Ultrafast single-droplet bouncing actuator with electrostatic force on superhydrophobic electrodes

RSC Advances ◽  
2016 ◽  
Vol 6 (71) ◽  
pp. 66729-66737 ◽  
Author(s):  
Seulah Lee ◽  
Sanggeun Lee ◽  
Hyunseok Hwang ◽  
Juree Hong ◽  
Soonil Lee ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Electrostatic Force ◽  
Single Droplet ◽  
Droplet Manipulation ◽  
First Time

The ultrafast bouncing motion of a liquid droplet has been investigated for droplet manipulation with a single droplet actuator using an electrostatic force for the first time.

A Frequency-Tunable Comb Resonator Using Spring Tension and Compression Effects

2004 ◽  
Author(s):  
Ki Bang Lee ◽  
Albert P. Pisano ◽  
Liwei Lin
Keyword(s):  
Resonant Frequency ◽  
Bias Voltage ◽  
Frequency Tuning ◽  
Electrostatic Force ◽  
Voltage Change ◽  
Tension And Compression ◽  
Frequency Tunable ◽  
Frequency Changes ◽  
Compression Effects ◽  
First Time

A 2μm-thick frequency-tunable microresoantor capable of either increasing or decreasing its resonant frequency by a combination of Joule heating and electrostatic force has been successfully demonstrated for the first time. For the heating voltage increase from 0 to 2V under fixed bias voltage of 40V, the resonant frequency changes from 22.2kHz to 16.2kHz, resulting in the 27% reduction in the resonant frequency. For the bias voltage change from 20V to 40V under the heating voltage of 0V, the resonant frequency increase from 19.0kHz to 23.6kHz, resulting in the 24.2% increase in the resonant frequency. As such, this surface-micromachined microactuator could assist complicated frequency tuning for applications of microsensors and microactuators.

DEVELOPMENT OF A NON-CONTINUOUS MICRO-FLOW OPTO-WETTING DROPLET MANIPULATION TECHNOLOGY

2005 ◽  
Vol 17 (06) ◽  
pp. 293-299 ◽  
Author(s):  
MING-YIH LEE ◽  
HUNG-CHIA LIN ◽  
HUNG-WEI CHIANG ◽  
WEI-XUN LEE ◽  
XIAN-DONG HUANG
Keyword(s):  
Surface Tension ◽  
Uv Light ◽  
Liquid Droplet ◽  
Average Particle Size ◽  
Base Material ◽  
Material Surface ◽  
Average Particle ◽  
Hydrophilic Property ◽  
Manipulation System ◽  
Droplet Manipulation

The aim of this study is to develop a non-continuous droplet manipulation technology in contrast to conventional continuous flow micro-fluidic systems. The droplets were manipulated based on the proposed opto-wetting effect. In addition, an experimental ultraviolet (UV) light actuated droplet manipulation system was developed for verifying the opto-wetting droplet manipulation. The proposed opto-wetting effect was achieved by utilizing ultraviolet to activate oxidation-reduction mechanism of nano-TiO2 photo catalyst coated base material. The water-affinity of the base material will changed due to the decreased free-energy of the material surface. Therefore, the contact angle between the liquid droplet and base material will also be changed which facilitates droplet manipulability. The main components of the proposed ultraviolet (UV) light actuated droplet manipulation system include ultraviolet masking device, moving platform and main frame structure. System software and user interface were designed by using Microsoft Visual Basic 6.0 toolkit. Upon completion of the proposed system, experiments were carried out to verify system functionalities. Follow by the controlled variable optimization using Taguchi method and liquid droplet manipulation experiments. The experiment results indicate that by exposure to 6.8mW UV light, the surface tension and hydrophilic property of nano-TiO2 (anatase type, 3.5% concentration, PH 1.5, and with average particle size of 69 nm) coated base material will changed. The change of surface tension and hydrophilic property were critical for droplet manipulation. The moving speed of the liquid droplet was measured as 3.33mm/sec. The results suggest that the opto-wetting system may be effective to overcome the shortcoming of traditional opto-electrowetting technique. The proposed opto-wetting droplet manipulation system could potentially applied for manipulating biomedical or pathological test specimens in the future.

