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Sensors and Actuators B 160 (2011) 616– 622

Contents lists available at SciVerse ScienceDirect

Sensors and Actuators B: Chemical

j o ur nal homep a ge: www.elsev ier .com/ locate /snb

CM based mercury vapor sensor modified with polypyrrole supportedalladium

.M. Sabria,∗, R. Kojimab, S.J. Ippolitoa, W. Wlodarski c, K. Kalantar-zadehc, R.B. Kanerb,c, S.K. Bhargavaa,∗

Advanced Materials and Industrial Chemistry Group, School of Applied Sciences, RMIT University, Melbourne, VIC 3001, AustraliaDepartment of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, CA 90095-1569, USASensor Technology Laboratory, School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC 3001, Australia

r t i c l e i n f o

rticle history:eceived 25 May 2011eceived in revised form 18 July 2011ccepted 16 August 2011vailable online 24 August 2011

eywords:

a b s t r a c t

Polypyrrole (PPy) nanofibers loaded with either palladium (II) acetate (PPy/Pd(O2CCH3)2) or palladium(II) nitrate (PPy/Pd(NO3)2) were characterized by TEM, SEM, EDX, Raman and FTIR techniques prior totheir use as sensing materials for QCM based mercury vapor sensors. The QCM based sensor loaded withPPy/Pd(O2CCH3)2 nanofibers was observed to perform better over that of the PPy/Pd(NO3)2 loaded QCMand is postulated to be due to the lack of Pd salt reduction in the PPy/Pd(O2CCH3)2 matrix. The developedsensor was observed to operate with a response precision of ±5% over a 16 h testing period, and can

◦

ercury

ensingalladiumolypyrroleCM

withstand the presence of different levels of humidity at an operating temperature of 28 C. Furthermore,the PPy/Pd(O2CCH3)2 based sensor was found to have a response time (t90) of ∼45 min towards a Hg vaporconcentration of 10.55 mg/m3 balanced in either dry nitrogen or in streams containing up to 38% RH atnear room temperature (28 ◦C). The stability of the developed sensor over 50 h of continuous testingtowards Hg vapor under varying humidity levels indicates that a PPy/Pd(O2CCH3)2 thin layer is a good

perat

choice for near room tem

. Introduction

Environmental contamination of Hg vapor has resulted fromndustrial discharges, mining, smelting, burning of fossil fuels and

aste disposal [1]. Airborne mercury vapor released into the atmo-phere can travel long distances from anthropogenic sources thus, its considered a global environmental issue [2]. Consequently, mer-ury released into the environment entering lakes, rivers, bays, seasnd oceans is subject to bacterial conversion into the highly toxicnd readily bioorganically available methylmercury [3].

Mercury sorption/amalgamation on noble metal films is wellnown [4–8] and forms the basis of many mercury vapor sen-ors such as those based on thin film resistors [5,9], piezoelectricesonators [4,10], MOS capacitors [11] and MOSFET’s [12]. Nobleetals such as gold are also used in commercially available mer-

ury vapor sensors (such as Tekran [13], Gardis [13] and Jerome14,15] analyzers) in order to pre–concentrate mercury prior to

eleasing it through heating and subsequent quantitative measure-ents by spectroscopic techniques [16,17]. Despite these sensors

eing capable of measuring Hg levels in the range of 0.1 ng/m3 to

∗ Corresponding authors. Tel.: +61 3 9925 2330.E-mail addresses: ylias.sabri@rmit.edu.au (Y.M. Sabri),

uresh.bhargava@rmit.edu.au (S.K. Bhargava).

925-4005/$ – see front matter © 2011 Elsevier B.V. All rights reserved.oi:10.1016/j.snb.2011.08.038

ure Hg vapor sensing applications.© 2011 Elsevier B.V. All rights reserved.

