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ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China

ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China. Zeolite thin films as new materials for chemically active layers in magneto-elastic sensors. D. Kouzoudis a , V. Nikolakis b , Th. Baimpos b a Editor-in-chief, Sensor Letters University of Patras, Greece b FORTH, Patra Greece.

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ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China

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  1. http://www.icmmm.net/ 2012.9.21-23 Beijing ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China

  2. Zeolite thin films as new materials for chemically active layers in magneto-elastic sensors D. Kouzoudisa,V. Nikolakisb,Th. Baimposb a Editor-in-chief, Sensor Letters University of Patras, Greece b FORTH, Patra Greece ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China http://www.icmmm.net/ 2012.9.21-23 Beijing

  3. Zeolite film ME sensor Zeolite thin films as new materials for chemically active layers in magneto-elastic sensors VOC • Outline • Zeolite films – excellent active sensing layers - Review • Magnetoelastic (ME) resonance sensors • Volatile Organic Compounds (VOC) • Detection of VOCs with Zeolite/ME sensors ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China http://www.icmmm.net/ 2012.9.21-23 Beijing

  4. Zeolites (Review on Sensing Applications) ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China http://www.icmmm.net/ 2012.9.21-23 Beijing

  5. Zeolites • Inorganic, crystalline,aluminosilicate materials • Chemically and thermally stable • Industry: Excellent catalysts, molecular sieves, ion-exchangers, water softeners • 170 different types, about 17 of them commercial interest ICMMM2011 , 8-10 Dec 2011, Zhengzhou, China http://www.icmmm.net/ 2012.9.21-23 Beijing

  6. Na+ Zeolites + + = • Consist of interconnected SiO2 and AlO2 tetrahedra & Cations+ • Tetrahedra form 3D frameworks with linked channels down to molecular level • High porosity, pores fixed down to nm sizes -> gas sensing • Exceptionally high specific-surface-area • 400 m2/gr (two large apartments in one gram !!!) http://www.icmmm.net/ 2012.9.21-23 Beijing

  7. Zeolite Building blocks SiO2 tetrahedra Chemical formula SiO2? Tetrahedra connected at corners Each Oxygen is shared by 2 tetrahedra All corners are connected 4 × ½ = 2 O atoms → Si Schematically, oxygen are shown as straight lines (bonds) and Si at the corners All corners are connected→ 4 lines from each Si Si Si O O O O Si Si http://www.icmmm.net/ 2012.9.21-23 Beijing

  8. Si Si Zeolite - Silicalite (MFI) O 1-D channels All bonds are homopolar → no polarity in the crystal → Extremely hydrophobic http://www.icmmm.net/ 2012.9.21-23 Beijing

  9. Zeolite - Silicalite (MFI) Simplified planar view (SiO2) http://www.icmmm.net/ 2012.9.21-23 Beijing

  10. Na+ Broken Bond Two Different Building blocks SiO2 AlO2 The Al cannot form heteropolar bond with one O => Local electronegativity => Extra cation Na+, Ca++ trapped => Polarity in the crystal http://www.icmmm.net/ 2012.9.21-23 Beijing

  11. Zeolite LTA, Si/Al = 1 Simplified planar view + Na Na+[(SiO2)(AlO2)- ]. zH2O http://www.icmmm.net/ 2012.9.21-23 Beijing

  12. Zeolite LTA, Si/Al = 1 + Simplified planar view + + + + + + Na Na+[(SiO2)(AlO2)- ]. zH2O http://www.icmmm.net/ 2012.9.21-23 Beijing

  13. Zeolite LTA, Si/Al = 1 + LTA + Cations cause polarity → attract polar molecules (water, CO2) http://www.icmmm.net/ 2012.9.21-23 Beijing

  14. Zeolite FAU, Si/Al ≠1 FAU + + + (Na+, Ca++) + Xm+y/m [(SiO2)x(AlO2)-y ]. zH2O http://www.icmmm.net/ 2012.9.21-23 Beijing

  15. Si 50% - Al 50% Cations Na, Ca Polar 3-D straight channels LTA Ring 8 Si 100% non-polar Hydrophobic 1-D channels MFI Ring 10 Si x% - Al y% Cations Na, Ca Polar 3-D entangled channels FAU Ring 12 http://www.icmmm.net/ 2012.9.21-23 Beijing

  16. Useful Zeolite properties for sensing Trap selectively gas molecules of the right size Trap selectively gas molecules of the right shape Trap selectively gas molecules of the right polarity Highly polar materials, ion conductors and ion exchangers Al+3 acidic site: catalyze a number of chemical reactions Room temperature operation High specific surface Molecular Sieving for octane-isomers LTA http://www.icmmm.net/ 2012.9.21-23 Beijing

