Ag nanoparticle film-based gas sensors Summary of findings for 2010

Ag nanoparticle film-based gas sensors Summary of findings for 2010
Defence Research and
Development Canada
Recherche et développement
pour la défense Canada
Ag nanoparticle film-based gas sensors
Summary of findings for 2010
T. Bond
Scott Nanochemistry Group
University of Saskatchewan
Saskatoon, SK S7N 5C9
Contract No. W7702-09R217
The scientific or technical validity of this Contract Report is entirely the responsibility of the Contractor and the contents do
not necessarily have the approval or endorsement of Defence R&D Canada.
Defence R&D Canada
Contract Report
DRDC Suffield CR 2011-014
September 2010
[Enter report no.]
Ag nanoparticle film-based gas sensors
Summary of findings for 2010
T. Bond
Scott Nanochemistry Group
University of Saskatchewan
Saskatoon, SK S7N 5C9
Contract Authority: D. Pedersen, DRDC Suffield
The scientific or technical validity of this Contract Report is entirely the responsibility of the Contractor and the contents do
not necessarily have the approval or endorsement of Defence R&D Canada.
Defence R&D Canada – Suffield
Contract Report
DRDC Suffield CR 2011-014
September 2010
Principal Author
T. Bond
Scott Nanochemistry Group, University of Saskatchewan
Approved by
D. Pedersen
Head Bio-Technology Section
Approved for release by
R.G. Clewley
Acting DRP Chair
Contract No. W7702-09R217
© Her Majesty the Queen in Right of Canada, as represented by the Minister of National Defence, 2010
© Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la Défense nationale,
2010
Abstract ……..
This report summarizes the work done by Robert Scott’s lab at the University of Saskatchewan as
part of a contract to investigate the gas-sensing properties of Ag nanoparticle films prepared by
Dr. Pedersen’s lab (Soldier and Systems Protection Group) at DRDC Suffield, AB. Toby Bond
was the researcher in the Scott group assigned to this project from its beginning in June of 2009
to the end of August 2010. This report covers results from Dec. 2009 to Aug. 2010.
Résumé ….....
Le présent rapport constitue un résumé des travaux exécutés au sein du laboratoire de
Robert Scott, à l’Université de la Saskatchewan, dans le cadre d’un contrat ayant pour objectif
d’étudier les propriétés de détection de gaz de films de nanoparticules d’argent (Ag) préparés
dans le laboratoire du groupe de protection des soldats et des systèmes de M. Pedersen (Ph.D.), à
RDDC Suffield, en Alberta. Le chercheur scientifique du groupe de M. Scott attitré au projet,
Toby Bond, en a assuré la direction dès le début, en juin 2009, jusqu’à la fin d’août 2010. Le
présent rapport traite des résultats obtenus de décembre 2009 à août 2010.
DRDC Suffield CR 2011-014
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Executive summary
Ag Nanoparticle Film-Based Gas Sensors: Summary of Findings
for 2010
Toby Bond; DRDC Suffield CR 2011-014; Defence R&D Canada – Suffield;
September 2010.
Introduction or background: DRDC Suffield is actively researching and developing
nanomaterials-based sensors for detection of toxic chemicals. A major aim of this effort is to
develop personal exposure indicators that would warn a soldier of any respiratory hazard, as well
as monitor the performance of protective equipment such as respirators. In this context, the
sensors also serve as end-of-service life indicators for canisters that provide an indication when
the canister capacity is exhausted. To be effective, the sensors must be able to detect toxic gases
at low concentrations, before they cause toxicological effects that impair the soldier. To
determine detection limits for chemical warfare agents and many toxic industrial chemicals,
DRDC Suffield uses a static gas cell. The Scott group at the University of Saskatchewan,
however, is able to measure detection limits for nanosensors under flow conditions, which are
more realistic representations of the actual operational conditions. Accordingly, the Scott group
has been contracted to study sensor performance under flow conditions.
Results: In its initial configuration, the flow system at the University of Saskatchewan was
generating noisy data. To improve the system, electronic flow meters were installed with the
effect of improving the signal to noise more than an order of magnitude. With the improved
apparatus, nanosensors responses to water were then thoroughly studied. Exposure to relatively
low concentrations of water was found to cause an increase in current. At exceptionally high
concentrations, the water caused a decrease in current that sometimes irreversibly damaged the
sensors. The detection limit for water was found to be 180 ppm. Preliminary results for HCl and
NH3 were also obtained but detection limits were not measured. The aging of sensors was also
examined. Over a two week period, the sensors were very stable. During the first week
following sensor fabrication at Suffield, the sensors exhibited a two order of magnitude increase
in current flow through, likely due to the adsorption of trace amounts of water.