scholarly journals Research on Novel CMUTs for Detecting Micro-Pressure with Ultra-High Sensitivity and Linearity

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1340
Author(s):  
Qi Ding ◽  
Hongliang Wang ◽  
Hanqiang Zhang ◽  
Xiao Huang ◽  
Xiaolei Sun ◽  
...  
Keyword(s):  
Electrostatic Force ◽  
High Sensitivity ◽  
Element Model ◽  
Total Width ◽  
Pressure Sensitivity ◽  
Maximum Displacement ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Design Flexibility ◽  
Combined Action ◽  
First Time

Capacitive micromachined ultrasonic transducers (CMUTs) have been indispensable owing to their resonance characteristics in the MHz frequency range. However, the inferior pressure sensitivity and linearity of traditional CMUTs themselves cannot meet the actual demands of micro-pressure measurements. In this paper, two novel CMUTs are proposed for the first time to improve the measuring performance of micro-pressure in the range of 0–10 kPa. The core concept of the enhancement is strengthening membrane deformability by partly adjusting the CMUT framework under the combined action of electrostatic force and uniform pressure. Two modified structures of an inverted frustum cone-like cavity and slotted membrane are presented, respectively, and a finite element model (FEM) of CMUT was constructed and analyzed using COMSOL Multiphysics 5.5. The results demonstrate that the maximum displacement and pressure sensitivity are improved by 16.01% and 30.79% for the frustum cone-like cavity and 104.22% and 1861.31% for the slotted membrane, respectively. Furthermore, the results show that the width uniformity of the grooves does not influence the characteristics of the membrane, which mainly depend on the total width of the grooves, greatly enriching design flexibility. In brief, the proposed structural designs can significantly improve the micro-pressure measurement performance of the CMUT, which will accelerate the rapid breakthrough of technical barriers in the fields of aerospace, industry control, and other sensing domains.

Polarization Measurements on Raman Scattering from Spherical Droplets

1992 ◽  
Vol 46 (7) ◽  
pp. 1189-1193 ◽  
Author(s):  
K. H. Fung ◽  
I. N. Tang
Keyword(s):  
Raman Scattering ◽  
Liquid Droplet ◽  
Ion Pairs ◽  
Chemical Characterization ◽  
Incident Beam ◽  
Strontium Nitrate ◽  
Spherical Droplet ◽  
Spherical Droplets ◽  
First Time ◽  
Depolarization Ratios

The polarization of Raman scattering from a single spherical droplet has been measured for the first time. Experiments are performed in a quadrupole cell, in which a charged liquid droplet is trapped by electro-dynamic forces. Raman scattering intensities at the 90° angle are measured for polarizations both parallel and perpendicular to that of the incident beam. The depolarization ratios thus obtained for the droplets are shown to be identical to those measured in the bulk samples. The present results indicate unequivocally that the depolarization ratio of Raman scattering is a molecular property and, as such, is not affected by the boundary conditions of the spherical droplets. Subsequently, the technique is applied to the chemical characterization of solution droplets. The presence of ion pairs in supersaturated strontium nitrate and bisulfate solutions is dramatically verified by distinct changes in the depolarization ratios.

Quantitative Defect Analysis of GaN Thick Films by TEM and AFM

2001 ◽  
Vol 693 ◽  
Author(s):  
Praveena Bhaskara ◽  
Changmo Sung ◽  
David Bliss ◽  
Michael Suscavage
Keyword(s):  
Dislocation Density ◽  
Electrostatic Force ◽  
Current System ◽  
Phase Growth ◽  
Plan View ◽  
Density Measurements ◽  
Force Microscopy ◽  
Gan Crystal ◽  
First Time ◽  
Potential Tool

