Développement de micro-préconcentrateurs pour l'analyse de traces de gaz et explosifs.

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1 Développement de micro-préconcentrateurs pour l'analyse de traces de gaz et explosifs. JP Viricelle a, P. Breuil a, C. Pijolat a, F James a, M. Camara b, D. Briand b a Ecole Nationale des Mines, SPIN-EMSE, CNRS:UMR5307, LGF, F Saint-Etienne, France b Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Sensors, Actuators and Microsystems Laboratory (SAMLAB), Neuchâtel, Switzerland 1

2 Outline Micro-preconcentrators Context / Principle Design and fabrication Adsorbent characterization / Parameters Applications VOC preconcentration test, GC analysis Explosive detection Conclusions 2

tube) Reduce dead volume and thermal mass MEMS technology Microfabricated preconcentrator

3 Introduction: context Challenge : Gas trace detection with sensor or analyzers with limited sensitivity Miniaturized system for in situ detection Conventional trap (preconcentration tube) Reduce dead volume and thermal mass MEMS technology Microfabricated preconcentrator Miniaturized analyzer : Micro-GC module Miniaturized system : Micro-GC /Micropreconcentrator coupling 3

4 Introduction: preconcentration principle Process : Accumulate a target gas, then desorbed it by a temperature pulse Gas pre-conditioning is of importance for the detection of chemical substances in trace level. Desorption Adsorption 1000 with preconcentration without preconcentration adsorbant Micro-préconcentrateur Sensor analyser 10 Heating 4

5 Introduction: Preconcentration factor Preconcentration factor : ratio of outlet to inlet concentration Si t 1 < temps de perçage, conservation de la matière : Preconcentration factor: PF = t 1f 1 t 2 f 2 = C 2 C 1 C 1. t 1. f 1 = C 2. t 2. f 2 C: concentration t: time f: flow Desorption Augmentation du facteur step de préconcentration PF implique : - un débit d adsorption élevé ; - un temps Adsorption d intégration le plus long possible ; - un débit de step désorption faible ; - enfin une désorption le plus rapide possible. Time (min) 5

Design Preconcentrator design Characteristics Values

preconcentrator/ 1euro External diameter capillary

µm 10 Ω Design and schematic device composition: a)

6 Design Preconcentrator design Characteristics Values Depth 500µm Chamber volume 14 μl Inlet/outlet channels preconcentrator/ 1euro External diameter capillary Internal diameter capillary Resistance value 500 µm 385 µm 10 Ω Design and schematic device composition: a) platinum heater, b) etched silicon wafer c) glass cover d) capillaries 6

7 Preconcentrator fabrication Microfabrication at EPFL, Neuchâtel Deep Reactive Ion Etching (DRIE) Structured Wafer DRIE Resin bonding (500 resine removal µm (Si/Pyrex : deep) design glass) Silicon Photoresist Pyrex glass Structured silicon wafer Silicon material -good thermal conductiviy, -suitable material for DRIE) MEMS preconcentrator 7

Temperature ( C) Temperature ( C) Heater deposition Heater

due to the silicon conductivity Pt Si SiO 2 Si 3 N 4

250 Température calculée à partir de la résistance mesurée

de Température ( C) 350 300 250 Calculed temperature with

mesurée Temperature set Consigne de température ( C) 200

8 Temperature ( C) Temperature ( C) Heater deposition Heater deposition by screen printing Pt Si SiO 2 Short circuit due to the silicon conductivity Pt Si SiO 2 Si 3 N 4 Better insulation with a layer of silicon nitride Température calculée à partir de la résistance mesurée Calculed temperature with R value Temperature set Consigne de Température ( C) Calculed temperature with R value Température calculée à partir de la résistance mesurée Temperature set Consigne de température ( C) Time (min) Time (min) 8

Micro-Preconcentrators development Etched Silicon

CAMARA (2010) F James (2015) 3 cm Heating element

Metallic capillaries sealed with ceramic cement,

9 Micro-Preconcentrators development Etched Silicon Microcomponent Platinum heater deposition by screen-printing. 1,5 cm 300 C 380 C T 405 C Thèses M. CAMARA (2010) F James (2015) 3 cm Heating element and temperature distribution Adsorbent chamber Metallic capillaries sealed with ceramic cement, with 1/16 connectors. Capillary : Ø interne 220 µm for 325µm deep IMT micro component. Micro-préconcentrateur device 9

nanopowder Characterizations Carbon Tenax TA

10 Sorbent deposition Carbon Nanopowder deposition by microfluidic method Mass deposition : 2 mg carbon nanopowder Characterizations Carbon Tenax TA Particule diameter 100 nm 200 µm Surface Area 95 m 2 /g 20 m 2 /g 10

