Author: Imperial Materials

Research Insights: Interview with Professor Baptiste Gault

Professor Baptiste Gault is a Professor of Materials in the Department of Materials and leader of Atom Probe Tomography research at the Max-Planck-Institut für Eisenforschung. He is the Group Leader for Atom Probe Tomography

Atom Probe Tomography is the only material analysis technique offering extensive capabilities for both 3D imaging and chemical composition measurements at the atomic scale. Since its early developments, Atom Probe Tomography has contributed to major advances in materials science.

In this blog post, Professor Baptiste Gault shares more about Atom Probe Tomography, his research journey and how materials will be crucial in transitioning to a zero-carbon world.

Can you tell us more about Atom Probe Tomography?

Atom probe tomography is a growing microscopy and microanalysis technique that provides three-dimensional compositional mapping with sub-nanometre resolution and a sensitivity that goes down in the range of parts-per-million across all elements of the periodic table. This essentially means that we can take a small piece of material and measure very locally and with a high precision how much there is of each element inside and how they are distributed with respect to one another.

Why is this interesting, you might ask…? In any given material, the way the atoms of the various components are organised controls the properties of interest of the material. If we wish to design materials that are stronger, more active, more resilient against failure, then we need to understand what in the atomic structure and distribution underpins these properties and how these evolve during service. That’s where atom probe tomography becomes useful: it can complement existing techniques – think optical and electron microscopies, wet chemistry or X-ray based diffraction and spectroscopies, for instance – and provide compositional analysis on an unparalleled scale. The facility that we’re establishing at Imperial will enable us to deploy multiple microscopy techniques on the same specimen to obtain structure and composition from correlating electron-based techniques and atom probe tomography.

The field has been expanding and evolving really fast in the past decade. During my PhD studies, there were more than a dozen groups worldwide and maybe 20 instruments in operation. Today there are over 120 and the community is growing. We described these recent developments and how the atom probe works in this Nature Reviews Methods Primer article published in late July.

The new Hydra Plasma Focused Ion Beam facility in the Department of Materials

What led you to research this area of Materials Science?

That’s a tougher question than you might think… like many other things in life, they often happen. I studied both physics and chemistry as I intended to become a secondary school teacher, then ended up picking up a master degree and materials science seemed closer to my interests; the list of internships had one with a recently appointed lecturer who seemed nice and fun, and I got into atom probe then… this might have been a trap!

I was then awarded a scholarship for a PhD and decided to continue working on the development of the atom probe instrumentation during my postdoctoral work and then as a senior scientist and now academic. I’ve kept an interest in method development and in the application of the technique to an ever-increasing range of materials systems and problems. It’s good fun, and I keep learning from all the amazing folks I end up collaborating with – that’s the most interesting side of this entire endeavour.

What are the main aims of your current research?

So my research really had two main directions.

On the one hand, “push the analytical limits of atom probe tomography” – this was my mission statement when I started my first postdoc at the University of Sydney in 2007 and still applies today. So part of the work of my close collaborators is a consequence of the development of new instrumental protocols, for instance, how can we transport samples from one instrument used for the preparation of suitable specimen into an atom probe while keeping them very cold (cryogenic temperature close to -200˚C) and under very high vacuum (somewhere in the range of what we find in outer space). We also work on developing methods to extract more meaningful information from the three-dimensional point cloud that we generate or to improve the reliability of the processing of the raw data from the instrument. For this, we explore the use of machine learning approaches, for instance.

On the other hand, we make use of the technique to provide insights into a range of materials, which includes steels for cars, nickel and titanium and aluminium alloys for various parts in planes, thermoelectrics and photovoltaics for energy conversion from heat or sunlight, hard and soft magnets for electric car engines or wind-power generators amongst other things. Because the microstructure of these materials is typically hierarchical and complex on multiple scales, we use a range of microscopy and microanalysis techniques which culminate with atom probe tomography performed on the bits of the material that have been identified as the most critical: the cherry on the cake.

Can you explain some of your recent results?

Materials will be critical to most aspects of the zero-carbon transition. Whether we want to extend the lifetime of engineering parts to limit the use of resources and their making, which is an important source of emissions, or design new materials with enhanced properties or activity towards enabling the hydrogen economy, atom probe can be used in complement to an arsenal of techniques to bring insights that are critical to understanding fundamental processes and apply those to engineer better materials.

LEAP 5000 XR Atom Probe Facility
LEAP 5000 XR Atom Probe Facility in the Department of Materials

Since the award of an ERC-Consolidator grant in 2018, the group has a specific focus on the analysis of hydrogen in materials and materials relevant to the hydrogen economy. We hear a lot more about hydrogen in the media at the moment, as it is an interesting candidate for decarbonisation of aspects of our society – maybe some parts of transportation and industrial processes, including steelmaking.

Hydrogen is also known to cause or facilitate embrittlement of most metallic materials, which becomes especially critical for high-strength alloys that are necessary for making lighter cars and planes to reduce carbon emissions, for instance. Hydrogen is the lightest of elements, and it remains elusive to most microscopy and techniques, so many questions regarding its interaction with the microstructure remain open.

In the group, we make use of our dedicated infrastructure involving an atom probe and a cryogenically-enabled focused-ion beam and the possibility to transfer samples from one instrument to another. This platform, located at MPIE in Germany, served as a template for the facility that is being installed at Imperial as we speak. First, we showed the possibility and critical importance of cryogenic specimen preparation. Then, we used isotopic-labelling, i.e. introduced “heavy hydrogen” inside a material, froze the sample to prevent hydrogen diffusion out of the material and then performed analysis to map the distribution of deuterium and help narrow down on some of the hydrogen embrittlement mechanisms and mechanisms of hydride growth. We use this knowledge to design new alloys as well. In parallel, we are looking at hydrogen-based ironmaking, for instance, and the synthesis of active materials for water splitting and subsequent analyses by APT to better understand how they form and what underpins their activity. So a relatively broad range of materials and problems.

What are the next steps for your research? 

