Selected Papers

Portable Aromatic VOC Gas Sensor for Onsite Continuous
Air Monitoring with 10-ppb Benzene Detection Capability
Tsutomu Horiuchi†, Yuko Ueno, Serge Camou,
Tsuneyuki Haga, and Akiyuki Tate
Abstract
We have developed a portable gas sensor using microfluidic devices (concentration and detection
cells) for detecting and identifying gaseous aromatic volatile organic compounds (VOCs), such as benzene, toluene, xylene, styrene, and ethylbenzene. To improve the sensor’s sensitivity, we introduced techniques for the precise control of gas transfer from the concentration cell to the detection cell and optimized the spectrum measurement conditions. We achieved a detection level of 10 ppb for benzene gas
as an example of aromatic VOC detection in a sampling time of 50 minutes. The calibration curve
showed good linearity in the range of 10–100 ppb of benzene. We also carried out gas-monitoring experiments in a garage. The results show the applicability of our aromatic VOC sensor for field monitoring.

1. Introduction
Airborne benzene, toluene, xylene, styrene, andethylbenzene*1 are aromatic volatile organic compounds (VOCs) of significant health concern due totheir toxicity and mutagenic or carcinogenic properties, even at concentrations of a few parts per billion(ppb). Benzene is a well-known human carcinogenfor all routes of exposure and it is a risk factor foraplastic anemia, leukemia, and lymphomas [1], while
toluene, xylene, styrene, and ethylbenzene are suspected of playing a major role in sick house and sickbuilding syndromes. In Japan, regulations limit benzene concentration to 3 µg/m3 (1.0 ppb) [2]. The
guidelines for the indoor upper concentration limitsof toluene, xylene, styrene, and ethylbenzene are 260,
870, 220, and 3800 µg/m3 (70, 200, 50, and 880 ppb),
respectively. The regulations for these aromatic
VOCs in Japan, the USA, and the EU are summarizedin Table 1 [3].
The amounts of these aromatic VOCs emitted into
the air per year in Japan are listed in Table 2 [4]. The
emission sources are categorized into three groups:† NTT Microsystem Integration Laboratories
Atsugi-shi, 243-0198 Japan
E-mail: thoriuch@aecl.ntt.co.jp

30

point sources (major industrial facilities, such as
chemical plants, steel mills, oil refineries, power
plants, and hazardous waste incinerators), areasources (small pollution sources, such as drycleaners,
gas stations, and auto body paint shops), and mobile
sources (exhaust gas from cars, trucks, buses, ships,
airplanes, and agricultural and construction equipment).
In Japan, indoor and outdoor concentrations of aromatic VOCs have been reduced sufficiently below thevalues in the respective guidelines. This success is theresult of the self-imposed limits on emissions frompoint sources and the reduction or replacement ofthese VOCs in paints, inks, and adhesives and theirsolvents. However, further reductions are required,because it is now clear that VOCs are sources of suspended particulate matter and photochemical oxidant. The Air Pollution Control Law was revised in2005 and will be enforced from April 2006. The
revised law requires major industrial facilities tomeasure VOC concentrations and keep them below
the permissible level.
For airborne benzene, the main source is exhaustgas from cars. In Japan, the Air Pollution Control*1 Benzene, toluene, and xylene are referred to as BTX; benzene,
toluene, ethylbenzene, and xylene are referred to as BETX.

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Table 1. Major regulations for aromatic VOCs.
Japan

US (EPA)EU (WHO)

Max. cont. indoor
air (WHO)

Benzene3 µg/m3(1 ppb)1.3 – 4.5 µg/m3

1.7 µg/m3

10 µg/m3

Toluene260 µg/m3(70 ppb)

400 µg/m3

260 µg/m3

200 µg/m3

Xylene870 µg/m3(200 ppb)

400 µg/m3—

100 µg/m3

Styrene2200 µg/m3(50 ppb)1000 µg/m3

260 µg/m3

20 µg/m3

Ethylbenzene

3800 µg/m3(880 ppb)

1000 µg/m3—

100 µg/m3

Table 2. Statistical data and chemical characteristics of major aromatic VOCs in Japan.
Source: 2003 Pollutant Release and Transfer Register (PRTR) 2003 data.
Emission amount to air Outdoor concentration(automobile exhaust gas)
(year)

Indoor concentration(year)

Half-life in air

Boiling point (°C)

Benzene16,500 ton(14,500 ton)