2 mg/m3, they are generally cross sensitive towards humidity andabrupt changes in Hg vapor concentrations which can reach higherthan 10 mg/m3 in, for example, industrial [18] and spill site situa-tions [15]. Furthermore, under certain conditions the regenerationof the absorbed mercury from gold surfaces can be difficult due tothe swift diffusion of Hg into gold thin–films [4,19,20]. Battistoniet al. [21] have shown that at relatively low vapor concentrations inthe �g/m3 range, Hg is only adsorbed by the first 5–6 nm sub–layerof a gold thin film when exposed over 30-min periods. Similarly,George et al. [22] showed that the film morphology plays a crit-ical role in Hg uptake for gold thin film based mercury sensors,and proposed that rougher, more porous films promote diffusionof the mercury through the films’ grain boundaries and into thebulk gold. Therefore the use of gold thin films [8,23–29] or goldnanoparticles [30] as sensitive layers or sorbent materials withinHg vapor analyzers still poses significant technical challenges withregard to improving their regeneration capability. Other materialswhich have high sorption capacity towards Hg vapor such as Ag, Pd,Pt, Al, Zn, Se, MnO2, PdCl2, hopcalite, and even fine dust collectedby a hot gas filter are generally used to collect Hg vapor [31–35];however, there are no reports of using any of these materials for

Hg vapor sensing applications.

Mass sensitive transducers such as a quartz crystal microbalance(QCM) is thought to be a desirable means for monitoring elemen-tal mercury vapor due to its unique combination of mechanical,

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lectrical, chemical and thermal properties [36,37]. By analyti-ally solving the one-dimensional equation of motion, Sauerbreyhowed that for an ideal layer of foreign mass deposited on theurface of a QCM, the frequency change (�f) is proportional to theeposited mass �m according to Eq. (1):

f = − 2f 20

A√

c66�q�m = −Sf �m (1)

here Sf represents the integral mass sensitivity or Sauerbreyonstant and is proportional to the square of the fundamen-al frequency, f0, inversely proportional to the surface area, A,nd increases proportionally with the overtone number [37]. Thearameters c66 and �q are the shear modulus and density of theuartz substrate. In this study, Pd based materials deposited onCM crystals are used to monitor Hg vapor in the presence ofumidity.

From the selective and sensitive material point of view, a sim-le and surfactant-free method to produce conductive polymeranofibers such as polyaniline (PANI), which functions as a reduc-

ng agent and stabilizer for the doping of Pd nanoparticles (NPs) haseen shown to be an active catalyst for phenol formation [38]. Pal-

adium containing polypyrrole (PPy) has also been synthesized andsed as catalysts in earlier studies [39]. Palladium nanoparticlesupported on polymers have been the subject of interest by severalroups [40,41] and is known to have strong interactions with Hg42]. In this study, it is shown that PPy nanofibers doped with Pdanoparticles can be used as a selective material for Hg vapor sens-

ng applications by drop casting them on titanium electrode basedCM transducers.

. Experimental

Analytical grade solvents, HNO3, HCl, H2SO4, KMnO4, and allther chemicals in the synthesis of polypyrrole nanofibers wereurchased from Sigma Aldrich, Australia and used as received. Mer-ury permeation tubes were purchased from VICI, TX, USA. The0 MHz blank quartz crystals with 7.5 mm diameter were pur-hased from Hy-Q crystals, Australia.

.1. Synthesis of Pd doped PPy nanofibers

Bipyrrole was synthesized in water using FeCl3.6H2O as the oxi-ant according to established procedures [43,44]. Reactions wereerformed in 20 mL glass vials in which pyrrole (50 mg) and bipyr-ole (3 mg) were dissolved in 10 mL of methanol and rapidly mixedith a separate solution of FeCl3 (120 mg) in 10 mL of deionizedater. The bipyrrole was introduced as an initiator to speed up theolymerization of pyrrole in the presence of FeCl3 as the oxidiz-

ng agent. The reaction mixture was vigorously shaken and theneft unagitated for 24 h. Thereafter, the crude product was puri-ed by centrifugation and washed multiple times with deionizedater. The purified product was resuspended in deionized water

o a concentration of 2 g/L.The undoped polymer samples were reduced to their low-

st oxidation state by treatment with hydrazine for 1 h, followedy washing with deionized water and acetone to remove excessydrazine. The reduced polypyrrole is sensitive to oxygen and wassed in the palladium uptake experiments soon after each prepara-ion. The crude fibers were purified by centrifugation and washedith deionized water, NaOH, and then three more times with water.

