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.

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%.

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.

On-chip organic synthesis enabled using an engine-and-cargo system in an electrowetting-on-dielectric digital microfluidic device

Lab on a Chip ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3054-3064 ◽  
Author(s):  
Matin Torabinia ◽  
Parham Asgari ◽  
Udaya Sree Dakarapu ◽  
Junha Jeon ◽  
Hyejin Moon
Keyword(s):  
Organic Synthesis ◽  
Chemical Reaction ◽  
Microfluidic Device ◽  
Electrowetting On Dielectric ◽  
On Chip ◽  
Digital Microfluidic

This paper presents a microfluidic chemical reaction using an electrowetting-on-dielectric (EWOD) digital microfluidic device.

Liquid-Liquid Extraction Based on Digital Microfluidics

2009 ◽  
Author(s):  
Hyejin Moon ◽  
Praveen Kunchala ◽  
Yasith Nanayakkara ◽  
Daniel W. Armstrong
Keyword(s):  
Room Temperature ◽  
Chemical Engineering ◽  
Digital Microfluidics ◽  
Liquid Extraction ◽  
Extraction Techniques ◽  
Immiscible Liquids ◽  
Liquid Liquid Extraction ◽  
Liquid Phases ◽  
On Chip ◽  
Digital Microfluidic

Liquid-liquid extraction techniques are one of the major tools in chemical engineering, analytical chemistry, and biology, especially in a system where two immiscible liquids have an interface solutes exchange between the two liquid phases along the interface up to a point where the concentration ratios in the two liquids reach their equilibrium values [1]. In this paper, we propose to use room temperature ionic liquid (RTIL) as a second liquid phase for extraction, which forms immiscible interface with aqueous solutions. We demonstrate liquid-liquid extraction with the EWOD digital microfluidic device, two model extraction systems were tested. One is organic dye extracted from RTIL(1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide or BMIMNTf2) to water and the other is iodine (I2) extracted from water to BMIMNTf2. Droplets of aqueous solution and BMIMNTf2 solution were generated on chip reservoir then transported for extraction and separated by EWOD actuation successfully.

Analytical Models to Determine the Electric Field Characteristics of a Multi-Electrode Impedimetric Immunosensor in a Digital Microfluidic Device

2014 ◽  
Author(s):  
Steffen O. P. Blume ◽  
Michael J. Schertzer ◽  
Ridha Ben Mrad ◽  
Pierre E. Sullivan
Keyword(s):  
Microfluidic Device ◽  
Digital Microfluidics ◽  
Electrode Array ◽  
Analytical Models ◽  
Element Analysis ◽  
Numerical Simulation Methods ◽  
Mapping Techniques ◽  
On Chip ◽  
Digital Microfluidic ◽  
Impedimetric Immunosensor

The level of integration of digital microfluidics is continually increasing to include the system path from fluid manipulation and transport, on to reagent preparation, and finally reaction detection. Digital microfluidics therefore has the capability to encompass all steps of common biochemical protocols. Reported here is a set of analytical models for the design of a coplanar interdigitated multi-electrode array to be used as an impedimetric immunosensor in a digital microfluidic device for on-chip chemical reaction detection. The models are based on conformal mapping techniques, and are compared to results obtained from finite element analysis to discuss limitations of the model. The analytical models are feasible and inexpensive surrogates for numerical simulation methods.

Time-Invariant Deformation of Blood During Necking on an Electrowetting Digital Microfluidic Platform

2019 ◽  
Author(s):  
Curtis Young ◽  
Anand K. Ramasubramanian ◽  
Melinda Simon ◽  
Sang-Joon John Lee
Keyword(s):  
Whole Blood ◽  
Tensile Tests ◽  
Exponential Model ◽  
Width Ratio ◽  
Electrowetting On Dielectric ◽  
Neck Width ◽  
On Chip ◽  
Digital Microfluidic ◽  
Time Invariant ◽  
Neck Radius

Abstract Recent developments in electrowetting-on-dielectric (EWOD) technology have expanded the possibilities for testing methods and investigation of blood. This work evaluated the development of necking geometry of whole blood on an EWOD-based digital microfluidic (DMF) platform. This was achieved by performing tensile tests on whole blood on an EWOD-based device, thereby inducing necking. A time-invariant method was used to evaluate the deformation of the tested dilutions, using minimum neck width and neck radius as two characteristic parameters of the necking geometry. Experiments were performed on blood diluted with phosphate-buffered saline (PBS) at dilutions of 1:20 and 1:10 by volume. Parameter measurements were obtained by recording microscope video of on-chip tensile tests and extracting the necking profile. Neck radius and neck width are obtained from the extracted necking profile and evaluated to compare results. Results from tensile tests on blood at different dilutions showed an exponential decrease in neck radius as neck width decreases. A four-parameter exponential model was fit to the collected data, showing that the 1:20 dilution had a higher neck radius to neck width ratio than the 1:10 dilution over a neck width interval of 0.3 mm to 1.7 mm, suggesting a viscosity effect on the necking geometry. The results demonstrate that the concentration of blood influences the necking profile when deformed under tension that is applied by electrowetting forces.