3.4 µg/m3 (1997)
1.9 µg/m3 (2003)—

7–13 day

80.5°C

Toluene188,100 ton(39,900 ton)

1.1–85 µg/m3 (1998)

85 µg/m3 (2001)
15 µg/m3 (2004)

1–3 day

110.8°C

Xylene106,700 ton(23,100 ton)o-xylene:
0.33–9.5 µg/m3 (1998)
m-xylene + p-xylene:
0.55–35 µg/m3 (1998)

39 µg/m3 (2001)
13 µg/m3 (2004)

0.6–1.2 day

Styrene6400 ton(2500 ton)

0.04–2.7 µg/m3 (1998)

9 µg/m3 (2001)
0 µg/m3 (2004)

0.3 day145.2°C

Ethylbenzene

30,700 ton(6500 ton)

0.09–10 µg/m3 (1998)

22 µg/m3 (2001)
4 µg/m3 (2004)

0.2–1 day

136°C

Law was revised in 1996 and the Environmental
Quality Standard level for benzene was set at 3 µg/m3
in 1997. In January 2000, the permissible upper limitof the benzene concentration in gasoline was lowered
to 1 vol.%.
The statistics indicate a gradual reduction in benzene concentration. They show averaged values ofmeasurements taken during limited time periods andat limited locations. It is obvious that the benzene
concentration in the air depends on many factors suchas traffic density, weather, and surrounding materials
that might absorb it. To ensure and maintain a benzene-free environment, we require multi-point, continuous, long-term monitoring.
In this paper, we report the development of a
portable aromatic VOC sensor for field monitoring.
2. Performance requirements for field
monitoring
The standard method of VOC analysis is gas chromatography*2 combined with mass spectrometry*3
Vol. 4 No. 1 Jan. 2006

o-xylene: 144°C
m-xylene: 139°C
p-xylene: 138°C

because it has several advantages including a partsper-trillion (ppt) detection limit, high selectivity, andhigh accuracy (Fig. 1). For measuring the total
amount of VOCs, the standard methods are flame
ionization detection*4 and catalytic oxidation/nondispersive infrared detection*5. However, these methods require manual air sampling on site and specially*2 Gas chromatography: A technique that can be used to separate
volatile organic compounds. The organic compounds are separated due to differences in their partitioning behavior between themobile gas phase and the stationary phase in the column.
*3 Mass spectrometry: A technique for separating ions by their massto-charge ratios to enable the identification of unknown compounds at very low concentration levels.
*4 Flame ionization detection: A technique for measuring the total
amount of VOCs. The VOCs are decomposed to C+ in a hydrogen
flame and the amount of C+, which corresponds to the concentration of all the VOCs, is determined by measuring the electricalcurrent that passes when a potential is applied between two electrodes set facing the flame.
*5 Catalytic oxidation/non-dispersive infrared detection: A techniquefor measuring the total amount of combustible vapors based on
measuring the infrared absorption of CO2 produced from them.

31Selected Papers

Required performance of the main VOC sensing devicesppt

Gas chromatograph
Mass spectrometer

Sensitivity

Goal

ppb
Environmental Quality Standards fortypical VOCs in Japanppm

Miniaturization
Improved sensitivity

InfraredUltraviolet
spectrometer spectrometer Photoacoustic Photoionazation
spectrometer
detector

100

10

Tube
sampler1

Equipment weight (kg)Fig. 1. Relationship between portability and sensitivity of main VOC sensing devices.

trained operators to perform the analysis. These factors lead to a high cost and long analysis time.
Benzene has the highest toxicity among the aromatic VOCs mentioned above. More than 80% of thebenzene emitted into the air comes from mobile
sources. Benzene is more stable in air (half-life: 7–13
days) than other VOCs, which makes it important tobe able to determine the concentration of each compound in the air separately for multi-point onsite field
monitoring. A portable system that can detect each
VOC species with a low operating cost is therefore
required for onsite monitoring.
Ultraviolet (UV) absorption spectroscopy is also
used to analyze aromatic hydrocarbons. The characteristic peaks of aromatic hydrocarbons appear in the
wavelength region of 200–300 nm, where there ishardly any influence from water or impurities in the
air. The optical components used in UV spectrometers are simple and easy to miniaturize. Operation is
also simple and easy. However, the sensitivity of UV
absorption spectroscopy is not high enough for accurate gas analysis. We have overcome the sensitivity
problem and developed a portable system by using
microfluidic devices, which should lead to higher
throughput, shorter analysis times, reduced sample
volumes, in situ operation, and reduced manufacturing and operating costs [5].
3. Detection mechanism
A photograph of the portable aromatic VOC gas
32

