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Rapid Particle Patterning in Surface Deposited Micro-Droplets of Low Ionic Content via Low-Voltage Electrochemistry and Electrokinetics.

Sidelman N, Cohen M, Kolbe A, Zalevsky Z, Herrman A, Richter S - Sci Rep (2015)

Bottom Line: However, the use of DC-induced electrokinetics in miniaturized devices is highly limited.We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis.This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering Faculty of Engineering &University Center for Nano Science and Nanotechnology Tel Aviv University, Tel-Aviv, 69978, Israel.

ABSTRACT
Electrokinetic phenomena are a powerful tool used in various scientific and technological applications for the manipulation of aqueous solutions and the chemical entities within them. However, the use of DC-induced electrokinetics in miniaturized devices is highly limited. This is mainly due to unavoidable electrochemical reactions at the electrodes, which hinder successful manipulation. Here we present experimental evidence that on-chip DC manipulation of particles between closely positioned electrodes inside micro-droplets can be successfully achieved, and at low voltages. We show that such manipulation, which is considered practically impossible, can be used to rapidly concentrate and pattern particles in 2D shapes in inter-electrode locations. We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis. This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning.

No MeSH data available.


Top: The equivalent electrical circuit of a two-electrode cell.Cdl and RF– the electric double layer capacitance and the faradaic resistance of the electrode-solution interface. Rs– the solution resistance. Bottom: The chronoamperograms of TiO2 particles in a droplet of ddH2O at 1.5 V (black) and 2.0 V (red).
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f3: Top: The equivalent electrical circuit of a two-electrode cell.Cdl and RF– the electric double layer capacitance and the faradaic resistance of the electrode-solution interface. Rs– the solution resistance. Bottom: The chronoamperograms of TiO2 particles in a droplet of ddH2O at 1.5 V (black) and 2.0 V (red).

Mentions: As previously described, water electrolysis is considered an unavoidable hindrance in DC-EKP. Yet, some sort of an electrochemical reaction at the electrodes is essential for DC-EKP to take place. In order for long-lasting EKP to occur, there must be a sustained and significant voltage drop across the droplet. As the model of electrode-solution interface (Fig. 3 top) describes11, This can occur only when there is charge transfer across the interface, i.e. when a faradaic reaction occurs.


Rapid Particle Patterning in Surface Deposited Micro-Droplets of Low Ionic Content via Low-Voltage Electrochemistry and Electrokinetics.

Sidelman N, Cohen M, Kolbe A, Zalevsky Z, Herrman A, Richter S - Sci Rep (2015)

Top: The equivalent electrical circuit of a two-electrode cell.Cdl and RF– the electric double layer capacitance and the faradaic resistance of the electrode-solution interface. Rs– the solution resistance. Bottom: The chronoamperograms of TiO2 particles in a droplet of ddH2O at 1.5 V (black) and 2.0 V (red).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543935&req=5

f3: Top: The equivalent electrical circuit of a two-electrode cell.Cdl and RF– the electric double layer capacitance and the faradaic resistance of the electrode-solution interface. Rs– the solution resistance. Bottom: The chronoamperograms of TiO2 particles in a droplet of ddH2O at 1.5 V (black) and 2.0 V (red).
Mentions: As previously described, water electrolysis is considered an unavoidable hindrance in DC-EKP. Yet, some sort of an electrochemical reaction at the electrodes is essential for DC-EKP to take place. In order for long-lasting EKP to occur, there must be a sustained and significant voltage drop across the droplet. As the model of electrode-solution interface (Fig. 3 top) describes11, This can occur only when there is charge transfer across the interface, i.e. when a faradaic reaction occurs.

Bottom Line: However, the use of DC-induced electrokinetics in miniaturized devices is highly limited.We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis.This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering Faculty of Engineering &University Center for Nano Science and Nanotechnology Tel Aviv University, Tel-Aviv, 69978, Israel.

ABSTRACT
Electrokinetic phenomena are a powerful tool used in various scientific and technological applications for the manipulation of aqueous solutions and the chemical entities within them. However, the use of DC-induced electrokinetics in miniaturized devices is highly limited. This is mainly due to unavoidable electrochemical reactions at the electrodes, which hinder successful manipulation. Here we present experimental evidence that on-chip DC manipulation of particles between closely positioned electrodes inside micro-droplets can be successfully achieved, and at low voltages. We show that such manipulation, which is considered practically impossible, can be used to rapidly concentrate and pattern particles in 2D shapes in inter-electrode locations. We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis. This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning.

No MeSH data available.