 |
Chargé de recherche ENS – Département de chimie Email: oleksandr.oliynyk@ens.psl.eu |
Research interests
- electrochemistry
- physical chemistry underlying biological processes
- mathematical modelling
- simulations
Publications
2009 |
Electrochemical determination of flow velocity profile in a microfluidic channel from steady-state currents: Numerical approach and optimization of electrode layout Article de journal C Amatore; O V Klymenko; A I Oleinick; I Svir Analytical Chemistry, 81 (18), p. 7667–7676, 2009. @article{Amatore:2009d, title = {Electrochemical determination of flow velocity profile in a microfluidic channel from steady-state currents: Numerical approach and optimization of electrode layout}, author = {C Amatore and O V Klymenko and A I Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70349111482&doi=10.1021%2fac9010827&partnerID=40&md5=7bf2289553d17260f98c547a65a503d5}, doi = {10.1021/ac9010827}, year = {2009}, date = {2009-01-01}, journal = {Analytical Chemistry}, volume = {81}, number = {18}, pages = {7667--7676}, abstract = {In this article, the numerical approach for flow profile reconstruction in a microfluidic channel equipped with band microelectrodes introduced previously by the authors, based on transient currents, is extended to the exclusive use of steady-state currents. It is shown that, although the currents obey steady state, the flow velocity profile in the channel may be reconstructed rapidly with a high accuracy, provided a sufficient number of electrodes performing under steady state are considered. The present theory demonstrates how the electrode widths and sizes of gaps separating them can be optimized to achieve better performance of the method. This approach has been evaluated theoretically for band microelectrode arrays embedded into one wall of a rectangular channel consisting of three, four, or five electrodes, all of which are operated in the generator mode. The results prove that the proposed approach is able to accurately recover the shape of the flow profile in a wide range of Peclet numbers and flow types ranging from the classical parabolic Poiseuille flow to constant electro-osmotic-type flow. © 2009 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this article, the numerical approach for flow profile reconstruction in a microfluidic channel equipped with band microelectrodes introduced previously by the authors, based on transient currents, is extended to the exclusive use of steady-state currents. It is shown that, although the currents obey steady state, the flow velocity profile in the channel may be reconstructed rapidly with a high accuracy, provided a sufficient number of electrodes performing under steady state are considered. The present theory demonstrates how the electrode widths and sizes of gaps separating them can be optimized to achieve better performance of the method. This approach has been evaluated theoretically for band microelectrode arrays embedded into one wall of a rectangular channel consisting of three, four, or five electrodes, all of which are operated in the generator mode. The results prove that the proposed approach is able to accurately recover the shape of the flow profile in a wide range of Peclet numbers and flow types ranging from the classical parabolic Poiseuille flow to constant electro-osmotic-type flow. © 2009 American Chemical Society. |
Theory of ion transport in electrochemically switchable nanoporous metallized membranes Article de journal C Amatore; A I Oleinick; I Svir ChemPhysChem, 10 (1), p. 211–221, 2009. @article{Amatore:2009g, title = {Theory of ion transport in electrochemically switchable nanoporous metallized membranes}, author = {C Amatore and A I Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-58149493254&doi=10.1002%2fcphc.200800481&partnerID=40&md5=46b009fde382b20b3a4cdefea211e316}, doi = {10.1002/cphc.200800481}, year = {2009}, date = {2009-01-01}, journal = {ChemPhysChem}, volume = {10}, number = {1}, pages = {211--221}, abstract = {A physicomathematical model of ion transport through a synthetic electrochemically switchable membrane with nanometric metal-plated pores is presented. Due to the extremely small size of the cylindrical pores, electrical double layers formed inside overlap, and thus, strong electrostatic fields whose intensities vary across the cross-sections of the nanopores are created. Based on the proposed model a relationship between the relative electrostatic energies experienced by ions in the nanopores and the potential applied to the membrane is established. This allows the prediction of transference numbers and explains quantitatively the ion-transport switching capability of such synthetic membranes. The predictions of this model agree satisfactorily with previous experimental data obtained for this type of devices by Martin and co-workers. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A physicomathematical model of ion transport through a synthetic electrochemically switchable membrane with nanometric metal-plated pores is presented. Due to the extremely small size of the cylindrical pores, electrical double layers formed inside overlap, and thus, strong electrostatic fields whose intensities vary across the cross-sections of the nanopores are created. Based on the proposed model a relationship between the relative electrostatic energies experienced by ions in the nanopores and the potential applied to the membrane is established. This allows the prediction of transference numbers and explains quantitatively the ion-transport switching capability of such synthetic membranes. The predictions of this model agree satisfactorily with previous experimental data obtained for this type of devices by Martin and co-workers. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA. |
