Characterization of porous thin films using quartz crystal shear resonators
A new model for the characterization of porous materials using quartz crystal impedance analysis is proposed. The model describes the equivalent electrical and/or mechanical impedance of the quartz crystal in contact with a finite layer of a rigid porous material which is immersed in a semi-infinite...
| Autor principal: | |
|---|---|
| Otros Autores: | |
| Formato: | Acta de conferencia Capítulo de libro |
| Lenguaje: | Inglés |
| Publicado: |
ACS
2000
|
| Acceso en línea: | Registro en Scopus DOI Handle Registro en la Biblioteca Digital |
| Aporte de: | Registro referencial: Solicitar el recurso aquí |
| Sumario: | A new model for the characterization of porous materials using quartz crystal impedance analysis is proposed. The model describes the equivalent electrical and/or mechanical impedance of the quartz crystal in contact with a finite layer of a rigid porous material which is immersed in a semi-infinite liquid. The characteristic porosity length (ξ), layer thickness (d), liquid density (ρ), an viscosity (η) are taken into account. For films thick compared with the characteristic porosity length (d ≫ ξ), the model predicts a net increase of the area which is translated into a linear relationship between the quartz equivalent impedance Z = R + XL (XL = iωL, ω = 2πf, f being the oscillation frequency of the quartz resonator) and the ratio d/ξ. For low-viscosity Newtonian liquids, for which the velocity decay length δ = (2ωη/ρ)1/2 is much smaller than ξ, Z corresponds to the impedance of a semi-infinite liquid in contact with an increased effective quartz area which scales with the ratio d/ξ. In this case, R = XL in agreement with Kanazawa equation. For liquids of higher viscosity, the effect of the fluid trapped by the porous matrix is apparent and is reflected in the impedance, which has an imaginary part (XL) higher than its real part (R). In the limit of a very viscous liquid, the movement of the porous film is completely transferred to the liquid and all the mass moves in-phase with the quartz crystal electrode. In this limiting case the model predicts a purely inductive impedance, which corresponds to a resonant frequency in agreement with the Sauerbrey equation. The model allows us, for the first time, to explain the almost linear behavior of R vs XL along the growth process of conducting polymers, which present a well-known open fibrous structure. Films of polyaniline-polystyrenesulfonate were deposited on the quartz crystal under several conditions to test the model, and a very good agreement was found. |
|---|---|
| Bibliografía: | Noel, M.A., Topart, P.A., (1994) Anal. Chem., 66, p. 484 Muramatsu, H., Kimura, K., (1992) Anal. Chem., 64, p. 2502 Etchenique, R.A., Calvo, E.J., (1997) Anal. Chem., 69 (23), p. 4833 Mason, W.P., Baker, W., McSkimin, H.J., Heiss, J.H., (1949) Phys. Rev., 75 (6), p. 936 Sauerbrey, G., (1959) Z. Phys., 155, p. 206 Nomura, T., Minemura, A., (1980) Nippon Kagaku Kaishi, p. 1621 Konash, P.L., Bastiaans, G.J., (1980) Anal. Chem., 52, p. 1929 Bruckenstein, S., Shay, M., (1985) J. Electroanal. Chem., 188, p. 131 Kanazawa, K.K., Gordon, J.G., (1985) Anal. Chim. Acta, 175, p. 99 Martin, J., Granstaff, V.E., Frye, G.C., (1991) Anal. Chem., 63, p. 2272 Reed, C.E., Kanazawa, K.K., Kaufman, J.H., (1990) J. Appl. Phys., 68, p. 1993 Granstaff, E., Martin, S.J., (1994) J. Appl. Phys., 75, p. 1319 Liess, H.-D., Knezevic, A., Rother, A., Muenz, J., (1997) Faraday Discuss., 107, p. 39 Daikhin, L., Urbakh, M., (1996) Langmuir, 12, p. 6354 Wolff, O., Seydel, E., Johannsmann, D., (1997) Faraday Discuss., 107, p. 91 Etchenique, R.A., Calvo, E.J., (1999) Electrochem. Commun., 1 (5), p. 167 Ferraris, J.P., Eissa, M.M., Brotherston, I.D., Loveday, D.C., Moxey, A.A., (1998) J. Electroanal. Chem., 459 (131), p. 57 Dinh, H.N., Ding, J., Xia, S.J., Birss, V.I., (1998) J. Electroanal. Chem., 459 (131), p. 45 DuBois C.J., Jr., McCarley, R.L., (1998) J. Electroanal. Chem., 454, p. 99 Topart, P.A., Noël, M.A., (1994) Anal. Chem., 66, p. 2926 Bandey, H.L., Hillman, A.R., Brown, M.J., Martin, S.J., (1997) Faraday Discuss., 107, p. 105 Etchenique, R., Brudny, V.L., (1999) Electrochem. Commun., 1, p. 441 Van Dyke, K., (1925) Phys. Rev., 25, p. 895 Sahimi, M., (1993) M. Rev. Modern Phys., 65, p. 1393 Rubinstein, J., Torquato, S., (1989) J. Fluid Mech., 206, p. 25 Brinkman, H.C., (1947) Appl. Sci. Res., A, 1, p. 27 Charlaix, E., Kushnick, A.P., Stokes, J.P., (1988) Phys. Rev. Lett., 61 (14), p. 1595 Johnson, D.L., Koplik, J., Dashen, R., (1987) J. Fluid Mech., 176, p. 379 Knackstedt, M.A., Sahimi, M., Chan, D.Y.C., (1993) Phys. Rev. E, 47 (4), p. 2593 Kanazawa, K.K., (1997) Faraday Discuss., 107, p. 77 Calvo, E.J., Etchenique, R., Bartlett, P.N., Singhal, K., Santamaria, C., (1997) Faraday Discuss., 107, p. 141 Calvo, E.J., Danilowicz, C., Etchenique, R., (1995) J. Chem. Soc., Faraday Trans., 91, p. 4083 Beck, R., Weil, K., (1992) J. Electrochem. Soc., 139, p. 453 Ferry, J.D., (1980) Viscoelastic Properties of Polymers, 3rd Ed., , Wiley: New York Etchenique, R., Weisz, A.D., (1999) J. Appl. Phys., 86 (4), p. 1994 |
| ISSN: | 07437463 |
| DOI: | 10.1021/la991145q |