environmental sensing

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UNIVERSITY COLLEGE DUBLIN DUBLIN CITY UNIVERSITY

Environmental Sensing

• Smart Landfill: Landfill gas analysis

• Smart Dust: Toxic dust analysis

• SmartCoast: Nutrient monitoring

• Marine Sensor Systems

• Chemical Plume Monitoring

• Toxic Metals in Water

This material is based upon work supported by Science Foundation Ireland under Grant No. 03/IN3/1361


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Smart Landfill

Breda Kiernan, Weimin Guo, Conor Slater

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Aims of the Project

•Sponsored by the Environmental Protection Agency, Ireland•Tasked with the development of an autonomous system for monitoring landfill gas emissions and landfill gas migration especially methane and carbon dioxide

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CH4

CO2

VOCs

Landfill gas generation

Borehole well

Gas sample extracted

Analysed using IR gas sensor

Chemometric program analyses data and decides if concentrations are within threshold limits

If thresholds are exceeded, a message to sent to personnel onsite to investigate further

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Base-station location

Gas monitoring points

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Current status• Infrared gas sensors (CO2 and CH4)

calibrated over the range necessary (0-1.2%)

• Wireless comms approaches have been evaluated (GSM, Bluetooth…)

• GPS can be used to locate each sensor node and used to generate a dynamic model of the whole landfill site.

• Predictions using artificial neural networks of the gas concentrations when compared with the voltage output of the sensors is within 5 %. Therefore, the Smart Landfill system has merit as a warning system using threshold values to determine which concentrations are “normal” and “high” .

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Infrared sensor for CO2

Perkin Elmer GX FTIR instrument

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Future Work• Power: Currently 9V battery with 7000 mAh. In the future systems

will function through local power scavenging (solar, wind…)

• Data retrieval: Inter-sensor distances will be typically 100-500m; ideally suited for variety of low power wireless communications approaches

• Field trials for system deployment on target for late September/early October

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Smart Plant

• Sponsored by EPA

• Monitoring of odorants at waste transfer stations.

• In the first instance, ammonia and hydrogen sulfide are being monitored.

• Used as a warning system for build up of chemicals beyond the olfactory threshold.



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EPA Project: “Autonomous sensors for environmental monitoring- detection of

heavy metals in dust”

Tanja Radu, Conor Slater, Daniel Kim

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Elements of the strategy therefore include:

• Simple sampling and sample processing - ideally on the solid material directly, without reagents

• Ability to detect a range of targets using a single approach

• Sufficient selectivity, sensitivity, LOD

• Relatively low power - sufficient to be operated from local power sources

• Compatible with digital communications

“How can we remotely monitor a range of toxic metals in dust blow-off in real time?”

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Lead in soil

Lead (mg/kg)

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NOTE: Median concentration of lead in Irish soil is 26 mg/kg !!

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Arsenic in soil

Arsenic (mg/kg)

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NOTE: Median concentration of arsenic in Irish soil is 12 mg/kg

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Gortmore

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Dust blow occurrence - a real threat

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Portable XRF- our method of choice

• Light, hand held instrument (0.8 kg)

• Ideal for field analysis

• Simultaneous analysis of up to 25 elements (Pb, Cd, Sb, Cu, As, Hg, Ag, Zn, Se…)

• Simple point and shoot operation

• Real time analysis of solid sample - no lengthy sample preparation

• Remote operation capability

• Non destructive method- sample preservation

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Excellent preliminary results- Pb analysis

Trial of XRF in DCU:

- for soil samples - excellent agreement with AAS

- For simulated dust samples- excellent correlation of XRF reading and calculated values

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How to automate XRF?

MICRO CHIP GSM SYSTEMXRF ANALYSISPUMP/SAMPLING

Input info: TemperaturePressureWindHumidity…

EXAMPLE:If T>20 oC, dryand wind = SEthen start sampling

High flow pumpBattery operatedRemote control

A unique sampling system has been developed by the ASG!

Wireless communication

Sending reading to Internet or mobile phone

Remotely controlled NITON 700 XRF instrument

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Sampler

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The vision for the future

• “Smart” instrument – taking samples only when dust blow is likely to occur

• Autonomous analytical measurement

• Remote control monitoring

• Low-power, environment friendly monitoring

• Real time monitoring

• Web-based air pollution monitoring systemUsing this approach we will deliver a remote, real time, system which, for the first time, will provide unambiguous data about the levels of these toxic metals associated with specific blow-off events



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SmartCoast:Autonomous Phosphate Sensor

John Cleary, Conor Slater

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Autonomous Phosphate Sensor• Component of “SmartCoast” project, which aims to

develop a smart water quality monitoring system, to aid compliance with increased monitoring requirements under the Water Framework Directive.