We’ve started making a dent into the possibility of analysing frozen liquids and liquid-metal interface, and that’s where the next frontier for us lies. The new facility at Imperial will help us perform these analyses at an unprecedented level of precision. We will be able to stop ongoing surface reactions, for instance, or wet corrosion “as it happens”, and these processes can be used to our advantage to tailor active surfaces, for example. This is extremely exciting for me!

PhD Spotlight: Enrico Manfredi-Haylock on chemical robots and new discoveries

Enrico Manfredi-Haylock is a Research Postgraduate in the Department of Materials. His research focuses on lead-acid battery recycling using novel solvents under the supervision of Professor David Payne.

During his research, Enrico received funding from the Natural Environment Research Council to build a chemical robot as a student project. Over the summer, he led a team of UROP students for 10 weeks, developing a chemical robot for the automated dissolution and dilution of lead materials in solvents.

In this blog post, Enrico explains more about the benefits of this robot and its potential on a larger scale.

1. Can you provide an overview of the main aims of your PhD research project?

While my project has changed due to COVID-19 and from new data gained from experiments, the aim has always been to discover new solvents to dissolve and recover lead materials from batteries.

I aim to find a solvent that is so effective at dissolving and recovering lead materials from batteries that a process built with it can completely replace smelting-based recycling, which is highly polluting and energy-intensive.

The solvents under investigation are called Deep Eutectic Solvents (DES). They are essentially mixtures of organic compounds that combine unique intermolecular interactions that result in a very chemically active liquid that is highly capable of dissolving metal oxides and other compounds. I’ve been actively exploring DES for lead-acid batteries since 2018 when I did a UROP for my 3rd year UG placement in David’s group. I then chose the project as my master’s project the following year, and doing a PhD in it seemed like a natural progression and a good way of answering the question that has always bugged me – how do these solvents work?

2. What led you to develop a chemical robot?

The problem with the solvents I use is that they are very viscous. This, combined with their chemistry, means that the reactions are very slow. This firstly presents a challenge because you have to keep the reaction going for a long time (sometimes days!) to get a time-resolved reaction profile. The second challenge is that in these very slow systems, processing parameters significantly affect the final dissolved lead content (how we measure how “good” a solvent is – the more lead dissolved, the better).

So if you stir it a bit faster, or you’re a little too slow in your dilution when the reaction is finished, you introduce significant error into your final readings of lead concentration in the solvent. The smallest error that I was getting after I’d been doing the experiment for months and had built up the experience and muscle memory was still 30%, which does not help figure out how the solvent works. So instead of using the same method, which clearly didn’t work, I asked myself what else I could try. After thinking about it for some time, automation seemed like the best solution.

3. Can you tell us more about the chemical robot you created? 

In its current form, the robot will automatically add lead solids to a vial filled with a deep eutectic solvent and stir it for a set amount of time. After mixing, it will automatically extract the mixture of solvents and residual solids into a syringe and then push it through a filter into a smaller vial. A micropipette will then pick up about 20 thousandths of a millilitre and place it in another vial filled with about 5 millilitres of acid. While this machine is a little slower to do the dilutions (400s) than by hand (~300s), it is much more precise and can keep track of the time taken, allowing for more consistency in the result.

It can also do 5 samples consecutively without stopping, allowing for uninterrupted multi-day mixing experiments with excellent time precision. This machine was originally built remotely in two parts by UROP students Dewen Sun (Materials) and Sarthak Das (Design Engineering) with Irdina Rohaimi shadowing the project. After the 10-week remote build phase, the parts were delivered to campus, where I integrated the systems into the final machine and tested it.

(A video of the chemical robot in action. This video has been sped up x4 for viewers)

4. How will the chemical robot help your research?

The current iteration of the robot is meant to be more of a proof-of-concept and a testbed for future iterations. However, this system will allow me to double my throughput since it can conduct about as many experiments as I can do independently (with cleaning in between). This is important for solvent discovery as we just need to try lots of solvents and combinations.

To some extent, this kind of work is perfect for automation because you only change starting materials, but other than that, the experiments are the same. Therefore, instead of being a machine myself, I can build one and spend the time doing more experiments or interpreting my data, which will take a load off my shoulders. In future, an upscaled version of this system will work much faster than me and will generate so much data that I won’t need to go into the lab at all except for maintenance and machine refills. I think this is a dream shared by many chemists, some of whom are also trying to automate their lab processes!

5. What are the next steps for your project? 

I have just applied for £80,000 to the Royce materials 4.0 feasibility & pilot scheme to build an upscaled version of the machine with David’s support.

The upscaled version will handle around 500 samples compared to the 5 of the current machine and will be able to run some processes in parallel. This machine should average 71 samples a day. For context, I can only do 15.

The core concept is the same – instead of starting from scratch, I intend to use a 3D printer as a starting point because it already has all of the XYZ handlings we need and a structured command language to execute these movements. However, instead of using a couple of cheap desktop printers with 12x12cm of accessible space, I will be using an industrial 3D printer with 180x60cm of accessible space.The 500-position syringe filtering system also needs to use a co-located robotic arm to access and actuate each position.

It’s a very ambitious scale-up but based on the concepts tested with the first prototype, I’m confident that it will work, and it may well end up being one of the largest automated chemistry robots out there!

Research Insights: Interview with Dr Stella Pedrazzini

Dr Stella PedrazziniAn image of Dr Stella Pedrazzini is a Lecturer in Engineering Alloys and Metallurgy in the Department of Materials.

She works on the environmental degradation of engineering alloys, with a particular interest in oxidation and hot corrosion of nickel and cobalt-based superalloys, aqueous corrosion of steel as well as advanced characterisation techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT). Dr Pedrazzini also teaches the 1st year undergraduate module in Materials Electrochemistry.

  1. Can you tell us more about your research area and the importance of investigating metallic corrosion?

Imperial College is based in central London, and yet no one comes to work by driving through Hammersmith bridge, even though avoiding it leads to a very long detour. There’s a very simple reason for this: the bridge is closed for the next 7 years. It is in immediate danger of collapse due to decades of unchecked corrosion[1]. And this is just the tip of the iceberg.