Fig. 2. Portable VOC sensor developed by NTT.

sensor for field monitoring is shown in Fig. 2. The
sensor is 33 cm wide, 15.5 cm deep, and 17 cm high.
It is controlled through a SCSI interface by a notebook personal computer running Windows 2000. It
requires a 100-V power source.
The detection mechanism of the sensor is illustrated in Fig. 3. The main components of the sensor are
shown in Fig. 4. The sensor box contains two
microfluidic devices, namely the concentration anddetection cells. Each consists of two Pyrex plates andis 3 cm × 1 cm. The adsorbent is mesoporous silicate
powder packed into the microchannel of the concentration cell. The sampling gas is introduced into theconcentration cell and the powder adsorbs aromatichydrocarbon molecules in the sampling gas over acertain period of time. Then, the molecules on theadsorbent are desorbed by heating the microchannel
to 250°C and maintaining that temperature for several tens of seconds. The heating is performed by a thinNTT Technical Review

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film platinum heater formed on the outer microchannel wall. The highly concentrated desorbed gas is thenintroduced to the next cell: the detection cell. Bothends of the channel are sealed with optical fibers, andthe channel is aligned between a UV light source anda UV spectrometer (Soma Optics, Fastevert S-2400,
12-bit analog-to-digital converter). The UV absorption spectra of the desorbed gas are measured in thedetection cell. The UV spectrum of the sampled gas isanalyzed and then decomposed by the least squares
method to the standard spectra of individual components, which are stored in the personal computer. The
concentration of each aromatic VOC is quantified byits proportionality to the standard spectrum.

4. Sensor improvements
4.1 Nanomaterial for adsorbent
We tested several kinds of glass powder for theadsorbent [6], including commercially available
amorphous silicon dioxide powder, as well as mesoporous silicate powder (SBA-16) that we synthesized
by the method described in Ref. 7. The cubicallyordered SBA-16 was synthesized using triblock
copolymer*6 EO100-PO65-EO100 (BASF Corporation:
Pluronic F127; Mw = 12,600) as template agents. This
mesoporous silicate powder has much greater adsorption capacity than ordinary glass powders because of
its large surface area. We successfully detected 100
ppb of benzene gas using SBA-16 with a preconcentration time of 30 minutes [8].

Detection mechanism
Battery

Concentration cell

Pump

UV
spectrometerUV lamp

Detection cellFig. 3. Detection mechanism of the portable VOC sensor.

4.2 Cell structure
We examined several concentration cells with different microchannel structures and heater shapes [9].
The heater was fabricated by the sputter deposition(platinum thickness: 150 nm) and lift-off techniques.
The microchannel in our initially developed concentration cell was formed from linear grooves made bydicing. When the amount of adsorbent in the*6 Copolymer: A polymer resulting from the polymerization reactionof two chemically different monomers.

(a)

50 nm

1 µm

(b)

(c)
Inlet

Gas flowThin-film heater

OutletAdsorbent

Inlet

Gas flow

OutletChannel & optical cellFig. 4. Main components of microfluidic device: (a) mesoporous silicate powder SBA-16, (b) concentration cell,and (c) detection cell.

Vol. 4 No. 1 Jan. 200633

Selected Papers

FilterBimor
pump

Solenoid
pinch
valve

Solenoid
micropumpPC

Controller

ConcentrationcellSpectrometer

Detectioncell

D2 lamp

Fig. 5. Block diagram.

microchannel was increased to increase the total
amount of adsorbate, it was difficult to obtain a sufficient gas flow rate because the flow resistance wasgreater. Therefore, we used sand blasting to fabricate
a microchannel with a large adsorbent capacity while
maintaining a high flow rate. The channel width was
gradually changed, so that the widths at the inlet andoutlet were minimum but that at the adsorbent-stopper was maximum. Using this concentration cellfilled with SBA-16, we achieved 50-ppb benzene gas
detection with a preconcentration time of 50 minutes.
The detection cell was also improved. In the firstdetection cell we developed, two short optical fibers
were arranged inline in a groove in a glass plate witha separation distance of 2 cm. The light intensity was
greatly decreased after traveling this distance becauseof the low efficiency of the waveguide in the
microchannel. After we coated the inside of the cell’s
microchannel with a reflective layer of platinum toimprove the waveguide efficiency [10], the signal-tonoise ratio (SNR) was increased by increasing theaccumulation number by shortening the exposure
time. Using this concentration cell filled with SBA16 and this platinum-coated detection cell, we haveachieved 25-ppb benzene gas detection with a preconcentration time of 50 minutes.
34

