www.cea.fr
DESIGN AND EVALUATION OF A DIFFUSION
CHARGING DIFFERENTIAL MOBILITY
CLASSIFIER TO MONITOR PERSONAL
EXPOSURE TO AIRBORNE NANOPARTICLES
Quentin Renot1, Michel Pourprix1, Jean-Baptiste Sirven2, Simon Clavaguera1| November, 08th 2016
1Univ. Grenoble Alpes, CEA Tech LITEN, PNS, DTNM, F-38000 Grenoble, France
2Univ. Paris Saclay, CEA DEN, SEARS, DPC, F-91191 Gif-sur-Yvette, France
22 NOVEMBRE 2016 | PAGE 1CEA | 10 AVRIL 2012
OUTLINE
General information
Context
Project goal
Collector information
Principle
Description
Results
Diffusion charging zone
Field charging zone
A posteriori analysis
Conclusion & Perspectives22 NOVEMBRE 2016 | PAGE 2CEA | 08th November 2016
GENERAL INFORMATION
Context
Increase of utilization and production of nanomaterials in research and industry
Discussions on potential health impacts caused by inhalation of particles
Risks?
Current scarcity of hazard data in nanotoxicologyParticle capacity to reach and deposit in the deep alveolar regions of lungs
Exposure can be hazardous
Studies realized on cells or on animals but complicate to extrapolate to human
To assess the efficiency of risk management measure, it is necessary to determine the personal exposure
22 NOVEMBRE 2016 | PAGE 3CEA | November, 8th 2016
GENERAL INFORMATION
Project goal
Developing a global solution to evaluate the personal exposure to particles
Validate a collection device based on electrostatic precipitation principle, coupled with on-line and off-line particles analysis
User friendly
Sampler (off-line analysis)
Monitor (on-line analysis)
In a broad range of size particles
Wide scope
Environmental, Health and Safety issues
Worker protection
Inhalation toxicology
22 NOVEMBRE 2016 | PAGE 4CEA | November, 8th 2016
Electrostatic precipitator developed
COLLECTOR INFORMATION
Principle
Five stagesAirborne particles capture
Particles charge by two mechanisms (field and diffusion charging)
Particles collection on a metallic substrate by size-dependent zone
On line measurement of concentration
Off line analysis of chemical composition, spatially resolved by Laser Induced
Breakdown Spectroscopy (LIBS)
22 NOVEMBRE 2016 | PAGE 5CEA | November, 8th 2016
COLLECTOR INFORMATION
22 NOVEMBRE 2016 | PAGE 6CEA | November, 8th 2016
To preferentially
charge particles
between 10 and
100 nm
Sort of particles
by their electric
mobility
< 100 nm on the first
substrate
> 100 nm
transported on the
field charging zone
For nanoparticles
(<100nm)
For submicro and
microparticles
(>100nm)
To charge larger
particles
RESULTS
Diffusion charging zone
Determination of the number of charges acquired by particleCorona wire + 4000 V
Grid + 50 V
Experimental set up
Two ELPI configurationsCharger ON / Trap ON / Device OFF → Determination particle number
Charger OFF / Trap OFF / Device ON → Measurement of current
Two samplesNano SiO2 50 nm
PSL 100 nm
22 NOVEMBRE 2016 | PAGE 7CEA | November, 8th 2016
NPs
SuspensionAtomizer
DMA (SMPS TSI
3080 )
Diffusion
charging zoneELPI(Dekati)
Neutralizer(85Kr)
RESULTS
Diffusion charging zone
22 NOVEMBRE 2016 | PAGE 8CEA | November, 8th 2016
Nano SiO2 50 nm
0
50
100
150
200
250
300
350
400
0,001 0,01 0,1 1
dN
/dlo
gDp
(1
/cm
3 )
Dp (µm)
ELPI stages 1 & 2 (40-70 nm)
Charger ON / Trap ON / Device OFF N = 49.3 ± 4.8 p/cm3
Charger OFF / Trap OFF / Device ONI = 2.74 ± 0.8 fA
0
5
10
15
20
25
30
35
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
0 1000 2000 3000 4000 5000
Co
ron
a d
isch
arge
(µ
A)
Cu
rren
t (f
A)
Wire Voltage (V)
Current
Corona discharge
Ncharge = I / (N.e.Q)
Ncharge = 2.1
RESULTS
Diffusion charging zone
22 NOVEMBRE 2016 | PAGE 9CEA | November, 8th 2016