alladium nanoparticles were grown by combining a 2 g/L aque-us nanofiber dispersion with a 10 mm solution of palladium (II)

itrate (Pd(NO3)2) or palladium (II) acetate (Pd(O2CCH3)2) in a:1 ratio before incubating for 24 h. The subsequent PPy and Pdoped PPy nanofibers were characterized by transmission electronicroscopy (TEM) (JOEL 100CX). Scanning electron microscope

ators B 160 (2011) 616– 622 617

(SEM) measurements were performed on a FEI Nova SEM instru-ment (Nova 200) with an AMETEK energy dispersive X-ray (EDX)system operated at an accelerating voltage of 10 kV for imaging30 kV for EDX analysis. EDX was used to confirm the presenceof Pd in the polymeric materials. Prior to SEM imaging, sampleswere thoroughly rinsed with Milli-Q water and dried under aflow of nitrogen. Raman measurements were carried out with aPerkinElmer Raman Station 400 at an excitation wavelength of785 nm. X-ray photoelectron spectroscopy (XPS) characterizationof the materials was done using a Thermo K-Alpha instrument at apressure better than 1 × 10−9 Torr. The core level binding energies(BEs) were aligned with the adventitious C 1s binding energy of285 eV.

2.2. QCM fabrication and PPy/Pd deposition

QCM based sensors were fabricated with titanium electrodesdeposited by thermal evaporation. The two faces of the opticallypolished AT-cut quartz substrates were patterned with thin filmsof Ti having a thickness of 300 nm at room temperature to formthe QCM electrodes. Ti was selected as the electrode material dueto its excellent adhesion with SiO2 [45] and low solubility in Hg[46,47] and therefore having a low affinity towards Hg vapor [48].This ensured that when exposed to Hg vapor, the sensor responsewas purely due to the interaction of Hg with the polymeric sensitivefilms and not the Ti surface of the QCM electrodes.

PPy nanofibers with and without doped Pd nanoparticles weredrop-cast directly onto one side of the QCM electrodes such thatQCM-1 through to QCM-4 were comprised of PPy, PPy/Pd(NO3)2,PPy/Pd(O2CCH3)2 and a non-modified Ti control, respectively. TheQCMs were electrically tested using a network analyzer (AgilentE5100A) to confirm their oscillation (large Q-factors >4000) andto assure that relatively similar amount of masses of polymericmaterials were deposited in each case.

2.3. Hg testing

The sensors were tested against 5 calibrated Hg vapor concen-trations throughout a 7-day testing period. Using a PID temperaturecontroller to heat the VICI permeation tubes, Hg concentrations of1.02, 1.87, 3.65, 5.70 and 10.55 ± 0.05 mg/m3 (balance dry N2) weregenerated. The Hg generator was calibrated to produce 5 differentHg vapor concentrations by using the KMnO4 trapping method atthe point where the gas enters the vapor cell housing the QCMbased sensors. The approximate volume of the chamber housingthe QCM sensors was ∼0.5 L. The KMnO4/H2SO4 solution was quan-tified using an adapted version of EPA method 101A [49] and usingan Agilent Technologies HP4500 series 300, ShieldTorch ICP-MSsystem for analysis. The QCM resonant frequency change, �f wasmeasured using an Agilent (53131A) frequency counter. Initially, allsensors were first exposed to a pulse of Hg at 5.70 mg/m3 for an 8 hperiod to stabilize the sensor surfaces. Our preliminary data showthat this pre-treatment procedure is necessary when monitoringHg vapor in order to improve QCM based sensor repeatability.Thereafter, the sensors were regenerated by dry N2 for 115 h atan operating temperature of 28 ◦C under a continuous flow of drynitrogen, thus completing the pre-treatment process. The sensorswere then exposed to sequential pulses of the 5 calibrated Hg vaporconcentrations at a constant temperature of 28 ◦C using 1 h expo-sure and 1 h recovery periods (hereafter referred to as a pulse). Aconstant flow rate of 200 sccm was maintained during the entirepre-treatment and testing periods by using a specially developed

4 channels mass flow controller system combined with a relativehumidity generator. The three relative humidity (RH) levels thatthe sensors were tested towards in the presence of Hg vapor were15.4%, 28.5% and 38%.

6 Actuators B 160 (2011) 616– 622

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18 Y.M. Sabri et al. / Sensors and

. Results and discussions

.1. Characterization

Following the deposition of 1 �L of each of the materials onheir respective QCMs as listed in Table 1, the QCMs were thenharacterized with the network analyzer. The Q-factors for all sen-ors were measured to be above 4000 following the drop-castingf 1 �L of either PPy or Pd doped PPy on the Ti based sensorlectrodes as shown in Table 1. The relatively high Q-factor read-ngs makes the sensors conducive for operation in inexpensiveand-held devices since they possess low noise/damping dur-

ng oscillation. Furthermore, mass depositions of 17.20 �g/cm2,0.83 �g/cm2 and 22.26 �g/cm2 for QCM-1, QCM-2 and QCM-3ere estimated, respectively indicating similar amounts of mate-

ial being deposited on all three QCMs.The TEM micrographs of the PPy and PPy/Pd are shown in Fig. 1.