Significance: These initial results demonstrate the establishment of capability at the University of
Saskatchewan to measure detection limits and other performance factors associated with
nanosensor-type personal exposure indicators. This capability provides an independent
verification of results generated in the Suffield labs. The detection limit measured for water is
180 ppm. This is 2 to 3 orders of magnitude higher than the detection limits measured by
Suffield for a number of toxic gases. The results demonstrate a general insensitivity to water
vapour, which is a desirable characteristic in sensors to be used in the field. The observed
sensitivity to HCl also confirms results determined at Suffield. The aging study demonstrates that
the sensors were extremely stable over a two week period.
Future plans: With capability established, the Scott group will now determine detection limits
for a number of toxic gases of military relevance including ammonia and hydrogen chloride. The
fundamental mechanism by which the nanosensors work will be elucidated. A comparison
between the nanosensors and other state-of-the-art technologies, like metal oxide sensors, will be
made to determine which technology is best as a personal exposure indicator.
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Sommaire .....
Détecteurs de gaz à base de films de nanoparticules d'Ag
Toby Bond, Université de la Saskatchewan; RDDC Suffield CR 2011-014; R & D
pour la défense Canada – Suffield.
Introduction : Les employés de RDDC Suffield exécutent des travaux de recherche importants
sur l’étude et la mise au point de détecteurs à base de nanomatériaux ayant la capacité de détecter
des produits chimiques toxiques. Les principaux objectifs de ces travaux comprennent la mise au
point de dispositifs indicateurs d’exposition personnelle, qui permettraient d’avertir les soldats de
tout danger de nature respiratoire et de surveiller le bon état de l’équipement de protection
comme les appareils respiratoires. Les détecteurs peuvent aussi servir, dans ce domaine,
d’indicateurs de la fin de durée de vie des boîtes filtrantes, lorsque la capacité de ces dernières est
épuisée. Pour constituer des dispositifs efficaces, les détecteurs doivent pouvoir détecter de
faibles concentrations de gaz toxiques, avant que ceux-ci aient des effets toxicologiques et nuisent
à la santé des soldats. Dans les installations de RDDC Suffield, on utilise une cellule à gaz
statique pour établir les limites de détection d’agents de guerre chimiques et de nombreux
produits industriels toxiques. Toutefois, les membres du groupe de recherche de M. Scott, à
l’Université de la Saskatchewan, ont la capacité de mesurer les limites de détection au moyen de
nanodétecteurs, dans des conditions d’écoulement dynamique, lesquelles correspondent plus
fidèlement aux conditions de fonctionnement réelles. C’est pourquoi un contrat a été conclu avec
le groupe de recherche de M. Scott afin qu’on y étudie la performance des détecteurs dans des
conditions d’écoulement dynamique.
Résultats : La configuration initiale du dispositif d’écoulement dynamique utilisé à l’Université
de la Saskatchewan produisait des données comportant un bruit important. Afin d’améliorer son
efficacité, on a installé des débitmètres électroniques, ce qui a permis d’accroître le rapport
signal/bruit par plus d’un ordre de grandeur. On a ensuite utilisé le dispositif amélioré pour
réaliser une étude détaillée de la réaction à l’eau des nanodétecteurs. Il a été établi que leur
exposition à des concentrations d’eau relativement faibles provoque une hausse de courant.
D’autre part, des concentrations d’eau exceptionnellement élevées provoquent une diminution du
courant, ce qui entraîne, dans certains cas, la détérioration irréversible des détecteurs. La limite de
détection établie pour l’eau est de 180 ppm. Des résultats préliminaires ont aussi été obtenus pour
HCl et NH3, mais leurs limites de détection n’ont encore été déterminées. On a en outre étudié le
vieillissement des détecteurs. Ceux-ci sont très stables sur une période de deux semaines. Durant
la première semaine suivant leur fabrication dans les installations de RDDC Suffield, les
détecteurs présentent une augmentation de deux ordres de grandeur du débit de courant, laquelle
est probablement attribuable à l’adsorption de quantités d’eau à l’état de traces.
Portée : Les résultats initiaux présentés démontrent la capacité des installations de l’Université
de la Saskatchewan de mesurer des limites de détection fiables ainsi que d’autres facteurs de
performance propres aux indicateurs d’exposition personnelle du type nanodétecteurs.