Theory of long-range diffusion of proteins on a spherical biological membrane: Application to protein cluster formation and actin-comet tail growth Article de journal C Amatore; A I Oleinick; O V Klymenko; I Svir ChemPhysChem, 10 (9-10), p. 1586–1592, 2009. @article{Amatore:2009h, title = {Theory of long-range diffusion of proteins on a spherical biological membrane: Application to protein cluster formation and actin-comet tail growth}, author = {C Amatore and A I Oleinick and O V Klymenko and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67650082758&doi=10.1002%2fcphc.200900176&partnerID=40&md5=b3794052ffc5ff12fb1ed1cb5b79a09b}, doi = {10.1002/cphc.200900176}, year = {2009}, date = {2009-01-01}, journal = {ChemPhysChem}, volume = {10}, number = {9-10}, pages = {1586--1592}, abstract = {Breaking of symmetry is often required in biology in order to produce a specific function. In this work we address the problem of protein diffusion over a spherical vesicle surface towards one pole of the vesicle in order to produce ultimately an active protein cluster performing a specific biological function. Such a process is, for example, prerequisite for the assembling of proteins which then cooperatively catalyze the polymerization of actin monomers to sustain the growth of actin tails as occurs in natural vesicles such as those contained in Xenopus eggs. By this process such vesicles may propel themselves within the cell by the principle of action-reaction. In this work the physicochemical treatment of diffusion of large bio-molecules within a cellular membrane is extended to encompass the case when proteins may be transiently poised by corral-like structures partitioning the membrane as has been recently documented in the literature. In such case the exchange of proteins between adjacent corrals occurs by energy-gated transitions instead of classical Brownian motion, yet the present analysis shows that long-range movements of the bio-molecules may still be described by a classical diffusion law though the diffusion coefficient has then a different physical meaning. Such a model explains why otherwise classical diffusion of proteins may give rise to too small diffusion coefficients compared to predictions based on the protein dimension. This model is implemented to examine the rate of proteins clustering at one pole of a spherical vesicle and its outcome is discussed in relevance to the mechanism of actin comet tails growth. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Breaking of symmetry is often required in biology in order to produce a specific function. In this work we address the problem of protein diffusion over a spherical vesicle surface towards one pole of the vesicle in order to produce ultimately an active protein cluster performing a specific biological function. Such a process is, for example, prerequisite for the assembling of proteins which then cooperatively catalyze the polymerization of actin monomers to sustain the growth of actin tails as occurs in natural vesicles such as those contained in Xenopus eggs. By this process such vesicles may propel themselves within the cell by the principle of action-reaction. In this work the physicochemical treatment of diffusion of large bio-molecules within a cellular membrane is extended to encompass the case when proteins may be transiently poised by corral-like structures partitioning the membrane as has been recently documented in the literature. In such case the exchange of proteins between adjacent corrals occurs by energy-gated transitions instead of classical Brownian motion, yet the present analysis shows that long-range movements of the bio-molecules may still be described by a classical diffusion law though the diffusion coefficient has then a different physical meaning. Such a model explains why otherwise classical diffusion of proteins may give rise to too small diffusion coefficients compared to predictions based on the protein dimension. This model is implemented to examine the rate of proteins clustering at one pole of a spherical vesicle and its outcome is discussed in relevance to the mechanism of actin comet tails growth. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. |
Capacitive and solution resistance effects on voltammetric responses at a disk microelectrode covered with a self-assembled monolayer in the presence of electron hopping Article de journal C Amatore; A Oleinick; O V Klymenko; I Svir Analytical Chemistry, 81 (20), p. 8545–8556, 2009. @article{Amatore:2009b, title = {Capacitive and solution resistance effects on voltammetric responses at a disk microelectrode covered with a self-assembled monolayer in the presence of electron hopping}, author = {C Amatore and A Oleinick and O V Klymenko and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-70450092364&doi=10.1021%2fac901513x&partnerID=40&md5=28c3f6b5e5d3992c65409f9dfb3181b8}, doi = {10.1021/ac901513x}, year = {2009}, date = {2009-01-01}, journal = {Analytical Chemistry}, volume = {81}, number = {20}, pages = {8545--8556}, abstract = {This article extends our previous works (Amatore, C.; Oleinick, A.; Svir, I. Anal. Chem.2008, 80, 7947-7956; 7957-7963.) about the effects of resistive and capacitive distortions in voltammetry at disk microelectrodes. The particular case of voltammetry of a self-assembled monolayer carrying one redox site per molecule is investigated here. In addition, the effect of an uneven distribution of the effective electrochemical potential on the possibility of electron hopping (EH) contributions is examined. An original model of EH has been developed considering both diffusion-type (i.e., related to concentration gradients) and migration-type (i.e., imposed by an uneven distribution of the electrical potential due to an ohmic drop and capacitance charging) contributions. This predicts that as soon as the system performs out of thermodynamic equilibrium and provided that the EH rate constants are not too small the system tends to re-establish its out-of-equilibrium state through EH. Hence, EH somewhat tries to compensate the voltammetric distortions that would be enforced by the uneven distribution of the electrochemical driving force incurred by the system due to an ohmic drop and capacitive charging. However, this rigorous analysis established that, thoughEHmay be effective under specific circumstances particularly near the electrode edge, its overall influence on voltammetric waves remains negligible for any realistic experimental situation. © 2009 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This article extends our previous works (Amatore, C.; Oleinick, A.; Svir, I. Anal. Chem.2008, 80, 7947-7956; 7957-7963.) about the effects of resistive and capacitive distortions in voltammetry at disk microelectrodes. The particular case of voltammetry of a self-assembled monolayer carrying one redox site per molecule is investigated here. In addition, the effect of an uneven distribution of the effective electrochemical potential on the possibility of electron hopping (EH) contributions is examined. An original model of EH has been developed considering both diffusion-type (i.e., related to concentration gradients) and migration-type (i.e., imposed by an uneven distribution of the electrical potential due to an ohmic drop and capacitance charging) contributions. This predicts that as soon as the system performs out of thermodynamic equilibrium and provided that the EH rate constants are not too small the system tends to re-establish its out-of-equilibrium state through EH. Hence, EH somewhat tries to compensate the voltammetric distortions that would be enforced by the uneven distribution of the electrochemical driving force incurred by the system due to an ohmic drop and capacitive charging. However, this rigorous analysis established that, thoughEHmay be effective under specific circumstances particularly near the electrode edge, its overall influence on voltammetric waves remains negligible for any realistic experimental situation. © 2009 American Chemical Society. |
