Archive for April, 2019

Emerging Investigator Series – Han Wei Hou

Dr. Han Wei Hou is currently an Assistant Professor at the School of Mechanical and Aerospace Engineering and the Lee Kong Chian School of Medicine (LKCMedicine), Nanyang Technological University (NTU), Singapore. He received his BEng (First Class Hons) and PhD degree in Biomedical Engineering from the National University of Singapore in 2008 and 2012, respectively. Upon graduation, he did his postdoctoral training at Massachusetts Institute of Technology (MIT), and subsequently joined LKCMedicine at NTU as the inaugural LKCMedicine Postdoctoral Fellow in 2014.

Dr. Hou has over 30 peer-reviewed scientific publications, and his work has been featured in online science (ScienceDaily, TheScientist, Cancerforall and Genomeweb), healthcare (News Medical), as well as technology magazines (Gizmag, Nanowerk). He has received several scientific awards including the Singapore-MIT Alliance for Research and Technology (SMART) Graduate Fellowship (2009), Young Investigator Award at the 6th World Congress of Biomechanics (2010), and LKCMedicine Postdoctoral Fellowship (2014).

 

His current research focus on developing novel microfluidics point-of-care testing, and biomimetic organ-on-chip technologies for translational diabetes and cardiovascular diseases research. (Research group website: www.hwhoulab.com)

Read Han Wei Hou’s Emerging Investigator article “Integrated inertial-impedance cytometry for rapid label-free leukocyte isolation and profiling of neutrophil extracellular traps (NETs)” and find out more about him in the interview below:

Your recent Emerging Investigator Series paper focuses on Integrated inertial-impedance cytometry for rapid label-free leukocyte isolation and profiling of neutrophil extracellular traps (NETs). How has your research evolved from your first article to your most recent Emerging Investigator article?

My first article when I was an undergraduate student was on the study of cancer biomechanics using microfluidics. Since then, I worked on other blood-related diseases such as malaria, sepsis and diabetes, and gradually became more interested towards microfluidics-enabled studies of host inflammation and immune responses in metabolic diseases. Regardless of disease type, our key idea is to develop integrated label-free cell sorting and biosensing approaches so that it can be cheap, fast and readily translated to clinical use. In my opinion, this work is a nice combination of all aspects.

What aspect of your work are you most excited about at the moment?

With this paper, we can now use a drop of blood to assess immune heath within minutes in a single-step user operation. We believe this work has great translational potential, and we are actively seeking new collaborators to test other diseases with immune dysfunctions.

In your opinion, what is the next step from creating your device to it being used for point-of-care testing in diabetes? and what are the most important questions to be asked/answered in this field of research?

Through this work and other recent work by our group, we have showed that diabetic leukocytes have distinct dielectric differences which can be used for immune health risk stratification. The next few important questions to ask is why are they different, and how we can further develop our technologies/assays to improve prognostic capabilities.

What do you find most challenging about your research?

As our work is highly interdisciplinary, the most challenging aspects are about finding the right people (collaborators, students etc.) and asking the right scientific questions (not too basic science, not too clinical and not too engineering)!

In which upcoming conferences or events may our readers meet you?

MicroTAS 2019 (Basel) and Microfluidics & Organ-on-a-Chip Asia Conference 2019 (Tokyo)

How do you spend your spare time?

Family time! Nowadays I enjoy spending time with my 18-month-old daughter Hannah, who never fails to amuse me or tire me out. If time permits, I will try to catch some US late-night talk shows too!

Which profession would you choose if you were not a scientist?

Tough choice! I’m torn between being a Lego/toy designer and a pilot.

Can you share one piece of career-related advice or wisdom with other early career scientists?

Talk to people outside your research disciplines. Learn to unlearn things if necessary because science and technology is advancing so fast.

 

 

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Microfluidics for improving the natural gas extraction process

 

shale rock

Figure 1. Natural gas extraction from shale rock.

Shale is a type of fine-grained rock that contains silt, clay, mineral particles, and pores ranging from meter to nanometer scales. The high organic material content in shale rock is used in natural gas extraction, for which shale reservoirs are mechanically stimulated to create permeability in the pores. A preferred stimulation method is called hydraulic fracturing, where a pressurized fluid fractures shale stone and keeps the fractures open for gas extraction (Figure 1). Natural gas extraction from shale rock is a relatively new process compared to existing energy sources. It has attracted growing interest in America and Asia especially after the 2000s because of being an environmentally friendly alternative to other consumable energy sources. On the other hand, the gas industry currently struggles with optimizing the use of pore space and fractions for efficient extraction of the gas. In a newly opened shale rock reservoir, volatile components vaporize from meter to micrometer-scale pores first, leaving heavier components in hard-to-access nanometer-scale pores. Extraction of the remaining components is necessary for full utilization of the reservoirs but poses a hard-to-solve problem for the industry.

 

 

 

 

In a recent study published in Lab on Chip, David Sinton and co-authors review the current state of the technology and demonstrate a nano-scale physical model of shale with pores. The authors also study the dynamics of gas production in nanopores via imaging the system optically and developing an analytical model for gas vaporization. They first created a microchip model matching shale nanoporous matrix properties (e.g., dominant pore sizes and permeability) (Figure 2). The microchip model contained approximately 5800 pores connected via 23000 throats, where a hydrocarbon mixture was injected. In the model, the number of the small pores (≤10 nm) is designed to be greater than the number of the larger pores (∼100 nm) to store most of the accessible hydrocarbons. This pore size distribution captures the influence of nanoscale throats connecting the larger pores and is relevant to shale production. High, medium, and low superheat was applied to the filled microchip to investigate the spatiotemporal dynamics of vaporization via optical imaging. An analytical model and experimental results showed that phase change (liquid to vapor) in a pore is largely independent of phase change in neighboring pores.

This work supports the hypothesis that the rapid decline in production rates is due to a shift from the large connected features to the nanoporous matrix, as over time the smallest pores become enriched with heavier fractions. The authors reveal that vaporization rate slows down 3000 times thanks to the nanoscale throat bottlenecks at high temperatures, while the rates reduce further with vaporization of light components in large pores at low temperatures. Even the pores with 10 nm and fewer diameters can significantly influence the production from larger pores by severely gating transport. The authors found that this problem can be solved by applying very low pressures, although currently not available in the field, during the later stages of hydraulic fracturing. This finding seems to open a new avenue in the field of shale rock processing for energy.

Figure 2. Close up view of shale rock, the description of how the evaporation works, and the description of the microchip operation.

To download the full article for free* click the link below:

Natural gas vaporization in a nanoscale throat connected model of shale: multi-scale, multicomponent and multi-phase

Arnav Jatukaran, Junjie Zhong, Ali Abedini, Atena Sherbatian, Yinuo Zhao, Zhehui Jin, Farshid Mostowfi and David Sinton

Lab Chip, 2018, Lab on a Chip Articles

DOI: 10.1039/c8lc01053f

*Article free to read until 7th May 2019

About the Webwriter

Burcu Gumuscu is a researcher in Mesoscale Chemical Systems Group at University of Twente in the Netherlands. Her research interests include the development of microfluidic devices for quantitative analysis of proteins from single-cells, next generation sequencing, compartmentalized organ-on-chip studies, and desalination of water on the microscale.

 

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