Dr. Warkiani is a Senior Lecturer in the School of Biomedical Engineering, UTS, Sydney, Australia. He received his Ph.D. in Mechanical Engineering from Nanyang Technological University (NTU, Singapore), and undertook postdoctoral training at Massachusetts Institute of Technology (MIT, USA). He is also a member of Institute for Biomedical Materials & Devices (IBMD) and Center for Health Technologies (CHT) at UTS, a visiting scientist at the Garvan Institute for Biomedical Research as well as Translational Cancer Research Network (TCRN).
Dr Warkiani’s current research activities focus on three key areas of (i) Microfluidics involving the design and development of novel microfluidic systems for particle and cell sorting (e.g., circulating tumor cells, fetal cells & stem cells) for diagnostic and therapeutic applications, (ii) Bio-MEMS involving the fabrication and characterization of novel 3D lab-on-a-chip systems to model physiological functions of tissues and organs, and (iii) 3D Printing involving the design and development of novel miniaturized systems (e.g., micromixers, micro-cyclones) for basic and applied research.
- Nanyang Outstanding Young Alumni Award (2016).
- MIT TR35 young investigator, Asia-Pacific Region (2016).
- Fresh Science Program, Australia (2015).
- Students’ Design Gold Award, Biomedical Engineering Society, Singapore, (2014).
- SMART prestigious fellowship (2013).
- Best student paper award at AMN-APLOC 2011, 5-7 January, Singapore.
- Best research proposal award at NanoMemCourse 2010 at Netherlands.
- A*STAR prestigious scholarship for PhD study at NTU (2009)
For more information, please visit my group homepage: http://www.warkianilab.com
Introduction to BioMEMS
Engineering Biomedical Polymer
Sofela, S., Sahloul, S., Rafeie, M., Kwon, T., Han, J., Warkiani, M.E. & Song, Y.-.A. 2018, 'High-throughput sorting of eggs for synchronization of C. elegans in a microfluidic spiral chip.', Lab on a chip.View/Download from: Publisher's site
In this study, we report the use of a high-throughput microfluidic spiral chip to screen out eggs from a mixed age nematode population, which can subsequently be cultured to a desired developmental stage. For the sorting of a mixture containing three different developmental stages, eggs, L1 and L4, we utilized a microfluidic spiral chip with a trapezoidal channel to obtain a sorting efficiency of above 97% and a sample purity (SP) of above 80% for eggs at different flow rates up to 10 mL min-1. The result demonstrated a cost-effective, simple, and highly efficient method for synchronizing C. elegans at a high throughput (4200 organisms per min at 6 mL min-1), while eliminating challenges such as clogging and non-reusability of membrane-based filtration. Due to its simplicity, our method can be easily adopted in the C. elegans research community.
Kwon, T., Prentice, H., Oliveira, J.D., Madziva, N., Warkiani, M.E., Hamel, J.-.F.P. & Han, J. 2017, 'Microfluidic Cell Retention Device for Perfusion of Mammalian Suspension Culture.', Scientific reports, vol. 7, no. 1, p. 6703.View/Download from: Publisher's site
Continuous production of biologics, a growing trend in the biopharmaceutical industry, requires a reliable and efficient cell retention device that also maintains cell viability. Current filtration methods, such as tangential flow filtration using hollow-fiber membranes, suffer from membrane fouling, leading to significant reliability and productivity issues such as low cell viability, product retention, and an increased contamination risk associated with filter replacement. We introduce a novel cell retention device based on inertial sorting for perfusion culture of suspended mammalian cells. The device was characterized in terms of cell retention capacity, biocompatibility, scalability, and long-term reliability. This technology was demonstrated using a high concentration (>20 million cells/mL) perfusion culture of an IgG1-producing Chinese hamster ovary (CHO) cell line for 18-25 days. The device demonstrated reliable and clog-free cell retention, high IgG1 recovery (>99%) and cell viability (>97%). Lab-scale perfusion cultures (350mL) were used to demonstrate the technology, which can be scaled-out with parallel devices to enable larger scale operation. The new cell retention device is thus ideal for rapid perfusion process development in a biomanufacturing workflow.
