scholarly journals Capacitance Effects of a Hydrophobic-Coated Ion Gel Dielectric on AC Electrowetting

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 320
Author(s):  
Taewoo Lee ◽  
Sung-Yong Park
Keyword(s):  
Contact Angle ◽  
Experimental Studies ◽  
Frequency Region ◽  
Mixing Enhancement ◽  
High Capacitance ◽  
Angle Change ◽  
Gel Layer ◽  
Resonance Frequencies ◽  
Ion Gel ◽  
Capacitance Effects

We present experimental studies of alternating current (AC) electrowetting dominantly influenced by several unique characteristics of an ion gel dielectric in its capacitance. At a high-frequency region above 1 kHz, the droplet undergoes the contact angle modification. Due to its high-capacitance characteristic, the ion gel allows the contact angle change as large as Δθ = 26.4°, more than 2-fold improvement, compared to conventional dielectrics when f = 1 kHz. At the frequency range from 1 to 15 kHz, the capacitive response of the gel layer dominates and results in a nominal variation in the angle change as θ ≈ 90.9°. Above 15 kHz, such a capacitive response of the gel layer sharply decreases and leads to the drastic increase in the contact angle. At a low-frequency region below a few hundred Hz, the droplet’s oscillation relying on the AC frequency applied was mainly observed and oscillation performance was maximized at corresponding resonance frequencies. With the high-capacitance feature, the ion gel significantly enlarges the oscillation performance by 73.8% at the 1st resonance mode. The study herein on the ion gel dielectric will help for various AC electrowetting applications with the benefits of mixing enhancement, large contact angle modification, and frequency-independent control.

A model to predict the oscillation frequency for drops pinned on a vertical planar surface

2021 ◽  
Vol 928 ◽  
Author(s):  
J. Sakakeeny ◽  
C. Deshpande ◽  
S. Deb ◽  
J.L. Alvarado ◽  
Y. Ling
Keyword(s):  
Contact Angle ◽  
Oscillation Frequency ◽  
Experimental Studies ◽  
Natural Oscillation ◽  
Bond Number ◽  
Equilibrium Contact Angle ◽  
Planar Surface ◽  
Lateral Oscillation ◽  
Resonance Frequencies ◽  
Oscillation Dynamics

Accurate prediction of the natural frequency for the lateral oscillation of a liquid drop pinned on a vertical planar surface is important to many drop applications. The natural oscillation frequency, normalized by the capillary frequency, is mainly a function of the equilibrium contact angle and the Bond number ( $Bo$ ), when the contact lines remain pinned. Parametric numerical and experimental studies have been performed to establish a comprehensive understanding of the oscillation dynamics. An inviscid model has been developed to predict the oscillation frequency for wide ranges of $Bo$ and the contact angle. The model reveals the scaling relation between the normalized frequency and $Bo$ , which is validated by the numerical simulation results. For a given equilibrium contact angle, the lateral oscillation frequency decreases with $Bo$ , implying that resonance frequencies will be magnified if the drop oscillations occur in a reduced gravity environment.

scholarly journals Effect of ethanol post-treatment on the bubble-electrospun poly(vinyl alcohol) nanofiber

2015 ◽  
Vol 19 (4) ◽  
pp. 1353-1356 ◽  
Author(s):  
Jiang-Hui Zhao ◽  
Lan Xu ◽  
Qixia Liu
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Vinyl Alcohol ◽  
Post Treatment ◽  
Poly Vinyl Alcohol ◽  
Water Contact ◽  
Angle Change ◽  
Potential Benefits

Poly(vinyl alcohol) nanofibers were prepared by bubble electrospinning. After the ethanol post-treatment, poly(vinyl alcohol) nanofibers showed enhanced hydrophobicity with water contact angle change from 0 to 78.9?, and the break strength of poly(vinyl alcohol) nanofibers was dramatically improved from 8.23 MPa to 17.36 MPa. The facile strategy with improved hydrophobicity and mechanical properties of poly(vinyl alcohol) nanofibers will provide potential benefits for applications of this material, especially in filtration field.

scholarly journals Increasing Damping of Thin-Walled Structures Using Additively Manufactured Vibration Eliminators

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2125 ◽  
Author(s):  
Paweł Dunaj ◽  
Stefan Berczyński ◽  
Karol Miądlicki ◽  
Izabela Irska ◽  
Beata Niesterowicz
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Steel Beam ◽  
Finite Element Models ◽  
Fem Model ◽  
Thin Walled Structures ◽  
Resonance Frequencies ◽  
Thin Walled ◽  
Parametric Analyses

The paper presents a new way to conduct passive elimination of vibrations consisting of covering elements of structures with low dynamic stiffness with polylactide (PLA). The PLA cover was created in 3D printing technology. The PLA cover was connected with the structure by means of a press connection. Appropriate arrangement of the PLA cover allows us to significantly increase the dissipation properties of the structure. The paper presents parametric analyses of the influence of the thickness of the cover and its distribution on the increase of the dissipation properties of the structure. Both analyses were carried out using finite element models (FEM). The effectiveness of the proposed method of increasing damping and the accuracy of the developed FEM models was verified by experimental studies. As a result, it has been proven that the developed FEM model of a free-free steel beam covered with polylactide enables the mapping of resonance frequencies at a level not exceeding 0.6% of relative error. Therefore, on its basis, it is possible to determine the parameters of the PLA cover. Comparing a free-free steel beam without cover with its PLA-covered counterpart, a reduction in the amplitude levels of the receptance function was achieved by up to 90%. The solution was validated for a steel frame for which a 37% decrease in the amplitude of the receptance function was obtained.