• Phosphate is a key limiting nutrient in freshwater ecosystems.

• Eutrophication: A major water quality problem in Ireland and many other

countries Elevated nutrient levels lead to excessive

growth of algae and aquatic plants Oxygen depletion fish kills Algal blooms toxicity in water bodies

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Objective and Requirements

• Develop an autonomous, remotely controlled phosphate sensor capable of monitoring PO4

3- at appropriate levels at remote locations over long deployments

• Requirements: Sensitive Stable chemistry Communicate wirelessly Low power Robust & portable Low cost & low maintenance requirements

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Principle of Operation• Yellow method for phosphate detection

Forms vanadomolybdophosphoric acid (yellow)

Absorption proportional to phosphate conc. Advantages

Excellent reagent stability Fast reaction time (minutes)

• Microfluidic technology Minimizes reagent consumption, storage

requirements and pumping power• UV-LED and photodiode

Low powered, inexpensive & sensitive optical detection

Talanta vol. 71, no. 3, pp. 1180–1185 , Feb. 2007.

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Field Trial• First generation sensor was trialled at Osberstown WWTP

• 3-week trial with validation using existing online monitor

• Good correlation achieved

IEEE Sensors Journal (Accepted Aug. 2007)

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Current Status• Mark II sensor designed to build

on the successes and address the limitations of the original.

• Improvements Lower power, more flexible fluid

handling system. More sensitive optical detection system. More reliable and lower powered

communications using GSM modem in SMS mode.

2 point calibration protocol. Solar panel for energy harvesting

during long deployments. Improved ruggedisation.

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Current Status• Preliminary experiments

show improvement inlimit of detection LOD ~60 ppb vs. ~300

ppb with original system

• Scale-up 5 units of Mark II Sensor have been fabricated Currently undergoing laboratory assessment Field trials to be carried out in coming months



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Marine Institute Desk Study:

Jer Hayes

Instrumentation interface, communications and data management architecture issues for marine sensor systems, including sea-floor observatories

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Background

•This desk study project aims to:

-To identify key niche areas of innovation in the areas of sensor systems (especially seabed observation) and identify and assess Irish technical and industry capabilities in the technologies involved

- To provide solutions to the emerging interface between sensor systems development and operational requirements under the Water Framework Directive

- To provide solutions for linking the data acquisition platforms currently in use and planned.

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SmartBay

• The component technologies of SmartBay will include:

- a fibre-optic cable from shore to an underwater hub- a variety of instrument nodes and sensor packages a calibration site/facility- multi-beam digital map and geotechnical survey of the area

- deployment of a moored buoy, and possibly drifting buoys- navigation and telemetry

infrastructure.

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Current Status

• Generated three reports –

Current sensory systems and returned data structures used across the MI

Establishing protocols for linking data acquisitions platforms with the MI data warehouse

The connection of buoys, submarine monitoring stations, coastal and on-shore monitoring systems

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Interoperability

Marine

Land

Prior to deployment the puck is loaded with the information that is necessary to fully use the instrument when it is plugged into an sea-floor observatory

backbone.

Wireless sensor networks – can link data acquisition platforms MI Newport

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Fish CageFish Cage

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MAC MOTE

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NCSR DO (Serial Output)

MI Rain Gauge

PSOC + WQ101 Temp sensor

Drive by data Collection

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Current Status

• Adaptive sensing / ambient conditions

Phosphate system

WebInterface

Phosphate Instrument

www.nra.ie

ww.met.ie

Monitoring program

GSM

Serial Server Database

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Additional information• Also worked on - Water purification process monitoring

using wireless sensor networks:



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Monitoring Chemical Plumes in an Environmental Chamber with a Wireless

Chemical Sensor Network

Stephen Beirne

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Opposing LED chemical sensor integrated with modified Mica2Dot wireless sensing platform

Modified Mica2Dot Mote

• Modified to include a power source suitable for laboratory sampling rates.

• Opposing LEDs sensor coated in BPB reagent – Sensitive to increase in acidity

• Real-time monitoring. Sensor sampled at a frequency of 0.5 Hz. One sample value per data packet

• Data Acquisition via Visual Basic interface

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Sensor mounting and protecting sub-assembly of Wireless chemical sensor node enclosure

Sensor Hood

Opposing LEDs Chemical Sensor

Sensor Mounting Sleeve and Hood connection point

¼” BSP threaded fitting drilled through

Ø 9mm

Limiting Collar

Semi-transparent view of wireless chemical sensor node enclosure assembly

Sensor mounting sub-assembly

Cylindrical casing

Mica2Dot Mote, Radio antenna, 2 x AA battery power supply & On/Off header switch

Casing End Cap

Wireless Chemical Sensor Assembly

• Sensor covered by hood to reduce ambient light.