4.3 Gas transfer system
We modified the gas transfer system to further
increase the SNR. The previous system had only one
pumping system, which was used to sample the air andtransfer the desorbed gas from the concentration cell tothe detection cell. It was a piezoelectric bimorph pump(bimor pump, Nitto Kohki Co., Ltd., BPF-465P, 7.2 cm
× 7.2 cm × 3.2 cm*7). A Teflon tube 7–8 cm long (innerdiameter: 0.5 mm) was used to connect the two cells.
The flow rate observed at the outlet of the detection cell
was typically 4–6 ml/min when the pump was operated with 100-V AC (50 Hz) using the concentration cellfilled with SBA-16. When the desorbed gas is transferred between the cells with this flow rate, the opticalmeasurement must be finished within only a few seconds, which is how long the desorb gas is present in thedetection cell. This limitation on measuring time prevents noise reduction by increasing the accumulation
number. On the other hand, high-flow-rate sampling
using the bimor pump was effective in increasing thesignal because of the large amount of adsorbate.
We added two components to the gas line. A block
diagram of the modified portable sensor is shown in
Fig. 5. The bold lines show the gas line and broken*7 http://www.nitto-europe.com/pumps/bimor/index.html

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lines show the light path. The major components arecontrolled electrically (thin lines). A solenoid pinch
valve (Bio-chem Valve Inc., 075P2N024-02S) was
placed between the concentration cell and the bimor
pump, and a solenoid micropump (Bio-chem Valve
Inc., 090SP24-8) between the concentration cell andthe filter. The solenoid micropump dispenses 8 µl persolenoid actuation. Several actuations can transfer thehighly concentrated desorbed gas from the concentration cell to the detection cell and keep it inside,even if pressure caused by the bimor pump remains in
the gas line, because the solenoid pinch valve closes
the path from the bimor pump. The main components
work as follows. In the preconcentration period, thebimor pump takes in an air sample and transfers it to
the concentration cell through the pinch valve, which
is normally open. The background and reference
spectra are measured during the preconcentration
period. Next, for the spectra measurement, the bimor
pump stops and the pinch valve is closed. The heater
turns on and the solenoid micropump starts working.
After several solenoid actuations (0.5-s intervals), thespectrum of the desorbed gas is measured with a large

accumulation number (typically 1000 × 10-ms exposure time). After spectrum measurement, the bimor
pump starts again and the solenoid pinch valve opens
to cool the cell and purge the gas lines with fresh air.
Typically, we set the preconcentration time to 50 minutes and one experiment takes one hour.
5. Detection limit
Spectra of benzene at 20, 10, and 5 ppb measured
using the modified system are shown by curves (a),(b), and (c) in Fig. 6, respectively. Curve (d) in Fig. 6
is a spectrum of 10-ppb benzene measured with theprevious system where the intensity is scaled to havethe same noise amplitude as curves (a)-(c). In the previous system, it was difficult to reduce the noise
amplitude by increasing the accumulation because
the desorbed gas immediately passed though thedetection cell. On the other hand, with the improved
system, 10-ppb benzene was measured with an adequate SNR (>3). This shows that the system can beused for quantitative analysis of benzene.
The calibration curves for both systems are shownin Fig. 7. The detection limit of the modified system

0.006
0.02

(b)

0.005
0.01

0.005
(a)

(a)

0.003

Absorbance (a.u.)

Absorbance (a.u.)

0.004

(b)

(c)

0.002

0.002

0.001

0.00050.001(d)0.0002

245

250

255

260

265

270

Wavelength (nm)

10

15 20

30

50

70 100 150

Concentration (ppb)

Fig. 6. Absorption spectra of benzene: (a) 20 ppb, (b)10
ppb, (c) 5 ppb, and (d) 10 ppb (measured with theprevious system).

Vol. 4 No. 1 Jan. 2006

Fig. 7. Calibration curves for benzene detection:(a) improved system and (b) previous system.