Metals have been used by mankind since about 3000 BC, and in thousands of years, we have not found a way to stop them from corroding. That is because most pure metals are a human creation: in nature, they are only found as ores. Ores are generally a mixture of metal oxides, chlorides or sulfides. We process ores to become pure metals, we “borrow them” from nature for a few years but there is always a strong driving force acting to revert them back to their stable state. We are fighting an uphill battle with corrosion.

Hammersmith Bridge
Hammersmith Bridge

But this is a battle worth fighting: we need metals. Metals have properties other materials just don’t have. They are ductile, strong, electrically and thermally conductive and their properties can be tailored through alloying. Over the years, our metallurgical investigation tools have become increasingly sophisticated, allowing step-changes in progress towards the understanding of metallic corrosion and protection techniques.

  1. What led you to study metallic corrosion?

When I was a student at the European School of Brussels I always favoured the sciences over other subjects, particularly chemistry. That’s part of the reason I chose to study Materials Science at university: it is a mixture of chemistry, physics and engineering.

Once I started the courses, I realised I had a particular interest in metallurgy, an interest which I pursued during my MEng and DPhil degrees at the University of Oxford. When I graduated, I started working on different metal investigation tools, such as atomic scale microscopy. It’s around this time when I started working on corrosion: corrosion is very difficult to investigate and I really enjoyed the challenge. I worked on corrosion as a researcher for almost 5 years, initially at the University of Oxford, then at the University of Cambridge, before establishing my own research group at Imperial College London.

To this day, very few research groups around the world work on corrosion due to the challenges involved in this type of investigation. I am delighted to receive support for my corrosion work from Imperial College, from the Engineering and Physical Sciences Research Council, from the Royal Academy of Engineering and from various industrial partners, all of which serves to highlight the industrial importance and economic impact of corrosion research.

  1. What are the main aims of your research?

Our aims are:

  • To be able to simulate in our labs the working environment of a metal (eg when used in a jet engine, industrial-scale furnace, industrial gas turbine, car engine, nuclear reactor, off-shore platform, wind farm etc). This allows us to corrode the metals in controlled laboratory experiments, without the costs and safety risks of them corroding in-service.
  • To understand the mechanisms by which the metals corrode so that we can prevent them. This can be done by changing the alloy composition, adding some in-built corrosion protection (like stainless steel), or by adding coatings or other protection mechanisms.
  • To use this knowledge to be able to predict how metals would corrode in-service in specific applications. This allows us to predict their lifetime, therefore reducing safety concerns.

My research group is divided by material: we have people working on steels, on nickel-based superalloys, on titanium alloys and more recently on zirconium too. The noble metals are the only ones that don’t corrode (…easily! Though that can be arranged too!), everything else is worthy of investigation.

  1. How could this research potentially benefit society or the way we live?
Dr Pedrazzini in the lab with her research group
Dr Pedrazzini in the lab with her research group in 2019

Corrosion has a huge environmental, safety and economic impact: it costs us 3.4% of global GDP yearly[2]. It presents challenges in almost every industry: construction, transportation, bio-medical, electronics, power generation and many more.

We only need to go through some newspaper headlines to realise the effect of corrosion on our daily lives. Bridges have been shut[3], or have collapsed[4], aeroplanes have been grounded[5], oil pipelines have burst[6], nuclear site accidents have happened[7], all due to unchecked corrosion. In addition, due to some recent high-profile retirements in the field, there is currently a strong need for more corrosion management professionals both in the UK and worldwide.

Some of the work from my own research group has helped inform the corrosion rates of aero-engines, industrial gas turbines, nuclear reactors and medical implants exposed to body fluids.

  1. What are your next steps are in your research? Are there any challenges ahead?

Since moving to Imperial in 2018 I have focussed all my efforts on building up our corrosion research capabilities. This involves building unique equipment that can allow us to simulate metal service conditions, so we can safely corrode metals in a controlled manner in the lab.

All this equipment has to be bespoke and homemade: no companies produce it or sell anything like it. This includes bespoke electrochemical cells that allow us to apply mechanical pressures on the samples while in a wet corrosive environment, or to handle corrosive gases while fatigue testing the metallic components. Some of it involves safely pressurising very corrosive gases like H2S, or heating the samples to over 1400 °C, if that is the environment they have to survive in-service. We also just received funding from the Engineering and Physical Sciences Research Council for a new microscopy facility which will be instrumental for analysing corroded samples.

All these new unique facilities are now coming together, so I am looking forward to being able to expand the range and tackle more corrosion problems as they arise.

[1] http://www.transport-network.co.uk/Hammersmith-Bridge-wont-open-until-2027-after-decades-of-unchecked-corrosion/16940

[2] http://impact.nace.org/economic-impact.aspx

[3] http://www.transport-network.co.uk/Hammersmith-Bridge-wont-open-until-2027-after-decades-of-unchecked-corrosion/16940

[4] https://www.independent.co.uk/news/world/europe/genoa-bridge-collapse-engineer-riccardo-morandi-warning-corrosion-rust-concrete-a8498716.html

[5] https://www.telegraph.co.uk/business/2018/11/09/rolls-royce-admits-yet-corrosion-problems-jet-engines/

[6] https://www.theguardian.com/environment/2015/jun/04/us-oil-pipeline-left-to-rust-to-paper-thin-before-145km-pacific-ocean-slick

[7] https://www.nytimes.com/2000/03/03/nyregion/corrosion-seen-as-a-plant-accident-cause.html

Student Interviews: Lukau Mbolokele on Black History Month

Lukau Mbolokele is a second-year undergraduate student in the Department of Materials. For Black History Month 2021, he has shared more about his journey into Materials Science, having pride in your achievements and the importance of diversity in Science.

The theme this year for Black History Month is #Proud to be (me). To find out more about events for Black History  Month and celebrations at Imperial, please visit our website.

What led you to study Materials Science at Imperial?

When I first realised the versatility of Materials Science – being interdisciplinary in Physics, Chemistry and Engineering. The concept of understanding, manipulating, and applying materials as solutions to the world’s problems reinforced my desire to pursue materials as a degree. Imperial was also my preferred university due to its specialisation in STEM courses and exposure to different cultures and mindsets.

What did you enjoy about your first year at Imperial, and what are you looking forward to this year?

