Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device

A fast high-frequency 'in situ' transfer-function measurement with a quartz crystal microbalance (QCM) has been obtained by an ac voltage divider formed by the quartz crystal impedance (ZQ) and a measuring resistor (Rm). The frequency is swept by a voltage-controlled oscillator (VCO) and t...

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Detalles Bibliográficos
Autores principales: Calvo, Ernesto Julio, Etchenique, Roberto
Publicado: 1995
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09565000_v91_n22_p4083_Calvo
http://hdl.handle.net/20.500.12110/paper_09565000_v91_n22_p4083_Calvo
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_09565000_v91_n22_p4083_Calvo
record_format dspace
spelling paper:paper_09565000_v91_n22_p4083_Calvo2023-06-08T15:56:04Z Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device Calvo, Ernesto Julio Etchenique, Roberto A fast high-frequency 'in situ' transfer-function measurement with a quartz crystal microbalance (QCM) has been obtained by an ac voltage divider formed by the quartz crystal impedance (ZQ) and a measuring resistor (Rm). The frequency is swept by a voltage-controlled oscillator (VCO) and the ratio of output (Eo) and input (Ei) ac voltages gives the transfer function of the device. A non-linear fit of the transfer-function modulus vs. frequency around the natural resonance frequency of the system in the 10 MHz range was performed with a Butterworth-Van Dyke equivalent circuit. Mass and viscoelastic components were evaluated with the Sauerbrey-Kanazawa-Bruckenstein equations. The method was tested by varying the viscoelasticity of the quartz surface in sucrose solutions [i.e. by varying the quantity (ρLηL)1/2] and mass sensitivity was calibrated by silver deposition. Fast measurements in non-steady-state experiments were performed with redox hydrogels undergoing oxidation and reduction with anion and water exchange with the outside solution. Deconvolution of both rigid mass (Δm) and viscous resistance (R) was achieved and this explained the abnormal behaviour of the resonance-frequency shift (Δf) during cyclic voltammetry of ferrocene-modified poly(allylamine) hydrogels on a resonant electrochemical QCM. Fil:Calvo, E.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Etchenique, R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1995 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09565000_v91_n22_p4083_Calvo http://hdl.handle.net/20.500.12110/paper_09565000_v91_n22_p4083_Calvo
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description A fast high-frequency 'in situ' transfer-function measurement with a quartz crystal microbalance (QCM) has been obtained by an ac voltage divider formed by the quartz crystal impedance (ZQ) and a measuring resistor (Rm). The frequency is swept by a voltage-controlled oscillator (VCO) and the ratio of output (Eo) and input (Ei) ac voltages gives the transfer function of the device. A non-linear fit of the transfer-function modulus vs. frequency around the natural resonance frequency of the system in the 10 MHz range was performed with a Butterworth-Van Dyke equivalent circuit. Mass and viscoelastic components were evaluated with the Sauerbrey-Kanazawa-Bruckenstein equations. The method was tested by varying the viscoelasticity of the quartz surface in sucrose solutions [i.e. by varying the quantity (ρLηL)1/2] and mass sensitivity was calibrated by silver deposition. Fast measurements in non-steady-state experiments were performed with redox hydrogels undergoing oxidation and reduction with anion and water exchange with the outside solution. Deconvolution of both rigid mass (Δm) and viscous resistance (R) was achieved and this explained the abnormal behaviour of the resonance-frequency shift (Δf) during cyclic voltammetry of ferrocene-modified poly(allylamine) hydrogels on a resonant electrochemical QCM.
author Calvo, Ernesto Julio
Etchenique, Roberto
spellingShingle Calvo, Ernesto Julio
Etchenique, Roberto
Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
author_facet Calvo, Ernesto Julio
Etchenique, Roberto
author_sort Calvo, Ernesto Julio
title Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
title_short Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
title_full Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
title_fullStr Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
title_full_unstemmed Measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
title_sort measurement of viscoelastic changes at electrodes modified with redox hydrogels with a quartz crystal device
publishDate 1995
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09565000_v91_n22_p4083_Calvo
http://hdl.handle.net/20.500.12110/paper_09565000_v91_n22_p4083_Calvo
work_keys_str_mv AT calvoernestojulio measurementofviscoelasticchangesatelectrodesmodifiedwithredoxhydrogelswithaquartzcrystaldevice
AT etcheniqueroberto measurementofviscoelasticchangesatelectrodesmodifiedwithredoxhydrogelswithaquartzcrystaldevice
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