PSL 100 nm
ELPI stages 2 & 3 (70-120 nm)
Charger ON / Trap ON / Device OFF N = 18.1 ± 2.0 p/cm3
Charger OFF / Trap OFF / Device ONI = 1.4 ± 0.2 fA
Ncharge = I / (N.e.Q)
Ncharge = 2.9
0
5
10
15
20
25
30
35
0,00
0,50
1,00
1,50
2,00
2,50
0 1000 2000 3000 4000 5000
Co
ron
a d
isch
arge
(µ
A)
Cu
rren
t (f
A)
Wire voltage (V)
Current
Corona discharge
0
1
2
3
4
5
6
7
8
0,001 0,01 0,1 1
dN
/dlo
gD
p (
1/c
m3)
Dp (µm)
RESULTS
Field charging zone
Evaluation of particles collectionCorona needle 4000 V
Experimental set up
Device configurationsPositive voltage
Different flowrates
Three samplesPSL 190 nm
PSL 490 nm
PSL 900 nm
22 NOVEMBRE 2016 | PAGE 10CEA | November, 8th 2016
NPs
SuspensionAtomizer
DMA (SMPS TSI
3080)
Field charging
zone
Counter(Fidas
mobile)
Neutralizer(85Kr)
RESULTS
Field charging zone
22 NOVEMBRE 2016
Positive Voltage – PSL 900 nm
0 – 3500 VCollection of di, tricharged particles
3500 – 4000 VCollection of initially neutral or
monocharged particles
Final concentration : 0 µg/m3 (100%)
0
1
2
3
4
5
6
0
5
10
15
20
25
30
0 1000 2000 3000 4000 5000C
oro
na
dis
char
ge (
µA
)
Co
nce
ntr
atio
n (
µg/
m3 )
Voltage (V)
Concentration
Corona discharge
RESULTS
Field charging zone
Evaluation of particles collectionPositive voltage
Three sizes (200, 495, 900 nm)
Four flowrates (0.25, 0.5, 1, 2.5 L/min)
22 NOVEMBRE 2016 | PAGE 12CEA | November, 8th 2016
98,6
98,8
99,0
99,2
99,4
99,6
99,8
100,0
200 nm 495 nm 900 nm
0.25 L/min 99,9 99,4 99,4
0.5 L/min 100,0 99,7 99,8
1 L/min 99,9 99,9 99,8
2.5 L/min 99,7 99,9 99,9
Effi
cien
cy (
%)
Very good results of collection efficiency
But collection on substrate? Loss to walls?
Optimization of field charging zone by numerical calculation (COMSOL Multiphysics™)
To improve ratio :
Particles on substrate
Particles collected
RESULTS
22 NOVEMBRE 2016 | PAGE 13CEA | November, 8th 2016
Collection zone – A posteriori analysis
Substrate analysis by LIBS (Laser Induced Breakdown Spectroscopy)Analysis spatially resolved
Rapid analysis
Analysis for each size zone
Possibility to map the substrate
Analysis size 1
Analysis size 2
Analysis size 3
Analysis size 4
y = 0.0112x + 0.0568R² = 0.9076
0
0,05
0,1
0,15
0,2
0,25
0 5 10 15 20
Rati
o A
g/C
u
Mass on substrat (µg)
Estimation of airborne
concentration :
During a 8h sample at 1L/min,
it is possible to detect an
particle aerosol of 0.6 µg/m3
and to quantify an aerosol of
1.9 µg/m3
Envisaged shot matrix
CONCLUSIONS
22 NOVEMBRE 2016 | PAGE 14CEA | 08th November 2016
Conclusions
Diffusion charging zone- Characterization of the aerosol
electric state
Collection zone - Possible particle sorting
knowing the aerosol electric
state – DMA principle
Field Charging zone- Collection efficiency > 95%
- Optimization of this part by
numerical calculation
Off line analysis to aerosol
estimation
- Spatially resolved analysis
- LOD & LOQ for Ag in µg/m3
Perspectives
On line measurement- Current measurement at the
substrate surface (fA range)
- High sensitivity electrometers
integration in our device
Calibration base for LIBS
analysis- Best conditions (min SNR)
- Standard calibration
Innovation
- Sampler and monitor
- Coupling on line measurement and chemical
analysis
- Discrimination between nanoparticle exposure and
submicro, microparticle exposure
DRT
DTNM
SEN
Commissariat à l’énergie atomique et aux énergies alternatives
Centre de Grenoble | 38054 Grenoble Cedex
T. +33 (0)4 38 78 44 00 | F. +33 (0)4 38 78 51 75
Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 01922 NOVEMBRE 2016
| PAGE 15
CEA | 10 AVRIL 2012
Quentin Renot
Simon Clavaguera
Thank you for
your attention !