My first year introduced me to a range of new interconnected concepts. Learning different topics every day helped keep my interest ablaze during the pandemic, and I enjoyed learning new skills like 3D printing and coding. This year I’m looking forward to connecting with the Imperial Materials community in person and continuing projects that have built transferable skills.

The theme of Black History Month 2021 is #Proud to be (me). Can you share what you are most proud of?

Coming from a low-income background, I wasn’t exposed to many opportunities to enrich my interests in STEM. There was also the challenge of overcoming the stereotypical barriers that have been imprinted on us from youth by the media.

I’m #Proudtobe a student who has reached one of the top universities in the world. My acceptance has brought so much happiness to my family and me.

What changes would you like to see for students studying STEM in the future?

I’d like to see a more diverse pool of students studying Materials Science (and STEM subjects in general!). Everyone must also strive for a place where all students can confidently attend university without feeling isolated or like an imposter.

An image of Lukau Mbolokele
Lukau Mbolokele standing on the steps outside the Royal School of Mines, Imperial College London.

Student Interviews: Our Summer placements

Many undergraduate students at Imperial College London decide to complete a placement based in a department, at another university or with industry over the summer. These placements are organised by the student independently.

In the blog posts below, two of our students have shared more about their experiences this year.

Harry Hughes – Undergraduate Research Opportunity Placement in the Department of Materials

An image of Harry HughesHi, I’m Harry! I am an incoming second-year undergraduate student studying Materials Science & Engineering at Imperial College London. I have recently completed a 10-week Undergraduate Research Opportunity Programme for the Engineering Alloys research group with Dr Stella Pedrazzini.

The project investigated stress corrosion, cracking and pitting corrosion that austenitic stainless steels experience under various salt exposures; this will be used in the context of the dry fuel store campaign that EDF Energy is conducting.

The motivation to complete a placement within this field was to further build on my experiences of working within corrosion and oxidation. I have previously worked as an intern for a year within EDF Energy’s Chemistry & CO2 Oxidation group, where I helped research boiler oxidation kinetics in the current fleet of UK AGR power stations.

Any placement comes with its own set of challenges, and the UROP was not an exception. As the research was independently run by myself and another student, I had to formulate an experimentation plan with limited lab experience and knowledge of the subject area. Time management was also a key factor in the success of the placement – due to the pandemic, time spent in the laboratory was limited to only 15 hours a week. This meant I had to be smart with my time and plan ahead to complete the investigation within 10 weeks.

In all honesty, I wasn’t keen to complete research before the UROP. However, its independent nature led me to fundamentally enjoy my experience and has made me consider completing a PhD after my undergraduate degree. I have always been a person who enjoys leading projects, and this UROP has exposed me to this. Working with Imperial has also been very different to working with EDF Energy. The internship at EDF Energy was more structured by having stricter objectives, and for the most part, I completed smaller remedial tasks. Compared to the UROP, whilst having a final goal, I could pick and choose areas within corrosion that I could investigate, which I really enjoyed.

My advice to anyone who is thinking of completing a UROP? Look up which professors research areas spark your interest the most and contact them directly to see whether any positions are available within their group. Imperial College London’s Careers Service and your personal tutor are also useful tools you can use to seek out any potential placement opportunities.

I hope this post has given you an understanding of how a materials UROP takes place, alongside its challenges, and has inspired you to apply for one. Good luck!

Jakub Lala – Summer Placement at the École Polytechnique Fédérale de Lausanne

An image of Jakub LalaThis summer, I completed a 10-week placement at the École Polytechnique Fédérale de Lausanne, specifically in the Computational Sciences and Modelling Lab led by Michele Ceriotti. EPFL has several placement programmes available, and I applied through both the E3 Engineering Programme (deadline around January) and the Research Internship Programme (applications open in October).

During the first five weeks, I worked on a visualisation tool called Chemiscope, improving its website and implementing a Jupyter Notebook integration. For the rest of the internship, I worked on a PyTorch model to optimize coupling parameters, reducing the amount of elemental information required for material structure datasets, hence improving the learning rate of machine learning models afterwards. Having both of these aspects during the placement showed me the importance of both software engineering and actual modelling science in the arena of modelling computation.

Although this will vary depending on the lab, I am extremely grateful that my direct supervisor was a PostDoc, who was almost always available, meaning whenever I felt frustrated or I was stuck in terms of progress, he would easily step in and helped me with valuable guidance. Posing stupid questions to him was not an issue, giving me the potential to learn a lot and advance fast. On the other hand, when he went on a summer vacation, the internship highlighted that one also needs independence during work to develop the necessary problem-solving skills without someone senior fixing his problems for him.

A snapshot of Chemiscope, a Visualisation tool that Jakub used for his research.

This opportunity also allowed me to taste life in another country, especially the work and societal cultures. This not only gave me important insight that may become helpful once applying for future jobs or PhDs abroad, but it also widened my perception of global opportunities by demonstrating that it is conceivable getting involved in impactful work all around the world, in all sorts of fields. More importantly, by talking to PhDs or PostDocs in the lab, you get invaluable information that will help you decide on your future career. Personally, I realised that an academic career is definitely something I do not want to pursue, but going for a PhD interlinked with the industry might be somewhat lucrative and exciting.

If you are trying to find an internship, use the network you already have. By asking your current professors or researchers, either sending them an email or visiting their office, you are doing yourself a favour in the long run, as they can recommend you suitable labs, professors, or companies in whatever field you might have interest in. For instance, my former Imperial UROP supervisor recommended Michele’s lab as an interesting place to apply to, and then in a similar manner, Michele was kind enough to suggest a potential MIT supervisor for my future Master’s thesis.

To find out more about Undergraduate Placement Opportunities, visit the Department of Materials website.

 

Research Insights: Interview with Dr Alessandra Pinna

Dr Alessandra PinnaDr Alessandra Pinna is an Imperial College Research Fellow in the Department of Materials. Her research interests involve developing novel nanostructured ceramic and hybrid organic-inorganic coatings, nanoparticles and nanocomposites for biomedical applications, with a particular interest in drug delivery, antimicrobials and antioxidants. Dr Pinna was awarded the June Wilson Award 2021.