AbstractEver since the discovery of the astonishing properties of GaN, many research groups have been involved in the processing of the perfect GaN crystal. Iodine Vapor Phase Growth (IVPG) technique was employed to grow GaN epilayer on a MOCVD pre-deposited buffer layer. This new epitaxial system was characterized by TEM, AFM and EFM. A complete AFM study involved the polarity measurements and the etch pit density measurements. For the first time a systematic study was performed of the dislocation density changing as a function of distance from the substrate. TEM performed on the cross-section, as well as the plan view, of the samples showed a remarkable decrease in the dislocations in the current system, compared to the samples that were solely deposited by MOCVD. Advanced analytical methods of polarity and dislocation density measurements have been established to understand the relation between microstructure and electrical properties of the thick film GaN. Electrostatic Force Microscopy has been suggested as a potential tool for obtaining polarity information.

scholarly journals Probing the Evaporation Dynamics of Ethanol/Gasoline Biofuel Blends Using Single Droplet Manipulation Techniques

2015 ◽  
Vol 119 (51) ◽  
pp. 12797-12804 ◽  
Author(s):  
Stella Corsetti ◽  
Rachael E. H. Miles ◽  
Craig McDonald ◽  
Yuri Belotti ◽  
Jonathan P. Reid ◽  
...  
Keyword(s):  
Single Droplet ◽  
Droplet Manipulation ◽  
Evaporation Dynamics

scholarly journals Contact-Mediated Nucleation of Subcooled Droplets in Melt Emulsions: A Microfluidic Approach

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1471
Author(s):  
Gina Kaysan ◽  
Alexander Rica ◽  
Gisela Guthausen ◽  
Matthias Kind
Keyword(s):  
Surfactant Concentration ◽  
Liquid Droplet ◽  
Continuous Phase ◽  
Single Droplet ◽  
Crystalline Particle ◽  
Subcooled Liquid ◽  
Stable Product ◽  
High Concentrations ◽  
The Impact ◽  
Successful Inoculation

The production of melt emulsions is mainly influenced by the crystallization step, as every single droplet needs to crystallize to obtain a stable product with a long shelf life. However, the crystallization of dispersed droplets requires high subcooling, resulting in a time, energy and cost intensive production processes. Contact-mediated nucleation (CMN) may be used to intensify the nucleation process, enabling crystallization at higher temperatures. It describes the successful inoculation of a subcooled liquid droplet by a crystalline particle. Surfactants are added to emulsions/suspensions for their stabilization against coalescence or aggregation. They cover the interface, lower the specific interfacial energy and form micelles in the continuous phase. It may be assumed that micelles and high concentrations of surfactant monomers in the continuous phase delay or even hinder CMN as the two reaction partners cannot get in touch. Experiments were carried out in a microfluidic chip, allowing for the controlled contact between a single subcooled liquid droplet and a single crystallized droplet. We were able to demonstrate the impact of the surfactant concentration on the CMN. Following an increase in the aqueous micelle concentrations, the time needed to inoculate the liquid droplet increased or CMN was prevented entirely.

Study on Spreading of Liquid Droplet Impacting on a Solid Dry Surface

2011 ◽  
Vol 66-68 ◽  
pp. 888-893
Author(s):  
Yun Chao Song ◽  
Chun Hai Wang ◽  
Zhi Ning
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Liquid Droplet ◽  
Single Droplet ◽  
Capillary Effects ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Wetting Model ◽  
Theoretical Results ◽  
Maximum Spreading

A numerical computation and theoretical model are presented on spreading of a single droplet impacting on a solid surface at low Weber number. The numerical simulation uses combined Level Set-VOF method and a precise wetting model. The singularity at the moving contact line was analyzed and removed by present wetting model. A theoretical model based on the energy balance was developed to predict the maximum spreading ratio, accounting for wetting effect by a correction factor. The droplets shapes, the dimensionless spreading radius and the dimensionless height of droplet calculated by present numerical method were compared with the experimental data. The theoretical model is used to predict the maximum spreading ratio. The numerical and theoretical results agree well with the experimental data. Present theoretical model indicates that capillary effects may be neglected if 6We(We/3+4)>>Re.

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