Shakeel Syed, M., Rafeie, M., Henderson, R., Vandamme, D., Asadnia, M. & Ebrahimi Warkiani, M. 2017, 'A 3D-printed mini-hydrocyclone for high throughput particle separation: Application to primary harvesting of microalgae', Lab on a Chip, vol. 17, no. 14, pp. 2459-2469.View/Download from: UTS OPUS or Publisher's site
© The Royal Society of Chemistry 2017. The separation of micro-sized particles in a continuous flow is crucial part of many industrial processes, from biopharmaceutical manufacturing to water treatment. Conventional separation techniques such as centrifugation and membrane filtration are largely limited by factors such as clogging, processing time and operation efficiency. Microfluidic based techniques have been gaining great attention in recent years as efficient and powerful approaches for particle-liquid separation. Yet the production of such systems using standard micro-fabrication techniques is proven to be tedious, costly and have cumbersome user interfaces, which all render commercialization difficult. Here, we demonstrate the design, fabrication and evaluation based on CFD simulation as well as experimentation of 3D-printed miniaturized hydrocyclones with smaller cut-size for high-throughput particle/cell sorting. The characteristics of the mini-cyclones were numerically investigated using computational fluid dynamics (CFD) techniques previously revealing that reduction in the size of the cyclone results in smaller cut-size of the particles. To showcase its utility, high-throughput algae harvesting from the medium with low energy input is demonstrated for the marine microalgae Tetraselmis suecica. Final microalgal biomass concentration was increased by 7.13 times in 11 minutes of operation time using our designed hydrocyclone (HC-1). We expect that this elegant approach can surmount the shortcomings of other microfluidic technologies such as clogging, low-throughput, cost and difficulty in operation. By moving away from production of planar microfluidic systems using conventional microfabrication techniques and embracing 3D-printing technology for construction of discrete elements, we envision 3D-printed mini-cyclones can be part of a library of standardized active and passive microfluidic components, suitable for particle-liquid separation.
Shirani, E., Razmjou, A., Tavassoli, H., Landarani-Isfahani, A., Rezaei, S., Abbasi Kajani, A., Asadnia, M., Hou, J. & Ebrahimi Warkiani, M. 2017, 'Strategically Designing a Pumpless Microfluidic Device on an "inert" Polypropylene Substrate with Potential Application in Biosensing and Diagnostics', Langmuir, vol. 33, no. 22, pp. 5565-5576.View/Download from: Publisher's site
© 2017 American Chemical Society. This study is an attempt to make a step forward to implement the very immature concept of pumpless transportation of liquid into a real miniaturized device or lab-on-chip (LOC) on a plastic substrate. "Inert" plastic materials such as polypropylene (PP) are used in a variety of biomedical applications but their surface engineering is very challenging. Here, it was demonstrated that with a facile innovative wettability patterning route using fluorosilanized UV-independent TiO 2 nanoparticle coating it is possible to create wedge-shaped open microfluidic tracks on inert solid surfaces for low-cost biomedical devices (lab-on-plastic). For the future miniaturization and integration of the tracks into a device, a variety of characterization techniques were used to not only systematically study the surface patterning chemistry and topography but also to have a clear knowledge of its biological interactions and performance. The effect of such surface architecture on the biological performance was studied in terms of static/dynamic protein (bovine serum albumin) adsorption, bacterial (Staphylococcus aureus and Staphylococcus epidermidis) adhesion, cell viability (using HeLa and MCF-7 cancer cell lines as well as noncancerous human fibroblast cells), and cell patterning (Murine embryonic fibroblasts). Strategies are discussed for incorporating such a confined track into a diagnostic device in which its sensing portion is based on protein, microorganism, or cells. Finally, for the proof-of-principle of biosensing application, the well-known high-affinity molecular couple of BSA-antiBSA as a biological model was employed.