n Fig. 1a, it may clearly be observed that the fibers have a widthf around 20 nm with large lengths ranging from 50 nm to sev-ral microns and containing particles of size 5–50 nm in diameterFig. 1b and c). The SEM images of the PPy and PPy/Pd depositedn the Ti electrodes of the QCM based sensors are shown in Fig. 2.he morphology of the polymeric materials on the QCM is showno have taken roughly the same morphology indicating that sim-lar surface areas of each of the materials are exposed. However,t is interesting to observe a lower nanoparticle density with thed(O2CCH3)2 when compared to the Pd(NO3)2 synthesized PPy/Pdanofibers (Fig. 1). This is most likely due to the well known fact thatd(NO3)2 is soluble in water [50] while Pd(O2CCH3)2 is insoluble51]. Therefore the formation of Pd nanoparticles is not expected inhe PPy/Pd(O2CCH3)2 nanofibers and this is confirmed by UV–vispectra shown in Fig. 3. The peak at ∼300 nm (indicated by anrrow) confirms the presence of Pd nanoparticles (elemental Pd)n the PPy/Pd(NO3)2 system, however, no such peak is seen in thePy/Pd(O2CCH3)2 nanofibers. This finding agrees with other studies39,52] where it is shown that the choice of anions determines thetate of the Pd incorporated into the polymer matrix. In the presentase, the Pd salt in the PPy/Pd(NO3)2 nanofibers has been reducedo elemental Pd (possibly nanoparticles) and incorporated in theolymer matrix while the Pd in the PPy/Pd(O2CCH3)2 nanofibersas remained in its initial form.

The Raman spectra for the developed PPy and PPy/Pd nanofibersre shown in Fig. 4. The Raman spectra correspond to thoseeported in the literature [53–55]. The main peaks are foundt 936, 980, 1052, 1244, 1494 and 1598 cm−1. Both PPy andPy/Pd(O2CCH3)2 nanofibers were observed to have similar spec-ra. The most significant wave number peak intensity change occurshen comparing the intensity of the 1244 cm−1 peak with that

f the 1380 cm−1 (shown with black arrows) for the differentanofibers. It is observed that the intensity ratio of 1244–1380eaks in the PPy/Pd(NO3)2 nanofibers was considerably lowerhen compared to the PPy and PPy/Pd(O2CCH3)2 nanofibers. The

ower ratio indicates that little or no reaction has occurred betweenhe PPy and Pd(O2CCH3)2 salt, suggesting that Pd reduction hasnly occurred in the PPy/Pd(NO3)2 nanofiber sample. The XPS spec-ra of all the samples shown in Fig. 5 provides further evidence forhe presence of Pd2+ on QCM-3 (PPy/Pd(O2CCH3)2 nanofibers). Fur-hermore, the peak at 335.5 eV (shown with arrows) is assigned tod0 3d5/2 [57] confirming the formation of Pd nanoparticles in thePy/Pd(NO3)2 matrix.

.2. QCM Hg testing

Following the 115 h pre-treatment, the QCM based sensorsere tested towards the 5 calibrated Hg vapor concentrations in

he range of 1.02–10.55 mg/m3 at an operating temperature of

represent 100 nm.

Y.M. Sabri et al. / Sensors and Actuators B 160 (2011) 616– 622 619

Table 1List of QCMs, their quality factors and the chemicals deposited on their electrodes as the sensitive layers.

Sample Chemical deposited on QCM electrode Q-factors before drop-cast Q-factors after drop-cast

QCM-1 Control 2–PPy 7000 5547QCM-2 PPy/Pd synthesized from Pd(NO3)2 5915 4786QCM-3 PPy/Pd synthesized from Pd(O2CCH3)2 5768 4323QCM-4 Control 1 – Ti sensitive layer 6720 –

3)2 de

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Fig. 2. SEM images of (a) PPy, (b) PPy/Pd(O2CCH3)2, (c) PPy/Pd(NO