Perfect metamaterial absorbers with polarization angle independency in X-band waveguide

2016 ◽  
Vol 30 (11) ◽  
pp. 1650186 ◽  
Author(s):  
Cumali Sabah
Keyword(s):  
Wireless Communication ◽  
Frequency Region ◽  
Polarization Angle ◽  
Perfect Absorption ◽  
Band Frequency ◽  
X Band ◽  
Resonance Frequencies ◽  
Metamaterial Absorbers ◽  
Space Boundary

The design and characterization of perfect metamaterial absorbers (MAs) based on simple configurations including square- and triangle-shapes, which operate in X-band frequency region are numerically and experimentally investigated. The proposed MAs provide perfect absorption with the polarization angle independency. In X-band waveguide, the absorption rates are 99.69% and 99.97% at the resonance frequencies of 10.57 GHz and 10.93 GHz for the square- and triangle-shaped MAs, respectively. In addition, the same configurations are numerically tested under free space boundary conditions to compare and discuss the obtained results. The suggested MAs enable myriad potential application areas for security and stealth technologies in X-band including wireless communication.

Numerical and Experimental Studies of Pendulum Dynamic Vibration Absorber for Structural Vibration

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Seon Il Ha ◽  
Gil Ho Yoon
Keyword(s):  
Experimental Studies ◽  
Point Of View ◽  
Structural Vibration ◽  
Vibration Absorber ◽  
Square Root ◽  
Vibration Absorbers ◽  
Structural Vibrations ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Resonance Frequencies

Abstract This research presents a pendulum dynamic vibration absorber (PDVA) consisting of a spring and a mass in order to attenuate structural vibrations at two frequencies of hosting structure. It is a convention to attach several dynamic absorbers to hosting structure for the sake of the attenuations of structural vibrations at multiple frequencies with enlarged bandwidth and often it increases the total mass and the installation cost. Therefore, the reduction of the number of vibration absorbers for multiple excitation frequencies is an important issue from an engineering point of view. To resolve these difficulties, this study proposes to adopt the vibration absorber framework of the spring-mass vibration as well as the pendulum vibration simultaneously with the present PDVA system. It is composed of a spring and a mass but being allowed to swing circumferentially, the structural vibrations at the two resonance frequencies, i.e., the square root of stiffness over mass and the square root of a length over gravidity, can be simultaneously attenuated. As the length of the spring of the present PDVA is varied, the effective ranges for the pendulum dynamic vibration absorber become widen. To prove the concept of the present PDVA, this research conducts several numerical simulations and experiments.

Finite Element Analysis and Experimental Studies on the Thickness Resonance of Piezocomposite Transducers

1996 ◽  
Vol 18 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Wenkang Qi ◽  
Wenwu Cao
Keyword(s):  
Finite Element ◽  
Resonance Frequency ◽  
Electromechanical Coupling ◽  
Effective Medium Theory ◽  
Experimental Studies ◽  
Effective Medium ◽  
Electromechanical Coupling Coefficient ◽  
Element Analysis ◽  
Medium Theory ◽  
Resonance Frequencies

Finite element method (FEA) has been used to calculate the thickness resonance frequency and electromechanical coupling coefficient kt for 2–2 piezocomposite transducers. The results are compared with that of the effective medium theory and also verified by experiments. It is shown that the predicted resonance frequencies from the effective medium theory and the unit cell modeling using FEA deviate from the experimental observations for composite systems with a ceramic aspect ratio (width/length) more than 0.4. For such systems, full size FEA modeling is required which can provide accurate predictions of the resonance frequency and thickness coupling constant kt.

Electrowetting of Nanofluids Containing Silver Nanoparticles

2008 ◽  
Author(s):  
Leonard Laroque ◽  
Abhishek Jain ◽  
Tie Wang ◽  
Karthik Chinnathambi ◽  
Ganapathiraman Ramanath ◽  
...  
Keyword(s):  
Contact Angle ◽  
Nano Particles ◽  
Voltage Range ◽  
Electrowetting On Dielectric ◽  
Angle Change ◽  
Wide Range ◽  
Fundamental Understanding ◽  
Electro Wetting ◽  
Metal Nano Particles

Application of voltage across a liquid-dielectric interface resulting in the change of fluid contact angle is known as electrowetting on dielectric (EWOD) effect [1]. EWOD actuation is one of the most preferred techniques to move liquid at microscale due to relatively low voltages, low currents and power consumption requirements, and the absence of electrolysis. Our recent work has shown that nanofluids containing semiconductor nanoparticles exhibit a very strong EWOD effect [2, 3]. In particular, in the tested voltage range of 0 to 60 V, nanofluids loaded with molecularly-capped bismuth telluride nanoparticles show enhanced stability and increased actuation range of contact angle change. Developing a fundamental understanding of the role of nanostructure inclusions in controlling and potentially enhancing the EWOD effect would pave the way for the efficient use of EWOD with nanofluids in a wide range or microfluidic applications. Here we extend the studies on the EWOD behavior of nanofluids, to a system containing noble metal nano particles. In this abstract we report the preliminary results of the electro-wetting studies on nanofluids containing silver nano particles.

Sign in / Sign up

Export Citation Format

Share Document