L’utilisation de ces capacités permet d’effectuer une vérification indépendante des résultats
obtenus dans les laboratoires de RDDC Suffield. La limite de détection établie pour l’eau est de
180 ppm, une valeur qui est de deux à trois ordres de grandeur plus élevée que celles des limites
de détection mesurées dans les installations de Suffield pour un certain nombre de gaz toxiques.
Les résultats indiquent que les détecteurs sont généralement insensibles à la présence de vapeur
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d’eau, ce qui constitue une caractéristique recherchée pour tout dispositif de ce type utilisé sur le
terrain. Les observations relatives à la sensibilité des détecteurs au HCl confirment aussi la
justesse des résultats obtenus dans les installations de Suffield. Les résultats de l’étude de
vieillissement des détecteurs confirment que ceux-ci sont très stables sur une période de
deux semaines.
Recherches futures : Ses capacités de recherche de pointe étant maintenant reconnues, les
membres du groupe de M. Scott peuvent maintenant entreprendre la détermination des limites de
détection d’un certain nombre de gaz toxiques d’intérêt militaire, y compris celles de l’ammoniac
et du chlorure d’hydrogène. L’exécution des travaux permettra d’élucider le mécanisme de
fonctionnement fondamental des nanodétecteurs. On comparera aussi la performance des
nanodétecteurs et celle d’autres technologies de pointe comme celle des détecteurs à base
d’oxydes métalliques, afin de déterminer laquelle est la plus adéquate dans le domaine des
détecteurs d’exposition personnelle.
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Table of contents
Abstract …….. ................................................................................................................................. i
Résumé …..... ................................................................................................................................... i
Executive summary ....................................................................................................................... iii
Sommaire ....................................................................................................................................... iv
Table of contents .......................................................................................................................... vii
List of figures .............................................................................................................................. viii
List of tables .................................................................................................................................. ix
Introduction ..................................................................................................................................... 1
Background ..................................................................................................................................... 1
Experimental (Upgrades to flow apparatus) .................................................................................... 2
Results and discussion ..................................................................................................................... 3
Response to water vapour................................................................................................................ 4
Hydrogen chloride and ammonia gas ............................................................................................ 10
Conclustions and future work........................................................................................................ 12
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List of figures
Figure 1: Schematic of flow apparatus. ........................................................................................... 1
Figure 2: a) Analogue flow controller used in previous experiments ............................................. 2
Figure 3: Graphical User Interface of in-house Flow Controller Software. .................................... 3
Figure 4: Typical erratic response of sensor to water vapour.......................................................... 5
Figure 5: Rise and fall of current with constant exposure to water vapour. .................................... 6
Figure 6: Reversible response to water vapour used for calibration. .............................................. 7
Figure 7: Rise and fall of signal from sensor used to make calibration curve................................. 8
Figure 8: Calibration curve of water vapour. .................................................................................. 9
Figure 9: Response to aqueous hydrochloric acid vapour. ............................................................ 10
Figure 10: Response of the hydrogen chloride gas........................................................................ 11
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List of tables
Table 1: Baseline currents of Ag nanoparticle films stored under ultrapure nitrogen
atmosphere (baseline not measured after exposure to analyte. ..................................... 4
Table 2: Signal and concentration data used for calibration curve.................................................. 9
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Introduction
This report summarizes the work done by Robert Scott’s lab at the University of Saskatchewan as
part of a long-term contract to investigate the gas-sensing properties of Ag nanoparticle films
prepared by David Pedersen’s lab (Soldier and Systems Protection Group) at Suffield, AB. Toby
Bond was the researcher in the Scott group assigned to this project from its beginning in June of
2009 to the end of August 2010. This report covers results from Dec. 2009 to Aug. 2010 (a report
describing the initial results is also available). A great deal of data is omitted from this report for
the sake of clarity, but all the raw data, as well as more detailed reports that were submitted
throughout the year, are available from the Scott lab upon request.
Background
The first months of the project were used mostly to determine appropriate storage and testing
conditions for the sensors and demonstrate basic sensor responses to hexane, ethanol, and water
vapour. The response is measured by applying a potential (usually 1 V) to the film and
monitoring the current over time as the sensor is exposed to analyte gas. The concentration of
analyte gas is controlled using 2 flow controllers: a clean channel with pure carrier gas (usually
nitrogen) and an analyte channel with saturated vapour from a bubbler or a tank containing
analyte gas (fig. 1).