8 ± 1 ◦C. The experiments were performed by exposing the sen-ors to a gas stream containing a mixture of dry nitrogen and anown concentration of Hg vapor for 1 h. Thereafter, the sensorsere regenerated by a continuous flow of dry nitrogen for 1 hhile maintaining the same operating temperature. This 2 h step

s referred to as a single pulse. The 3.65 mg/m3 Hg vapor concen-ration pulse was tested twice consecutively in order to test theepeatability of the sensors as shown by the example responseurves presented in Fig. 6. Furthermore, Fig. 6 also shows thathe titanium control (QCM-4) exhibited no response as expected,ue to the very weak interaction between Ti and Hg [47]. Theeveloped sensor with relatively high sensitivity towards Hg vaporas observed to be the PPy/Pd(O2CCH3)2 synthesized nanofibers

QCM-3). The t90 response of QCM-3 was found to be 45 min at ag vapor concentration of 10.55 mg/m3. It was also observed that

he response magnitudes can be correlated to the 5 different Hgapor concentrations tested with a large dynamic range betweenhe different Hg concentrations. Interestingly, QCM-1 containingnly the PPy nanofibers also showed a response towards Hg vapor

posited on (d) a titanium substrate. Scale bars represent 500 nm.

however, with an extremely low signal to noise ratio. On the otherhand, QCM-2 should have produced a similar response magni-tude towards Hg as that of QCM-3 if the Pd salts in both matriceshad been reduced and formed Pd nanoparticles; however, no suchobservation occurred. QCM-2 was found to be highly noisy withno detectable response magnitude making it an impractical selec-tion as a potential mercury vapor sensor. There are two conclusionsthat can be made from the QCM results. First, it is thought thatPd(O2CCH3)2 was not reduced in the PPy matrix and had a highaffinity towards Hg vapor due to the presence of Pd2+, which haspreviously been used as a Hg sorbent material [35,56]. On the otherhand, Pd(NO3)2 was reduced to Pd0 nanoparticles resulting in lit-tle affinity towards Hg vapor. In order to confirm the low affinityof Pd0 as compared to Pd2+ towards Hg vapor, a QCM electrodecoated with a 10 nm Ti adhesion layer and 300 nm Pd film was

also exposed to Hg vapor, the response of which towards a Hgconcentration of 5.7 mg/m3 at 28 ◦C is shown in Fig. 6b. Althoughthe number of Pd atoms per area (atoms/cm2) on the QCM elec-trode surface containing the Pd film is expected to be higher than

620 Y.M. Sabri et al. / Sensors and Actuators B 160 (2011) 616– 622

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he dispersed nanoparticles in the PPy matrix, the response mag-itude of the PPy/Pd(O2CCH3)2 is found to be ∼4 times that of thed film based QCM towards Hg vapor.

Fig. 7 shows the response magnitudes of QCM-3 towards the calibrated Hg vapor concentrations both in dry and humid con-itions. It can be seen that the sensor response towards mercuryapor is linear at Hg concentrations of up to 5.70 mg/m3 and onlyeaches saturation at the highest tested Hg vapor concentration of0.55 mg/m3. From Fig. 7 it is also apparent that upon the intro-uction of 28.5% RH the response magnitude of QCM-3 towards Hgapor increased significantly when compared to the data obtained

n dry nitrogen (0% RH). This is an indication of an interferingffect that has occurred due the presence of humidity. However,nterestingly, upon increasing the humidity level from 28.5% RHo 38% RH a relatively minor increase in response magnitude was

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Fig. 7. The response magnitude of the PPy/Pd(O2CCH3)2 based sensor (QCM-3)towards Hg vapor under both dry and humid conditions at an operating temperatureof 28 ◦C.

observed for each Hg vapor concentration tested. This suggeststhat the PPy/Pd material has adsorption sites suitable for humid-ity adsorption and that deviations of ∼10% RH has little affect onthe sensor response towards Hg vapor when operated in a humidenvironment. The response of QCM-3 was observed to return to thebaseline when tested towards Hg vapor under dry conditions for asecond time indicating the near-full desorption of H2O moleculesfrom the PPy/Pd(O2CCH3)2 surface. The sensor may therefore becalibrated and used either in a dry or humid environment for Hg

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vapor concentrations ranging from 1–10 mg/m3. The response pre-cision of QCM-3 was also calculated and found to be approximately±5% under dry conditions and towards a Hg vapor concentrationof 5.70 mg/m3 over a 16 h testing period (8–pulses). Although, the

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recision of QCM-3 is found to be similar to that of the commerciallyvailable sensors [57], the concentration range at the higher Hgevels of 1–10 mg/m3 is remarkable, making the sensor potentiallyseful for many industrial applications where high concentrationsf Hg are present [58]. Other applications include testing for unsafeg levels in areas where Hg spills occur such as dental amalgamandling and households where thermometer breakage results ing spills and therefore air contamination [3,15]; however, the sen-

or would need to be calibrated and coupled against the ambientumidity conditions of the environment.