  17. Main Disadvantages: • Polar Zeolites adsorb humidity, need initial degassing • Slow Diffusion (gas out) http://www.icmmm.net/ 2012.9.21-23 Beijing

  18. Basically there are 5 different ways on how to use Zeolites for Sensing Applications: Mass Load Film Properties Filter Guest/Host Composite http://www.icmmm.net/ 2012.9.21-23 Beijing

  19. zeolite microbalance Mass Load: Selective adsorption of certain molecules → Microbalance senses mass load QCM, SAW, Magneto-elastic, Microcantilever http://www.icmmm.net/ 2012.9.21-23 Beijing

  20. V Film: Selective adsorption of certain molecules → Redox interactions with cations → Change of film property zeolite Impedance Spectroscopy Resistive Sensors Capacitive Optical http://www.icmmm.net/ 2012.9.21-23 Beijing

  21. Filter : Selective adsorption of certain molecules → make it to the sensitive layer (+ catalysis ) zeolite sens. layer MOS silicon sensors sensor http://www.icmmm.net/ 2012.9.21-23 Beijing

  22. Guest/Host: Certain molecular complexes pinned at zeolite sites act as sensing centers such as fluorophores, dyes complex Fluorescent Optical sensors zeolite http://www.icmmm.net/ 2012.9.21-23 Beijing

  23. Composite: Zeolite placed inside a matrix in order to improve its sensing properties zeolite Conductive Polymer sensors matrix http://www.icmmm.net/ 2012.9.21-23 Beijing

  24. Xiaowen Xu, Jing Wang, and Yingcai Long, Sensors 2006, 6, 1751-1764 http://www.icmmm.net/ 2012.9.21-23 Beijing

  25. Zeolite based gas sensors http://www.icmmm.net/ 2012.9.21-23 Beijing

  26. zeolite CTO V Electrical resistance of chromium titanium oxide (CTO) sensors overlaid with zeolites Detection ethanol / isopropanol in dry air operated at 4000C ethanol isopropanol BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011 http://www.icmmm.net/ 2012.9.21-23 Beijing

  27. CTO V Typically ethanol / isopropanol react with O-- ions, producing CO2 and releasing electrons => Change of resistance They give similar signal because of same functional group Bare Sensor ethanol O-- isopropanol BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011 http://www.icmmm.net/ 2012.9.21-23 Beijing

  28. zeolite CTO V The zeolite can make the difference acting as both as a shieve and catalyst enhancing the reaction ethanol isopropanol BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011 http://www.icmmm.net/ 2012.9.21-23 Beijing

  29. +LTA zeolite Bare Sensor ethanol Sensor Signal Bare Sensor +LTA isopropanol Time BINIONS et al.: IEEE SENSORS JOURNAL, VOL. 11, NO. 5, MAY 2011 http://www.icmmm.net/ 2012.9.21-23 Beijing

  30. Hydrocarbon C3H8 Gas Detection – Impedance sensor Z The ionic conductivity is measured by impedance spectroscopy http://www.icmmm.net/ 2012.9.21-23 Beijing Gunter Hagen and Ralf Moos, SENSOR LETTERS 9, 110–113, 2011

  31. Humidity Detection – Optical Sensor methylene blue mordenite zeolite UV–VIS diffuse reflectance spectra change in color upon protonation /deprotonation of dye molecules intercalated into the zeolite http://www.icmmm.net/ 2012.9.21-23 Beijing S. Sohrabnezhad et al. / Materials Letters 61 (2007) 2311–2314

  32. QCM(Quartz crystal microbalance ) left: Top electrode, right: back electrode http://www.icmmm.net/ 2012.9.21-23 Beijing WWW.wikipedia.com

  33. Sensing ofSO2, FAU zeolite When SO2 is adsorbed on FAU, the mass increase reduces QCM frequency http://www.icmmm.net/ 2012.9.21-23 Beijing M. Osada, I. Sasaki, M. Nishioka, M. Sadakata, T.Okubo, Microporous and Mesoporous Materials 23 (1998) 287–294

  34. Micro-Cantilevers Micro-Cantilevers: rectangular-shaped bars of Si, less than 1 μm thick.Adsorptionresults in bending of the cantilever Mass Loads as small as ~ 5 ng. http://www.icmmm.net/ 2012.9.21-23 Beijing Cantilever array sensorby Hans Peter Lang1,2*, Martin Hegner1, and Christoph Gerber1

  35. Outgased Zeolite Sensor Non-Outgased Zeolite Sensor Humidity sensor using ZSM-5 single crystals L.Scandella, G. Binder, T. Mezzacasa, J. Gobrecht, R. Berger, H.P. Lang, Microporous & Mesoporous Materials 21 ( 1998) 403 http://www.icmmm.net/ 2012.9.21-23 Beijing

