Micropumping by Electrowetting

2001 ◽  
Author(s):  
Chang-Jin “CJ” Kim
Keyword(s):  
Surface Tension ◽  
Recent Effort ◽  
Different Types ◽  
Digital Microfluidic

Abstract This paper introduces the recent effort to use surface tension in MEMS, especially, to use electrowetting for efficient pumping in microfluidics. Importance of surface tension in microscale is explained, and examples of utilizing it to design microdevices are presented. Development of several devices employing different types of electrowetting is explained. Empowered by the efficient pumping by electrowetting microactuation, a programmable digital microfluidic circuit chip is proposed.

scholarly journals Interactions between an Associative Amphiphilic Block Polyelectrolyte and Surfactants in Water: Effect of Charge Type on Solution Properties and Aggregation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1729
Author(s):  
Patrizio Raffa
Keyword(s):  
Surface Tension ◽  
Self Assembly ◽  
Interaction Model ◽  
Industrial Applications ◽  
Molecular Organization ◽  
Different Types ◽  
Solution Rheology ◽  
Interesting Class ◽  
First Time

The study of interactions between polyelectrolytes (PE) and surfactants is of great interest for both fundamental and applied research. These mixtures can represent, for example, models of self-assembly and molecular organization in biological systems, but they are also relevant in industrial applications. Amphiphilic block polyelectrolytes represent an interesting class of PE, but their interactions with surfactants have not been extensively explored so far, most studies being restricted to non-associating PE. In this work, interactions between an anionic amphiphilic triblock polyelectrolyte and different types of surfactants bearing respectively negative, positive and no charge, are investigated via surface tension and solution rheology measurements for the first time. It is evidenced that the surfactants have different effects on viscosity and surface tension, depending on their charge type. Micellization of the surfactant is affected by the presence of the polymer in all cases; shear viscosity of polymer solutions decreases in presence of the same charge or nonionic surfactants, while the opposite charge surfactant causes precipitation. This study highlights the importance of the charge type, and the role of the associating hydrophobic block in the PE structure, on the solution behavior of the mixtures. Moreover, a possible interaction model is proposed, based on the obtained data.

Effect of surfactants on capacitance properties of carbon electrodes

2011 ◽  
Vol 1333 ◽  
Author(s):  
Krzysztof Fic ◽  
Grzegorz Lota ◽  
Elzbieta Frackowiak
Keyword(s):  
Surface Tension ◽  
Alkaline Solution ◽  
Surfactant Concentration ◽  
Alkaline Solutions ◽  
Carbon Electrodes ◽  
Current Load ◽  
Target Concentration ◽  
Electrolyte Additives ◽  
Different Types ◽  
Triton X

ABSTRACTEffect of surfactants present in alkaline solutions on the capacitance of carbon electrodes has been studied. Different types of surfactants have been selected for this target. Concentration of these electrolyte additives was 0.005 mol L-1. Decreasing the surface tension in the electrode/electrolyte interface allows better penetration of electrolyte into the pores. Detailed analysis of capacitance versus current load, frequency dependence as well as self-discharge, cyclability and behaviour in wider voltage window proved a useful effect of Triton X-100 on capacitor operating in alkaline solution. Influence of surfactant concentration has also been investigated.

WRINKLING ATOP SHAPE MEMORY MATERIALS

2012 ◽  
Vol 19 (02) ◽  
pp. 1250010 ◽  
Author(s):  
L. SUN ◽  
Y. ZHAO ◽  
W. M. HUANG ◽  
H. PURNAWALI ◽  
Y. Q. FU
Keyword(s):  
Surface Tension ◽  
Surface Roughness ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Patterned Surfaces ◽  
Advantages And Disadvantages ◽  
Different Types ◽  
Shape Memory Materials ◽  
Processing Techniques

Many surface related properties, such as surface roughness, surface tension and reflection etc are heavily dependent on the surface morphology of materials. Patterned surfaces may have significant effects on these properties. In this paper, we compare wrinkles produced atop three different types of shape memory materials, namely, shape memory alloy, shape memory polymer and shape memory hybrid. We show the advantages and disadvantages of them in terms of the processing techniques and the resultant wrinkle patterns.

The evolution of a viscous thread pulled with a prescribed speed

2016 ◽  
Vol 795 ◽  
pp. 380-408 ◽  
Author(s):  
J. J. Wylie ◽  
B. H. Bradshaw-Hajek ◽  
Y. M. Stokes
Keyword(s):  
Surface Tension ◽  
Critical Exponent ◽  
Large Time ◽  
Asymptotic Form ◽  
Numerical Solutions ◽  
Long Wavelength ◽  
Asymptotic Expressions ◽  
Different Types ◽  
Long Time ◽  
Special Case

We examine the extension of an axisymmetric viscous thread that is pulled at both ends with a prescribed speed such that the effects of inertia are initially small. After neglecting surface tension, we derive a particularly convenient form of the long-wavelength equations that describe long and thin threads. Two generic classes of initial thread shape are considered as well as the special case of a circular cylinder. In these cases, we determine explicit asymptotic solutions while the effects of inertia remain small. We further show that inertia will ultimately become important only if the long-time asymptotic form of the pulling speed is faster than a power law with a critical exponent. The critical exponent can take two possible values depending on whether or not the initial minimum of the thread radius is located at the pulled end. In addition, we obtain asymptotic expressions for the solution at large times in the case in which the critical exponent is exceeded and hence inertia becomes important. Despite the apparent simplicity of the problem, the solutions exhibit a surprisingly rich structure. In particular, in the case in which the initial minimum is not at the pulled end, we show that there are two very different types of solution that exhibit very different extension mechanics. Both the small-inertia solutions and the large-time asymptotic expressions compare well with numerical solutions.

