Wireless Sensor Networks for Monitoring

Carbon Monoxide in Ambient Air

Tim C. KeenerMingming LuMingming Lu

Chaichana Chaiwatpongsakornand

Soon-Jai Khang

School of Energy, Environmental, Biological and Medical EngineeringCollege of Engineering and Applied Science

University of CincinnatiCincinnati, Ohio

A&WMA International Specialty ConferenceA&WMA International Specialty Conference

U.S.A. 45221-0077Tim.keener@uc.edu

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p yp yLeapfrogging Opportunities for Air QualityLeapfrogging Opportunities for Air Quality

ImprovementImprovementMay May 1010--1414, , 20102010

Xi’an, Shaanxi Province, ChinaXi’an, Shaanxi Province, China

OutlineOutline

IntroductionResearch objectivesResearch objectivesExperimental Design– Test chamber setup– Sensor data validation

ResultsConclusionConclusionFuture work

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Why is CO of interest?Why is CO of interest?

A criteria air pollutant under the National Ambient Air Quality Standard (NAAQS):

– 9 parts per million (ppm) (10 mg/m3) for an 8-hour9 parts per million (ppm) (10 mg/m ) for an 8 hour average and

– 35 ppm (40 mg/m3) for a 1- hour average. Health effects: can bind with hemoglobin which leads to gcarboxyhemoglobin (COHb), as hemoglobin has an affinity for CO approximate 240 times its affinity to oxygen;Symptoms:

– 30%-50% COHb → Headache, nausea, shortness of breath, dizziness, confusion, increase pulse and respirator> 50% COHb con lsion collapse coma death

3– > 50% COHb → convulsion, collapse, coma, death.

Sources of COSources of CO

Incomplete oxidation of C-containing materialsmaterials – Incomplete combustion of C-containing

fuels;fuels;– Mobile sources are major → dynamic,

non-steady combustion process;y p ;– Others include furnaces, boilers,

biological processes.

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CO Analytical Methods*CO Analytical Methods*

Gas Chromatography - Flame Ionization (GC-FID)Gas Chromatography - Mercury Liberation (GC-Gas Chromatography Mercury Liberation (GCML)Tunable Diode Laser Spectroscopy (TDLs)Resonance FluorescenceResonance FluorescenceBiological MeasurementNDIR system → has several advantages over other monitoring techniques and it is theother monitoring techniques and it is the measurement technique for ambient air pollution monitoring recommended by US EPA. However, these systems are complex costly and not so

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these systems are complex, costly and not so portable

*Air Quality Criteria for Carbon Monoxide; EPA 600/P-99/001F; June 2000

Current Air Quality Monitoring Current Air Quality Monitoring

Current CO Monitoring: Only one station in Cincinnati: one (historic) in downtown;( )Issues: not enough monitoring sites, high operating cost, limited data; Th d l ti d t tThe needs: real time; more data at meaningful sites; lower costs; take advantage of new technologyadvantage of new technology.

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Research ObjectivesResearch ObjectivesTo develop a low cost, easily deployable CO measurement technique that can be used for ambient monitoringused for ambient monitoring.

To develop this CO monitoring platform in j i i h i l kconjunction with a wireless sensor network

for the purpose of long term monitoring at the major intersections around the jUniversity of Cincinnati’s West Campus.

7Air Quality Research GroupDept. of Civil &Environmental Engineering

RequirementsRequirements

Design, build and validate an environmental sampling chamber capable of sensor calibration; To develop a suitable calibration methodologymethodology

– Test at real ambient conditions, such as relative humidity, temperature and CO concentration

– statistical analyses that will compare the accuracystatistical analyses that will compare the accuracy and precision of sensor outputs to those from the reference methods

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CO itCO wireless sensorCO wireless sensor

- CO sensor unit- Data acquisition board

Each unit is comprised of- CO electrochemical sensor;- Wireless radio

module- Radio antenna

sensor;- Data acquisition board with temperature and relative humidity sensors;Radio antenna

- Batteriesrelative humidity sensors;- Wireless radio module;- Radio antenna;

B tt i- Batteries.

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CO Wireless Sensor Networks (COCO Wireless Sensor Networks (CO--WSNs)WSNs)

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CO Wireless Sensor CircuitCO Wireless Sensor CircuitEach unit is comprised of

- MICAz Radio Transceiver ModuleA t- Antenna

- 4 AA rechargeable batteries- 4 “9V” rechargeable batteries

2 sets of 6 V 100 mA thin film- 2 sets of 6 V, 100 mA thin film solar panels- 2 sets of 12 V, 100 mA thin film solar panelssolar panels- CO chemical sensor model (RCO100F KWJ Engineering Inc.)- MDA 300 Data acquisition board

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q

All components commercially Available.