  36. Detection of dissolved organics in water Adsorption alters zeolite index of refraction → altering the optical reflectivity → reducing reflected signal power. SEM image of MFI thin films grown on endface of an optical fiber http://www.icmmm.net/ 2012.9.21-23 Beijing Jian Zhang and Junhang Dong, Langmuir 2005, 21, 8609-8612

  37. Calibration curve of pentanoic acid http://www.icmmm.net/ 2012.9.21-23 Beijing

  38. Typical Zeolite Synthesis Precursors Commercial Ludox (Si source) Aluminum foil, Al2O3 (Al source) NaOH: Sodium hydroxide (Na source) + organics (catalysts, need removal) TEA: Triethanolamine TPAOH: Tetrapropylamonium hydroxide (also TEOS:tetraethyl orthosilicate) http://www.icmmm.net/ 2012.9.21-23 Beijing

  39. Typical Synthesis on Metglas strip Create Nucleation site: Dip substrate in solution with FAU crystals (older solution or commercial batch) Hydrothermal SynthesisQ: Put in autoclave 6 days 4.17 Na2O/ Al2O3/ 6 TEA/ 1.87 SiO2/ 460 H2O T=85 oC (S. Qiu, et al. Microporous Mesoporous Mater., 21, (1998) 245-251) Remove organics: Heat treat composite at 300 oC for 12 hrs Metglas’ cross section surface after synthesis Metglas surface before synthesis http://www.icmmm.net/ 2012.9.21-23 Beijing

  40. Magnetoelastic Sensors http://www.icmmm.net/ 2012.9.21-23 Beijing

  41. b)Forced Magnetostriction Magneto-Elastic ribbons Metglas Magneto-Elastic materials: Alter their shape under magnetic field H a) Spontaneous Magnetostriction H=0 Length increase Un-magnetized Magnetized-up H≠0 H>>0 http://www.icmmm.net/ 2012.9.21-23 Beijing

  42. Magneto-Elastic ribbons An alternating magnetic field induces vibrations in the sensor V = V0 sin(ωt) A pick up coil detects magnetic flux changes → generates AC voltage EMF V0 The amplitude V0 peaks when excitation frequency equals resonance frequency f0 Frequency http://www.icmmm.net/ 2012.9.21-23 Beijing Elastic modulus density

  43. The resonance frequency depends on mass m and elastic (Young) modulus • Mass loads decrease frequency • E is constant in most solid materials but in magnetoelastic materials it depends on constant (biasing) fields H and stresses σ • H and σincrease or decrease frequency • Change on the mass molecules adsorbed in the zeolite’s crystal reflects to changes on the sensor’s resonance frequency http://www.icmmm.net/ 2012.9.21-23 Beijing [1]Grimes CA, Mungle CS, Zeng ZF, et al., Sensors 2 (7): 294-313 JUL 2002

  44. Shift in resonance frequency zeolite CO2 ME sensor EMF (mV) Frequency (kHz) Τ=30οC http://www.icmmm.net/ 2012.9.21-23 Beijing Cyclic gas changes

  45. Sensor fabrication Cut ofMetglas ribbon (20 mmx 6mm x 30μm) FAU sensor Metglas cleaning i)CH3CCl3 ii)CH3OH MFI sensor Deposition of FAU crystals on Metglas strip by dip coating Hydrothermal syntesis 4.17 Na2O + Al2O3 + 1.87 SiO2 + 460 H2O + organics T=85 oC Autoclave Ozonication to remove organics at 2000 C Heat treat 280 oC 12 hrs to remove organics Zeolite20-30 mm 2826Metglas 30mm http://www.icmmm.net/ 2012.9.21-23 Beijing Zeolite20-30 mm

  46. Synthesis details [1] S. Qiu, J. Yu, G. Zhu, O. Terasaki, Y. Nozue, W. Pang, R. Xu, Microporous and Mesoporous Mater., 21, 245, (1998) [2] G. J. Myatt, P. M. Budd, C. Price, and S. W. Carr, J. Mater. Chem. 2, 1103, (1992) [3] Tuan, V. A.; Li, S. G.; Falconer, J. L.; Noble, R. D, Journal of Membrane Science, 196, 111, (2002) http://www.icmmm.net/ 2012.9.21-23 Beijing

  47. LTA FAU MFI http://www.icmmm.net/ 2012.9.21-23 Beijing

  48. FAU LTA MFI http://www.icmmm.net/ 2012.9.21-23 Beijing

  49. Volatile Organic Compounds http://www.icmmm.net/ 2012.9.21-23 Beijing

  50. Volatile Organic Compounds - VOCs • Organic liquids with high vapor pressure • Common by-products in several industrial processes but are also found in everyday life. • Most of the VOCs vapors are considered harmful and their sensing is a necessity VOC Organic http://www.icmmm.net/ 2012.9.21-23 Beijing

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