Can you tell us more about your research area?

The key feature of my research is the use of inorganic materials and their dissolution ions as therapeutic agents, replacing the need for conventional drugs. In some cases, the inorganic ions (e.g. nanoparticles) can be more effective and more targeted than drugs, and cause fewer side effects.

What is the main aim of your research?

The main goal of my research is to develop an affordable, nanoparticle targeted drug delivery system that can penetrate across the blood-brain barrier (BBB) to treat different types of brain diseases such as Meningitis, Parkinson, and Alzheimer’s.

In collaboration with Francis Crick Institute, I’m currently researching the treatment of Tuberculous Meningitis (TBM) caused by a bacterium called mycobacterium tuberculosis, which is responsible for the most severe form of tuberculosis infection. I have used the sol-gel method to develop inorganic therapeutic nanoparticles. This is because it can produce nanoparticles at low temperatures with carefully controlled properties, using simple techniques. The nanocarrier is synthesised from biodegradable mesoporous silica nanoparticles (the vehicle), loaded with antibiotics (the drugs) and nanoceria (an anti-inflammatory agent), to kill the mycobacterium tuberculosis resident inside the brain and diminish the damage caused by inflammation associated with this infection.

An image of a nanostar and blood-brain barrier
Spiky Nanoparticles (grey) and Nanostars (black) crossing the blood-brain barrier.

Can you explain some of your recent results?

We have discovered that “spiky” nanoparticles can cross the blood-brain barrier in significant amounts and that silica mesoporous nanostars are better internalised by cells than spherical particles. Silica mesoporous nanostars, due to their high surface area, also demonstrated a higher loading capacity for antibiotics because of the spherical counterpart.

The novel multifunctional therapeutic nanostars that cross the blood-brain barrier and deliver the targeted drug to the brain could be a highly promising strategy to tackle any type of brain disease such as neurodegenerative disease, cancer or meningitis.

How could your results potentially benefit society?

Public Health England (PHE) is committed to meeting the World Health Organisation (WHO) Tuberculosis elimination targets by 2035. Reaching the WHOs End TB Strategy target by 2035 was always challenging, and the COVID-19 pandemic adds additional complexities.

Tuberculous Meningitis is the most severe form of tuberculosis infection. Worldwide, 100,000 individuals develop Tuberculous Meningitis each year, and 150 – 200 cases are reported in the UK. In general, those most at risk from Tuberculous Meningitis are children under four years, the elderly, and HIV-positive patients. Mortality rates can be high and in addition, around 30% of HIV-infected adults and 20% of children will suffer long-term after-effects from the infection.

The novel multifunctional therapeutic nanostars will enhance the delivery of antibiotics and anti-inflammatory by targeting the brain and achieving a controlled release of more than one drug at a time. Moreover, by providing new therapies for Tuberculous Meningitis, we will be able to tackle antimicrobial resistance.

What are your next steps are in your research? Are there any challenges ahead?

First, the big challenge is to prove the therapeutic efficacy of the nanostars. Once validated, their efficacy as a new therapeutic drug the translation strategy will be the next important step towards their use for other brain diseases.

Dr Andrew Cairns on his research and LGBTQ+ role models in STEM

Dr Andrew CairnsDr Andrew Cairns is a Research Fellow in the Department of Materials. He is also a part of the LGBTQ+ community and Mental Health First Aider. To mark the end of Pride 2021, Dr Cairns shares more about his current research, his motivations for studying Materials Science and the importance of having an LGBTQ+ role model in STEM.

Hi, I’m Andrew, and I’m a Research Fellow in the Department of Materials. To give you an overview of my research: I investigate materials that behave in the opposite way than you might expect: so, instead of expanding when heated, they shrink. Even more bizarrely, under pressure, they expand rather than compressing in every direction.

We have found examples of these behaviours that are very extreme in a class of materials called molecular frameworks. We continue to look for larger and even more unusual properties and link properties together to engineer multi-functional materials. The challenge that drives me is how to manipulate matter — atom by atom — to realise advanced functionality.

Motivating this work further is the impact such unusual materials could have on future technologies. These properties — today mostly seen as curiosities — could enable more sensitive touch screens, devices with variable-pressure recognition, more accurate sensors, or more efficient data storage. We aim for a step-change in device performance that will only be possible with radically different materials than those currently used. So, alongside making new materials, we are working to fabricate these materials into prototype forms (like very thin coatings) that could be integrated into devices.

‘Science is AMAZING’

Like most of us in science, there is huge joy when you discover something no one else has ever seen before. During my doctoral studies, I remember the first time this happened: my supervisor and I were staring at an Excel workbook, systematically inputting numbers as the machine outputted data, and not believing our eyes. We worked in almost silence until we went to lunch and could say, ‘is it true?… This is amazing!’ Who knew an Excel file would ever be that interesting?

A photo of Dr Andrew Cairns at the European Synchrotron Radiation Facility (ESRF)
Dr Andrew Cairns at the European Synchrotron Radiation Facility (ESRF)

Of course, not every day is eureka-central: it takes a lot of patience and many failed experiments to get to that point. In those times, the things I enjoy most are the people and amazing facilities I am very fortunate to work with. I worked previously at the European Synchrotron Radiation Facility (ESRF), one of the most intense sources of X-rays in the world. I was blown away by the dedication of the scientists there and the ingenuity of the engineers who keep such a massive machine working (it has a circumference of over 800 m). Today, I continue to work with groups close to home, such as the Henry Royce Institute and all around the world. Getting involved in projects and seeing ideas develop with others is rewarding every day, including supporting students and colleagues to achieve great results.

The importance of LGBTQ+ role models in STEM

I was extremely fortunate that my doctoral supervisor, Prof Andrew Goodwin, is one of only a few LGBT+ academics in STEM. I was not aware of this when I first met him, but I am sure that having this role model has changed my experience in science. On one level, having someone to look up to gives confidence that my sexuality shouldn’t hold me back. This makes it easier each time I have to come out in a professional context. On another, I know that if ever I did experience hostility (I am fortunate this has never happened), I have a large group of supporters who would make it clear that such behaviour was not acceptable. There is huge power in knowing you are not alone.

