Three-dimensional digital microfluidics using an alternative current electrowetting-on-dielectric (AC-EWOD)

2013 ◽  
Author(s):  
J. B. Chae ◽  
I. U. Shin ◽  
K. Rhee ◽  
S. K. Chung
Keyword(s):  
Digital Microfluidics ◽  
Three Dimensional ◽  
Electrowetting On Dielectric ◽  
Alternative Current

scholarly journals Electrowetting on Dielectric (EWOD) Device with Dimple Structures for Highly Accurate Droplet Manipulation

2019 ◽  
Vol 9 (12) ◽  
pp. 2406 ◽  
Author(s):  
Katsuo Mogi ◽  
Shungo Adachi ◽  
Naoki Takada ◽  
Tomoya Inoue ◽  
Tohru Natsume
Keyword(s):  
High Speed ◽  
Thin Sheet ◽  
Digital Microfluidics ◽  
Three Dimensional ◽  
Substrate Type ◽  
Droplet Motion ◽  
Electrowetting On Dielectric ◽  
Flat Substrate ◽  
Single Substrate ◽  
Droplet Manipulation

Digital microfluidics based on electrowetting on dielectric (EWOD) devices has potential as a fundamental technology for the accurate preparation of dangerous reagents, the high-speed dispensing of rapidly deteriorating reagents, and the fine adjustment of expensive reagents, such as the preparation of for positron emission tomography (PET). To allow single substrate type EWODs to be practically used in an automatic operation system, we developed a dimple structure as a key technique for a highly accurate droplet manipulation method. The three-dimensional shape of the dimple structure is embossed onto a disposable thin sheet. In this study, we confirmed that the dimple structure can suppress unintended droplet motion caused by unidentified factors. In addition, the stability of the droplets on the dimple structures was evaluated using a sliding experiment. On a flat substrate, the success rate of a droplet motion was lower than 70.8%, but on the dimple structure, the droplets were able to be moved along the dimple structures correctly without unintended motion caused by several environmental conditions. These results indicated that the dimple structure increased the controllability of the droplets. Hence, the dimple structure will contribute to the practical application of digital microfluidics based on single substrate type EWODs.

Numerical and theoretical analyses of the dynamics of droplets driven by electrowetting on dielectric in a Hele-Shaw cell

2018 ◽  
Vol 839 ◽  
pp. 468-488 ◽  
Author(s):  
Yasufumi Yamamoto ◽  
Takahiro Ito ◽  
Tatsuro Wakimoto ◽  
Kenji Katoh
Keyword(s):  
Theoretical Model ◽  
Contact Line ◽  
Three Dimensional ◽  
Simulation Method ◽  
Movement Speed ◽  
Electrowetting On Dielectric ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Droplet Movement ◽  
Hele Shaw Cell

Droplet movement by electrowetting on dielectric (EWOD) in a Hele-Shaw cell is analysed theoretically and numerically. We propose a simple theoretical model for the motion, which describes well the voltage dependency of droplet speed below the saturation voltage as measured experimentally. The simulation method for numerical analyses is constructed by using the Young–Lippmann equation to represent EWOD and the generalised Navier boundary condition to represent the moving contact line in the context of the front-tracking method. With an adjusted slip parameter, the present full three-dimensional numerical simulation reproduces well the shape evolution and movement speed of droplets as observed experimentally. We verify the proposed theoretical model in numerical experiments with various shapes and voltages. Furthermore, we analyse theoretically the behaviour of the contact line at the onset of droplet motion as observed in the simulation and experiment, and we are able to estimate very well the time scale on which the contact angle changes.

Numerical Simulation of Digital Microfluidics Based on Electro-Dynamic Model

2012 ◽  
Vol 2 (3) ◽  
pp. 14-23
Author(s):  
Liguo Chen ◽  
Mingxiang Ling ◽  
Deli Liu
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Contact Line ◽  
Contact Area ◽  
Digital Microfluidics ◽  
Phase Contact ◽  
Electrowetting On Dielectric ◽  
Three Phase ◽  
Internal Mechanism ◽  
Contact Domain

Aiming at the doubt and divarication about the internal mechanism of electrowetting on dielectric (EWOD) in digital microfluidics, the authors attempted to explain the internal mechanism of EWOD through electro-dynamic-based numerical simulation model. First, the boundary conditions for the governing equation were found. Then the influence of mesh number on simulation results was analyzed and feasibility of the simulation model was verified by comparing numerical results with theoretical ratiocination. Finally, they compared the electro-dynamic actuation force acting on the surface of droplet on three digital microfluidic structures, which have the same three-phase contact line but different area of contact domain. Analytical results showed that electro-dynamic force generated solely by the accumulation of induced charges in contact domain was three times larger than that generated by three-phase contact line. Induced charges accumulated on both three-phase contact line and contact area of droplet gave the contribution to EWOD, but contact area played a major role in the change of contact angle of droplet.

scholarly journals Designing Splicing Digital Microfluidics Chips Based on Polytetrafluoroethylene Membrane

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1067
Author(s):  
Haoqiang Feng ◽  
Zichuan Yi ◽  
Ruizhi Yang ◽  
Xiaofeng Qin ◽  
Shitao Shen ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Silicone Oil ◽  
Digital Microfluidics ◽  
Simultaneous Detection ◽  
Driving Voltage ◽  
Electrowetting On Dielectric ◽  
Practical Applications ◽  
Multiple Components ◽  
Ito Glass ◽  
Off Time