Figure 1: Schematic of flow apparatus.
A drop in current was observed for hexane and ethanol vapour, while a delayed increase in
current was observed for water vapour. Reproducibility, signal drift, and signal noise were
significant issues encountered during the initial testing. After trying a variety of storage
conditions and carrier gases, it was found that the sensors were only stable under dry nitrogen
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1
(both for storage and as a carrier gas). Even under these conditions, only some sensors (generally
those that were less conductive – ie. lower particle density) yielded reversible gas sensing
responses. The report from 2009 (mentioned previously) details these results as well as the
apparatus used. Papers published by Pedersen et al describe the synthesis and characterization of
the nanoparticle films used.
Experimental (upgrades to flow apparatus)
The previous flow apparatus employed analogue flow controllers which (fig 2a) had limited
accuracy and had to be adjusted manually. Manual operation of the meter was somewhat
cumbersome and required 30-40 seconds to adjust the meters to the desired analyte level. To
overcome these limitations, considerable time was invested in building an apparatus using digital
flow controllers which were both controlled simultaneously from a computer. The flow
controllers used were two Smart Trak 2 Digital Flow Controllers from Sierra Instruments (fig.
2b).
Figure 2: a) Analogue flow controller used in previous experiments
b) Smart Trak 2 Digital Flow Controller used in experiments from April 2010 onward.
The Smart Trak 2 is operated by setting a desired flow rate, or “setpoint,” which is achieved using
a feedback system in the controller. The setpoint will usually be reached with high precision (±
0.01 scc/min) within 4 seconds, up to a maximum flow rate of 265 scc/min. The precision of the
analogue flow controllers was approximately ±8 scc/min. The controllers can be remotely
operated from a PC using an RS-232 interface. Software was included with the controllers for
this purpose; however it lacked two important features: the ability to operate more than one
controller simultaneously, and the ability to save flow data recorded by the controller. To this
end, we decided to write our own software using LabView – a graphical programming
environment specifically designed for hardware interfacing and data acquisition. After several
weeks of programming and debugging, a working program was successfully implemented which
simultaneously operates both flow controllers and stores the collected flow data on the hard drive
(see fig 3).
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Figure 3: Graphical User Interface of in-house Flow Controller Software.
This data is displayed on the same graphs as the response data from April onward. To run the
software, the user inputs a total flow rate that is maintained (which is simply the sum of the flow
rates of the two controllers) and sets the %-concentration of analyte gas to be injected. The
software then calculates the two setpoints based on these values and sends them to the controllers,
which automatically adjust to their respective setpoints simultaneously. Although the program is
fully operational, it still contains one bug which has eluded attempts to fix it, where certain
setpoints (namely, at 80 scc/min and 120 scc/min) will cause the flow rate to drop to zero. A
temporary workaround to this problem is to use setpoints that are 0.1 scc/min above or below
these faulty setpoints, but it is hoped that a solution may still be found to this problem. In all
other respects though, the apparatus functions with accuracy and injection times which are
improved by orders of magnitude compared to the analogue setup.
Results and discussion
Although initial results have been obtained for hexane, ethanol, and water vapour, we decided to
focus on the response to water vapour in an effort to demonstrate reproducible results and to
obtain a calibration curve and detection limits for at least one analyte. Though much of the actual
testing focused on water, some preliminary results were also obtained for ammonia, aqueous
hydrochloric acid vapour, and hydrogen chloride gas.
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Since the switch to ultrapure nitrogen as a carrier gas and atmosphere for storage, baseline
currents have been relatively stable under storage. Table 1 shows the baselines of a batch of
sensors from April during the testing period. A baseline signal is no longer recorded after the
sensor has been exposed to analyte (which often irreversibly alters the baseline).
Table 1: Baseline currents of Ag nanoparticle films stored under ultrapure nitrogen atmosphere
(baseline not measured after exposure to analyte.
The baseline drift observed during initial experiments is also no longer observed, making
calibration more feasible. Despite the stability in baselines, the sensors still cease to yield a
response to analyte gasses after 1-2 weeks (even when exposed only to nitrogen atmosphere).
Response to water vapour
It has been known since early on in the project that the sensors are sensitive to moisture (which
likely contributed to the signal drift observed initially). We decided to focus our attention on
water vapour in the hope of obtaining more consistent, reproducible results for a single system.