. Conclusions

Hg vapor sensors based on Pd salts supported by PPy nanofibersere developed. It was found that the developed sensor’s perfor-ance was not affected by saturation issues even when exposed

o Hg concentrations up to 10.55 mg/m3. The sensor having thealladium acetate doped PPy nanofibers was observed to have

precision of ±5% when exposed to a Hg vapor concentrationf 5.70 mg/m3 over the 16 h testing period. Although in highemand, no commercially available sensor exists that can han-le such high concentrations of Hg vapor. This work shows that

QCM based Hg vapor sensor using palladium acetate dopedPy nanofibers could potentially be used for industrial applica-ions when coupled or cross-calibrated against a separate relativeumidity sensor. Note that the increased signal of the developedensor presented in this study may be further improved by deposit-ng the PPy/Pd(C2OOCH3)2 nanofibers on both sides of the Tilectrodes of the QCMs as opposed to just one side used in thistudy. Furthermore, the high response towards the presence ofumidity may make these materials viable for humidity sensinghere near-full desorption (i.e. regeneration) is observed.

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iographies

lias M Sabri is a Research Fellow in the advanced materials and industrial chemistryroup at RMIT University, Australia. He received his B.Eng. (2003) and a Ph.D. (2010)t RMIT University, Australia. His research interests include chemical sensors, nano-echnology, materials sciences and catalysis. He is currently involved in the surface

odification of metallic thin films to study the interaction of gas phase mercuryn order to develop an online Hg vapor sensor in the presence of contaminants for

ndustrial applications.

obert Kojima is a Postdoctoral Scholar at UCLA. He received his B.Sc. (2005) and ah.D. (2010) at UCLA, Los Angeles. His research interests include polymer chemistry,onducting polymers, chemical sensing and materials chemistry in general.

ators B 160 (2011) 616– 622

Dr. Samuel Ippolito was awarded a BEng(Hons) in computer systems engineeringfrom RMIT University in 2002 and a PhD in chemical sensor technology in 2006. Cur-rently, Samuel is a Research Fellow in the in the advanced materials and industrialchemistry group at RMIT University, Australia. His major research interest areasinclude chemical sensors, acoustic devices, mercury detection and removal fromindustrial processes, nanotechnology and materials science.

Wojtek Wlodarski received the MScEE, PhD, and DSc degrees, all from WarsawUniversity of Technology, Warsaw, Poland, in 1962, 1971, and 1980, respectively.He has worked in the areas of sensor technology and instrumentation for over 40years. He is a professor with RMIT University, Melbourne, Australia, and heads theSensor Technology Laboratory at the School of Electrical and Computer Engineering.

Kourosh Kalantar-zadeh is an Associate Professor at RMIT University, Australia. Hereceived his B.Sc. (1993) and M.Sc. (1997) degree from Sharif University of Technol-ogy, Iran, and Tehran University, Iran, respectively, and a Ph.D. at RMIT University,Australia (2001). His research interests include chemical and biochemical sensors,nanotechnology, microsystems, materials sciences, electronic circuits, and microflu-idics.

Richard B. Kaner is professor of chemistry and professor of materials science andengineering at UCLA. He received a PhD in inorganic chemistry from the Universityof Pennsylvania in 1984, followed by two and a half years of postdoctoral research atUC Berkeley. He joined UCLA in 1987 as an assistant professor, earned tenure in 1991and became a full professor in 1993. He works on new routes to materials includingintercalation compounds, carbon nanoscrolls, graphene, fulleride superconductors,and conducting polymers nanowires.

Suresh K Bhargava received his PhD in 1982 and Honorius Causa D.Sc. in 2009. Heis the Deputy Pro Vice Chancellor (International) and leads the Advanced Materialsand Industrial Chemistry group at the College of Science, Engineering and Technol-ogy at RMIT University. His research has provided innovations in Chemical industryin fields as diverse as the removal of organics from Bayer process by CWAO in alu-

processes for minerals characterization and solution speciation, and waste treat-ment of magnesium sulphate from nickel laterite processing. He has been creditedwith five industry related patents and over 182 peer reviewed papers in prestigiousinternational journals.