Research Paper Nmin

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INTRODUCTION

Background of the Study

Nowadays, different areas all over the world especially in the Philippines are

experiencing massive air pollution according to different agencies concerning environmental

issues. Because of this, people particularly the students of this generation are doing their best to

find ways to provide the public solutions to this hazardous problem that will benefit not only

mankind but also the environment. The latest invention that was made to solve this matter is by

sensing perilous gases such as Ozone, Oxides of Nitrogen, unburned Hydrocarbons, and

particularly Carbon Monoxide. The detection of these toxins in the atmosphere is very vital in

assessing threats to human health. This device is known as a Gas Sensor.

Gas Sensors are mechanisms that identify different concentrations of toxic gases in

different areas. There are many types of gas sensors but according to different researches, the

most efficient and widely used are the nanomaterial based gas sensors. This kind of gas sensor

uses inorganic nanomaterials that are not only abundant but also cheap. Some of these sensors

are made from ZnO and SnO2 nanomaterials because these compounds have proven to be very

efficient by thorough experimentations.

Because of these concerns and because of the calamities that we are experiencing due to

different types of pollution, the members of this research group are convinced that they need to

take initiative to help the government in rehabilitating the environment that had been damaged.

The researchers also decided to concentrate in making this study successful for the future

generations reference purposes that will lead to another research project that will contribute in

the protection of our environment.

Statement of the Problem

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This study aims to make a nanomaterial based SnO2 gas sensor prototype that is sensitive

to Carbon monoxide gas by growing a nanomaterial using different growth temperatures.

Objectives

a.) General Objective

To make a prototype device that is sensitive to Carbon monoxide gas by utilizingTin oxide as nanomaterial

b.) Specific Objectives specifically aims to:

1. Determine the growth temperature that will be appropriate in this alternativeprocess

2. Test the SnO2 nanomaterial as a CO gas sensor prototype

3. Measure the sensitivity of the prototype via voltage readings

Significance of the Study

This study intended to make a sensitive nanomaterial based SnO2 gas sensor prototype

using a cheaper and more efficient method for the use of the government and citizens in

detecting toxic Carbon monoxide concentrations. Furthermore, this study addressed itself to:

government officials especially those assigned under the Department of Health that they may

gain valuable insights and benefits from this while keeping our society safe from the dangers of

the toxic gas for future generations; individual private sectors that they gain inspiration to make

the patented device from this studys prototype in order to help our society redeem its safety; and

students and other individuals that they gain motivation to make other studies that will contribute

the rehabilitation of our environment from the pollutions and damages that we have done to it.

Scope and Limitations

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This study involving the Fabrication of Tin oxide nanomaterial as Carbon monoxide gas

sensor prototype is a research project that is limited to detecting the presence of Carbon

monoxide gas concentration for it is incapable of providing the reading of the concentration itself

of Carbon monoxide present in a certain area. In this research project, we only used a voltage

meter to detect the presence of Carbon monoxide gas and the sensitivity of the nanomaterial to

the toxic gas mentioned. Aside from its incapability to give the concentration reading, the gas

sensor prototype has a limitation of being a bit time consuming in setting it up for it has too

many individual, heavy, and large, parts such as the power supply and the switchbox. Since we

are just high school students, we have insufficient knowledge and financial assistance that will

enable us to make a compact gas sensor. Another thing is that the prototype is most efficient

during the initial belch of smoke. There will be no confusion in assembling the set-up and

analyzing the readings for the prototype is user-friendly. This prototype is a step forward for our

generation in developing advanced devices and students will gain more knowledge from this

prototype and also inspiration to make more complicated and useful devices in the future.

REVIEW OF RELATED LITERATURE

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In the present time, air pollution is one of the worst problems of the world. Because of

this environmental issue, scientists are trying to make a sensor that could detect the amount of

these harmful gases. Many products are readily available in the market. But this research wouldbe more effective because the resultant product of this project is easier to handle and manipulate.

Not only can it detect or sense harmful gases in the air but it also serves as a carbon monoxide

meter for it shows readings of concentrations on the screen.

Carbon monoxide

Carbon monoxide is a colorless, odorless, tasteless, toxic gas. It is one of the most

common poisons in the environment and is responsible for thousands of deaths and hospital

emergency room visits each year in the United States. Most governmental agencies have set a

recommended limit out of 35 ppm for periods of up to eight hours. For purposes of comparison,

the normal concentration of carbon monoxide in the atmosphere in an open area tends to be less

than 1 ppm. But in urban areas or other locations with many vehicles, gas heaters, wood burning

stoves, or other sources of carbon monoxide, carbon monoxide levels can be much higher.

