New Publication: Graphene coated fabrics by ultrasonic spray coating for wearable electronics and smart textiles

Congratulations to second year PGR Kavya Sadanandan, whose paper ‘Graphene coated fabrics by ultrasonic spray coating for wearable electronics and smart textiles’ was recently published in Journal of Physics: Materials.

Abstract

The seamless incorporation of electronics in textiles have the potential to enable various applications ranging from sensors for the internet of things to personalised medicine and human-machine interfacing. Graphene electronic textiles are a current focus for the research community due to the exceptional electrical and optical properties combined with the high flexibility of this material, which makes it the most effective strategy to achieve ultimate mechanical robustness of electronic devices for textile integrated electronics. An efficient way to create electronic textiles is to fabricate devices directly on the fabric. This can be done by coating the textile fabric with graphene to make it conductive. Here we discuss successful and efficient methods for coating graphene nanoplatelets on textile substrates of nylon, polyester and meta-aramid using ultrasonic spray coating technique. These coatings are characterised by scanning electron microscopy, contact angle and electrical conductivity measurements in order to identify the optimal textile electrode.  Our study provides the foundation for the large-area fabrication of graphene electronic textiles.

New Publication: Bimetal-organic framework derived multi-heterostructured TiO2/CuxO/C nanocomposites with superior photocatalytic H2 generation performance

Congratulations to final year PGR Zahid Hussain for his new publication ‘Bimetal-organic framework derived multi-heterostructured TiO2/CuxO/C nanocomposites with superior photocatalytic H2 generation performance’, which was recently published in Journal of Materials Chemistry A (JMCA).

In this work, In-situ formation of p-n heterojunctions between TiO2 and CuxO in heteroatoms-doped carbon nanocomposites and their applications in photocatalytic H2 evolution were demonstrated. One-step pyrolysis of bimetal-organic-frameworks NH2-MIL-125(Ti/Cu) in water steam at 700 ºC forms phasejunction between nitrogen/carbon co-doped anatase and rutile TiO2, accompanied by the formation of CuxO heterostructures. Moreover, p-n heterojunction is also formed between TiO2/CuxO nanoparticles. These multi-heterostructures are embedded in N-containing and hydrophilic carboxyl functionalised carbon. The optimised TiO2/CuxO/C composites absorb more visible light and offer multiple pathways for photoinduced electrons and holes migration. Also, these nanocomposites provide increased active sites for photocatalytic reactions. Without loading expensive noble metals, TiO2/CuxO/C nanocomposites exhibited superior photocatalytic H2 generation activity of 3298 µmol gcat-1 h-1 under UV-Visible light, 40 times higher than commercial TiO2. This work offers a simple approach to fabricate novel photocatalytic nanocomposites for efficient H2 generation.

Zahid’s previous publications include a translation of Carlo Rovelli’s “Seven Brief Lessons on Physics” into Urdu and ‘Surface functionalized N-C-TiO2/C nanocomposites derived from metal-organic framework in water vapour for enhanced photocatalytic H2 generation’ , of which he was lead author, published in Journal of Energy Chemistry.

Ned Taylor passes his viva!

Ned Taylor

Congratulations to CDT student Ned Taylor, who has just finished his PhD. His thesis was titled ‘Ab Initio Exploration of Interface Structures and Their Properties’.

Ned published five papers during his time as part of the CDT and presented at national and international conferences. He was also involved with the Metabuddies scheme- an outreach scheme led by our PGRs, who visit local schools to engage their students in physics and engineering.

Ned looks back on the experience of undertaking his PhD:

It is finally over. I have written my thesis, had my viva, completed my corrections and have been awarded my doctorate. Yesterday I had a final trek up to the Uni as a PhD student to pick up a copy of my thesis that I had printed for prosperity. It is weird to think that it is all over now; below are some of thoughts on my time as a postgraduate researcher.

A PhD is a unique experience for everyone. For me, it was a wonderful time and, although sometimes stressful, it was always worth it. I have relished in the opportunity to conduct research and the freedom to choose my path of study. I have learnt more about the materials that surround us than I had ever expected. The work was demanding, but that was never an issue as the topics were always fascinating. It was amazing going to conferences and have people attend talks to listen to the research that I conducted. Writing scientific papers was often rather tedious, but the outcome was definitely worth it and really helped in the process of writing my thesis.

