2009) 65–72
[18] J. Kanungo, S. Maji, H. Saha, S. Basu,” Stable aluminium ohmic contact to surface modified
porous silicon”, journal of Solid-State Electronics 53 (2009) 663–668
[19] T. Serdiuk, V. Lysenko b, S. Alekseev a,c, V.A. Skryshevsky ,” Size tuning of luminescent
silicon nanoparticles with meso-porous silicon membranes”, Journal of Colloid and Interface Science
364 (2011) 65–70
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17. Thank you