Someone traveling inside a car on a busy freeway, for example, may be exposed to carbon

monoxide levels of up to 25 ppm. Concentrations of up to 100 ppm have been measured in the

center of busy downtown urban areas. (Newton et.al, 2006)

Gas Sensor

A gas sensor is a necessity since it is not easy to detect carbon monoxide because of its

being odorless. One cannot easily conclude that toxic carbon monoxide is present in a certain

area. Its concentration is fatal to everyone even in minute amount. A device that reads the

concentration of the said substance in an area will help in the deterrence of hazardous effects

caused by the gas.

Sensors

A sensor is a form of transducer which converts a physical or chemical quantity into an

electrical, optical or other measurable quantity. Various semiconducting materials have been

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investigated for applications in gas sensors, such as ZnO, SnO2, WO3, Al2O3, In2O3, SiO2, V2O5,

Ga2O5, TiO2, CdS, ThO2, -Fe2O3, CO3O4, Ag2O, and MoO3. Among these materials, ZnO has

been widely studied and is easily fabricated by both chemical and physical methods. (Cao &

Fryxell, 2007)

But the latest carbon monoxide sensor is expensive. The devices, which retail for $20-

$60USD and are widely available, can either be battery-operated or AC powered (with or

without a battery backup). Battery lifetimes have been increasing as the technology has

developed and certain battery powered devices now advertise a battery lifetime of over 6 years.

All CO detectors have "test" buttons like smoke detectors.

(http://en.wikipedia.org/wiki/Carbon_monoxide_detector)

At least, by making a cheaper device that could measure the amount of carbon monoxide

in the air would help warn people with regard to their exposure to the toxic gas that is hazardous

to their health. Tin oxide also is used in carbon monoxide gas sensors for home and industry.

Adsorption of carbon monoxide at contacts between particles of SnO2 produces local charge

states that alter the electric properties (e.g., resistance, capacitance) of the porous, polycrystalline

material. When life-threatening concentrations of carbon monoxide are detected, an alarm is

triggered. By changing the temperature of operation, the sensor can be made selective for a

variety of reducing gas species such as hydrogen, carbon monoxide, and hydrocarbons.

(http://www.britannica.com...)

METHODOLOGY

A. Flowchart

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Gathering of Materials

Preparation of Experimental Set-up

Sealing of Quartz TubesHeating the Quartz Tubes in theFurnace (in varying temperatures)Voltage Current Test using CO2Voltage Current Test using COAnalyzing the data gathered
http://en.wikipedia.org/wiki/Carbon_monoxide_detectorhttp://www.britannica.com/EBchecked/topic/596489/tin-oxidehttp://en.wikipedia.org/wiki/Carbon_monoxide_detectorhttp://www.britannica.com/EBchecked/topic/596489/tin-oxide


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B. General Procedure

The SnO2powder was analyzed using the Scanning Electron Microscope. Four

quartz tubes of the same sizes were utilized. One end of each quartz tube was sealed and after

which, the quartz tubes were sonicated. An amount of 0.35 grams of high purity tin oxide

powder was weighed and placed in every tube (0.35 g each tube). Each end of the tubes that

were not sealed was first covered with Parafilm in order for the powder to not be

contaminated and each tube was inserted to a rubber ring. A small part of the Parafilm is

removed and this end was attached to the vacuum system (10 -6 Torr). A part of the tube

inserted in the vacuum was heated in order to seal the tube. This process was repeated for the

remaining three.

When a quartz tube is already sealed, it was placed on the furnace and heated

with the assigned temperature. Values such as the running time for the furnace to heat the

tube were inputted to the furnace machine. The different growth temperatures were 800C,

900C, 1000C, and 1200C with a growth time of 3 hours. The heated quartz tube was

divided into three zones and each zone was marked. The quartz tube was cracked and a

sample from each zone was put under the Scanning Electron Microscope. The samples then

underwent the EDX. The samples from the 900C and 1000C growth temperatures were

taken to consideration to be used for the Voltage Current Test because of their properties.

The nanomaterial samples from the 900C and 1000C will be mounted on a metal plate then

it will be connected to the switch box and a current is supplied. The switchbox was

connected to a power supply.

The whole set-up was considered to be the prototype device. The prototype was

then tested with the use of Carbon Dioxide then later on, with Carbon Monoxide for each of

the growth temperature. The resulting voltage reading from the two samples were compared

with each other.

