Lab on a Chip Blog

We are delighted to announce that in January 2021, Professor Aaron Wheeler (University of Toronto, Canada) will take over as the new Editor-in-Chief for Lab on a Chip.

Professor Wheeler is Canada Research Chair in Microfluidic Bioanalysis at the University of Toronto. He has been recognized with a number of honors including the E.W.R. Steacie Memorial Fellowship from the Canadian National Sciences and Engineering Research Council, the Arthur F. Findeis Award from the American Chemical Society, and the Joseph Black Award from the Royal Society of Chemistry. Professor Wheeler’s research group develops microfluidic tools to solve problems in chemistry, biology, and medicine.

Aaron has been an Associate Editor for Lab on a Chip since 2013, and we are delighted that he will continue to handle submissions for Lab on a Chip. Aaron’s experience and knowledge of the journal and its community, combined with his academic experience, mean he will be a fantastic Editor-in-Chief for the journal.

“I’m honored to be taking up the duties of Editor-in-Chief for Lab on a Chip, “Perhaps uniquely relative to other journals, Lab on a Chip played a critical role in the birth and growth of a new field of research. Since the year 2000, the journal has been the ‘home’ for the best that the community has to offer, and I look forward to continuing that tradition going forward” says Aaron, “I am in awe of the diversity of topics that the Lab on a Chip community has made an impact in, be that cells or gels, soil or oil, or trees or bees, there is a Lab on a Chip for that. I can’t imagine a community that is more fun to be a part of.”

This news does of course mean that Professor Abe Lee will be standing down as Editor-in-Chief of Lab on a Chip. Professor Lee has served on the Editorial Board of Lab on a Chip for eleven years, first as an Editorial Board member, then an Associate Editor and finally as our Editor-in-Chief, and we are extremely grateful to Abe for his creativity and leadership throughout this period. We wish him all the best, and look forward to continuing to work with him as he moves to hold a position on our Advisory Board.

Read some of Aaron’s most recent publications below, free to access until 17^th December 2020.

Direct loading of blood for plasma separation and diagnostic assays on a digital microfluidic device
Christopher Dixon, Julian Lamanna and Aaron R. Wheeler
Paper
Lab Chip, 2020, 20, 1845-1855

When robotics met fluidics
Junjie Zhong, Jason Riordon, Tony C. Wu, Harrison Edwards, Aaron R. Wheeler, Keith Pardee, Alán Aspuru-Guzik and David Sinton
Perspective
Lab Chip, 2020, 20, 709-716

Digital microfluidics and nuclear magnetic resonance spectroscopy for in situ diffusion measurements and reaction monitoring
Ian Swyer, Sebastian von der Ecken, Bing Wu, Amy Jenne, Ronald Soong, Franck Vincent, Daniel Schmidig, Thomas Frei, Falko Busse, Henry J. Stronks, André J. Simpson and Aaron R. Wheeler
Paper
Lab Chip, 2019, 19, 641-653

Towards a personalized approach to aromatase inhibitor therapy: a digital microfluidic platform for rapid analysis of estradiol in core-needle-biopsies
Sara Abdulwahab, Alphonsus H. C. Ng, M. Dean Chamberlain, Hend Ahmado, Lucy-Ann Behan, Hala Gomaa, Robert F. Casper and Aaron R. Wheeler
Paper
Lab Chip, 2017, 17, 1594-1602

Pre-concentration by liquid intake by paper (P-CLIP): a new technique for large volumes and digital microfluidics
Darius G. Rackus, Richard P. S. de Campos, Calvin Chan, Maria M. Karcz, Brendon Seale, Tanya Narahari, Christopher Dixon, M. Dean Chamberlain and Aaron R. Wheeler
Paper
Lab Chip, 2017, 17, 2272-2280

Lab on a Chip is delighted to introduce our most recent Emerging Investigator, Katherine Elvira!

Katherine received her undergraduate Master’s degree in Chemistry from Imperial College London in 2007. She started working in the field of microfluidics during her PhD (2012, Imperial College London), by building digital microfluidic platforms to perform automated chemical reactions. Katherine then moved to ETH Zürich (Switzerland) working firstly as a Postdoctoral Researcher and then as a Senior Scientist in the Institute for Chemical and Bioengineering. Since 2017, Katherine is the Canada Research Chair in New Materials and Techniques for Health Applications and an Assistant Professor in the Department of Chemistry at the University of Victoria, Canada. Katherine’s group currently develops microfluidic technologies to build bespoke artificial cells for the quantification of pharmacokinetic parameters in vitro. Katherine has recently presented this work at the Gordon Research Conference on Drug Metabolism (2019), is Co-Chair for the Gordon Research Conference on the Physics and Chemistry of Microfluidics (2023) and is a Scientific Mentor for the Creative Destruction Lab.

Read Dr Elvira’s Emerging Investigator paper* “A bespoke microfluidic pharmacokinetic compartment model for drug absorption using artificial cell membranes” and find out more about her and her research in the interview below.