2008 |
A new approach to the determination of the stellate neuron activity function in rat's brain Article de journal O Klymenko; A Oleinick; C Amatore; I Svir Russian Journal of Physical Chemistry A, 82 (9), p. 1428–1433, 2008. @article{Klymenko:2008, title = {A new approach to the determination of the stellate neuron activity function in rat's brain}, author = {O Klymenko and A Oleinick and C Amatore and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50249155325&doi=10.1134%2fS0036024408090021&partnerID=40&md5=fc9c75c1fbaef40a88ad6ed90ce3b67f}, doi = {10.1134/S0036024408090021}, year = {2008}, date = {2008-01-01}, journal = {Russian Journal of Physical Chemistry A}, volume = {82}, number = {9}, pages = {1428--1433}, abstract = {In this work, we present the results of a mathematical modelling of NO • release by neurons and its transport in the brain by diffusion. The model is applied to analyze the experimental data on NO • release from a neuron monitored during its patch-clamp stimulation by an ultramicroelectrode introduced into a slice of living rat's brain. The neuron activity function was obtained by numerical deconvolution of the experimental data using the response function of the electrode to an instantaneous spike of neuronal activity. The Gaussian decomposition of NO • release activity function allows qualitative and quantitative conclusions to be drawn about neuron activity. Since the integral activity function is readily obtained by deconvolution, the decomposition can be performed using other more relevant descriptions of NO• bursts emerging from active neurons. © 2008 Pleiades Publishing, Ltd.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this work, we present the results of a mathematical modelling of NO • release by neurons and its transport in the brain by diffusion. The model is applied to analyze the experimental data on NO • release from a neuron monitored during its patch-clamp stimulation by an ultramicroelectrode introduced into a slice of living rat's brain. The neuron activity function was obtained by numerical deconvolution of the experimental data using the response function of the electrode to an instantaneous spike of neuronal activity. The Gaussian decomposition of NO • release activity function allows qualitative and quantitative conclusions to be drawn about neuron activity. Since the integral activity function is readily obtained by deconvolution, the decomposition can be performed using other more relevant descriptions of NO• bursts emerging from active neurons. © 2008 Pleiades Publishing, Ltd. |
Capacitive and solution resistance effects on voltammetric responses of a thin redox layer attached to disk microelectrodes Article de journal C Amatore; A Oleinick; I Svir Analytical Chemistry, 80 (21), p. 7957–7963, 2008. @article{Amatore:2008, title = {Capacitive and solution resistance effects on voltammetric responses of a thin redox layer attached to disk microelectrodes}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-55549142999&doi=10.1021%2fac8012972&partnerID=40&md5=685d762dbe37ae798986e37750886484}, doi = {10.1021/ac8012972}, year = {2008}, date = {2008-01-01}, journal = {Analytical Chemistry}, volume = {80}, number = {21}, pages = {7957--7963}, abstract = {A rigorous theoretical analysis of cyclic voltammetry of surface-attached redox layers at disk microelectrodes is presented when effects enforced by the solution resistance and the electrode capacitance cannot be neglected. This allows a precise quantitative evaluation of the influence of each of the current components (faradaic, resistive, and capacitive) on the voltammetric shapes through numerical simulation. It is shown that the consideration of the solution resistance and capacitance effects is crucial for the correct treatment of experimental voltammograms at high-voltage scan rates when the resistance is not compensated. © 2008 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A rigorous theoretical analysis of cyclic voltammetry of surface-attached redox layers at disk microelectrodes is presented when effects enforced by the solution resistance and the electrode capacitance cannot be neglected. This allows a precise quantitative evaluation of the influence of each of the current components (faradaic, resistive, and capacitive) on the voltammetric shapes through numerical simulation. It is shown that the consideration of the solution resistance and capacitance effects is crucial for the correct treatment of experimental voltammograms at high-voltage scan rates when the resistance is not compensated. © 2008 American Chemical Society. |
Theory and simulation of diffusion-reaction into nano- and mesoporous structures. Experimental application to sequestration of mercury(II) Article de journal C Amatore; A Oleinick; O V Klymenko; C Delacôte; A Walcarius; I Svir Analytical Chemistry, 80 (9), p. 3229–3243, 2008. @article{Amatore:2008f, title = {Theory and simulation of diffusion-reaction into nano- and mesoporous structures. Experimental application to sequestration of mercury(II)}, author = {C Amatore and A Oleinick and O V Klymenko and C Delac\^{o}te and A Walcarius and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-42949095265&doi=10.1021%2fac702420p&partnerID=40&md5=af08160400599036b57adfddf0a0bf48}, doi = {10.1021/ac702420p}, year = {2008}, date = {2008-01-01}, journal = {Analytical Chemistry}, volume = {80}, number = {9}, pages = {3229--3243}, abstract = {The complex problem of diffusion-reaction inside of bundles of nanopores assembled into microspherical particles is investigated theoretically based on the numerical solutions of the physicochemical equations that describe the kinetics and the thermodynamics of the phenomena taking place. These theoretical results enable the delineation of the main factors that control the system reactivity and examination of their thermodynamic and kinetic effects to afford quantitative predictions for the optimization of the particles' dimensional characteristics for a targeted application. The validity and usefulness of the theoretical approach disclosed here are established by the presentation of the complete