Bubble Manipulation Driven by Alternating Current Electrowetting: Oscillation Modes and Surface Detachment.
Langmuir
; 37(23): 6898-6904, 2021 Jun 15.
Article
in En
| MEDLINE
| ID: mdl-34060843
ABSTRACT
In this paper, a millimeter-sized bubble in water pending on a substrate is manipulated by applying an alternating current (AC) electric field, known as electrowetting on dielectric. In this setup, standing waves on the bubble surface are observed. The amplitude of these waves varies with frequency, and three resonance peaks (21, 76, and 134 Hz) can be identified. By incorporating the nonlinear friction force for the contact line to an existing surface mode model, a significant improvement to explain the spectrum of the oscillations is obtained, predicting three peak positions, widths, and heights with good accuracy. We also show that bubble detachment correlates with the low-frequency resonance peak. It is found experimentally that if close enough to this peak, then bubbles at sufficiently high voltages are observed to detach from the substrate. This suggests that inertial effects can effectively promote bubble detachment. To confirm this hypothesis, the bubble dynamics is simulated with COMSOL using the full Navier-Stokes equation with a two-phase field and electrostatic stresses. It was found that the bubble experimental detachment process is quite well-reproduced in the simulation, confirming the role of fluid inertia for the detachment process. Given the nice correspondence between the experimental state diagrams and the theoretical modeling, this work contributes to identify a window for precise and reliable bubble manipulation by means of AC electrowetting.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Type of study:
Prognostic_studies
Language:
En
Journal:
Langmuir
Journal subject:
QUIMICA
Year:
2021
Document type:
Article