Chaudhuri, P.K., Ebrahimi Warkiani, M., Jing, T., Kenry & Lim, C.T. 2016, 'Microfluidics for research and applications in oncology', Analyst, vol. 141, no. 2, pp. 504-524.View/Download from: Publisher's site
© The Royal Society of Chemistry 2016. Cancer is currently one of the top non-communicable human diseases, and continual research and developmental efforts are being made to better understand and manage this disease. More recently, with the improved understanding in cancer biology as well as the advancements made in microtechnology and rapid prototyping, microfluidics is increasingly being explored and even validated for use in the detection, diagnosis and treatment of cancer. With inherent advantages such as small sample volume, high sensitivity and fast processing time, microfluidics is well-positioned to serve as a promising platform for applications in oncology. In this review, we look at the recent advances in the use of microfluidics, from basic research such as understanding cancer cell phenotypes as well as metastatic behaviors to applications such as the detection, diagnosis, prognosis and drug screening. We then conclude with a future outlook on this promising technology.
Tay, A., Pavesi, A., Yazdi, S.R., Lim, C.T. & Warkiani, M.E. 2016, 'Advances in microfluidics in combating infectious diseases.', Biotechnology advances, vol. 34, no. 4, pp. 404-421.View/Download from: Publisher's site
One of the important pursuits in science and engineering research today is to develop low-cost and user-friendly technologies to improve the health of people. Over the past decade, research efforts in microfluidics have been made to develop methods that can facilitate low-cost diagnosis of infectious diseases, especially in resource-poor settings. Here, we provide an overview of the recent advances in microfluidic devices for point-of-care (POC) diagnostics for infectious diseases and emphasis is placed on malaria, sepsis and AIDS/HIV. Other infectious diseases such as SARS, tuberculosis, and dengue are also briefly discussed. These infectious diseases are chosen as they contribute the most to disability-adjusted life-years (DALYs) lost according to the World Health Organization (WHO). The current state of research in this area is evaluated and projection toward future applications and accompanying challenges are also discussed.
Zarepour, E., Hassan, M., Chou, C.T. & Ebrahimi Warkiani, M. 2016, 'Characterizing terahertz channels for monitoring human lungs with wireless nanosensor networks', Nano Communication Networks, vol. 9, pp. 43-57.View/Download from: Publisher's site
© 2016 We characterize terahertz wireless channels for extracting data from nanoscale sensors deployed within human lungs. We discover that the inhalation and exhalation of oxygen and carbon dioxide causes periodic variation of the absorption coefficient of the terahertz channel. Channel absorption drops to its minimum near the end of inhalation, providing a window of opportunity to extract data with minimum transmission power. We propose an algorithm for nanosensors to estimate the periodic channel by observing signal-to-noise ratio of the beacons transmitted from the data sink. Using real respiration data from multiple subjects, we demonstrate that the proposed algorithm can estimate the minimum absorption interval of the periodic channel with 98.5% accuracy. Our analysis shows that by confining all data collections during the estimated low-absorption window of the periodic channel, nanosensors can reduce power consumption by six orders of magnitude. Finally, we demonstrate that for wireless communications within human lungs, 0.1–0.12 THz is the least absorbing spectrum within the terahertz band.
Zhang, J., Yan, S., Yuan, D., Alici, G., Nguyen, N.-.T., Ebrahimi Warkiani, M. & Li, W. 2016, 'Fundamentals and applications of inertial microfluidics: a review.', Lab on a chip, vol. 16, no. 1, pp. 10-34.View/Download from: Publisher's site
In the last decade, inertial microfluidics has attracted significant attention and a wide variety of channel designs that focus, concentrate and separate particles and fluids have been demonstrated. In contrast to conventional microfluidic technologies, where fluid inertia is negligible and flow remains almost within the Stokes flow region with very low Reynolds number (Re 1), inertial microfluidics works in the intermediate Reynolds number range (~1 < Re < ~100) between Stokes and turbulent regimes. In this intermediate range, both inertia and fluid viscosity are finite and bring about several intriguing effects that form the basis of inertial microfluidics including (i) inertial migration and (ii) secondary flow. Due to the superior features of high-throughput, simplicity, precise manipulation and low cost, inertial microfluidics is a very promising candidate for cellular sample processing, especially for samples with low abundant targets. In this review, we first discuss the fundamental kinematics of particles in microchannels to familiarise readers with the mechanisms and underlying physics in inertial microfluidic systems. We then present a comprehensive review of recent developments and key applications of inertial microfluidic systems according to their microchannel structures. Finally, we discuss the perspective of employing fluid inertia in microfluidics for particle manipulation. Due to the superior benefits of inertial microfluidics, this promising technology will still be an attractive topic in the near future, with more novel designs and further applications in biology, medicine and industry on the horizon.