analysis of the performance of thiol-functionalized microspheres aimed for sequestration of Hg(II) ions from solutions to be remediated. This allows the comparison of the microparticles' performance at two different pH (2 and 4) and the rationalization of the observed changes in terms of the main microscopic parameters that define the system. © 2008 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The complex problem of diffusion-reaction inside of bundles of nanopores assembled into microspherical particles is investigated theoretically based on the numerical solutions of the physicochemical equations that describe the kinetics and the thermodynamics of the phenomena taking place. These theoretical results enable the delineation of the main factors that control the system reactivity and examination of their thermodynamic and kinetic effects to afford quantitative predictions for the optimization of the particles' dimensional characteristics for a targeted application. The validity and usefulness of the theoretical approach disclosed here are established by the presentation of the complete analysis of the performance of thiol-functionalized microspheres aimed for sequestration of Hg(II) ions from solutions to be remediated. This allows the comparison of the microparticles' performance at two different pH (2 and 4) and the rationalization of the observed changes in terms of the main microscopic parameters that define the system. © 2008 American Chemical Society. |
C Amatore; A Oleinick; I Svir Analytical Chemistry, 80 (21), p. 7947–7956, 2008. @article{Amatore:2008i, title = {Theoretical analysis of microscopic ohmic drop effects on steady-state and transient voltammetry at the disk microelectrode: A quasi-conformal mapping modeling and simulation}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-55549117140&doi=10.1021%2fac8010268&partnerID=40&md5=2d85a27062161be5bad06280c8ac9945}, doi = {10.1021/ac8010268}, year = {2008}, date = {2008-01-01}, journal = {Analytical Chemistry}, volume = {80}, number = {21}, pages = {7947--7956}, abstract = {The effect of uncompensated solution resistance on steady-state and transient voltammograms at the disk microelectrode was for the first time treated theoretically and numerically at the microscopic level using specific quasi-conformal mapping for the case of absence of electric migration. It has been shown that microscopic distributions of electric potential and current density at a disk microelectrode affect the voltammetric waves at different degrees across the electrode surface due to the variation of elementary resistances and elementary current fluxes over the electrode surface which leads to nonlinear effects that have not been discussed in existing theoretical treatments of ohmic drop at microelectrodes. The analysis of steady state voltammetry in strongly resistive media under Nernstian conditions has allowed justification by appropriate analytical derivations of the widely used potential-shift correction of steady state voltammograms by plotting i vs (E - iRe). © 2008 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The effect of uncompensated solution resistance on steady-state and transient voltammograms at the disk microelectrode was for the first time treated theoretically and numerically at the microscopic level using specific quasi-conformal mapping for the case of absence of electric migration. It has been shown that microscopic distributions of electric potential and current density at a disk microelectrode affect the voltammetric waves at different degrees across the electrode surface due to the variation of elementary resistances and elementary current fluxes over the electrode surface which leads to nonlinear effects that have not been discussed in existing theoretical treatments of ohmic drop at microelectrodes. The analysis of steady state voltammetry in strongly resistive media under Nernstian conditions has allowed justification by appropriate analytical derivations of the widely used potential-shift correction of steady state voltammograms by plotting i vs (E - iRe). © 2008 American Chemical Society. |
2007 |
Reconstruction of hydrodynamic flow profiles in a rectangular channel using electrochemical methods of analysis Article de journal O V Klymenko; A I Oleinick; C Amatore; I Svir Electrochimica Acta, 53 (3 SPEC. ISS.), p. 1100–1106, 2007. @article{Klymenko:2007, title = {Reconstruction of hydrodynamic flow profiles in a rectangular channel using electrochemical methods of analysis}, author = {O V Klymenko and A I Oleinick and C Amatore and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-35348984500&doi=10.1016%2fj.electacta.2007.03.066&partnerID=40&md5=fbafd84878e267d0036c14530228fceb}, doi = {10.1016/j.electacta.2007.03.066}, year = {2007}, date = {2007-01-01}, journal = {Electrochimica Acta}, volume = {53}, number = {3 SPEC. ISS.}, pages = {1100--1106}, abstract = {We propose a theoretical method for reconstructing the shape of a hydrodynamic flow profile occurring locally within a rectangular microfluidic channel based on experimental currents measured at double microband electrodes embedded in one channel wall and operating in the generator-collector regime. The ranges of geometrical and flow parameters providing best conditions for the flow profile determination are indicated. The solution of convection-diffusion equation (direct problem) is achieved through the application of the specifically designed conformal mapping of spatial coordinates and an exponentially expanding time grid for obtaining accurate concentration and current distributions. The inverse problem (the problem of flow profile determination) is approached using a variational formulation whose solution is obtained by the Ritz's method. The method may be extended for any number of electrodes in the channel and/or different operating regimes of the system (e.g. generator-generator). © 2007 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a theoretical method for reconstructing the shape of a hydrodynamic flow profile occurring locally within a rectangular microfluidic channel based on experimental currents measured at double microband electrodes embedded in one channel wall and operating in the generator-collector regime. The ranges of geometrical and flow parameters providing best conditions for the flow profile determination are indicated. The solution of convection-diffusion equation (direct problem) is achieved through the application of the specifically designed conformal mapping of spatial coordinates and an exponentially expanding time grid for obtaining accurate concentration and current distributions. The inverse problem (the problem of flow profile determination) is approached using a variational formulation whose solution is obtained by the Ritz's method. The method may be extended for any number of electrodes in the channel and/or different operating regimes of the system (e.g. generator-generator). © 2007 Elsevier Ltd. All rights reserved. |