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Figure 1.0

General set-up

Figure 2.0 Figure 2.1

Voltage reading of 900C at 0 seconds Voltage reading of 1000C at 0 seconds

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RESULTS AND DISCUSSION

The following graphs show the Elemental content of Tin oxide nanomaterial during the

EDX.

(1000C trial 1)SEMQuant results. Listed at 2:02:22 PM on 10/4/10Operator: johnLdGClient: All ISIS usersJob: Demonstration data SiLi detectorSpectrum label: Q Sci 1000 deg

System resolution = 61 eV

Quantitative method: ZAF ( 4 iterations).Analysed all elements and normalised results.

4 peaks possibly omitted: -0.02, 0.22, 2.14,9.70 keV

Standards :O K Quartz 01/12/93Si K Quartz 01/12/93Sn L Sn 01/12/93

Elmt Spect. Element AtomicType % %

O K ED 18.12 61.71Si K ED 0.47 0.90Sn L ED 81.42 37.39 Figure 3.0 1000C trial 1

Total 100.00 100.00

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1000C trial 2)

SEMQuant results. Listed at 2:15:57 PM on 10/4/10Operator: johnLdG

Client: All ISIS usersJob: Demonstration data SiLi detectorSpectrum label: Q SCI 1000 deg trial 5



3 peaks possibly omitted: -0.02, 0.20, 2.14 keV

Standards :

O K Quartz 01/12/93Si K Quartz 01/12/93Sn L Sn 01/12/93


O K ED 36.95 80.65Si K ED 0.84 1.05Sn L ED 62.21 18.30

Total 100.00 100.00 Figure 3.1

1000C trial 2

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(900C trial 1)SEMQuant results. Listed at 2:10:08 PM on 10/4/10Operator: johnLdGClient: All ISIS usersJob: Demonstration data SiLi detectorSpectrum label: Q Sci ate gwen



3 peaks possibly omitted: 0.04, 2.14, 9.68 keV



O K ED 30.01 72.55Si K ED 4.41 6.08Sn L ED 65.58 21.37

Total 100.00 100.00 Figure 3.2 900C

trial 1

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Operator: johnLdGClient: All ISIS usersJob: Demonstration data SiLi detectorSpectrum label: Q Sci 900 deg 3



5 peaks possibly omitted: -0.02, 0.22, 2.14,4.96, 9.70 keV



O K ED 27.12 73.10Si K ED 0.36 0.55 Figure 3.3 900C trial 2Sn L ED 72.52 26.35Total 100.00 100.00

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Figure 4.0 Graph of Table 1.0

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1000C TEMP 900C TEMP

TIME READINGS in Volts

0 seconds 241.5 206.7

4 seconds 245.5 183

8 seconds 370.6 280.7

12 seconds 357.4 201.5

16 seconds 387 288

20 seconds 364.4 274.7

24 seconds 296.5 274.4

28 seconds 263.6 253.9

32 seconds 246.5 239.3

36 seconds 238 207.9

40 seconds 229.6 184.1


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Computation:

T-Test

Null Hypothesis: Ho: 1=2

There is no significant difference between the mean sensitivity (voltage reading) of the

nanomaterial grown at 900C and at 1000C.

Alternative Hypothesis: Ha: 1>2

The mean sensitivity of the nanomaterial at 1000C is greater than that of 900C.

Level of Significance:

=0.05

Degrees of freedom:

df=11+11-2

df=20

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VoltageReadings(V)

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Critical Value:

2.09

1000C:

1=(241.5+245.5+370.6+357.4+387+364.4+296.5+263.6+246.5+238+229.6)/11

1=294.6;

s1=

s1=62.5034719

900C:

2=(206.7+183+280.7+201.5+288+274.7+274.4+253.9+239.3+207.9+184.1)/11

2=235.8363636s2=

s2=40.4305645

t=

t=2.618174592

Decision:

According to the solution for the calculation of the T-value, the decision is that the H oshould berejected and that there is a significant difference between the mean sensitivity of thenanomaterial grown at 1000C and 900C since the calculated T-value is greater than thetabulated one. This also shows that the nanomaterial grown at 1000C is more sensitive toCarbon monoxide gas than the one at 900C.

CONCLUSION

This study was conducted to determine if Tin oxide is sensitive to Carbon monoxide gas.

It is also conducted to identify the appropriate temperature to grow the nanomaterial in order to

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make it sensitive to the toxic gas. The voltage emitted by the nanomateial grown at 1000C and

at 900C was measured using the Fluke Multimeter.