Water vapour turned out to be a fairly elusive analyte, giving seemingly conflicting responses
with different batches of sensors. Many tests indicated that the response of water was an increase
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in current, which was the opposite response of all other analytes tested to date. This increase was
characterized by delayed, terraced, and unpredictable spikes in current, a typical example of
which is given in Fig. 4.
Figure 4: Typical erratic response of sensor to water vapour.
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5
Toward the end of a given sensor’s testing life, this increase would no longer be observed, and
eventually the current began to decrease as water vapour was applied which continued until the
sample was no longer conductive within our detection limits (I < 0.14 nA). It was found in later
experiments that this increase in current is cumulative at fairly low concentrations of water: In
one experiment (fig. 5) a sensor was exposed to a constant concentration of water vapour (10% of
saturation) until the current reached a plateau. When the water concentration was increased, the
drop in current was observed which leveled out when the water was shut off.
Figure 5: Rise and fall of current with constant exposure to water vapour.
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Although all sensors displayed this type of response eventually, some sensors (mostly those with
lower particle density) demonstrated a different type of response initially, where the current
dropped in response to applied water vapour, before the rise in current. In June of this year, one
sensor in particular (which was low-density, having an initial baseline current of 3.61 x 10-6 A)
produced this type of response reproducibly enough that it was used to make a 4-point calibration
curve, the raw data for which is shown in Fig. 6.
Figure 6: Reversible response to water vapour used for calibration.
DRDC Suffield CR 2011-014
7
After this calibration was performed, the sensor was accidentally exposed to 100% saturated
water (due to the previously mentioned software/hardware bug) which caused an abrupt drop and
subsequent spike in current. After drying under nitrogen flow for several hours, a reproduction of
the 10% measurement was attempted, which did result in a drop in current, but the subsequent
recovery exhibited the rise-and-fall behaviour observed in previous experiments (fig. 7).
Figure 7: Rise and fall of signal from sensor used to make calibration curve
(after calibration data was collected).
The current continued to drop until the sensor was no longer conductive. This seems to suggest
that lower-particle-density sensors do indeed respond in a reversible manor to water vapour until
the sensor is rendered inoperative by whatever processes cause this rise-and-fall response to
occur.
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In order to construct a calibration curve for water vapour, we measured the response as the
change in current as a percentage of the initial baseline (∆I/I0) and plotted it against the mole
fraction of water (calculated by multiplying the mole fraction of saturated water at 21 C by the
flow rate fraction of the water vapour channel). The resulting data is given in table 2.
Table 2: Signal and concentration data used for calibration curve.
%-saturation of
water
10
20
30
Mole% of
water (@
21 C)
0.2461
0.4922
0.7383
I0 (A)
Response I (A)
ΔI (A)
%-change
(ΔI / I0)
2.766 x 10-6
2.765 x 10-6
2.761 x 10-6
2.672 x 10-6
2.615 x 10-6
2.544 x 10-6
9.941 x 10-8
1.150 x 10-7
2.175 x 10-7
3.40
5.42
7.88
The resulting plot shows a linear calibration curve (including a current change of zero for the
absence of water) with little error (fig. 8).
Figure 8: Calibration curve of water vapour.
The noise in this particular experiment has an outer range of 4.862 x 10-9 A, which corresponds to
0.1758 % of the initial baseline (2.766 x 10-6 A). This can be used to estimate the detection limit
by assuming that the limit is about 3 times the noise range. Using the calibration curve, the
detection limit for water under these conditions is approximately 180 ppm.
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9
Hydrogen chloride and ammonia gas
Although most of the sensors were used up in tests with water, some initial tests were also run
with aqueous hydrochloric acid vapour, dry hydrogen chloride gas, and ammonia gas. The
concentration of the hydrogen chloride and ammonia gasses was adjusted using a similar setup as
shown in the experimental section, but the analyte channel consisted of a cylinder of analyte
hooked up directly to one flow controller (which was then mixed with nitrogen flow from the
clean channel). The hydrochloric acid vapour was injected using the same method used for other
vapours.
In general, both the aqueous hydrochloric acid and hydrogen chloride gas showed a similar rise
and fall in current observed with water, but on a much smaller timescale (especially for hydrogen
chloride). The response to hydrochloric acid vapour is shown in fig. 9.
Figure 9: Response to aqueous hydrochloric acid vapour.
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The noise in these experiments is markedly higher compared to the response for water (possibly
due to oxidation of the film by chloride during the experiment). The response to HCl gas is
similar, but much more rapid (fig. 10).
Figure 10: Response of the hydrogen chloride gas.