Modeling and Simulation of Unequal Droplet Splitting in Electrowetting Based Digital Microfluidics

2011 ◽  
Author(s):  
Biddut Bhattacharjee ◽  
Homayoun Najjaran
Keyword(s):  
Digital Microfluidics ◽  
Vital Role ◽  
Open Loop ◽  
Loop Model ◽  
Efficient Technology ◽  
Flow Rates ◽  
Electrowetting On Dielectric ◽  
Droplet Splitting ◽  
Digital Microfluidic ◽  
Spatially Varying

Electrowetting-on-dielectric (EWOD) is a highly efficient technology to perform biological and medical analyses through the manipulation of pico- to nano-liter droplets on digital microfluidic systems (DMS). Droplet splitting is one of the basic fluidic operations that play a vital role in microscale mixing and concentration control. This paper presents the results of numerical investigation of unequal droplet splitting. In order to gain insight into the mechanism of droplet splitting, a three-electrode splitting system is simulated in FLOW-3D® for given geometry and material properties. When unequal voltages are applied to the adjacent electrodes on both sides of a droplet the distribution of electric field exerts spatially varying stress causing the deformation of the interface. The resulting unequal fluid flow rates towards the activated electrodes are determined by the coupled electro-hydrodynamics. The results of multiple simulation runs in terms of liquid flow rates with different ratios of the applied voltage will be very useful in developing the open-loop model of droplet splitting that can be later adopted to design a controller for unequal splitting in DMS.

A Robust Superhydrophobic Surface for Digital Microfluidics

2011 ◽  
Author(s):  
David Barona ◽  
A. Amirfazli
Keyword(s):  
Superhydrophobic Surface ◽  
Mechanical Stability ◽  
Contact Angle Hysteresis ◽  
Digital Microfluidics ◽  
Microfluidic Devices ◽  
Contact Angles ◽  
Lab On Chip ◽  
Adverse Conditions ◽  
On Chip ◽  
Digital Microfluidic

Digital microfluidics depends on efficient movement of individual drops for a variety of tasks, e.g. reagent delivery, mixing, sampling, etc. Superhydrophobic (SH) coatings generally show high repellency and low adhesion for a variety of liquids. Therefore, SH coatings can provide for an efficient drop delivery and hence low energy requirements for a fluidic chip. However, wide application of such coatings is hampered by fragile nature of such coatings to date. A new SH coating is developed that addresses the fragility challenge of such coatings. It is based on application of nanoparticles to fluoropolymers. The mechanical stability, wear resistance and durability under prolonged liquid exposure of this new coating is discussed. It is shown that the new SH coating can maintain high contact angles, low contact angle hysteresis needed for drop mobility under adverse conditions/application of digital microfluidic devices. The developed SH coating can also be sprayed onto various surfaces, including glass used in traditional lab-on-chip (LOC) devices, or even paper for enabling novel Lap-on-paper (LOP) devices.

scholarly journals Droplet Transportation through an Orifice on Electrode for Digital Microfluidics Modulations

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1385
Author(s):  
Ting-Chia Chu ◽  
Yen-Wen Lu
Keyword(s):  
Digital Microfluidics ◽  
Electrical Potential ◽  
Core Shell ◽  
Droplet Deformation ◽  
Electrowetting On Dielectric ◽  
The Core ◽  
Paper Based Microfluidics ◽  
Digital Microfluidic ◽  
Interface Chip

A digital microfluidic modular interface (chip-to-chip interface) which possesses an electrode with an orifice to vertically transport core–shell droplets is presented. The electrodes were geometrically designed to promote droplet deformation and suspension. The droplets were then applied with an electrical potential for insertion into and passage through the orifice. The concepts were tested with three types of droplets at the volume of 0.75~1.5 μL, which is usually difficult to transfer through an orifice. The integration of electrowetting on dielectric (EWOD) with paper-based microfluidics was demonstrated: the droplet could be transported within 10 s. More importantly, most of the core droplet (~97%) was extracted and passed through with only minimal shell droplets accompanying it.

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