35

Selected Papers

0.01
0.005
Absorbance (a.u.)

is 10 ppb. A linear relationship was obtained between
the benzene concentration and absorbance in therange of 10–100 ppb for the modified system. We
could also detect 5-ppb benzene qualitatively as
shown in Fig. 6(c).
This system can operate continuously for long periods without maintenance, which is very advantageous for application in the field. We have conducteda one-month experiment to investigate its reliability
and durability. The absorbance change in a 10-ppb
benzene equivalent experiment (5-minute preconcentration of 100-ppb benzene) is shown in Fig. 8. The
average absorbance was 0.242 × 10–2, and the standard deviation was 0.989 × 10–4.

360.0005

0

5

10

15

20

25

30

Time (days)

Fig. 8. Reliability and durability test.
0.04

0.03

(a)
(b)

Absorbance (a.u.)

0.02

0.01

(c)
0
(d)

(e)
0.01
(f)
240

7. Conclusion
We have optimized several operating conditions of
the portable aromatic VOC gas sensor to lower its
detection limit. We achieved 10-ppb benzene gas
detection with good linearity in a low concentration
range (10–100 ppb). This was accomplished by effectively reducing the noise amplitude through precise
gas transfer control for increased spectrum accumulation. We tested this system on air in a residential
garage. The sensor indicated that the air in the garage
contained high levels of benzene and toluene. Withfurther improvements, the sensor is expected to

0.001

0.0002

6. Test using a real sample
The portable VOC sensor was tested on a real sample in preparation for field deployment. The sensor
was placed in a residential garage containing a Japanese car with its engine running and the garage door
was left open. Curve (a) in Fig. 9 shows the raw data
for a 50-minute sampling. Many characteristic peaks
from aromatic VOCs can be observed along the largetilted baseline (curve (b)). The origin of this baseline
is unknown at this point. We removed the baseline
manually and conducted further analysis using thesubtracted spectrum (curve (c)). There were no large
characteristic peaks around 270–275 nm, indicatingthat xylene concentrations were not significant. Thenthe subtracted spectrum was decomposed into
toluene and benzene (curves (e) and (f), respectively).
The composition of curves (e) and (f) corresponds tocurve (d), which agrees well with the measured spectrum shown by curve (c). The concentrations of benzene and toluene in the gas sampled at the garage
were estimated to be 23 and 250 ppb, respectively, byreferring to previously measured standard spectra.

0.002

250

260

270

280

290

300

Wavelength (nm)Fig. 9. Measurement of garage air: (a) raw spectrum, (b)baseline, (c) baseline subtracted spectrum, (d)simulation spectrum, (e) toluene component, and(f) benzene component.

approach and exceed the detection values specified ingovernmental guidelines and be applied to field monitoring.
References[1]

See for example: “Carcinogenic Effects of Benzene: An Update,

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[2]

[3]

[4]

1998,” EPA/60/P-97/001F; U.S. Environmental Protection Agency,
U.S. Government Printing Office: Washington, DC, 1998.
“Environmental Quality Standards in Japan—Air Quality,” Environmental Quality Standards of Benzene, Trichloroethylene and Tetrachloroethylene, 1997, http://www.env.go.jp/en/lar/regulation/
aq.html; Ministry of the Environment.
Technology Transfer Network Air Toxics Website: U.S. Environmental Protection Agency. See for example: http://www.epa.gov/
ttnatw01/hlthef/benzene.html
Fact sheets for chemical substances: Ministry of the Environment,
http://www.env.go.jp/chemi/communication/factsheet.html (inJapanese); Monitoring results of hazard air pollutants: Ministry of theEnvironment, http://www.env.go.jp/air/osen/monitoring/index.html(in Japanese); News releases and speeches: Ministry of the Environment, http://www.env.go.jp/en/news/index.html, http://www.env.
go.jp/chemi/kurohon/http2002/siryo2.html (in Japanese); Survey
results of chemical substances indoor air (2004): Ministry of Land,
Infrastructure and Transport, http://www.mlit.go.jp/kisha/kisha05/07/
070510_.html (in Japanese).