Bringing your whole self to work is something I feel is so important in a job like being an academic for LGBT+ scientists or any other underrepresented group. We are often working 1:1 with collaborators, students and colleagues to support one another where trust and openness are key. Having been supported in my own journey makes me absolutely committed to doing my best for those around me.

I am therefore passionate about doing great science but working to make academia more welcoming and diverse. To me, these are one in the same: if we treated our equipment badly, we would expect bad data and therefore bad science, so why expect anything different from our people? More broadly, why does academia shelter, and in some cases celebrate, harassers and bullies? All our efforts in equality, diversity, and inclusion should be celebrated as a central part of being a scientist. And I continue to learn: to do my best science and to be the best scientist I can be. I am sure I will make mistakes in both areas, but I never want to lose the desire to do the right thing.

An image of Dr Andrew Cairns and Prof Andrew Goodwin
An image of Dr Andrew Cairns and Prof Andrew Goodwin. Photo credit: ESRF/C. Argoud.

My advice for the next generation of LGBTQ+ Scientists and Engineers

Find your champion! I was lucky this was someone who I was interacting with every day, but there are more and more visible LGBT+ scientists and engineers out there who want to support the next generation. It might be that you are comfortable to come out and share your experiences with these people, to find that community, and that is great. Or it might be that you are less comfortable, and so even just checking the Twitter account of an LGBT+ scientist or engineer you admire can help give you a sense of connection.

We also must recognise how different parts of our community have different challenges, and others may live in countries where it is simply not possible to be out. Everyone has a responsibility to respect difference, acknowledge privilege and educate ourselves. In particular, current attacks on the trans* community are deeply worrying, reminding us all that rights that may seem to be won can be taken away just as easily. If you can, fly the flag and celebrate – but remember Pride is still a protest, and there is work to be done.

Meet the team: Zyme Biosciences reach WE Innovate finals

Dr Marta Broto Aviles leads the Zyme Biosciences team

Zyme Biosciences have made the finals of the WE Innovate 2021, a scheme led by the Imperial Enterprise Lab. WE Innovate provides a platform to showcase the incredible progress being made in women’s entrepreneurship at Imperial – with winning teams winning a part of a 30K prize fund for their ideas. In this post, the team explain more about their potential product and the scheme.

Introducing the team

We are a team of researchers from the Department of Materials, working under Professor Molly Stevens. A lot of the work we do is focused on translatable technology for point-of-care diagnostics. When COVID-19 came along last year there was a large shift in the outlook of our field, as organisations around the world quickly began to understand the value of accessible diagnostics. It was this that motivated our team lead, Dr Marta Broto Aviles, to enter us in the WE innovate programme, to learn more about how we could move some of our work to the market.

Our team of four is a small-scale representation of the research group at large, and the work we are pitching is the culmination of years of work from various group members. Our WE innovate team consists of three post-doctoral researchers; Marta, Leah, and Paresh, and one PhD student; Schan. We come from a mix of academic backgrounds, but we have all been in the Stevens group for multiple years and have expertise centring on nano-diagnostics.

Developing our product: QuickZyme
The venture we have taken through the accelerator is called Zyme Biosciences, pitching our product: QwikZyme. QwikZyme is a small, user-friendly device that utilises novel nanomaterials to detect a range of disease biomarkers, most recently we have optimised the assay to detect proteins located in the SARS-CoV-2 virus. By focussing on COVID-19 biomarkers, for now, we believe we have a relevant entry to the market for this diagnostic platform that can be expanded to detect non-communicable diseases such as cancer.

An image of Schan Dissanayake-Perera

What we’ve learned through the WE Innovate scheme

As academic researchers, the prospect of dipping your toes into the world of business can be a terrifying prospect. But the higher up the ladder you climb the more it becomes clear just how interdependent two streams of academia and business really are. The whole landscape can be quite tricky to navigate but luckily, Imperial has a few different programmes to help researchers get off the ground and learn about what it takes to translate an idea from the lab to the boardroom.

WE innovate has been an amazing opportunity, not only in terms of networking but also in developing our soft skills such as pitching. One workshop that stood out, was one given by a pair of professional magicians who taught us how pitching, like magic, is all about directing the attention of an audience for a specific purpose. We are all used to presenting science in an academic context but selling an idea to a potential investor requires a whole different approach.

A challenge that has been unique to our venture, and likely to many other university spinouts, is the navigation of a complex intellectual property landscape. Understanding exactly who owns an idea is quite important if you are looking to sell or license that idea so it has been really useful to be put in touch with a number of IP law experts in this area.

We are really excited to have made it through to the final of the WE innovate programme and are extremely grateful for all the help we have received along the way!

Update: The team won the People’s Vote: Lauren Dennis Award in the finals, winning 3 months of personalised coaching to develop their product, as well as £1,500 towards the development of their product and the Engineers in Business Fellowship award.

Research Insights: Interview with Dr Robert Hoye

Dr Robert HoyeDr Robert Hoye is a lecturer in the Department of Materials. In this post, he explains the potential for halide perovskites and their derivatives in renewable energy. Dr Hoye recently led one of the key roadmaps for the Henry Royce Institute, identifying halide perovskites as one of the key technologies for the UK to achieve carbon neutrality by 2050. 

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Photovoltaics produce clean electricity from sunlight and are one of the leading renewable technologies. As such, it is vital to accelerate the deployment of this technology. However, realising a high electrification future will require the number of photovoltaic devices installed every year to increase by over an order of magnitude. A rapid expansion in the manufacturing of photovoltaics is needed, and this may be fulfilled by a newcomer to the photovoltaics scene: halide perovskites.

What are halide perovskites?

Figure 1. Structure of perovskites
Figure 1. Structure of perovskites

The term ‘perovskite’ refers to a family of materials with the crystal structure shown in Figure 1. The prototypical perovskite (calcium titanate) was found nearly 200 years ago in the Ural mountains by Gustav Rose, who named the material after Lev Perovskiy. Other perovskites include barium titanate, strontium titanate, lead titanate, and others, and these materials have been used in ferroelectrics, piezoelectrics and pyroelectrics. It was only recently that halide perovskites have come to prominence for photovoltaics.

