Fluid processes in smart microengineered devices: Hydrodynamics and thermodynamics in microspace

Lead Research Organisation: University College London
Department Name: Chemical Engineering

Abstract

The current microfluidic devices market is $2 Billion and expected to double by 2016. Such microdevices are usually integrated in multifunctional units, which not only offer numerous advantages over traditional large-scale technologies, but also provide a multitude of potential uses in many different research fields that exploit fluids in confined geometries. They have numerous practical applications including drug delivery (e.g. inhalers, microneedles), analytical devices, point of care diagnostics, continuous flow small scale intensified manufacturing, pharmaceutical research, clinical and veterinary diagnostics, etc. In microchannel devices fluids flow in confined geometries and although significant progress has been made, understanding how the different phenomena occurring across a wide range of lengths scales, from molecular-scale processes to macroscopic hydrodynamic ones, and how they are related to each other, is still lacking. More specifically, the proposed research focuses on how microstructures, e.g. membranes, microcontactors, or patterned substrates, affect the hydrodynamics and thermodynamics of multiphase flows in microspace; and more importantly how they are influenced by the presence of the microstructure. Such understanding is critical for furthering the applications of microfluidic devices and their utilisation for heat-mass transport enhancement.

The study of microengineered devices in the presence of microstructure posseses many challenges from both a fundamental and applied research point of view. It is our belief that a complete and systematic study of such devices should involve an interdisciplinary approach that requires the use of tools and the development of new methodologies from different areas. This proposal seeks funding for a comprehensive four-year research programme into a novel synergistic approach that will combine state-of-the-art experimental techniques, sophisticated computational fluid dynamics and molecular modeling as well as advanced theoretical physics elements, never attempted before. We aim at rationally understanding, and quantitatively characterising fluid processes in microstructured confined geometries, on both the molecular/thermodynamic and hydrodynamic level, hence establishing connections between phenomena occurring at widely separated scales. As a main case study we shall consider microscale fluid separation which highlights some of the currently unresolved, yet key issues in microengineering technology, namely vapour-liquid equilibrium in confined geometries and breakthrough process (i.e. one phase invading into another). Our main findings will also be used to explore other applications where microstructures play a central role, such as microdistillation, or slip flows and droplet formation.

The work will be undertaken by a team from the Chemical Engineering Department at Imperial College London with complementary skills and strengths: Kalliadasis (Hydrodynamics/Statistical Mechanics -- Computations, Theory), Galindo (Statistical Mechanics/Molecular Dynamics -- Computations), and Pradas (Statistical/Theoretical Physics -- Computations, Theory); and a team from the Chemical Engineering Department at University College London: Gavriilidis (Experimental Microchemical Engineering and Microfluidics), Kuhn (Microfluidics, Multiphase Flows Modelling and Experiments), and Sorensen (Process Design, Microdistillation).

Publications

10 25 50
 
Description In this project, a more detailed understanding of how gases can be separated from liquids in the microscale was sought. A microfluidic device, fabricated using semiconductor processing techniques, was tested to observe its operational limits in terms of successful gas-liquid separation. Results deviated from known theoretical equations and hence a more detail analysis was carried out. A digital microscope with a high-speed imaging camera was commissioned and videos of the separation process recorded. A computational script was written on a programming language called Python, to automatically analyse the properties of the liquid from the high-speed videos. A theoretical analytical model was then developed, directly based on these experimental results, without the need for any arbitrary tuning variables as commonly found in literature. This model was able to accurately estimate the separation performance of the gas-liquid separation device, which can now be applied to create designs with better separation performances. The model also helped us better understand how gas separates from liquids in the microscale. Secondly, knowledge gathered on gas-liquid interactions in the microscale is being applied currently to study an industrially important operation - distillation. There is a dire need to improve the distillation capabilities, both in terms of yielding higher-purity liquids and reducing the energy demands, while maintaining a comparable volume of production. Using novel microscale devices, we can aim to achieve a better contact of the gas and the liquid than in a larger scale device. Work is being carried out in hybrid silicon-glass devices with precision fabricated capillaries and intricate mixing geometries (i.e., herring-bone structures). Simultaneously, work is also being carried out on devices with novel metallic candle wick-like coatings (similar to a heat pipe).
Exploitation Route Separation of valuable chemicals constitutes 10-15% of the world's energy consumption. With ever-growing demands, new sustainable strategies are being researched and developed. Among these are specialty devices that exploit the advantages of capillarity (as in a candle wick). The model developed can be used by scientists and engineers to predict when a gas-liquid or liquid-liquid separation stops working without performing costly experiments. This model can also be used to develop newer and better designs, thereby avoiding expensive and tedious trial-and-error based prototyping steps. Furthermore, the underlying phenomenon, with a better understanding, can also be applied to study various subjects like drug delivery, self-cleaning materials, anti-microbial surfaces, etc. With regards to micro-distillation, the novel devices being tested and characterised for their separation efficiency can be scaled-up for larger volumes of production at lower energy demands. This will be of particular interest in the industrial sector where operational costs can be significantly reduced with higher efficiency devices.
Sectors Chemicals,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

 
Description Centre for Nature Inspired Engineering (CNIE) Inspiration Grant
Amount £4,980,773 (GBP)
Funding ID EP/K038656/1 
Organisation University College London 
Sector Academic/University
Country United Kingdom
Start 03/2018 
End 11/2018
 
Description 70th Annual Meeting of the American Physical Society - Division of Fluid Dynamics, 2017, "Dynamical phase separation using a microfluidic device: experiments and modeling" 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral Presentation - Benjamin Aymard, Urbain Vaes, Anand Radhakrishnan, Marc Pradas, Asterios Gavriilidis, & Serafim Kalliadasis; "Dynamical phase separation using a microfluidic device: experiments and modeling"; November 2017, 70th Annual Meeting of the American Physical Society - Division of Fluid Dynamics, Volume 62, Number 14.
Year(s) Of Engagement Activity 2017
URL http://meetings.aps.org/link/BAPS.2017.DFD.F15.3
 
Description IChemE, Mixing Subject Interest Group, 2016, "High-content Data Extraction from Multiphase Flow Systems via Optical High-speed Imaging Methodology" 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Poster presentation
A. N. Pallipurath Radhakrishnan, G. Valitov, L. Mazzei, A. Gavriilidis, "High-content Data Extraction from Multiphase Flow Systems via Optical High-speed Imaging Methodology", in Transport and Mixing in Micro-Scale Flow, IChemE, Mixing Subject Interest Group, UCL, 11th November, 2016.
Year(s) Of Engagement Activity 2016
 
Description Keynote Talk - Micro and Millifluidic Separation Processes 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited Keynote Lecture by A Gavriilidis, L. Mazzei, A. Radhakrishnan, & G. Valitov, on "Micro and Millifluidic Separation Processes" at IMRET 2018, 15th International Conference on
Micro Reaction Technology; Karlsruhe, Germany.
Year(s) Of Engagement Activity 2018
 
Description Nonlinear Dynamics of Gas-Liquid Separation in a Capillary Microseparator 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Oral Presentation - Anand Radhakrishnan, Marc Pradas, Serafim Kalliadasis, & Asterios Gavriilidis; "Nonlinear Dynamics of Gas-Liquid Separation in a Capillary Microseparator"; June 2018, ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels; Dubrovnik, Croatia
Year(s) Of Engagement Activity 2018
URL http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2698575