The nanomaterial grown at 1000C produced a much higher voltage than that of the

nanomaterial grown at 900C. This data supports the findings that Tin oxide is conductive and is

sensitive to Carbon monoxide gas. It was also substantiated that the difference of the voltages

emitted by the manomaterial grown at1000C and that of the nanomaterial at 900C was

significant through the use of T-test.

The research hypothesis that the higher the temperature of the furnace where the

nanomaterial is cooked, the more sensitive the nanomaterial.

RECOMMENDATIONS

In lieu of the results of the investigatory project, it is recommended that in future

researches, more trials should be made to show accuracy in the voltage readings. Furthermore,

the fabrication of other nanomaterials can be undertaken. Also, the elemental Silicon should be

isolated in order to obtain only the elemental Tin.

The researchers also recommend that a compact and user-friendly device be made in

order to extend the scope of the investigation.

BIBLIOGRAPHY

Cao, Guozhong, Fryxell, Glen E. (2007)Environmental Applications of Nanomaterials;

Synthesis, Sorbents and Sensors. London: Imperial College Press

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Tseng, Ampere A. (2008)Nanofabrication: Fundamentals and Applications. Singapore:

World Scientific Publishing Co. Pte. Ltd.

Carpenter, Everett E., Cleary, David A., Dean, Nancy F., Lalena, John N. (2008)Inorganic

Materials Synthesis and Fabrication. New Jersey: John Wiley & Sons, Inc.

conductive ceramics. (2010). InEncyclopdia Britannica. Retrieved July 03, 2010, from

Encyclopdia Britannica Online:

http://www.britannica.com/EBchecked/topic/131690/conductive-ceramics

Carbon Monoxide Gas Detector. (2010). In Wikipedia. Retrieved July 03, 2010, from

Wikipedia: http://en.wikipedia.org/wiki/Carbon_monoxide_detector

Gas Sensors. (2010). In Futurlec, Retrieved July 03, 2010, from Futurlec:

http://www.futurlec.com/Gas_Sensors.shtml

Fraden, Jacob. (2004)Handbook of Modern Sensors. Second Edition. pp. 524-528

Paquette, Leo A., (1995)Encyclopedia of Reagents for Organic Synthesis Volume 2. pp. 990-

991

Newton, David E., Schlager, Neil, Weisblatt, Jayne.(2006) Chemical Compounds Volume 3 .

pp. 885-888

Newton, David E., Schlager, Neil, Weisblatt, Jayne.(2006) Chemical Compounds Volume 1 .

pp. 183-187

Journal

Jayaprakash,R., Krishnakumar, T., Mehta, B.R., Phani, A.R., Singh, V.N. Synthesis and

Characterization of Tin Oxide Nanoparticle for Humidity Sensor Application. Journal of

Nanoresearch Volume IV.pp. 91-101

Synthesis and characterization of crystalline tin oxide nanoparticles. (2010). In Journal of

Materials Chemistry. Retrieved July 03, 2010, from Journal of Materials Chemistry:

http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?

doi=b203049g&JournalCode=JM

APPENDIX

Formulae:

Mean=n

X

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http://www.britannica.com/EBchecked/topic/131690/conductive-ceramicshttp://www.britannica.com/EBchecked/topic/131690/conductive-ceramicshttp://en.wikipedia.org/wiki/Carbon_monoxide_detectorhttp://www.futurlec.com/Gas_Sensors.shtmlhttp://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b203049g&JournalCode=JMhttp://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b203049g&JournalCode=JMhttp://www.britannica.com/EBchecked/topic/131690/conductive-ceramicshttp://en.wikipedia.org/wiki/Carbon_monoxide_detectorhttp://www.futurlec.com/Gas_Sensors.shtmlhttp://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b203049g&JournalCode=JMhttp://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b203049g&JournalCode=JM


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t=

2

2

2

1

2

1

21

n

s

n

s

+

s=1

)(2

n

x

Pictures:

Sealing of Quartz Tube

Sealed Quartz tube The tube inserted in the furnace.

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Quartz tube ready to be cracked Gold-coating machine

Cracked sample with gold coating ready to cracked sample for CO testingbe analyzed through SEM

Sample holder with sample Soldering of longer wires

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Longer wires are now attached General set-up

Experimentation starts Reading at 0 seconds (900C)

Reading at 0 seconds (1000C) IP8

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Research Paper Nmin