• Node housed in an enclosure to protect electronics from corrosive acetic acid. Also allows for attachment to the Environmental Sensing Chamber.

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Sensor Reproducibility

Smoothed Response Data of Wireless Chemical Sensor Node Exposed to Three Consecutive Plumes of Acetic Acid Laden air

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• Exposed to acidic vapour by means of a bubbler unit. Bubbler contents 2:1 ratio of Water and Conc. Acetic acid.

• Response to stimulus is clearly distinguishable.

• Sensor shows excellent reproducibility.

• Not a “Single Shot” device – Can be used to monitor consecutive events

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Sensitive to Plume Flow Rate

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• Sensor exposed to acidic plumes at varying flow rates.

• Higher flow rate induces higher concentration level at node location, as shown by collected data

• Data displayed as % Deviation from initial baseline value – Multiple nodes will not have a common baseline

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Wireless Chemical Sensor Network Arrangement

• Developed node allows for a network of similar nodes to be deployed to monitor a chemical plume event.

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Plume Tracking using a low-cost Wireless Chemical Sensor Network

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• Sensor network exposed to acidic plume for a period of 200 s (approx).

• Dense acetic-acid constrained by river channel walls

• Data allows the tracking of plume development through the chamber.

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Reactive Wireless Chemical Sensor

Actuator Network (WCSAN)

• Have displayed the ability to track a chemical plume in real-time using a low cost chemical sensor network.

• What should we do with the data? …. Use collaborative sensor information.

• Event classification - 2 or more sensors display a significant change in response.

• Data acquisition software allows output control.

• Respond to this event in real-time by sending a control signal from the interface to activate an electro-mechanical purge system.

• Results in a real-time reactive Wireless Chemical Sensor Actuator Network (WCSAN)



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Miniaturized all-solid-state sensors for trace analysis of substances relevant to health and welfare

(MASTRA)

Aleksandar Radu

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Aim of the project•To develop miniaturised all-solid-state ion sensors with low detection limit based on materials science and ion selective electrodes (ISEs) technology.

Plan•To construct sensors based on novel conducting polymers coupled with novel ion-selective membranes able to achieve trace-level ion detection and stable sensor performance.

•To miniaturize created potentiometric device

•To apply the sensing device for determination of toxic heavy metals and other ions of

importance to human health and welfare.

Miniaturized all-solid-state sensors for trace analysis of substances relevant to health and welfare (MASTRA)

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Current status •Understanding factors that lead to lowering of the detection limit in classical potentiometric sensors

Potential response of Cs+-selective ISE.

A) classically prepared ISE.

B) ISE with optimised inner solution.

C) Response obtained for electrode B under higher stirring rate of the sample (reducing aqueous diffusion layer thickness).

D) Response obtained by increasing of the amount of PVC in the membrane cocktail (reduced ion diffusion) and decreasing of the amount of ionic sites.

Radu, Aleksandar; Peper, Shane; Bakker, Eric; Diamond, Dermot: Electroanalysis, 2007, 19 (2-3), 144-154

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Current status cont’d•Development of solid-state potentiometric sensors with low detection limit

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log Pb2+

emf

29.6 mV

DL=20 ppb

Response of Pb-selective, solid-contact ISEs in 10-3 M nitric acid.

McGraw, Christina; Radu, Tanja; Radu, Aleksandar; Diamond, Dermot: Electroanalysis, submited

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Current status cont’d•Application of developed soil-contact potentiometric sensor in soil analysis

y = 1.1083x - 0.1771

R2 = 0.959

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Comparison of Pb2+ concentrations in soil samples digested in 1 × 10-3 M nitric acid obtained by AAS and ISEs.

Radu, Tanja; Radu, Aleksandar; Diamond, Dermot: Proceeding of SPIE Europe, Remote Sensing, Florence, 2007, accepted

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Future directions•Miniaturization of developed solid-state ISEs (lot of experience and expertise in the group, i.e. miniature, microfluidic-based chip in optical analysis (see picture on the right))

•Integration of miniaturized solid-state ISEs with miniaturized solid-state reference electrode (developed by Abo Academi, Finland) (lot of experience and expertise in the group, i.e. field deployable devices (see picture on the right))

•Application in environmental analysis

environmental sensing

Documents