Miniaturised microfluidic technology to probe the fundamentals of heterogeneous ice nucleation (EPSRC DTP)


Professor Ben Murray and Dr Jung-uk Shim

Contact Professor Ben Murray ( to discuss this project further informally.

Project description

The heterogeneous nucleation of ice is a critical process in fields as diverse as cryopreservation through to atmospheric cloud formation, yet it is extremely poorly understood.

There are a range of materials which nucleate ice including minerals such as feldspars through to macromolecules from biogenic materials such as pollen or fungus.

We can quantify how efficiently these materials nucleate ice, but we do not understand how these materials nucleate ice and we have no predictive capacity for determining how well any given material will trigger nucleation. This hampers our ability to select nucleants for use in the control of ice nucleation in cryopreservation applications and restricts our predictive understanding of ice nucleation by atmospheric aerosol particles.

In this project, the postgraduate researcher will focus on improving our basic knowledge of ice nucleation through novel laboratory experimentation utilising the unique equipment and resources which have been developed in the Leeds Ice Nucleation Group.

In particular, the candidate will use and further develop our new microfluidics device for quantifying ice nucleation. The researcher will also be uniquely positioned to exploit their discoveries in the fields of: nucleation of ice in clouds and the control of the formation of ice in biological samples during cryopreservation.

Ice nucleation in clouds helps define life on Earth since clouds play a central role in our planet’s climate and its hydrological cycle, while the control of ice nucleation is a key limitation in a range of areas, such as the supply of cells for the high throughput toxicology screening of pharmaceutical products.

The successful candidate will capitalise on our unique position where we use fundamental knowledge of ice formation in the atmosphere to underpin the control of ice formation in cryopreservation (and vice versa). In doing so, the postgraduate researcher will contribute to a better prediction of climate change, one of humanities greatest challenges, as well as improving the storage of biological specimens which will lead to life saving new drugs and treatments. Hence, this PhD will equip the candidate for a future in a range of careers.

Objectives: This project will be based around making use of and improving our new microfluidics device with the objective of improving our fundamental understanding of why some materials nucleate ice and why.

This may involve the following:

1. Learn to use and apply our current microfluidic device for quantifying ice nucleation in flowing droplets.

2. Improve the design with the object of creating an instrument to measure ice nucleating particles in the atmosphere on a semi-autonomous basis. This will involve coupling the microfluidics device to an aerosol particle sampler and possibly replacing the bulky high speed microscope set-up with a much more compact laser scattering system. This will also involve testing the instrument against other standard techniques.

3. Design a chip to explore different time-scales of nucleation in order to characterize the stochastic vs deterministic properties of nucleation.

4. Couple the microfluidics device to a size exclusion chromatography column to identify and isolate specific ice nucleating macromolecules.

5. Use a new frozen vs. unfrozen flow separation device to separate ice nucleating particles from inert particles in order to determine what makes these particles nucleate ice.

6. Potentially use the new knowledge of what makes an effective ice nucleation site in order to artificially create ice nucleation sites which might be used for the control of ice nucleation in applications such as cryopreservation. This would be an excellent opportunity to interact with our partner cryopreservation company.

7. Potentially take part in a field campaign. While this project is laboratory focused, there will be opportunities to take part in field campaigns around the world where we study ice nucleation. In past campaigns we have travelled to the high Arctic, Barbados and Iceland, amongst other places. We also work on the UK research aircraft (FAAM) and research ships.

Key benefits:

Potential for high impact outcome: The Ice Nucleation Group in Leeds is unique in that we go from fundamental studies of ice nucleation through to field work and application of the new discoveries in models where we can describe the formation of ice in clouds. In addition, we also apply our knowledge to the field of cryopreservation and past students have been included in patents relating to ice nucleation. This unique combination of people into a group which crosses scales and disciplines means we regularly achieve high impact outcomes.

Ice nucleation remains a major limitation in our quantitative understanding of clouds in the climate system and new discoveries in this area have the potential to alter the way many scientists think about clouds. We have a strong track record of producing high impact papers with several articles in Nature in recent years.

In addition, there is the potential to make an impact in the commercial sector of cryopreservation. The market for cryopreserved cells and the technology to freeze, store and thaw cells is global. We are in a strong position to grow and exploit this market.

We have identified the high throughput toxicology screening market as a priority area in our commercialisation strategy. The total market for in vitro toxicology testing is estimated to reach $27 billion by 2021 from $14 billion in 2016 and in our opinion is held back by the lack of frozen format cells supplied in multiwell plates. Single multiwell plates of traceable fresh format hepatocyte cells for toxicology testing can cost in the high hundreds of pounds. 

A frozen format would offer significant advantages, hence there is a major commercial opportunity in this high-value end of the market. There is also a societal impact, where stem cell therapies that can in principle cure ailments such as cancer, rely on the availability of appropriate stem cells.  Again, there is a significant advantage in frozen format cells which could be stored until they are needed. This potentially offers advantages for human health and well-being, in addition to obvious commercial opportunities.

Entry requirements

Applications are invited from candidates with or expecting a minimum of a UK upper second class honours degree (2:1) or equivalent, and/or a Master's degree in the relevant subject area.

If English is not your first language, you must provide evidence that you meet the University’s minimum English Language requirements.

How to apply

Formal applications for research degree study should be made online through the university's website.

If you require any further information, please contact the Graduate School Office e:, or t: +44 (0)113 343 1634.

We welcome scholarship applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.