Experimental and Theoretical Approach to Mixed Systems of Non-Ionic Cremophor EL and Cationic Gemini Surfactants in Aqueous Solution

2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Andleeb Z. Naqvi ◽  
Sahar Noori ◽  
Kabir-ud-Din
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
Gemini Surfactants ◽  
Cremophor El ◽  
Practical Applications ◽  
Surfactant Solutions ◽  
Cationic Gemini Surfactants ◽  
Mixing Behavior ◽  
Different Types ◽  
Mixed Systems

AbstractSurfactant solutions in practical applications usually are mixtures of different types, especially ionic and nonionic ones. The mixing behavior of nonionic Cremophor EL-cationic gemini systems was therefore investigated by surface tension measurements. The Gemini surfactants used were of the type alkanediyl –

scholarly journals A contact angle study of different greywater sources with hydrophobic membranes

2020 ◽  
Vol 55 (3) ◽  
pp. 310-326
Author(s):  
Mohammad Ramezanianpour ◽  
Muttucumaru Sivakumar ◽  
Natalie Osborn ◽  
Ying Zhang ◽  
Hakim Kawa
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Pure Water ◽  
Membrane Distillation ◽  
Hydrophobic Membrane ◽  
Flat Sheet ◽  
Hydrophobic Membranes ◽  
Different Types ◽  
The Impact ◽  
Surface Tension Forces

Abstract The wetting phenomenon is a major problem in the membrane distillation (MD) process, and it is the main reason that limits MD being used in wastewater reclamation. Active surfactant in the detergents reduces the contact angle between the liquid and the hydrophobic membrane surface, which could result in wetting. Extensive laboratory research was conducted using commercial hydrophobic flat-sheet membranes to identify the impact of anionic surfactants and surface tension forces on these membranes. The aim of this paper is to find a suitable membrane for pure water production from greywater using MD, as well as to provide a relationship between surfactant concentration and the contact angle for different types of membrane. The absorbance of each sample was measured by a spectrophotometer prior to the contact angle test on four different types of hydrophobic membranes. It was concluded that the polypropylene membrane would be unsuitable for the treatment of greywater directly due to the loss of surface tension forces upon the addition of an anionic surfactant. However, the polytetrafluoroethylene membrane could be effective in this process while the concentration of surfactant in the feed source is kept constant. The results from the experimental tests proposed a relationship between the contact angle of a water droplet on the surface of a flat-sheet membrane and the concentration of surfactant in the solution.

scholarly journals Basic singularities in the theory of internal waves with surface tension

1986 ◽  
Vol 9 (1) ◽  
pp. 145-159
Author(s):  
M. A. Gorgui ◽  
M. S. Faltas
Keyword(s):  
Surface Tension ◽  
Internal Waves ◽  
Constant Depth ◽  
Two Fluids ◽  
Interface Wave ◽  
Different Types ◽  
Superposed Fluids ◽  
Wave Problems ◽  
Effect Of Surface ◽  
Finite Constant

The study of linearized interface wave problems for two superposed fluids often involves the consideration of different types of singularities in one of the two fluids. In this paper the line and point singularities are investigated for the case when each fluid is of finite constant depth. The effect of surface tension at the surface of separation is included.

Multipole expansions for two superposed fluids, each of finite depth

1982 ◽  
Vol 91 (2) ◽  
pp. 323-329 ◽  
Author(s):  
S. E. Kassem
Keyword(s):  
Surface Tension ◽  
Internal Waves ◽  
Finite Depth ◽  
Constant Depth ◽  
Two Fluids ◽  
Different Types ◽  
Multipole Expansions ◽  
Superposed Fluids ◽  
Finite Constant

AbstractProblems dealing with the generation of internal waves at the surface separating two fluids involves the consideration of different types of singularities in one of the two fluids. In this paper the velocity potentials describing line and point multipoles are obtained for the case when each fluid is of finite constant depth, neglecting effects of surface tension at the surface of separation.

scholarly journals Interactions Between an Associative Amphiphilic Block Polyelectrolyte and Surfactants in Water: Effect of Charge Type on Solution Properties and Aggregation

2021 ◽  
Author(s):  
Patrizio Raffa
Keyword(s):  
Surface Tension ◽  
Self Assembly ◽  
Interaction Model ◽  
Industrial Applications ◽  
Molecular Organization ◽  
Different Types ◽  
Solution Rheology ◽  
Interesting Class ◽  
First Time

The study of interactions between polyelectrolytes (PE) and surfactants is of great interest for both fundamental and applied research. These mixtures can represent, for example, models of self-assembly and molecular organization in biological systems, but they are also relevant in industrial applications. Amphiphilic block polyelectrolytes represent an interesting class of PE, but their interactions with surfactants have not been extensively explored so far, most studies being restricted to non-associating PE. In this work, interactions between an anionic amphiphilic triblock polyelectrolyte and different types of surfactants bearing respectively negative, positive and no charge, are investigated via surface tension and solution rheology measurements for the first time. It is evidenced that the surfactants have different effects on viscosity and surface tension, depending on their charge type. Micellization of the surfactant is affected by the presence of the polymer in all cases; shear viscosity of polymer solutions decreases in presence of same charge or nonionic surfactants, while the opposite charge surfactant cause precipitation. This study highlights the importance of the charge type, and the role of the associating hydrophobic block in the PE structure, on the solution behavior of the mixtures. Moreover, a possible interaction model is proposed, based on the obtained data.

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