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Title: Microfluidics without walls
Vincent Marichez is the CEO of Qfluidics, a startup in microfluidics developing a liquid-tube technology initially born in the laboratories of the university of Strasbourg, France. He first graduated in 2013 from ECPM (Ecole de Chimie, Polymeres et Materiaux de Strasbourg, France) where he studied Chemical Engineering and Chemistry. He then joined the laboratory of non-equilibrium complex systems for a PhD under the supervision of Prof. Thomas M. Hermans where he studied mechanical chiral resolution (using shear flows) and dissipative supramolecular self-assembly at ISIS (Institut de Science et d Ingenierie Supramoleculaire de Strasbourg). His PhD was immediately followed by a Post-Doc in 2018 in the same laboratory where he could assist the early development of the very first liquid tube which led 1 year after to the creation of Qfluidics in January 2019
In microfluidics, where fluidic channels are scaled down to the micrometer, flow rates are limited by solid walls, due to friction and high pressure drop. Many methods to tackle this issue have been explored, from hydrophobic coatings, through atomically flat channels, to electrowetting in order to reduce solid-wall interactions. Here we propose a new approach, where wall-less aqueous liquid channels are stabilized by a quadrupolar magnetic field that acts on a surrounding immiscible magnetic liquid. This liquid tube is self-healing, uncloggable and it can deliver a very low-shear flow due to the liquid-liquid interface. This “wall-less” approach allows us to transport viscous and shear sensitive liquids without damaging them while allowing basic fluidic operations (valving, mixing, pumping,etc.) by reconfiguring in real time the liquid tube with an external magnetic field. We believe that liquid tubes could pave the way to reconfigurable low pressure nanofluidics.
Venkat Gundabala currently is professor in the department of Chemical engineering at IIT Bombay. He obtained his M.S. from Drexel University, USA and his PhD from University of Sheffield, UK, both in Chemical engineering. After that he had postdoctoral stints at University of Cambridge, UK and Georgia Institute of Technology, USA, before Joining IIT Bombay in 2012. He has worked in a variety of areas such as droplet-based Microfluidics, Lab-on-a-chip for biological applications, Nano-composites, and water-based coatings. At IIT Bombay, his main research includes using Microfluidic tools to synthesize nano-materials and developing Lab-on-a-chip devices for biological applications (particularly for studying C. elegans). His other research interests include nano-composites and functional coatings.
In this work we present a microfluidics based implementation of electrohydrodynamics for generation microparticles and capsules. Electric fields are applied through a novel interface-crossing of the precursor single and double emulsion droplet. The particles are alginate based and the capsules have oil core with alginate shell. The particle and capsule sizes were investigated as functions of the applied electric field strength, when the droplet generation happened in the electrodripping mode. It was observed that the obtained particle/capsule sizes were much lower than non-EHD methods and the monodispersity is much better than external EHD approaches. Thus we show an efficient approach that couples EHD with microfluidics to generate uniformly sized microparticles and microcapsules.
Oral Session 1:
- Droplet-based, Digital and Centrifugal Microfluidics | Novel Micro Sampling, Separation and Detections | Microfluidics Research and Advances
University of British Columbia, Canada
Indian Institute of Technology (IIT), India
Title: A Novel Plug-and-Play Coaxial Microfluidic Device and Preparation of Hierarchical Porous Carbon Microsperes
Dr. Li Zhang is a professor at East China University of Science and Technology. Her research focuses on microfluidics, heat transfer enhancement technology and advanced manufacturing of energy materials. She has published more than 50 papers in reputed journals at home and abroad.
Carbon microspheres with macro-meso-microporous hierarchical pore has increasingly become a subject of great interest, driven by the need to obtain high performing carbons in multidisciplinary fields, such as lithium battery materials, catalyst carriers, capacitor electrode materials, adsorption materials and drug delivery. Numerous methods like arc discharge, hydrothermal , chemical vapor deposition and template are generally chosen to prepare carbon microspheres. However, these methods has poor experimental repeatability and wide particle size distribution. Notably, the droplet-based microfluidic technique is useful for the generation of various uniform microparticles, reducing the experimental errors and ensuring stability and quality.
To prepare uniform particles, we developed a novel plug-and-play coaxial microfluidic device . The capillary device was based on commercial components that can readily be assembled, adjusted and cleaned. In this device, regardless of surface wettability of fluidic channel, monodisperse droplets with average diameter in the range of 50-800μm could be controllably prepared. This design strategy allows for generation of various granular material and simplifies the fabrication process to meet different conditions during preparation, which would be an attractive tool in the future.
