scholarly journals Microdroplet Actuation via Light Line Optoelectrowetting (LL-OEW)

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Christoph Doering ◽  
Johannes Strassner ◽  
Henning Fouckhardt
Keyword(s):  
Analytical Chemistry ◽  
Digital Microfluidics ◽  
Light Sources ◽  
Chip Surface ◽  
Chip Design ◽  
Optical Components ◽  
Electrowetting On Dielectric ◽  
Layer Sequence ◽  
Light Line ◽  
Light Beams

Meanwhile, electrowetting-on-dielectric (EWOD) is a well-known phenomenon, even often exploited in active micro-optics to change the curvature of microdroplet lenses or in analytical chemistry with digital microfluidics (DMF, lab on a chip 2.0) to move/actuate microdroplets. Optoelectrowetting (OEW) can bring more flexibility to DMF because in OEW, the operating point of the lab chip is locally controlled by a beam of light, usually impinging onto the chip perpendicularly. As opposed to pure EWOD, for OEW, none of the electrodes has to be structured, which makes the chip design and production technology simpler; the path of any actuated droplet is determined by the movement of the light spot. However, for applications in analytical chemistry, it would be helpful if the space both below as well as that above the lab chip were not obstructed by any optical components and light sources. Here, we report on the possibility to actuate droplets by laser light beams, which traverse the setup parallel to the chip surface and inside the OEW layer sequence. Since microdroplets are grabbed by this surface-parallel, nondiverging, and nonexpanded light beam, we call this principle “light line OEW” (LL-OEW).

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.

Micro-optics in lighting applications

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Wolfgang Mönch
Keyword(s):  
Light Emitting Diodes ◽  
Light Sources ◽  
Large Area ◽  
Light Emitters ◽  
Optical Elements ◽  
Optical Components ◽  
Light Emitting ◽  
Reflection And Refraction ◽  
Automotive Lighting ◽  
The Individual

AbstractThe intention of this article is to give a concise overview on current applications of micro-optical components in lighting, including general lighting, automotive lighting, projection, and display backlighting. Regarding the light sources, the focus of this paper is on inorganic light-emitting diodes (LEDs) and the characteristic problems encountered with them. Lasers, laser diodes, and organic light-emitting diodes (OLEDs) are out of scope of this paper. Micro-optical components for current applications of inorganic LEDs may be categorized essentially into three classes: First, components for light shaping, i.e., adjusting the intensity distribution to a desired target; second, components for light homogenization with respect to space and color, and third, large-area micro-optical elements. These large-area elements comprise micro-optical slabs and sheets for guiding, reflection, and refraction of light and are designed without regard to particular details of type, design, arrangement, and layout of the individual light emitters. References are given to textbooks and review articles to guide the interested reader to further and more detailed studies on the problems discussed here.

Uniform illumination by diffractive shaping of independent light beams

2011 ◽  
Vol 19 (2) ◽  
Author(s):  
A. Sobczyk ◽  
M. Sypek ◽  
Ag. Siemion ◽  
M. Makowski ◽  
A. Siemion ◽  
...  
Keyword(s):  
Beam Shaping ◽  
Light Distribution ◽  
Light Sources ◽  
Uniform Illumination ◽  
Common Area ◽  
Total Light ◽  
Set Up ◽  
Light Beams ◽  
Constant Shape ◽  
Led Arrays

AbstractThis article presents a new optical set-up for illumination of a common area with a few independent light sources. The main aim is to create a uniform light distribution of a constant shape even if one of the light sources will stop working. In such a case, the shape of the light distribution should remain unchanged, however, the total light intensity will be lower. The novelty of the proposed solution is based on the usage of a small number of the independent light sources in opposite to a well known LED arrays approach. The beam shaping is made using Dammann gratings and specially designed blazed phase diffractive gratings. The article contains the theoretical analysis and the computer simulation verified by the experiment.

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