I have learnt a lot throughout my PhD. In addition to the science, the courses offered by the CDT were, overall, very rewarding and useful. I learnt how to present, how to understand and communicate with others in a team, how to manage projects, how to put myself forward and highlight my skills. I feel that these skills will be vital for progressing beyond the PhD.

The community of PhD students in the CDT offered the chance to forge good friendships. Going on this journey with other PhD students helped me to relax and enjoy the experience. I am also extremely grateful for the support and guidance that my supervisors, Steve Hepplestone and Eros Mariani, have given me throughout the past four years.

As became a theme in the Hepplestone research group near the end of my PhD (before multiple lockdowns, that is), I shall summarise this chapter of my life with a haiku:

DFT was fun
Lots of time spent fighting tech
PhD is done

With my PhD complete, I am now transitioning over into the field of computer science. I have just started a postdoctoral research fellow position at University of Exeter, looking at ways of automating transport models for use in reducing the carbon impact of traffic systems.

We wish Ned all the best with his new role.

Below is a list of Ned’s publications, and conferences he has presented at:

Ned has co-authored the following publications:

2020

2019

2017

Ned has presented at the following conferences:

 

Training and other events: January 2021 to March 2021

Please find below a table of all upcoming XM² training and other events from January 2021 to March 2021, as far as planning currently allows and subject to change.

PGRs, please highlight any XM²-training related absence times to your supervisors. In regards to annual leave or other absence time planning: all confirmed events have been sent to the PGRs via an Outlook calendar invitation, but please ensure to check the CDT in Metamaterials Outlook calendar and to liaise with your supervisors and the CDT in Metamaterials office (metamaterials@exeter.ac.uk) for approval BEFORE you make any bookings, as there might be a few more events coming up that are yet to be confirmed.

Supervisors, please be mindful of the XM² events when setting expectations on research deliverables with the PGRs.

January
04.01.21 CDT Group Meetings All PGRs 16:30-17:30 via Teams
12.01.21 Write About Science (Part 1) 1st years 09:00-13:00 via Zoom
13.01.21 Write About Science (Part 2) 1st years 09:00-13:00 via Zoom
22.01.21 ALL: Metamaterials Colloquium, Prof. Roland A. Fischer. Technical University of Munich, ‘Integration of Metal-Organic Frameworks to Devices: (SUR)MOF-Derived Electrocatalysts for Water-Splitting and Fuel Cell Applications’ All PGRs 12:30-13:30 via Zoom
27.01.21 Wave Theory 1st years 09:30-10:30 TBC
28.01.21 OPTIONAL: SPARK (Entrepreneurial Skills Course) 4th years, 3rd years, 5th years 09:30-10:30 via Zoom
February
01.02.21 CDT Groups All PGRs 16:30-17:30 via Teams
03.02.21 Wave Theory 1st years 09:30-10:30 TBC
10.02.21 Wave Theory 1st years 09:30-10:30 TBC
16.02.21 Month 6 Assessment Briefing 1st years 10:00-11:00 via Microsoft Teams
17.02.21 and 18.02.21 Leadership Training 3rd years 09:30-16:30 (on both days) via Zoom
24.02.21 Wave Theory 1st years 09:30-10:30 TBC
March
03.03.21 Wave Theory 1st years 09:30-10:30 TBC
10.03.21 Wave Theory 1st years 09:30-10:30 TBC
17.03.21 Wave Theory 1st years 09:30-10:30 TBC
17.03.21 Presentation Skills 1st years 14:00-15:00 via Teams (sign-up required)
24.03.21 Wave Theory 1st years 09:30-10:30 TBC
25.03.21 Interview Skills 4th years 09:00-17:00 TBC
31.03.21 Wave Theory 1st years 09:30-10:30 TBC

After six months, (e.g. after the Month 6 project is complete), first year PGRs can undertake teaching and demonstrating, provided that they complete LTHE online training first. The course is self-paced so you can take it whenever you like but please note it is mandatory and you will not be able to undertake teaching and demonstrating until you have completed it.

