Piezo-driven acoustic streaming in an electrowetting-on-dielectric digital microfluidics device

2017 ◽  
Vol 21 (12) ◽  
Author(s):  
Andrew C. Madison ◽  
Mathew W. Royal ◽  
Richard B. Fair
Keyword(s):  
Acoustic Streaming ◽  
Digital Microfluidics ◽  
Electrowetting On Dielectric

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.

Numerical Simulation of Multi-Physical Fields Coupling and Design of a Digital Microfluidics Chip

2012 ◽  
Vol 503 ◽  
pp. 359-365 ◽  
Author(s):  
Tao Chen ◽  
Li Guo Chen ◽  
Ming Qiang Pan ◽  
Ming Xiang Ling ◽  
Li Ning Sun
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Microfluidic Chip ◽  
Stokes Equations ◽  
Driving Forces ◽  
Geometric Model ◽  
Digital Microfluidics ◽  
Electrowetting On Dielectric ◽  
Physical Fields ◽  
Digital Microfluidic

Due to its simple structure, low consumption of energy but strong driving forces, Electrowetting on Dielectric (EWOD) is used most frequently in digital microfluidics for manipulation and control of droplets. In this paper, the internal mechanism of EWOD is explained though establishing the geometric model of the unipolar board structure digital microfluidic chip. And the boundary conditions of equations are determined. Three coupling physical fields: electric field, flow field and temperature field in the digital microfluidic chip are simulated and analyzed. With the electric field equation coupled, Navier-Stokes equations and energy equation of the temperature control, the numerical simulation of the chip is conducted. The results show that the internal flow of micro-droplets is counterclockwise and swirling flow. The external flow velocity of micro-droplet is greater than the internal velocity. In addition, micro-droplets near the electrode applied temperature are higher than the internal temperature. Surface micromachining technologies are employed to fabricate the chip. Experimental results show that the droplet can be driven in a velocity of 25cm/s. It will possibly provide an effective solution to the manipulation of droplets.

scholarly journals Interfacing Digital Microfluidics with Ambient Mass Spectrometry Using SU-8 as Dielectric Layer

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 649 ◽  
Author(s):  
Gowtham Sathyanarayanan ◽  
Markus Haapala ◽  
Tiina Sikanen
Keyword(s):  
Mass Spectrometry ◽  
Dielectric Layer ◽  
Digital Microfluidics ◽  
Drug Distribution ◽  
Substrate Material ◽  
Ambient Mass Spectrometry ◽  
Electrowetting On Dielectric ◽  
On Chip ◽  
Ambient Ms ◽  
Digital Microfluidic

This work describes the interfacing of electrowetting-on-dielectric based digital microfluidic (DMF) sample preparation devices with ambient mass spectrometry (MS) via desorption atmospheric pressure photoionization (DAPPI). The DMF droplet manipulation technique was adopted to facilitate drug distribution and metabolism assays in droplet scale, while ambient mass spectrometry (MS) was exploited for the analysis of dried samples directly on the surface of the DMF device. Although ambient MS is well-established for bio- and forensic analyses directly on surfaces, its interfacing with DMF is scarce and requires careful optimization of the surface-sensitive processes, such as sample precipitation and the subsequent desorption/ionization. These technical challenges were addressed and resolved in this study by making use of the high mechanical, thermal, and chemical stability of SU-8. In our assay design, SU-8 served as the dielectric layer for DMF as well as the substrate material for DAPPI-MS. The feasibility of SU-8 based DMF devices for DAPPI-MS was demonstrated in the analysis of selected pharmaceuticals following on-chip liquid-liquid extraction or an enzymatic dealkylation reaction. The lower limits of detection were in the range of 1–10 pmol per droplet (0.25–1.0 µg/mL) for all pharmaceuticals tested.

Digital Microfluidic Device for Hotspot Cooling in ICS Using Electrowetting on Dielectric

2012 ◽  
Author(s):  
Govindraj Shreyas Bindiganavale ◽  
Hyejin Moon ◽  
Seung Mun You ◽  
Miguel Amaya
Keyword(s):  
Indium Tin Oxide ◽  
Single Phase ◽  
Cooling System ◽  
Liquid Droplet ◽  
Digital Microfluidics ◽  
Small Scale ◽  
Cooling Performance ◽  
Electrowetting On Dielectric ◽  
Drop Motion ◽  
Before And After

To meet the increasing demand of efficient cooling performance in small scale, this paper presents a digital microfluidics (DMF) microscale liquid cooling system which works on the principle of electrowetting on dielectric (EWOD). In EWOD DMF, fluids are handled drop-wise by external electric field. When the dispensed liquid droplet arrives at the hotspot by EWOD DMF operation, it picks up heat and removes heat when it leaves. This process can be repeated for a series of droplets by using a completely automated LabVIEW controlled system connected to the PCB package. With the help of indium tin oxide (ITO) thin film resistance temperature detectors (RTD) and pre-calibrated temperature coefficient of resistance (TCR) data, the temperatures of the hotspot before and after the residence of liquid droplet (i.e., cooling) can be recorded for different frequencies (dwelling time period of droplet on the hotspot) of the drop motion and varying heater power. Future work will involve RTD resistance data collection to plot the heat flux and the temperature difference (before and after cooling) for different frequencies of drop motion. Although the primary focus is to study single phase cooling, the DI water drop will experience considerable evaporation resulting in higher cooling performance. The single phase cooling studies will help in establishing a robust platform for future two-phase cooling analysis in which evaporation effects will be considered.

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