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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


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)


COLLECTOR INFORMATION


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


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


NPs

SuspensionAtomizer

DMA (SMPS TSI

3080 )

Diffusion

charging zoneELPI(Dekati)

Neutralizer(85Kr)

RESULTS



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



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


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)


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


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

[email protected]

Thank you for

your attention !

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