11 Intensity (a.u) Sorbent material study Temperature Programmed Desorption Thermal desorption of gas species analyzed by mass spectrometry Carbon nanopowder Vapor exposure : 1 ppm of Toluene during1 hour at 10L/h 2,0E-08 1,5E-08 1,0E-08 5,0E-09 Pv=2,9 kpa b.p = 110 C Toluene Blank Thermal desorption: Desorption temperature at C 0,0E Temperature ( C) 11

12 Preconcentration test. Laboratory test bench Setup Permeation tube Carbon Preconcentrator Photo Ionisation Detector (PID) for Vapour Organic Compounds (VOCs) 12

13 Concentration (ppm) Concentration (ppm) Preconcentration test. Parameter influence Heating rate and flow rate influence Vapor exposure : 1 ppm of Toluene during 5 min at 10L/h Heat Montée rate en : 40 C/s to à reach 300 C 300 C Heat Montée rate en : 15 C/s to reach à 300 C 300 C Time (min) High heating rate for high peak detection désorption Flow rate :1L/h à 1L/h désorption Flow rate :3L/h à 3L/h désorption Flow rate :5L/h à 5L/h désorption Flow rate :10L/h à 10L/h 10 10, , ,5 13 Time (min) C out Low flow rate for high peak detection Number of desorbed flow rate particles 13

14 1 rst application : GC Analysis. Industrial Setup Setup and GC process Heating and Sampling injection Preconcentrator 6 ways valve Preconcentrator as a sample loop 14

1 rst application : GC Analysis Chromatograms ppm trace level analysis Industrial applications: Gas mixture analysis (Toluene,Methylisobutyketone, Chloroforme, Vinyl acetate) PF= A 2 A 1 A : peak

15 1 rst application : GC Analysis Chromatograms ppm trace level analysis Industrial applications: Gas mixture analysis (Toluene,Methylisobutyketone, Chloroforme, Vinyl acetate) PF= A 2 A 1 A : peak area Target Gas Initial Preconcentration Concentrations factors (PF) Toluene 8 ppm 689 Vinyl acetate monomer 9 ppm 658 Chloroform 11 ppm 438 MIBK 7 ppm 576 ppb trace level analysis with interferences (natural gas) Target Gas Initial Preconcentration Concentrations factors (PF) Toluene 37 ppb 200 Vinyl acetate monomer 39 ppb 800 Chloroform 46 ppb 600 MIBK 35 ppb

Micropreconcentration of DNT (Dinitrotoluène) Use of porous silicon (composant wall) as adsorbant

of DNT on porous silicon Preconcentration test of DNT on porous silicon 1,0E-12 Silicium poreux 3500

16 Intensité (u.a) Concentration (ppb) 2 nd application : Explosive detection Explosive detection Micropreconcentration of DNT (Dinitrotoluène) Use of porous silicon (composant wall) as adsorbant pore size Ø : 1-2 µm and thickness: µm ppb trace level analysis Thermal Programmed Desorption of DNT on porous silicon Preconcentration test of DNT on porous silicon 1,0E-12 Silicium poreux ,0E C 6,0E ,0E-13 2,0E DNT adsorption 300 ppb Silicium poreux Silicium normal 0,0E Temperature ( C) Temps (min) 16

17 Conclusions Microfabricated MEMS preconcentrator Low volume :14 µl Fast Heating rate :40 C/s Flow rate : 1 to 20 L/h Various adsorbent material : Carbon nanopowder or nanotubes, Tenax, porous silicon, Good adsorption capacity for large range of VOCs, explosives, drugs Wide range of applications Coupling micropreconcentrator/µ-gc or with other analyzer Air quality monitoring (VOCs) Security applications (explosives, drugs) Any need of traces detection 17

18 Acknowledgments L analyse en ligne au coeur des procédés EC project on Explosive detection FP7-SEC N TraceTech Security Thank you for attention 18

MODELING, DESIGN AND EXPERIMENTAL CARACHTERIZATION OF MICRO-ELECTRO ELECTRO-MECHANICAL- SYSTEMS FOR GAS- CHROMATOGRAPHIC APPLICATIONS

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