Controlled Environmental Controlled Environmental Chamber SetupChamber Setup

CO Wireless Sensor Calibration System

Operating condition- Temperature: 5-40 ºCp- Humidity: 0-90%

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Experimental SetupExperimental SetupAn environmental chamber for CO sensor calibrationAn environmental chamber for CO sensor calibration

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Sample CO Sensor Calibration CurveSample CO Sensor Calibration Curve

CO sensor output (V) CO-NDIR (ppm)

0 0.0

Relationship between CO sensor output and CO-NDIR

0.0120.00061 0.1

0.001221 1.00.001831 1.50.003052 2.80 004273 3 6

y = 0.0011x + 0.0002R2 = 0.9961

0 004

0.006

0.008

0.01

enso

r ou

tput

(V)

0.004273 3.60.004883 4.30.007324 6.70.007935 7.40.009155 8.0

0

0.002

0.004

0 1 2 3 4 5 6 7 8 9CO -NDIR (ppm)

CO

se

Condition: 25 ̊ C and 50% RHLowest detection limit: 0.1 ppm

0.009766 8.5(pp )

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Calibration Results for Temperature

60Temperature dataY = 0.957X + 2.977, R2 = 0.9998

95% Confidence Interval

40

erat

ure

(oC

) 95% Confidence Interval95% Prediction Interval

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asur

ed T

emp

Mea

150 20 40 60Actual Temperature (oC)

0

Calibration Results for Humidity Calibration Results for Humidity SensorSensor

80The humidity data from wireless system were compared with polymer

iti d

80

y(%

RH

)

RH dataY = 0.81X + 5.38, R2 = 0.9995% Confidence Interval95% Prediction Intervalcapacitive and

semiconductor sensor hygrometer.

60

tive

Hum

idity 95% Prediction Interval

40as

ured

Rel

at

0 20 40 60 8020

Me

16Actual Relative Humidity (%RH)

Test Chamber ConclusionsTest Chamber Conclusions

Results from the experiments indicate a linear relation (R2~0.99) between CO concentrations and sensor responses inconcentrations and sensor responses in the range of

– CO: ~ 0.5 – 10 ppm– Temperature: 8 – 35ºC;– Temperature: 8 35 C;– Relative humidity: 30 – 70%;

The calibration methodology and theThe calibration methodology and the unite seems effective.

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CO wireless sensor unitCO wireless sensor unitSolar panel 12 V

18Solar panel 6 V

Current Deployment of CO WirelessCurrent Deployment of CO WirelessCurrent Deployment of CO Wireless Current Deployment of CO Wireless SensorsSensors

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f CO Sf CO SDeployment of CO Wireless SensorsDeployment of CO Wireless Sensors

UC West Campus

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Preliminary ResultsPreliminary Results

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Preliminary ResultsPreliminary ResultsPreliminary Results Preliminary Results (National University Of Singapore)(National University Of Singapore)

Clementi – Kent Ridge Crescent intersection

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intersection, Singapore

Preliminary Results, con’t.Preliminary Results, con’t.At the Clementi – Kent Ridge Crescent intersection, CO portable analyzer model # T15 (Langan) was used to compare the CO data with the CO wireless sensorsensor.

CO portable model # T15 (Langan)

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ConclusionsConclusionsCO wireless sensor can be provided a good correlation (R2 = 0.99) compared with the reference method and thewith the reference method and the lowest detection limit is 0.1 ppm equal to CO-NDIR technique;

CO wireless sensor unit assembled with solar panel can be measured CO

t ti i th l tconcentration in the long term monitoring at the intersection;

C t bl ( $650 it)24

Costs are reasonable (~$650 per unit).

Future ActivitiesFuture Activities

Network optimization and deployment at UC Ad-hoc sampling at high impact locations: near roadways, at urban schools near highways or major roads, or at underground garagesLong term data comparison of the WSN and NDIRLong term data comparison of the WSN and NDIR at the Hamilton County Department of Environmental Services (HCDOES) as they have CO and ozone monitoring onsite with traditionalCO and ozone monitoring onsite with traditional methods, about 3 miles away from the base station.

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AcknowledgementsAcknowledgements

NSF Grant # 0529063 The co-authors Mr. William A. Kaldy, Mr. Harry St. Clair and Ms. Anna Kelley at HCDOES

i d iDr. Heng Wei, and Dr. Liya E. YuStudents in the Transportation and Air Quality Research Groups: Brad Jiangchuan Hu Vijay YaoResearch Groups: Brad, Jiangchuan Hu, Vijay, Yao Zhuo and Carlos

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Thank YouThank YouThank YouThank You

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ExtrasExtras

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MDA 300 Data Acquisition Board

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