[5]

Y. Ueno, T. Horiuchi, T. Morimoto, and O. Niwa, “Microfluidic
device for airborne BTEX detection,” Anal. Chem. 73, 4688, 2001.
[6] Y. Ueno, T. Horiuchi, M. Tomita, O. Niwa, H. Zhou, T. Yamada, andI. Honma, “Separate detection of BTX mixture gas by a microfluidic
device using a function of nanosized pores of mesoporous silica
adsorbent,” Anal. Chem. 74(20), 5257, 2002.
[7] D. Zhao, Q. Huo, J. Feng, B. F. Chmelka, and G. D. Stucky, “Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures,” J. Am. Chem. Soc., 120, 6024, 1998.
[8] Y. Ueno, A. Tate, O. Niwa, H. Zhou, T. Yamada, and I. Honma,“High benzene selectivity of mesoporous silicate for BTX gas sensing
microfluidic devices,” Anal. Bioanal. Chem. 382, 804, 2005.
[9] Y. Ueno, T. Horiuchi, and O. Niwa, “Air-Cooled Cold Trap Channel
Integrated in a Microfluidic Device for Monitoring Airborne BTEX
with an Improved Detection Limit,” Anal. Chem. 74(7), 1712, 2002.
[10] S. Camou, Y. Ueno, A. Tate, and O. Niwa, “Absorption detection on
glass microchip with reflective layer coating for portable BTX measurements,” Micro Total Analysis Systems 2004. 2, 455, 2004.

Tsutomu Horiuchi

Tsuneyuki Haga

Senior Research Scientist, Network Hardware
Integration Laboratory, NTT Microsystem Integration Laboratories.
He received the B.S. and M.S. degrees inphysics from Waseda University, Tokyo in 1983
and 1985, respectively, and the Ph.D. degree inchemistry from Keio University, Kanagawa in
1994. He joined NTT Ibaraki Electrical Communication Laboratories in 1985. He has been
engaged in research of electrochemistry, biosensors, and chemical sensors. He was a visiting scientist at New Mexico State University, Las
Cruces, NM, USA, in 1997. He is a member of
the Japan Society of Applied Physics (JSAP).

Senior Research Engineer, Supervisor, Network Hardware Integration Laboratory, NTT
Microsystem Integration Laboratories.
He received the B.E. and M.E. degrees in electrical engineering from Kyoto University, Kyoto
in 1987 and 1989, respectively. He joined NTT
LSI Laboratories, Kanagawa in 1989. He has
been engaged in R&D of X-ray and extreme
ultraviolet lithography using synchrotron radiation. He was a visiting scientist at the Center for
X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA, USA from 2000 to 2001.
He received the Young Scientist Award for the
Presentation of an Excellent Paper from JSAP in
1996. He is a member of JSAP.

Yuko Ueno

Akiyuki Tate

Research Scientist, Network Hardware Integration Laboratory, NTT Microsystem Integration Laboratories.
She received the B.S., M.S., and Ph.D. degrees
in chemistry from the University of Tokyo,
Tokyo in 1995, 1997, and 2002, respectively.
She joined NTT Integrated Information & Energy Systems Laboratories, Tokyo in 1997. She
was a post-doctorial fellow at the University ofCalifornia at Berkeley and at Lawrence Berkeley
National Laboratory, Berkeley, CA, USA, from2004 to 2005. She is a member of the Chemical
Society of Japan, the Japan Society for Analytical Chemistry, and the Spectroscopical Societyof Japan.

Senior Manager, Materials Analysis Center,
Leading-Edge Key Technology Business Headquarters, NTT Advanced Technology Corporation.
He received the B.S. and M.S. degrees inapplied physics from Hokkaido University,
Hokkaido in 1976 and 1979, respectively. After
joining NTT Laboratories in 1979, he wasinvolved in the development of various types of
optical functional materials, devices and equipment ranging from organics, semiconductors, silica glass, and opto-magnetic materials to ferroelectric materials for future photonic communication and information processing. He moved to
NTT Advanced Technology in 2005. He is amember of JSAP, the Physical Society of Japan,
the Optical Society of Japan, and the Institute ofElectronics, Information and Communication
Engineers of Japan.

Serge Camou
Research Scientist, Network Hardware Integration Laboratory, NTT Microsystem Integration Laboratories.
He received the B.S., M.S., and Ph.D. degrees
in physics from Cergy-Pontoise University, Paris
7 University, and Franche-Comte University,
France in 1994, 1996, and 2000, respectively.
After two years as a JSPS (Japan Society for the
Promotion of Science) fellow at the University ofTokyo doing research on DNA lab-on-chip
devices, he moved to NTT Microsystem Integration Laboratories (Biosensing group) in 2003 asa post-doctorate and was involved in the BTX
portable sensor development. His work concerned the design and testing of a highly efficient
detection cell for better sensitivity and reliabilityof BTX measurement at low concentrations. In
2005, he was hired as a permanent researcher andcontinues to work in the Biosensing group. He iscurrently involved in the BTX and SPR sensors
projects.

Vol. 4 No. 1 Jan. 200637