 

 

New Publication: Tunable pseudo-magnetic fields for polaritons in strained metasurfaces

Congratulations to final year PhD student Charlie-Ray Mann whose theory paper, entitled ‘Tunable pseudo-magnetic fields for polaritons in strained metasurfaces’, has been published in the prestigious journal Nature Photonics.

The work has also been featured on the University of Exeter’s news website.

Charlie-Ray Mann, the lead scientist and author of the study, explains:

Charlie-Ray Mann- lead scientist and author of the paper published in Nature Photonics

The interaction between charged particles and magnetic fields gives rise to some of the most fascinating phenomena in physics, ranging from the beautiful Aurora Borealis to the famous quantum-Hall effect. Unfortunately, because photons do not have an electric charge they are inert to real magnetic fields as they do not experience a Lorentz force.

Taking inspiration from graphene physics, we have shown that you can generate `artificial’ magnetic fields for light by distorting honeycomb metasurfaces in a specific way. These distortions generate a ‘synthetic’ Lorentz force which can deflect the surface polaritons into effective cyclotron orbits, and for larger distortions one can also observe Landau quantization of the polaritons — phenomena once thought to be exclusive to charged particles.

However, the main drawback with this approach is that to change the artificial magnetic field one is usually required to modify the distortion in the lattice. This is extremely challenging, if not impossible to do with photonic structures, hindering our ability to tune the artificial magnetic field after the structure has been fabricated — that is, the artificial magnetic fields are usually fixed by design.

In this theoretical work we have proposed an alternative mechanism to tune the artificial magnetic fields, which requires no change to the metasurface distortion. By exploiting the hybrid light-matter character of the surface polaritons, we show that one can tune the artificial magnetic field by modifying the real electromagnetic environment surrounding the metasurface.

Specifically, we’ve shown that by embedding the metasurface inside a photonic cavity or waveguide, one can tune the artificial magnetic field by modifying a single external parameter: the cavity width. In fact, we’ve even demonstrated that you can switch off the artificial magnetic entirely at a critical cavity width, without having to remove the distortion in the metasurface — something that is impossible to do in graphene or any system that emulates graphene.

Using this new mechanism you can bend the trajectory of the polaritons using a tunable Lorentz-like force that can be switched on/off, and you can drastically reconfigure the polariton Landau level spectrum by simply changing the cavity width.

Earlier this year, Charlie-Ray Mann was awarded a £5,000 prize from the Rank Prize Funds 2020.

Management Board and Admin Team- last working dates for this year

Please find below a table of the last working days for this year for CMRI Management Board and the admin team, and their first working day of 2021.

We hope you enjoy the festive season!

Management Board
Staff member Last day in First day back
Alastair Hibbins Tuesday 15th December Monday 4th January
Anja Roeding Wednesday 16th December Thursday 7th January
David Wright Wednesday 23rd December Monday 4th January
Admin
Deb Lee Thursday 17th December Monday 4th January
Kelyn Luther Friday 18th December Monday 4th January

Exeter’s Centre for Metamaterial Research and Innovation to provide novel research for £2m government offshore windfarm development

Exeter’s Centre for Metamaterial Research and Innovation (CMRI) will develop novel methods for creating conductive coating for turbine blades that adsorb radar in partnership with TWI Ltd as part of the £2M offshore windfarm development boost spearheaded by the Ministry of Defence (MOD)’s Defence and Security Accelerator (DASA) on behalf of the Department for Business, Energy and Industrial Strategy (BEIS), the Royal Air Force (RAF), and the Defence Science and Technology Laboratory (Dstl). 

In a move that could significantly boost the UK’s renewable energy growth, contracts have been awarded not only to the TWI Ltd / Exeter CMRI partnership, but also to Thales, QinetiQ, Saab, and Plextek DTS to fast-track their ideas for technologies that could mitigate the impact of windfarms on the UK’s air defence radar system.