Shemesh, J., Jalilian, I., Shi, A., Heng Yeoh, G., Knothe Tate, M.L. & Ebrahimi Warkiani, M. 2015, 'Flow-induced stress on adherent cells in microfluidic devices.', Lab on a chip, vol. 15, no. 21, pp. 4114-4127.View/Download from: Publisher's site
Transduction of mechanical forces and chemical signals affect every cell in the human body. Fluid flow in systems such as the lymphatic or circulatory systems modulates not only cell morphology, but also gene expression patterns, extracellular matrix protein secretion and cell-cell and cell-matrix adhesions. Similar to the role of mechanical forces in adaptation of tissues, shear fluid flow orchestrates collective behaviours of adherent cells found at the interface between tissues and their fluidic environments. These behaviours range from alignment of endothelial cells in the direction of flow to stem cell lineage commitment. Therefore, it is important to characterize quantitatively fluid interface-dependent cell activity. Common macro-scale techniques, such as the parallel plate flow chamber and vertical-step flow methods that apply fluid-induced stress on adherent cells, offer standardization, repeatability and ease of operation. However, in order to achieve improved control over a cell's microenvironment, additional microscale-based techniques are needed. The use of microfluidics for this has been recognized, but its true potential has emerged only recently with the advent of hybrid systems, offering increased throughput, multicellular interactions, substrate functionalization on 3D geometries, and simultaneous control over chemical and mechanical stimulation. In this review, we discuss recent advances in microfluidic flow systems for adherent cells and elaborate on their suitability to mimic physiologic micromechanical environments subjected to fluid flow. We describe device design considerations in light of ongoing discoveries in mechanobiology and point to future trends of this promising technology.
Ebrahimi Warkiani, M., Lou, C.P. & Gong, H.Q. 2011, 'Fabrication of multi-layer polymeric micro-sieve having narrow slot pores with conventional ultraviolet-lithography and micro-fabrication techniques', Biomicrofluidics, vol. 5, no. 3.View/Download from: Publisher's site
Fast detection of waterborne pathogens is important for securing the hygiene of drinking water. Detection of pathogens in water at low concentrations and minute quantities demands rapid and efficient enrichment methods in order to improve the signal-to-noise ratio of bio-sensors. We propose and demonstrate a low cost and rapid method to fabricate a multi-layer polymeric micro-sieve using conventional lithography techniques. The micro-fabricated micro-sieves are made of several layers of SU-8 photoresist using multiple coating and exposure steps and a single developing process. The obtained micro-sieves have good mechanical properties, smooth surfaces, high porosity (40%), and narrow pore size distribution (coefficient of variation < 3.33%). Sample loading and back-flushing using the multi-layer micro-sieve resulted in more than 90% recovery of pathogens, which showed improved performance than current commercial filters. © 2011 American Institute of Physics.
Teymourtash, A.R. & Ebrahimi Warkiani, M. 2009, 'Natural convection over a non-isothermal vertical flat plate in supercritical fluids', Scientia Iranica, vol. 16, no. 6 B, pp. 470-478.
In many applications, convection heat transfer is coupled with conduction and radiation heat transfer, which generate temperature gradients along the walls and may greatly affect natural convection heat transfer. The main objective of this study is to calculate the heat-transfer characteristics for natural convection from a non-isothermal vertical flat plate into a supercritical fluid. The influence of the non-uniformity of wall temperature on the heat transfer by natural convection along a vertical plate, having a linearly distributed temperature (characterized by the slope S) is also investigated. The thermal expansion coefficient is considered as a function of the temperature, the pressure, the van der Waals constants and the compressibility factor. The trends of the curves obtained with this equation and with values from tables of thermodynamic properties were similar and diverged at a critical point. These features confirmed the validity of this equation. Then, the governing systems of partial differential equations are solved numerically using the finite difference method. The local Nusselt number was then calculated and plotted as a function of the local Rayleigh number. It was observed that a positive slope of temperature distribution increases the heat transfer rate and a negative slope decreases it. © Sharif University of Technology, December 2009.