In 2009, Tsutomu Miyasaka and colleagues reported methylammonium lead iodide as a sensitizer in liquid-junction solar cells, demonstrating a power conversion efficiency of 3.8%. In subsequent years, a series of developments transformed this material from yet another novel solar absorber to the dominant next-generation photovoltaic technology. In 2020, the certified record efficiency of perovskite solar cells reached 25.5%, which is already on the cusp of matching the record performance of solar cells based on single-crystalline silicon (26.7%), the dominant commercial technology. Remarkably, whilst crystalline silicon required 6 decades of development, halide perovskites have only been developed for one decade. Furthermore, halide perovskites hold several critical advantages over crystalline silicon:

1. Halide perovskites can be grown at significantly lower temperatures, with the absorber typically processed at only ~100 °C. This reduces the carbon footprint of perovskite solar cells, as well as the energy and cost required for its production;

2. Halide perovskites have significant chemical versatility, with the bandgap tunable over the entire visible wavelength range by controlling the composition or dimensionality.

Figure 2. Structure of a tandem solar cell comprised of two solar cells, absorbing in different parts of the solar spectrum, joined together with a recombination contact
Figure 2. The structure of a tandem solar cell comprised of two solar cells, absorbing in different parts of the solar spectrum, joined together with a recombination contact

An important implication of these factors is that perovskite solar cells can be used to produce ‘tandem’ photovoltaics with silicon solar cells (Figure 2). Much like tandem bicycles, tandem photovoltaics electrically couple together two solar cells (in this case perovskites and silicon) to work together to generate more power. Such devices can exceed the efficiency limit of each device working individually. Critically, by adding a perovskite solar cell over a silicon solar cell, increases inefficiencies can be achieved without significantly adding to the total cost, thus reducing the ratio of the cost of the solar cell compared to the total power produced, such that photovoltaics become more cost-competitive against fossil fuels.

How perovskites photovoltaics be pushed from lab to market?

Halide perovskite solar cells have risen in efficiency faster than any other photovoltaic technology and are already at the level at which they can be commercialised. However, their fast rise has also meant that most research on this technology has been performed at the lab scale, in which the most efficient solar cells have device areas smaller than a fingernail. By contrast, manufacturing perovskite photovoltaics at the level needed to make an impact on climate change will require at least several million square metres of devices per year. Achieving this will require fabricating with speed and at scale. Perovskites can be grown over a large area by printing, spraying or evaporating, but it is critical that these techniques can grow devices rapidly in order to maximise the number of devices produced per manufacturing hour and therefore reduce the overall costs.

Another critical concern is the operating lifetime of the devices. The original perovskite composition, methylammonium lead iodide, is thermodynamically unstable and degrades in ambient air within days. There has been substantial work on developing alternative compositions, as well as passivating materials at surfaces, with improved stability in air containing moisture. Through these efforts, and coupled with encapsulation, devices stable for longer than a year have been demonstrated, and modules that pass industry-standard stability tests have been achieved. However, the stability tests were developed for silicon solar cells, and the degradation modes in perovskites can be substantially different. It will therefore be critical to developing accelerated degradation tests specifically for perovskites, and the field data that is starting to be collected will be valuable in this effort.

How can we systematically find lead-free alternatives to the perovskites?

Beyond the scale-up and stability challenges, halide perovskites are also limited by the presence of lead, which is toxic and regulated in many jurisdictions worldwide. Currently, outdoor photovoltaics are exempt from European lead regulations, and there is debate over the extent to which the lead content of halide perovskites could limit its adoption worldwide. Nevertheless, the astonishing rise of halide perovskites has posed the critical question of how such performance could be replicated in alternative materials.

The search for these lead-free alternatives has mostly proceeded in the same way solar absorbers were identified before lead-halide perovskites were found, that is by trial-and-error. Not only does this have a low success rate, there are also too many materials to systematically explore without encountering false negatives or positives.

A more systematic approach that has been adopted is to identify materials that could replicate the defect tolerance of halide perovskites. Developing defect-tolerant semiconductors is the opposite approach to traditional semiconductor engineering. Historically, the approach taken has been to grow semiconductors to minimise the density of defects, which usually involves high temperature, slow and expensive growth methods. What the lead-halide perovskites have shown is how materials can be efficient without being defect-free if most defects have energy levels close to the band-edges and have limited ability to capture electrons or holes. Thus, although halide perovskites have millions of times more defects than silicon, they have comparable performance in photovoltaic devices.

Figure 3. Selection of the periodic table with the 8-hr workplace exposure limit of elements shown. Safe elements shaded green, toxic elements shaded red. Poisoner’s corridor circled, comprised of toxic (Hg, Tl and Pb) and radioactive (Po, At, Rn) elements. Adapted from Adv. Energy Mater. 2021, 2100499 (DOI: 10.1002/aenm.202100499) under the terms of the CC-BY license.
Figure 3. Selection of the periodic table with the 8-hr workplace exposure limit of elements shown. Safe elements shaded green, toxic elements shaded red. Poisoner’s corridor circled, comprised of toxic (Hg, Tl and Pb) and radioactive (Po, At, Rn) elements. Adapted from Adv. Energy Mater. 2021, 2100499 (DOI: 10.1002/aenm.202100499) under the terms of the CC-BY license.

A proposition is that the defect tolerance of halide perovskites comes about from its electronic structure. This has prompted efforts to find materials that are electronically analogous. Many of the materials identified are bismuth-based compounds, such as bismuth oxyiodide. This is because bismuth is next to lead on the periodic table (Figure 3), but has no evidence for toxicity, and is used in over-the-counter stomach medicine. Such materials are termed ‘perovskite-inspired materials’. Thus far, there have been a handful of materials found to demonstrate similar defect tolerance to the halide perovskites. But the understanding of what gives rise to defect tolerance is only now emerging and is an active area of research.

What else can we use the new perovskites and derivatives for?