C Amatore; O V Klymenko; A Oleinick; I Svir ChemPhysChem, 8 (12), p. 1870–1874, 2007. @article{Amatore:2007h, title = {In situ and on-line monitoring of hydrodynamic flow profiles in microfluidic channels based on microelectrochemistry: Optimization of channel geometrical parameters for best performance of flow profile reconstruction}, author = {C Amatore and O V Klymenko and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548415044&doi=10.1002%2fcphc.200700297&partnerID=40&md5=31246c7d1b9436391bbb92c63e0dd3ad}, doi = {10.1002/cphc.200700297}, year = {2007}, date = {2007-01-01}, journal = {ChemPhysChem}, volume = {8}, number = {12}, pages = {1870--1874}, abstract = {A theoretical approach for flow profile reconstruction in a rectangular microfluidic channel equipped with one or two microband electrodes working in generator-collector and generator-generator regimes was proposed by us previously (ChemPhysChem 2005, 6, 1581-1589; ChemPhysChem 2006, 7, 482-487). The purpose of the current study is to determine the ranges of dimensionkss parameters corresponding to the highest sensitivity of the minimized functional to the shape of the flow profile. By application of a cubic spline to approximate the flow profile and analysis of the least-squares functional, which can then be represented as a function of one variable, we derive the area of optimal method performance. Thus, mathematical confirmation of our previous theoretical physical predictions could be obtained. © 2007 Wiley-VCH Verlag GmbH&Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A theoretical approach for flow profile reconstruction in a rectangular microfluidic channel equipped with one or two microband electrodes working in generator-collector and generator-generator regimes was proposed by us previously (ChemPhysChem 2005, 6, 1581-1589; ChemPhysChem 2006, 7, 482-487). The purpose of the current study is to determine the ranges of dimensionkss parameters corresponding to the highest sensitivity of the minimized functional to the shape of the flow profile. By application of a cubic spline to approximate the flow profile and analysis of the least-squares functional, which can then be represented as a function of one variable, we derive the area of optimal method performance. Thus, mathematical confirmation of our previous theoretical physical predictions could be obtained. © 2007 Wiley-VCH Verlag GmbH&Co. KGaA. |
Confocal microscopy imaging of electrochemiluminescence at double band microelectrode assemblies: Numerical solution of the inverse optical problem Article de journal C Amatore; A Oleinick; O V Klymenko; L Thouin; L Servant; I Svir ChemPhysChem, 8 (11), p. 1664–1676, 2007. @article{Amatore:2007, title = {Confocal microscopy imaging of electrochemiluminescence at double band microelectrode assemblies: Numerical solution of the inverse optical problem}, author = {C Amatore and A Oleinick and O V Klymenko and L Thouin and L Servant and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547739027&doi=10.1002%2fcphc.200700216&partnerID=40&md5=858c3942bb5e0f07605eea8f5a741a22}, doi = {10.1002/cphc.200700216}, year = {2007}, date = {2007-01-01}, journal = {ChemPhysChem}, volume = {8}, number = {11}, pages = {1664--1676}, abstract = {A realistic theoretical model describing the outcome of confocal microscopic imaging of electrochemiluminescence (ECL) light emission is derived for a two parallel band microelectrodes assembly operated under steady state. The model takes into account the experimental distortions ensuing from a) the specific finite shape of the sampling volume in confocal microscopy, b) the light arising directly from out-of-focus area but transmitted through the microscope diaphragm or c) transmitted after reflection from the polished platinum band electrodes. The model is based on a detailed optical, physico-mathematical and numerical analysis of the problem at hand, and on simulations of the concentration distribution of the species giving rise to the ECL generation. Its outcome allows the reconstruction of the real spatial distribution of ECL light emission based on the confocal microscopy measurements upon correcting for the effect of experimental distortions using numerical fitting procedure. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A realistic theoretical model describing the outcome of confocal microscopic imaging of electrochemiluminescence (ECL) light emission is derived for a two parallel band microelectrodes assembly operated under steady state. The model takes into account the experimental distortions ensuing from a) the specific finite shape of the sampling volume in confocal microscopy, b) the light arising directly from out-of-focus area but transmitted through the microscope diaphragm or c) transmitted after reflection from the polished platinum band electrodes. The model is based on a detailed optical, physico-mathematical and numerical analysis of the problem at hand, and on simulations of the concentration distribution of the species giving rise to the ECL generation. Its outcome allows the reconstruction of the real spatial distribution of ECL light emission based on the confocal microscopy measurements upon correcting for the effect of experimental distortions using numerical fitting procedure. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
2006 |