As a laboratory-on-a-chip application tool, digital microfluidics (DMF) technology is widely used in DNA-based applications, clinical diagnosis, chemical synthesis, and other fields. Additional components (such as heaters, centrifuges, mixers, etc.) are required in practical applications on DMF devices. In this paper, a DMF chip interconnection method based on electrowetting-on-dielectric (EWOD) was proposed. An open modified slippery liquid-infused porous surface (SLIPS) membrane was used as the dielectric-hydrophobic layer material, which consisted of polytetrafluoroethylene (PTFE) membrane and silicone oil. Indium tin oxide (ITO) glass was used to manufacture the DMF chip. In order to test the relationship between the splicing gap and droplet moving, the effect of the different electrodes on/off time on the minimum driving voltage when the droplet crossed a splicing gap was investigated. Then, the effects of splicing gaps of different widths, splicing heights, and electrode misalignments were investigated, respectively. The experimental results showed that a driving voltage of 119 V was required for a droplet to cross a splicing gap width of 300 μm when the droplet volume was 10 μL and the electrode on/off time was 600 ms. At the same time, the droplet could climb a height difference of 150 μm with 145 V, and 141 V was required when the electrode misalignment was 1000 μm. Finally, the minimum voltage was not obviously changed, when the same volume droplet with different aqueous solutions crossed the splicing gap, and the droplet could cross different chip types. These splicing solutions show high potential for simultaneous detection of multiple components in human body fluids.

scholarly journals Phase separation of multiphase droplets in a digital microfluidic device

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Mun Mun Nahar ◽  
Hyejin Moon
Keyword(s):  
Phase Separation ◽  
Capillary Number ◽  
Digital Microfluidics ◽  
Separation Performance ◽  
Comprehensive Investigation ◽  
Electrowetting On Dielectric ◽  
Splitting Technique ◽  
Droplet Splitting ◽  
Two Phases ◽  
Digital Microfluidic

Abstract This study reports the first comprehensive investigation of separation of the immiscible phases of multiphase droplets in digital microfluidics (DMF) platform. Electrowetting-on-dielectric (EWOD) actuation has been used to mechanically separate the phases. Phase separation performance in terms of percentage residue of one phase into another phase has been quantified. It was conceived that the residue formation can be controlled by controlling the deformation of the phases. The larger capillary number of the neck forming phase is associated with the larger amount of deformation as well as more residue. In this study, we propose two different ways to control the deformation of the phases. In the first method, we applied different EWOD operation voltages on two phases to maintain equal capillary numbers during phase separation. In the second method, while keeping the applied voltages same on both sides, we tested the phase separation performance by varying the actuation schemes. Less than 2% of residue was achieved by both methods, which is almost 90% improvement compared to the phase separation by the conventional droplet splitting technique in EWOD DMF platform, where the residue percentage can go up to 20%.

scholarly journals Scaling Electrowetting with Printed Circuit Boards for Large Area Droplet Manipulation

MRS Advances ◽  
2018 ◽  
Vol 3 (26) ◽  
pp. 1475-1483 ◽  
Author(s):  
Udayan Umapathi ◽  
Samantha Chin ◽  
Patrick Shin ◽  
Dimitris Koutentakis ◽  
Hiroshi Ishii
Keyword(s):  
Printed Circuit Boards ◽  
Dielectric Material ◽  
Point Of Care ◽  
Digital Microfluidics ◽  
Microfluidic Devices ◽  
Electrode Arrays ◽  
Large Area ◽  
Lab On Chip ◽  
Electrowetting On Dielectric ◽  
Droplet Manipulation

ABSTRACTDroplet based microfluidics (digital microfluidics) with Electrowetting on dielectric (EWOD) has gained popularity with the promise of being technology for a true lab-on-chip device with applications spanning across assays/library prep, next-gen sequencing and point-of-care diagnostics. Most electrowetting device architecture are linear electrode arrays with a shared path for droplets, imposing serious limitations -- cross contamination and limited number of parallel operations. Our work is in addressing these issues through large 2D grid arrays with direct addressability providing flexible programmability.Scaling electrowetting to larger arrays still remains a challenge due to complex and expensive cleanroom fabrication of microfluidic devices. We take the approach of using inexpensive PCB manufacturing, investigate challenges and solutions for scaling electrowetting to large area droplet manipulation. PCB manufactured electrowetting arrays impose many challenges due to the irregularities from process and materials used. These challenges generally relate to preparing the surface that interfaces with droplets -- a dielectric material on the electrodes and the top most hydrophobic coating that interfaces with the droplets. A requirement for robust droplet manipulation with EWOD is thin (<10um) hydrophobic dielectric material which does not break down at droplet actuation voltages (AC/DC, 60V to 200V) and has a no droplet pinning. For this, we engineered materials specifically for large area PCBs.Traditionally, digital microfluidic devices sandwich droplets between two plates and have focussed on sub-microliter droplet volumes. In our approach, droplets are on an open surface with which we are able to manipulate droplets in microliter and milliliter volumes. With milliliter droplet manipulation ability on our electrowetting device, we demonstrate “digital millifluidics”. Finally, we report the performance of our device and to motivate the need for large open arrays we show an example of running multiple parallel biological experiments.

Digital microfluidics for spheroid-based invasion assays

Lab on a Chip ◽  
2016 ◽  
Vol 16 (8) ◽  
pp. 1505-1513 ◽  
Author(s):  
Brian F. Bender ◽  
Andrew. P. Aijian ◽  
Robin. L. Garrell
Keyword(s):  
Drug Discovery ◽  
Cell Invasion ◽  
Cell Biology ◽  
Digital Microfluidics ◽  
Three Dimensional ◽  
Multicellular Spheroids ◽  
Microfluidic Platform ◽  
Digital Microfluidic ◽  
Biology Research ◽  
Invasion Assays

A digital microfluidic platform that enables the formation, gel encapsulation, and assaying of three-dimensional multicellular spheroids is described. Such a platform can facilitate automation of cell invasion assays for cell biology research and drug discovery.

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