By radical polymerization and two-phase shear flows in the microchannel, a three-dimensional network structure of light-cured spherical gel was formed . After high-temperature carbonization and activation , hybrid resin transformed to carbon and spherical carbon particles with well-balanced pore distribution and uniform size were obtained. Comparing the characterization results of various activation, it shows that carbon microspheres using chemical activation process have a richer microporous network. When the mass ratio of activator and carbon is 4:1, the pore size distribution is concentrated and the range of pore size is 0.5 to 0.8 nm, with a specific surface area up to 1800 m2/g, which implies great potential of engineering applications.
Seyedehhamideh Razavi, is pursuing PhD studies in University of British Columbia, Canada
Microencapsulation of probiotics using biomaterials such as alginate is a highly effective strategy for probiotic delivery to prevent the degradation of probiotics from harsh conditions in the gastrointestinal tract.1, 2 This work demonstrates an efficient method for the encapsulation of anaerobic Lactobacillus probiotics in calcium cross-linked alginate microparticles by using on-chip microfluidics to form monodisperse and highly-stable microbeads. In this study, we performed the numerical simulation of the droplet formation method (Fig 1). Following this, we investigated the size variation of microdroplets with different ratios of flow rates of the dispersed and continuous phases (Fig 3). The morphology of the microparticles was characterized using optical microscopy and scanning electron microscopy (SEM). We assessed the viability of encapsulated bacteria using SYTO 9 dye and fluorescence microscopy. The chemical structure of the microparticles containing Lactobacillus was analyzed via Fourier transform infrared spectroscopy (FTIR). We also calculated the encapsulation efficiency of bacteria by measuring their survival after encapsulation. The survival rate percentage of encapsulated versus non-encapsulated probiotic cells was determined at various storage times (at 7, 14, 21 and 28 days). The results indicated the successful entrapment of Lactobacillus within highly stable and uniform microdroplets using the developed microfluidic platform. The optical microscopy and SEM images determined that the probiotic bacteria occupied almost all of the inner space of hydrogel alginate microbeads and the morphology of microparticles were regular spherical structures (Fig 2). Fluorescent images revealed the presence of living bacteria inside the microbeads (Fig 4). The encapsulation yield of the freshly prepared alginate microparticles was 86.95 %. The storage results confirmed that the encapsulated cells stored at -15 ºC showed a relatively high survival rate compared to free cells (Fig 6). SEM results indicated that bacterial cells were successfully entrapped, and freeze-dried microbeads exhibited irregularly shaped with cracks on the surface (Fig 5). The Lactobacillus-encapsulated in alginate microparticles also provided prolonged viability and enhanced shelf-life. Taken together, the results demonstrate the promising potential of our microfluidic flow-focusing system to be used as a high-throughput single-step process that provides stable and uniform microparticles containing anaerobic probiotic bacteria.
Title: Modular Non-contact and Non-intrusive Microwave-Microfluidic Sensing Platform for Energy and Biomedical Engineering
Hamid Sadabadi is an entrepreneur and researcher in the field of Microfluidics, Lab-on-a-chip and sensors/biosensors. He has completed his PhD in microfluidic from Concordia University in Montreal. He is recipient of 8 prestigious awards/scholarships inducing Quebec Doctoral Merit Scholarship and University of Calgary Eyes High Postdoctoral Fellowship where he did his postdoc researches. He is the currently CTO of Wireless Fluidics, a sensing technology development start-up. He has published more than 12 US patents, book chapters, and more than 16 papers in reputed journals.
A novel flow sensor is presented to measure the flow rate within microchannels in a real-time, noncontact and nonintrusive manner. This patented sensing technology can be further used in measuring a physical characteristic of a fluid in a microfluidic system. The sensing platform includes a microfluidic chip that has a thin deformable membrane that separates a microfluidic channel from a microwave resonator sensor. The membrane is deformable in response to loading from interaction of the membrane with the fluid. Loading may be fluid pressure in the channel, or shear stress or surface stress resulting from interaction of the membrane with the fluid. The deformation of the membrane changes the permittivity in the region proximate the sensor. A change in permittivity causes a change in the electrical parameters of the sensor, thereby allowing for a characteristic of the fluid, such as flow rate, or a biological or chemical characteristic, to be measured.