C Amatore; A I Oleinick; I Svir Journal of Electroanalytical Chemistry, 597 (1), p. 77–85, 2006. @article{Amatore:2006a, title = {Construction of optimal quasi-conformal mappings for the 2D numerical simulation of diffusion at microelectrodes. Part 2. Application to recessed or protruding electrodes and their arrays}, author = {C Amatore and A I Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33749234145&doi=10.1016%2fj.jelechem.2006.07.035&partnerID=40&md5=af1cb9c3461803b4f1e50a84601ab87d}, doi = {10.1016/j.jelechem.2006.07.035}, year = {2006}, date = {2006-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {597}, number = {1}, pages = {77--85}, abstract = {The application of the quasi-conformal mapping obtained by our recent approach (see Part 1 of this series, C. Amatore, A.I. Oleinick, I. Svir, J. Electroanal. Chem. (2006), in press, doi:10.1016/j.jelechem.2006.08.001) for efficient numerical solution of 2D diffusion problems in systems with recessed disk microelectrodes is described. The ensuing quasi-conformal transformation allows effective resolution of singularities present at the electrode edge and at those of the insulating material in which the electrode rests. This enables, in particular, fast and precise simulations of single recessed/protruding disk (band) microelectrodes with arbitrary inclination angles as well as their arrays. © 2006 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The application of the quasi-conformal mapping obtained by our recent approach (see Part 1 of this series, C. Amatore, A.I. Oleinick, I. Svir, J. Electroanal. Chem. (2006), in press, doi:10.1016/j.jelechem.2006.08.001) for efficient numerical solution of 2D diffusion problems in systems with recessed disk microelectrodes is described. The ensuing quasi-conformal transformation allows effective resolution of singularities present at the electrode edge and at those of the insulating material in which the electrode rests. This enables, in particular, fast and precise simulations of single recessed/protruding disk (band) microelectrodes with arbitrary inclination angles as well as their arrays. © 2006 Elsevier B.V. All rights reserved. |
Modelling release of nitric oxide in a slice of rat's brain: describing stimulated functional hyperemia with diffusion-reaction equations Article de journal A I Oleinick; C Amatore; M Guille; S Arbault; O V Klymenko; I Svir Mathematical Medicine and Biology-a Journal of the Ima, 23 (1), p. 27-44, 2006, (Times Cited: 12). @article{, title = {Modelling release of nitric oxide in a slice of rat's brain: describing stimulated functional hyperemia with diffusion-reaction equations}, author = {A I Oleinick and C Amatore and M Guille and S Arbault and O V Klymenko and I Svir}, year = {2006}, date = {2006-01-01}, journal = {Mathematical Medicine and Biology-a Journal of the Ima}, volume = {23}, number = {1}, pages = {27-44}, note = {Times Cited: 12}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2005 |
Diffusion within nanometric and micrometric spherical-type domains limited by nanometric ring or pore active interfaces. Part 1: Conformal mapping approach Article de journal C Amatore; A Oleinick; I Svir Journal of Electroanalytical Chemistry, 575 (1), p. 103–123, 2005. @article{Amatore:2005a, title = {Diffusion within nanometric and micrometric spherical-type domains limited by nanometric ring or pore active interfaces. Part 1: Conformal mapping approach}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-12444328703&doi=10.1016%2fj.jelechem.2004.09.006&partnerID=40&md5=8a65c225d60f47819059ad8f1754e45d}, doi = {10.1016/j.jelechem.2004.09.006}, year = {2005}, date = {2005-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {575}, number = {1}, pages = {103--123}, abstract = {A theoretical approach is developed for investigation of diffusion within nanometric or micrometric spherical-type domains limited by two types of active interfaces. Typical representative examples of either system consist in: (a) insoluble droplets (defined by spherical cupolas) of electroactive liquids or redox dendrimers adsorbed onto an electrode surface placed in an electrolyte or (b) biological vesicles during exocytotic release occurring in living cells. In situation (a), the active interface is an infinitely small ring defined along the triple-phase interface at the junction between the droplet surface, the electrode surface, and the electrolyte. In situation (b), the interface is a nanometric pore connecting the inside of the vesicle to the outer medium. Either situation imposes extremely difficult conditions for modeling the diffusional behavior of these two systems because of: (a) the conflicting symmetries between the spherical domains shapes vis-\`{a}-vis the pore or ring active interface which acts as a diffusional sink or a source and (b) the near-infinite and heterogeneous concentration gradients which develop at the active interface. Despite these intrinsic severe difficulties, introducing an original conformal mapping transform leads to a great simplification of the numerical solution of diffusional problems. This allows the development of fast and extremely precise simulations of the problem at hand. The efficiency of the simulations is tested in each case by imposing diffusion-controlled conditions so as to examine situations which enhance the intrinsic difficulties of the problems. In this first part, only diffusion within the inner domain defined by the vesicle or the droplet is considered in simulations since this is the domain in which the most difficult diffusional situations occur, but the general theory developed encompasses the most global circumstances, viz., when diffusion in both the inner and outer domains controls the system's behavior and when generalized Butler-Volmer-type kinetics apply at the active interface. It is also shown that this conformal mapping approach leads to the design of a one-dimensional approximation which provides results accurate within a few percent compared to the full treatment of the system. Such equivalence, which is reminiscent of the hemisphere-disk or hemicylinder-band equivalence at ultramicroelectrodes, provides efficient and accurate simulations of the system at hand and may prove extremely valuable for semi-quantitative predictions. © 2004 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A theoretical approach is developed for investigation of diffusion within nanometric or micrometric spherical-type domains limited by two types of active interfaces. Typical representative examples of either system consist in: (a) insoluble droplets (defined by spherical cupolas) of electroactive liquids or redox dendrimers adsorbed onto an electrode surface placed in an electrolyte or (b) biological vesicles during exocytotic release occurring in living cells. In situation (a), the active interface is an infinitely small ring defined along the triple-phase interface at the junction between the droplet surface, the electrode surface, and the electrolyte. In situation (b), the interface is a nanometric pore connecting the inside of the vesicle to the outer medium. Either situation imposes extremely difficult conditions for modeling the diffusional behavior of these two systems because of: (a) the conflicting symmetries between the spherical domains shapes vis-à-vis the pore or ring active interface which acts as a diffusional sink or a source and (b) the near-infinite and heterogeneous concentration gradients which develop at the active interface. Despite these intrinsic severe difficulties, introducing an original conformal mapping transform leads to a great simplification of the numerical solution of