Katherine Elvira

Image credit: UVic Photo Services

Your recent Emerging Investigator Series paper focuses on a new type of pharmacokinetic compartment model for the prediction of drug absorption. How has your research evolved from your first article to this most recent article?

Funnily enough, my first ever article was a very early precursor to this work. We built a microfluidic platform for the formation of droplet interface bilayers (DIBs) in high-throughput. I didn’t work with DIBs again until I started as a Canada Research Chair at the University of Victoria, but they are the basis for the new type of pharmacokinetic compartment model that we show in the Emerging Investigator article. We can now make them mimic human cell membranes and hence they form the building blocks for the compartments in the pharmacokinetic compartment model. In between, my research involved making microfluidic devices for application in many different fields, such as drug discovery, organic chemistry and food science. I also spent some time investigating why microfluidic droplets rarely behave perfectly, and how we can mitigate this. I like that paper because we included a poster in the ESI which my group still uses in the lab to determine what is going wrong with their chips.

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

I am really excited about some cool new artificial cell and tissue models that we are building, and how they can be used to model disease and drug behaviour in humans. My group is full of outstanding researchers, which makes it really easy to be excited about the work they are doing!

In your opinion, what is the biggest advantage of using your microfluidic platform over other methods?

It’s two things, really. Firstly, the fact that we are able to build networks of different compartments and artificial cell membranes on a chip. This allows us to build an in vitro model of the pathway that a drug would take in a human, from the intestine to the blood. And secondly, the fact that we can make these artificial cell membranes using phospholipids that are found in human cells. This makes our in vitro model quite biomimetic. In fact, we are able to predict molecular transport into cells three times better than the state-of-the-art in vitro commercial technique.

What do you find most challenging about your research?

Let’s face it, PDMS is awesome in some ways, but awful in others. I would love to find another material that has the advantages of PDMS, such as being cheap, transparent, and good for prototyping, but that has really stable and modifiable surface chemistry, and that we can mass produce for commercial applications.

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

I am part of the Technical Program Committee for MicroTAS 2020, so I will be at the online conference in October. And next year I am co-Vice Chair of the Gordon Research Conference on the Physics and Chemistry of Microfluidics, which will hopefully be taking place in Italy.

How do you spend your spare time?

I am really lucky to live in beautiful British Columbia on the West coast of Canada. During the winter months I get to go backcountry snowboarding in some of the most outstanding mountains in the world. In the summer, I switch my snowboard for a stand-up paddle board along the beaches in Victoria. I also love travelling, which I do a lot, both for work and for fun. I need my yoga classes to keep me relaxed, and have a slight obsession with cooking all the European foods that I miss from home.

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

I wanted to be an astronaut when I was younger. It still sounds cool but I am also happy staying on earth and being an academic, it’s a pretty great life.

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

I don’t always find it easy being a woman in science, so I would encourage early career female scientists to persevere, we need diversity in academia. I would tell their male colleagues to be good allies.

*Dr Elvira’s paper is free to access with an RSC account for the next month.

Dr. Ye Ai is currently an Associate Professor at Singapore University of Technology and Design (SUTD). He obtained his B.S. in Mechanical Engineering from Huazhong University of Science and Technology (China) in 2005 and his Ph.D. in Mechanical and Aerospace Engineering from Old Dominion University (USA) in 2011. Prior to joining SUTD as an assistant professor in 2013, he worked as a postdoctoral researcher at the Bioscience Division of Los Alamos National Laboratory from June 2011 to January 2013. He was a visiting scholar at Massachusetts Institute of Technology (MIT) from August 2014 to July 2015. He was promoted to associate professor with tenure in September 2019. Dr. Ai’s research interest focuses on developing novel microfluidic technologies for particle/cell manipulation and single cell analysis. His research team is also striving to translate their innovative microfluidic technologies to commercial market through collaborations with industry.

Read Dr Ai’s recent Emerging Investigator Series paper: Microfluidic impedance cytometry device with N-shaped electrodes for lateral position measurement of single cells/particles in the most recent issue of Lab on a Chip, and find out more about him and his work below.

1. Your recent Emerging Investigator Series paper focuses on measuring the lateral position of single cells or particles. How has your research evolved from your first article to this most recent article?

My first research article when I was a PhD student was to develop a finite element model with dynamically deformed mesh that can simulate the transient motion of finite-size particles in microscale fluid flows. My PhD research mainly focused on electrokinetics for manipulating particles, cells and ions in micro/nanoscale. My postdoctoral training at the Bioscience Division of Los Alamos National Laboratory exposed me to a lot of biological problems, in particular the need in high-throughput cellular analysis at the single cell level. My previous research experience has somehow shaped my current research focus into single cell manipulation and analysis using novel microfluidic technologies when I become an independent principal investigator in Singapore.

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

I am most excited to apply our developed microfluidic technologies for solving real biomedical problems and enabling new biological studies. As an example, in 2017 my team published our single cell sorting technology using a highly focused acoustic beam in Lab Chip (DOI: 10.1039/c7lc00678k). Later, I was approached by quite a number of research teams worldwide who wanted to try our sorting technology. These email communications have encouraged me to apply our developed prototype for real biomedical problems. Right now, I have established collaboration with a few biomedical research institutes in Singapore and we have found that our sorting technology is not causing any cell damage, which is however challenging for conventional FACS machine. We currently have the idea to commercialize this single cell sorting technology. Let us see what is going to happen in the next few years.