Demonstrating a new material in efficient photovoltaics opens up many possibilities for applying the material in a broad range of alternative applications. One such application is for indoor light harvesting. These energy-havesting devices are needed to power low-cost, low-power electronic devices that can communicate with each other via the Internet – such as a mobile phone. This ecosystem of devices is termed the ‘Internet of Things’ (IoT), which is giving rise to infrastructure (e.g., houses, cities, hospitals) that are responsive to the users. Currently, most IoT devices are powered by batteries, which only have a limited lifetime. Given that there are over tens of billions of IoT devices worldwide, millions of batteries need to be recycled daily, creating substantial waste. This sustainability challenge will only increase in the future as the IoT ecosystem exponentially grows in size.

To solve this challenge, photovoltaics can be embedded into each IoT device to harvest energy from light to recharge the energy storage device (which could be a capacitor or a rechargeable battery) that then powers the IoT device in the dark. Currently, the standard indoor photovoltaic material is hydrogenated amorphous silicon, but the photovoltaic efficiencies are below 10% under indoor lighting. Halide perovskites have already demonstrated 37% efficiency indoors, which increases the power harvested from the microwatt range to the milliwatt range.

However, lead may be less tolerated in consumer or healthcare products than for outdoor photovoltaics. Recent work into lead-free perovskite-inspired materials for indoor photovoltaics, and optical analyses has shown that devices made from these materials could match or exceed the performance of halide perovskites indoors, and deliver high efficiencies with non-toxic materials that can be manufactured through low-toxicity processes. Beyond indoor light-harvesting, halide perovskites and perovskite-inspired materials can be used to harvest sunlight to split water and CO2 to produce clean fuels, or to more effectively detect X-rays, and therefore be used to make safer medical detectors.

 

Further reading

C. A. R. Perini, T. A. S. Doherty, S. D. Stranks,* J.-P. C.-B.,* R. L. Z. Hoye.* Pressing Challenges in Halide Perovskite Photovoltaics – From the Atomic to Module Level. Joule, 2021, 5, In Press. DOI: 10.1016/j.joule.2021.03.011

R. L. Z. Hoye,* J. Hidalgo, R. A. Jagt, J.-P. Correa-Baena, T. Fix,* J. L. MacManus-Driscoll.* The Role of Dimensionality on the Optoelectronic Properties of Oxide and Halide Perovskites, and their Halide Derivatives. Advanced Energy Materials, 2021, 2100499, Early View. DOI: 10.1002/aenm.202100499.

Materials Science from home: First year students share more about their lab-in-a-box projects

During Autumn Term 2020, our first-year students in the Department of Materials started using lab-in-a-box projects to support their learning from home. These projects are used as a bridge between in-person teaching, while our students are learning remotely due to the pandemic. Two of our students have shared their experiences using the lab-in-a-box projects and what they’ve learned.

An image of Anjali Devadasan

Anjali Devadasan

The lab in the box was an incredibly exciting aspect of the first few weeks of term. The doorbell rang, I collected the parcel and immediately opened the box to explore the contents inside. The most discussed object on the year group chat (after the vernier callipers of course) was the mini microscope. We shared images of objects under the microscope and guessed what the objects examined were, which ranged from oranges, leaves, paper, and even phone screens.

An image of an apple leaf through the mini-mircoscope
An image of an apple leaf through the mini-microscope

Remote learning has resulted in spending most of our time in front of laptop/computer screens, but the lab in a box has provided us with a change of scenario on many Friday afternoons. The first time I used something from the box was in the Design Study drawing lesson where our task was to sketch a couple of 3D printed parts. Little did we know that the same parts would help us measure density with Arduino in the near future! Arduino sessions began with a short lecture describing the task for the day and for the next three or four hours, I would work through PDF instructions alongside my design study company and the much-appreciated help from our GTA, Harry. We guided each other, laughed at our mistakes, and were confused together and I think the challenges really brought our company together as a team.

Once we gained enough experience with Arduino, we did some lab work in company sub-groups of four. Labs consisted of the various subgroups measuring electrical and thermal conductivity and density using the Arduino setups we had learned. We also did hardness testing for different samples – where we used our mini microscopes! I enjoyed learning the Arduino together as it was fulfilling when we solved the problems with the setup and managed to get it working to receive some real values.

My favourite set up was the very first time we managed to display temperature readings on the little LCD screen. It was exciting when realistic temperatures for room temperature would appear or when they would change if we put different objects near the sensor, such as ice. It will be interesting to use this set up for the upcoming polymer labs.

 

An image of Amélie Mattheus
An image of Amélie Mattheus

Amélie Mattheus

I thought that the lab in a box project was a very creative idea. Picking up my lab box allowed me to see my peers for the first time. Even though it was socially distanced and completely COVID safe, it was nice to put a face to the names I had been seeing on Teams. When arriving back in my accommodation, I was very excited to open the box, it was like receiving a surprise delivery.

The box contained several recognisable objects which made me feel relieved at first, however, there were objects that I had never seen before. The Arduino lab was something completely new to me. Hence it was very exciting to see my LED light turn on after completing the lab. There were some struggles with the following Arduino labs due to technical constraints like the wires not being soldered hence not being able to get a connection. The meeting allowed me to see examples of other people’s work that did work. It was nice to be in smaller groups as you can talk more freely.

An image of the LED Experiment
An image of the LED Experiment

The GTA was very helpful and helped us through some long labs. He was always prepared to answer our questions when we got stuck. We also had a hardness lab, where they provided us with a spring, materials to test, and a tube. The hardness lab was the lab I enjoyed the most because it was directly related to materials and one of the properties that we had previously learned about. The goal was to indent the material and measure the radius of the indent. We were provided with a microscope that allowed us to measure even the smallest indents on rubber, which tends to go back to its original shape. In addition, due to doing the labs at home, you are able to use the equipment outside of class as well, for example, one of my group mates pointed out that with the microscope you were able to see the pixels on your laptop screen.

An image of pixels taken through the mini-microscope
An image of pixels taken through the mini-microscope

In the end, we were given some extra data due to the constraints of doing it at home. However, the given data allowed us to still analyse the data and use the software available for that. I enjoyed the labs at home, especially because I was still able to discuss and compare my results with those of others. I thought it was a creative alternative that allowed us to still do labs and achieve the skills learned by doing these.