diffusional problems. This allows the development of fast and extremely precise simulations of the problem at hand. The efficiency of the simulations is tested in each case by imposing diffusion-controlled conditions so as to examine situations which enhance the intrinsic difficulties of the problems. In this first part, only diffusion within the inner domain defined by the vesicle or the droplet is considered in simulations since this is the domain in which the most difficult diffusional situations occur, but the general theory developed encompasses the most global circumstances, viz., when diffusion in both the inner and outer domains controls the system's behavior and when generalized Butler-Volmer-type kinetics apply at the active interface. It is also shown that this conformal mapping approach leads to the design of a one-dimensional approximation which provides results accurate within a few percent compared to the full treatment of the system. Such equivalence, which is reminiscent of the hemisphere-disk or hemicylinder-band equivalence at ultramicroelectrodes, provides efficient and accurate simulations of the system at hand and may prove extremely valuable for semi-quantitative predictions. © 2004 Elsevier B.V. All rights reserved. |
2004 |
Simulation of diffusion-convection processes in microfluidic channels equipped with double band microelectrode assemblies: Approach through quasi-conformal mapping Article de journal C Amatore; A Oleinick; I Svir Electrochemistry Communications, 6 (11), p. 1123–1130, 2004. @article{Amatore:2004d, title = {Simulation of diffusion-convection processes in microfluidic channels equipped with double band microelectrode assemblies: Approach through quasi-conformal mapping}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-5644232082&doi=10.1016%2fj.elecom.2004.09.002&partnerID=40&md5=49a367670887390269d4106fa2767587}, doi = {10.1016/j.elecom.2004.09.002}, year = {2004}, date = {2004-01-01}, journal = {Electrochemistry Communications}, volume = {6}, number = {11}, pages = {1123--1130}, abstract = {Two different applications of conformal mapping approaches are proposed for the treatment of double band assemblies operating in a microfluidic channel: (i) a quasi-conformal map for the numerical simulation of diffusion-convection processes occurring when the channel is submitted to a microfluidic flow, and (ii) a conformal map specifically designed for obtaining the steady-state analytical solution for the pure diffusional regime (i.e., without flow) within the same channel. The latter applies also when such assemblies perform within a thin film of electrolyte. The results are presented for a generator-collector operation of the assemblies but the methods apply also to other situations (e.g., generator-generator mode). © 2004 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two different applications of conformal mapping approaches are proposed for the treatment of double band assemblies operating in a microfluidic channel: (i) a quasi-conformal map for the numerical simulation of diffusion-convection processes occurring when the channel is submitted to a microfluidic flow, and (ii) a conformal map specifically designed for obtaining the steady-state analytical solution for the pure diffusional regime (i.e., without flow) within the same channel. The latter applies also when such assemblies perform within a thin film of electrolyte. The results are presented for a generator-collector operation of the assemblies but the methods apply also to other situations (e.g., generator-generator mode). © 2004 Elsevier B.V. All rights reserved. |
Simulation of diffusion at microring electrodes through conformal mapping Article de journal C Amatore; A Oleinick; I Svir Journal of Electroanalytical Chemistry, 564 (1-2), p. 245–260, 2004. @article{Amatore:2004c, title = {Simulation of diffusion at microring electrodes through conformal mapping}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-1342285686&doi=10.1016%2fj.jelechem.2003.10.016&partnerID=40&md5=5390dc1e1d1735d7d7ee53c6fcd9d63d}, doi = {10.1016/j.jelechem.2003.10.016}, year = {2004}, date = {2004-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {564}, number = {1-2}, pages = {245--260}, abstract = {Predicting diffusion at ring electrodes of any thickness poses a specific series of difficulties owing to the fact that on the one hand, ring electrodes resemble disk electrodes (thick rings) and on the other hand, they resemble band electrodes (thin rings). These difficulties are imposed onto any simulation program designed to determine accurately the concentration profiles and henceforth chronoamperometric or voltammetric currents at ring electrodes. In this article, we show that all these intrinsic difficulties are de facto resolved simply by employing a new conformal mapping approach for simulation of the diffusional problems at a ring electrode. This method affords precise and effective solutions, though the computation time remains extremely modest. The speed of the numerical solutions may be even boosted by using a non-uniform exponentially expanding time grid, which is also described in this article. © 2003 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Predicting diffusion at ring electrodes of any thickness poses a specific series of difficulties owing to the fact that on the one hand, ring electrodes resemble disk electrodes (thick rings) and on the other hand, they resemble band electrodes (thin rings). These difficulties are imposed onto any simulation program designed to determine accurately the concentration profiles and henceforth chronoamperometric or voltammetric currents at ring electrodes. In this article, we show that all these intrinsic difficulties are de facto resolved simply by employing a new conformal mapping approach for simulation of the diffusional problems at a ring electrode. This method affords precise and effective solutions, though the computation time remains extremely modest. The speed of the numerical solutions may be even boosted by using a non-uniform exponentially expanding time grid, which is also described in this article. © 2003 Elsevier B.V. All rights reserved. |