3. In your opinion, what are the key considerations when designing a microfluidic platform for real-time measurements?

My research team is currently developing both hydrodynamic and acoustic cell sorting platforms. The conventional way to quantify the sorting performance (e.g. purity and recovery) is to run additional cell analysis of collected samples, typically using a flow cytometer. In this work (DOI: 10.1039/c9lc00819e), we designed and validated a new impedance cytometry device that enables the measurement of the lateral positions and physical properties of individual particles and cells. The integration of this new device with any cell sorting platform will allow the evaluation of the sorting performance to be implemented in the same system.

The key consideration of integrating these real-time measurements really depends on whether there is a critical need. But I do see a lot of sorting applications need these real-time, in-line measurements for the purposes of quality control and workflow simplification. And any integration will somehow complicate the system and increase the cost, so the other key consideration is the ease of integration. Integration of electronics is generally easier compared to optics, and we are measuring intrinsic biophysical properties rather than labelling approaches; therefore, I do see great opportunities to integrate our new impedance cytometry device with a variety of cell sorting platforms.

4. What do you find most challenging about your research?

The microfluidics and Lab on a chip research area is interdisciplinary in nature. My challenge is always to find the right people (e.g. students, postdoctoral fellows, collaborators) and secure sufficient resources to work on real impactful research problems.

5. How do you spend your spare time?

I am trying to make a balance between work and personal life, so I mainly spend my spare time with my family members, especially my second kid is only 8 months old. I also spend some of my spare time to do physical exercise, which can help relax and leave some time for free thinking.

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

I rarely thought about this before. Perhaps I would choose to be a doctor.

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

Based on my own experience, it is important to define a unique research domain based on your own expertise and the surrounding research ecosystem when early career scientists start their independent research. It is also wise to have a clear vision about what you want to achieve in the next five years.

Cancers typically originate in one organ yet can spread to distant regions of the body forming secondary tumours called metastases. This happens as cells from the primary tumour migrate into the circulatory system and then travel to other organs. These cells, which are a very rare population within the circulatory system, are termed circulating tumor cells (CTCs). Because of their role in cancer biology, they have garnered a lot of interest lately. Their detection and isolation present several analytical challenges. For one, they are the proverbial “needle in a haystack”, with counts on the order of one CTC for every billion blood cells. This has traditionally led to a paradox: these rare cells are best handled in microscale systems but the world-to-chip mismatch limits microfluidic devices from rapidly processing the large (> 5 mL) samples necessary. Second, recent studies have revealed CTCs to be very heterogeneous populations, limiting the use of surface markers for labelling and capturing a broad range of CTCs. Because there is much still to learn about CTCs, there’s also an interest in recovering viable CTCs for further analysis. In their recent report, Zhao et al. demonstrate a microfluidic device capable of enriching CTCs using magnetic separation. But it’s not that typical magnetophoretic separations you may be familiar with!

Rather than using magnetic particles to bind to surface antigens and eventually separate out CTCs, they capitalize on a phenomenon known as “negative magnetophoresis”. Cells are suspended within a uniformly magnetic medium and application of a non-uniform magnetic field results in a magnetic buoyant force. (This is akin to how negative dielectrophoresis exerts a force on particles in a non-uniform electric field.) The advantage of this method is that the “working principle applies to every non-magnetic material,” according to Prof. Leidong Mao. “Naturally,” he thought “it could apply to CTC enrichment.” However, despite previous work separating different cell populations with negative magnetophoresis, moving to CTC enrichment is not so straightforward. CTC enrichment is the most challenging separation. “All previous applications in our group are with cells at high concentrations,” mentioned Prof. Mao. The main challenge in developing the chip was trying to preserve the characteristics of an “ideal” CTC enrichment device; one that could process a significant amount of blood quickly, have a high recovery rate of CTCs, give reasonable purity of isolated CTCs, and retain cell integrity and viability for further analysis.

With this method, heterogeneous populations of CTCs can be enriched as selection is size dependent rather than based on expression of certain surface markers. This also avoids the costs associated with traditional magnetic labelling – typically used to label and deplete the millions of white blood cells. The device is capable of working at flow rates of 5-7 mL/hr, which is what is necessary to process an entire blood sample and can achieve high recovery rates (>90%). While the authors report purities that appear low (10-12%), they are working on improving purity. One strategy they suggest in their report is to follow the route of the iChip and combine size based separations with magnetic WBC depletion.

To read the full paper for free*, click the link below:

Label-free ferrohydrodynamic cell separation of circulating tumor cells
DOI: 10.1039/C7LC00680B (Paper) Lab Chip, 2017, 17, 3097-3111

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About the Webwriter

Darius Rackus is a postdoctoral researcher at the University of Toronto working in the Wheeler Lab. His research interests are in combining sensors with digital microfluidics for healthcare applications.

*free to access until 14th December 2017