Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was inves... more Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was investigated by means of scanning probe microscopy. Under high relative humidity, above 95%, the presence of water droplets was observed on domain surfaces. The droplets were up to 20 nm high and their morphology changed when electrical field was applied between the single crystal substrates and droplets via scanning probe microscopy. With an electric field applied parallel to the (001) top surface, the droplets on c domains spread out, followed by complete recovery upon switching the electric field off. However, few droplets on a domains tend to shrink with the electrical field application. It is shown that the screening surface charges and induced charges on droplets surface play a dominant role in droplets behavior.
ABSTRACT Electrowetting is the change in apparent surface energy of a liquid in an applied electr... more ABSTRACT Electrowetting is the change in apparent surface energy of a liquid in an applied electric field. It has shown great promise in diverse applications including lab-on-a-chip and electronic displays. The electrowetting response is typically considered independent of the actuation voltage polarity. This paper describes a new approach that achiees actuation in different directions for positive and negative voltage polarities using the electrochemical characteristics of aluminum electrodes. This paper presents a concept for continuous actuation of a droplet using a single electrode and DC voltage based on this effect. Initial experiments demonstrate that droplet motion is possible. Measurements of voltage drop across aluminum electrodes confirms the polarity-dependent response of the electrodes.
PurposeThe aim of this paper is to show that the use of energy distribution plot (EDP), usually e... more PurposeThe aim of this paper is to show that the use of energy distribution plot (EDP), usually employed by researchers to characterize the behavior of electrochemical signals in the framework of wavelet transform, could provide better understanding of the electrochemical behavior of a corroding surface if used along with the plot that is obtained from the standard deviation (SD) of partial signals (SDPS). A partial signal (PS) is obtained by limiting the inverse discrete wavelet transform to one crystal, and hence an SDPS is obtained by computing the SD of the corresponding PS.Design/methodology/approachThe electrochemical current signals, obtained from two identical working electrodes (carbon steel electrodes) exposed to simulated concrete pore solution, sparged simultaneously with SO2 and CO2 were studied using wavelet transforms.FindingsThe results show two steps of passive oxide layer formation: formation of defective passive oxide layer, and strengthening of the passive oxide ...
PurposeOne way to analyze electrochemical signals is the wavelet transform, which transforms a si... more PurposeOne way to analyze electrochemical signals is the wavelet transform, which transforms a signal into another representation whereby the signal information is presented in a multi‐scale manner. Using the inverse wavelet transform, it is also possible to split a signal into different components of different frequency intervals. The inverse wavelet transform is the concept underpinning this paper, the aim of which is to demonstrate that high‐frequency variations in current signals are as valuable as low‐frequency variations.Design/methodology/approachThe set‐up for the experiments carried out consisted of two identical carbon steel working electrodes exposed to simulated concrete pore solution, sparged simultaneously with SO2 and CO2. The corresponding electrochemical current signal was studied using wavelet transform.FindingsHigh‐frequency components of current signals are as informative as low‐frequency components. High‐frequency variations could show some electrochemical activ...
This work presents an electrowetting system in which the actuation direction depends on the polar... more This work presents an electrowetting system in which the actuation direction depends on the polarity of the applied voltage. Since electrowetting response depends on the voltage squared, it is typically independent of voltage sign to first order. However, the introduction of an electrochemical diode into the equivalent electrical circuit permits polarity-dependent behavior. Electrochemical diodes were created by making holes in the dielectric. The aluminum electrodes passivate and prevent current flow in one direction, creating diodelike electrical behavior with high breakdown voltage. The resulting actuation forces were directly measured and are of comparable magnitude for both actuation directions.
Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cyto... more Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cytop surface, without electrical connection to the substrate. The effect is caused by the charge separation in the floating electrode. A highly resistive thermally grown SiO2 layer underneath the Cytop enables the droplet to hold charges without leakage, which is the key contribution. Electrowetting with a SiO2 layer shows a memory effect, where the wetting angle stays the same after the auxiliary electrode is removed from the droplet in both conventional and floating electrode electrowetting. Floating electrode electrowetting provides an alternative configuration for developing advanced electrowetting-based devices.
Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was inves... more Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was investigated by means of scanning probe microscopy. Under high relative humidity, above 95%, the presence of water droplets was observed on domain surfaces. The droplets were up to 20 nm high and their morphology changed when electrical field was applied between the single crystal substrates and droplets via scanning probe microscopy. With an electric field applied parallel to the (001) top surface, the droplets on c domains spread out, followed by complete recovery upon switching the electric field off. However, few droplets on a domains tend to shrink with the electrical field application. It is shown that the screening surface charges and induced charges on droplets surface play a dominant role in droplets behavior.
ABSTRACT Electrowetting is the change in apparent surface energy of a liquid in an applied electr... more ABSTRACT Electrowetting is the change in apparent surface energy of a liquid in an applied electric field. It has shown great promise in diverse applications including lab-on-a-chip and electronic displays. The electrowetting response is typically considered independent of the actuation voltage polarity. This paper describes a new approach that achiees actuation in different directions for positive and negative voltage polarities using the electrochemical characteristics of aluminum electrodes. This paper presents a concept for continuous actuation of a droplet using a single electrode and DC voltage based on this effect. Initial experiments demonstrate that droplet motion is possible. Measurements of voltage drop across aluminum electrodes confirms the polarity-dependent response of the electrodes.
PurposeThe aim of this paper is to show that the use of energy distribution plot (EDP), usually e... more PurposeThe aim of this paper is to show that the use of energy distribution plot (EDP), usually employed by researchers to characterize the behavior of electrochemical signals in the framework of wavelet transform, could provide better understanding of the electrochemical behavior of a corroding surface if used along with the plot that is obtained from the standard deviation (SD) of partial signals (SDPS). A partial signal (PS) is obtained by limiting the inverse discrete wavelet transform to one crystal, and hence an SDPS is obtained by computing the SD of the corresponding PS.Design/methodology/approachThe electrochemical current signals, obtained from two identical working electrodes (carbon steel electrodes) exposed to simulated concrete pore solution, sparged simultaneously with SO2 and CO2 were studied using wavelet transforms.FindingsThe results show two steps of passive oxide layer formation: formation of defective passive oxide layer, and strengthening of the passive oxide ...
PurposeOne way to analyze electrochemical signals is the wavelet transform, which transforms a si... more PurposeOne way to analyze electrochemical signals is the wavelet transform, which transforms a signal into another representation whereby the signal information is presented in a multi‐scale manner. Using the inverse wavelet transform, it is also possible to split a signal into different components of different frequency intervals. The inverse wavelet transform is the concept underpinning this paper, the aim of which is to demonstrate that high‐frequency variations in current signals are as valuable as low‐frequency variations.Design/methodology/approachThe set‐up for the experiments carried out consisted of two identical carbon steel working electrodes exposed to simulated concrete pore solution, sparged simultaneously with SO2 and CO2. The corresponding electrochemical current signal was studied using wavelet transform.FindingsHigh‐frequency components of current signals are as informative as low‐frequency components. High‐frequency variations could show some electrochemical activ...
This work presents an electrowetting system in which the actuation direction depends on the polar... more This work presents an electrowetting system in which the actuation direction depends on the polarity of the applied voltage. Since electrowetting response depends on the voltage squared, it is typically independent of voltage sign to first order. However, the introduction of an electrochemical diode into the equivalent electrical circuit permits polarity-dependent behavior. Electrochemical diodes were created by making holes in the dielectric. The aluminum electrodes passivate and prevent current flow in one direction, creating diodelike electrical behavior with high breakdown voltage. The resulting actuation forces were directly measured and are of comparable magnitude for both actuation directions.
Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cyto... more Floating electrode electrowetting is caused by dc voltage applied to a liquid droplet on the Cytop surface, without electrical connection to the substrate. The effect is caused by the charge separation in the floating electrode. A highly resistive thermally grown SiO2 layer underneath the Cytop enables the droplet to hold charges without leakage, which is the key contribution. Electrowetting with a SiO2 layer shows a memory effect, where the wetting angle stays the same after the auxiliary electrode is removed from the droplet in both conventional and floating electrode electrowetting. Floating electrode electrowetting provides an alternative configuration for developing advanced electrowetting-based devices.
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Papers by Mehdi Khodayari