It is interesting to note that the current did not immediately drop to zero after the rise and fall in
signal, but simply stopped responding to further injections of HCl gas. After this experiment, the
sensor was re-examined after 5 minutes and did show zero conductivity.
Ammonia gas was tested once with a fairly high-conductivity sensor (with a baseline of 0.5 mA)
which did not show any response even at the highest allowable concentration (1000 ppm – the
concentration of ammonia gas in the analyte cylinder). This result should not be taken as
conclusive, as a lower particle density sensor could still yield a response, but there is nothing to
report for this initial experiment.
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11
Conclusions and future work
Although many sensors did not exhibit a useful response to water vapour, sensors with
sufficiently low particle density do respond to water vapour with a drop in current which is
reversible until sensor function is lost, at which point there is a rise in current with a subsequent
drop to zero conductivity. This reversible response can be calibrated and shows a linear
relationship between the drop in current (relative to the baseline) and mole fraction of water
vapour present in the cell. Using this information, the detection limit for water of the film tested
is estimated to be 180 ppm.
Hydrochloric acid and HCl gas both show a comparatively rapid increase and decrease of current.
This effect, observed for both water and HCl, is likely due to different processes governing the
respective increase and decrease in current. For example, the increase could be due to a change
of the dielectric constant between barriers while the decrease could be due to structural
rearrangement or oxidation of the film (formation of silver oxide or silver chloride). A single
experiment with ammonia gas has shown no response up to 1000 ppm, but it is still possible that
a sensor with lower particle density could show a response (as has been observed with other
analytes in the past).
Using digital flow meters has allowed us to see much more clearly when there is a delay between
the injection of analyte and the observed response, as well as perform calibration with
significantly greater accuracy. Sensor responses are still too unpredictable at this point to use
automated injection to test the sensors without human intervention, but if the sensors can be made
to respond more predictably, higher throughput could be achieved by adding automation features
to the software, allowing testing and calibration to occur overnight without supervision.
Experiments to be performed in the near future include reproduction of the calibration curve
using another low particle density sensor for comparison, performing a calibration with another
analyte such as hexane, (which has shown a proportional response in the past) and testing of the
sensors with new gases, including repeated tests with ammonia. Since the lower particle density
films appear to respond much better, investigating in greater detail the relationship between
particle density and detection limits should also be one of the long-term goals of the project.
An effort was made to set up a cell to test other types of sensors (such as metal oxides) that can be
compared with these films under the same conditions. Unfortunately, problems with one of the
flow controllers did not allow for this to be completed before the end of the summer, but this will
be one of the next tasks to be performed by our group.
Despite initial difficulties with reproducibility, the results from this past year have been
encouraging, and it will be interesting indeed to see if such a linear calibration curve can be
produced for other analytes. Although this project is still at the stage of basic research, the
potential for these films as novel gas sensors is certainly promising.
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Ag Nanoparticle Film-Based Gas Sensors: Summary of Findings for 2010
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13. ABSTRACT (A brief and factual summary of the document. It may also appear elsewhere in the body of the document itself. It is highly desirable
that the abstract of classified documents be unclassified. Each paragraph of the abstract shall begin with an indication of the security classification
of the information in the paragraph (unless the document itself is unclassified) represented as (S), (C), (R), or (U). It is not necessary to include
here abstracts in both official languages unless the text is bilingual.)
This report summarizes the work done by Robert Scott’s lab at the University of Saskatchewan
as part of a contract to investigate the gas-sensing properties of Ag nanoparticle films prepared
by Dr. Pedersen’s lab (Soldier and Systems Protection Group) at DRDC Suffield, AB. Toby
Bond was the researcher in the Scott group assigned to this project from its beginning in June of
2009 to the end of August 2010. This report covers results from Dec. 2009 to Aug. 2010.
14. KEYWORDS, DESCRIPTORS or IDENTIFIERS (Technically meaningful terms or short phrases that characterize a document and could be
helpful in cataloguing the document. They should be selected so that no security classification is required. Identifiers, such as equipment model
designation, trade name, military project code name, geographic location may also be included. If possible keywords should be selected from a
published thesaurus, e.g. Thesaurus of Engineering and Scientific Terms (TEST) and that thesaurus identified. If it is not possible to select
indexing terms which are Unclassified, the classification of each should be indicated as with the title.)
nanosensors, nanoparticles, sensors, gas sensors, hydrogen chloride
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www.drdc-rddc.gc.ca
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