Efficient quasi-conformal map for simulation of diffusion at disk microelectrodes Article de journal A Oleinick; C Amatore; I Svir Electrochemistry Communications, 6 (6), p. 588–594, 2004. @article{Oleinick:2004, title = {Efficient quasi-conformal map for simulation of diffusion at disk microelectrodes}, author = {A Oleinick and C Amatore and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-2442607712&doi=10.1016%2fj.elecom.2004.04.010&partnerID=40&md5=60f1344a8f10e18867ee99de8aac8a2a}, doi = {10.1016/j.elecom.2004.04.010}, year = {2004}, date = {2004-01-01}, journal = {Electrochemistry Communications}, volume = {6}, number = {6}, pages = {588--594}, abstract = {A new quasi-conformal map for simulation of electrochemical problems at a microdisk electrode is proposed. This map allows to conduct the presently most efficient and accurate simulations based on their comparison with reported analytical solutions. The origin of the advantages of this transform compared to the three previous maps already proposed is discussed. This allows also a classification of the four transforms according to their intrinsic properties and to their advantages in terms of accuracy and efficiency for finite differences simulations. © 2004 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new quasi-conformal map for simulation of electrochemical problems at a microdisk electrode is proposed. This map allows to conduct the presently most efficient and accurate simulations based on their comparison with reported analytical solutions. The origin of the advantages of this transform compared to the three previous maps already proposed is discussed. This allows also a classification of the four transforms according to their intrinsic properties and to their advantages in terms of accuracy and efficiency for finite differences simulations. © 2004 Elsevier B.V. All rights reserved. |
2003 |
Simulation of the double hemicylinder generator-collector assembly through conformal mapping technique Article de journal C Amatore; A I Oleinick; I B Svir Journal of Electroanalytical Chemistry, 553 (SUPPL.), p. 49–61, 2003. @article{Amatore:2003h, title = {Simulation of the double hemicylinder generator-collector assembly through conformal mapping technique}, author = {C Amatore and A I Oleinick and I B Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0042191903&doi=10.1016%2fS0022-0728%2803%2900269-9&partnerID=40&md5=9bb2cfbc18670431dcbdd6e72d3f6039}, doi = {10.1016/S0022-0728(03)00269-9}, year = {2003}, date = {2003-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {553}, number = {SUPPL.}, pages = {49--61}, abstract = {A conformal mapping technique ideally suited for the numerical simulation of double hemicylinder parallel-electrode assemblies is presented. This transform is shown to allow precise and fast simulations of their behavior when they perform in the generator-collector mode. This is thoroughly established for chronoamperometric experiments but the slight modifications required to treat voltammetry are also presented. Furthermore it permits the derivation of an analytical formulation of the generator and collector currents under steady-state. This allows one to compare the response at double-hemicylinder and double-band generator-collector assemblies, and hence to evaluate the effect of electrode protuberance on the electrochemical response. The same conformal transform is also used for the simulation of the single hemicylindrical electrode chronoamperometric behavior. The ensuing results are tested against Szabo's empirical analytical expression and the agreement found to be excellent. © 2003 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A conformal mapping technique ideally suited for the numerical simulation of double hemicylinder parallel-electrode assemblies is presented. This transform is shown to allow precise and fast simulations of their behavior when they perform in the generator-collector mode. This is thoroughly established for chronoamperometric experiments but the slight modifications required to treat voltammetry are also presented. Furthermore it permits the derivation of an analytical formulation of the generator and collector currents under steady-state. This allows one to compare the response at double-hemicylinder and double-band generator-collector assemblies, and hence to evaluate the effect of electrode protuberance on the electrochemical response. The same conformal transform is also used for the simulation of the single hemicylindrical electrode chronoamperometric behavior. The ensuing results are tested against Szabo's empirical analytical expression and the agreement found to be excellent. © 2003 Elsevier B.V. All rights reserved. |
Theory of transient and steady-state ECL generation at double-hemicylinder assemblies using conformal mapping and simulations Article de journal C Amatore; A Oleinick; I Svir Electrochemistry Communications, 5 (12), p. 989–994, 2003. @article{Amatore:2003i, title = {Theory of transient and steady-state ECL generation at double-hemicylinder assemblies using conformal mapping and simulations}, author = {C Amatore and A Oleinick and I Svir}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0242441651&doi=10.1016%2fj.elecom.2003.09.011&partnerID=40&md5=6eaf0693daea3aacd0469b7856601b41}, doi = {10.1016/j.elecom.2003.09.011}, year = {2003}, date = {2003-01-01}, journal = {Electrochemistry Communications}, volume = {5}, number = {12}, pages = {989--994}, abstract = {Rigorous analytical expressions for steady-state currents and electrogenerated chemiluminescence (ECL) intensities are derived for two-hemicylinder assemblies operating in the ECL generation mode based on a specific conformal mapping transform. This transform is also used for fast and accurate simulations of transient currents and ECL intensities leading to an excellent agreement at long times with the analytical steady state solutions. These results are compared to those relative to two-band assemblies to investigate the effect of hemicylindrical electrode protuberance on ECL efficiencies. This evidence that electrode protuberance results in a drastic increase of the ECL generation and shortening of commutation times when the gap is not too large as compared to the electrode radii. © 2003 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Rigorous analytical expressions for steady-state currents and electrogenerated chemiluminescence (ECL) intensities are derived for two-hemicylinder assemblies operating in the ECL generation mode based on a specific conformal mapping transform. This transform is also used for fast and accurate simulations of transient currents and ECL intensities leading to an excellent agreement at long times with the analytical steady state solutions. These results are compared to those relative to two-band assemblies to investigate the effect of hemicylindrical electrode protuberance on ECL efficiencies. This evidence that electrode protuberance results in a drastic increase of the ECL generation and shortening of commutation times when the gap is not too large as compared to the electrode radii. © 2003 Elsevier B.V. All rights reserved. |