Find out more: https://www.gov.uk/government/news/offshore-windfarm-development-boosted-by-2-million-research

 

Month 6 Presentation Prize Winners Announcement

This year, we have a joint win for our Month 6 Presentation Prize: congratulations to first year PGRs Joe Pitfield (also the winner of the Month 13 Presentation Prize)and Leanne Stanfield. They will be collecting their mystery prize soon…

The Month 6 presentations are given each May by first year PGRs, at the end of the six month mini project the students undertake before beginning their PhD project work. Feedback scores are given by their peers and by academic chairs (this year Dr Anna Katharina Ott and Dr Eric Hébrard took on these roles). Leanne’s presentation was titled ‘Graded negative index surface wave lens’ and Joe’s was titled ‘Structural stability of TMDC Heterostructures in the Presence of Water ’.  Please find their projects aims and methodology below.

Graded negative index surface wave lens

Leanne Stanfield

Aim:

Model, fabricate and characterise a graded negative index surface wave lens. One study has
already produced a free-space negative index gradient lens [1]. The aim here is to do this with surface
waves.

Methodology:

1. Develop Comsol modelling of microwave metasurfaces made of simple meta-atoms to give easy control of the surface wave index. Then vary the size of the individual elements to design a simple surface wave GRIN lens. This is a very demanding task using Comsol as the GRIN lens will need
modelling in its entirety. Once this task is complete the lens will be fabricated using wax-ink printing
and etching before being fully characterised using the XY microwave scanner.
2. Repeat the above with a more elaborate meta-atom, following on from the work of Tremain
et al [2], to give almost almost isotropic negative dispersion. Once again then vary the size of the
individual elements so that they allow for spatial control of the effective surface mode index. Then
combine such elements in a 2D metasurface structure to form a negative index GRIN lens. As for the
conventional lens this is a very demanding task using Comsol as again the GRIN lens will need
modelling in its entirety. The complete lens will then be fabricated using wax-ink printing and etching
before being fully characterised using the XY microwave scanner.

References

[1] Driscoll T, Basov DN, Starr AF, Rye PM, Nemat-Nasser S, Schurig D and Smith DR (2006) Applied
Physics Letters 88, 081101 ‘Free-space microwave focusing by negative-index gradient lens.’
[2] Tremain B’ Hooper I R, Sambles JR and Hibbins AP (2018) Scientific Reports 8, 7098 ‘Isotropic
Backward Waves Supported by a Spiral Array Metasurface.’

Structural stability of TMDC Heterostructures in the Presence of
Water

Joe Pitfield

Aim:

To explore the random structures and reorganisation of TMDC metamaterials in the presence of
water, with addition consideration of substrate effects.

Methodology:

First principles calculations combined with analytic Gibb’s Free energy arguments. In
addition, random structure prediction will be developed as a tool. This tool will require a sound
understanding of both physical and chemical environments and allow the prediction of new phases of
structures. It will need to be benchmarked against known phases.

References:

[1] F. Davies et al. TMDC Heterostructure band structure theory (submitted – preprint available)
[2] G. Schusteritsch et al. First-principles structure determination of interface materials: The NixInAs
nickelides, Phys. Rev. B, 2015.
[3] Heifets et al, BaZrO3, Phys. Rev. B, 75, 155431 (2007)

Elizabeth Martin wins Best Poster Award at 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020)

Elizabeth with the Best Poster Award Certificate

Congratulations to final year PGR Elizabeth Martin, who won the Best Poster Award at the 65th Annual Conference on Magnetism and Magnetic Materials (MMM 2020) (2nd-6th November 2020). This is an international conference that includes all aspects of fundamental and applied magnetism, which for the first time was held virtually. The conference had over 16000 attendees- including third year CDT PGRs Connor Sait, David Newman, Katie Lewis, Konstantinos Chatzimpaloglou and Oliver Latcham– with ~ 700 different talks and ~370 different posters as well as several different symposia, workshops, and tutorials.

One of our final year students, Elizabeth Martin, presented her research in one of the poster sessions and won a best poster award. Her poster was titled “Investigation of a Coupled Elasto-Magnetic Discs for Low Reynolds Number Pumps”. The presentation was in the format of a 90-second pitch with the poster, which could be viewed at any time throughout the conference on the conference platform, as well as an additional live Q&A session on Zoom.

The virtual format of the conference was a new experience for most of our researchers, they all enjoyed the conference and learnt a lot from the different presentations. However, they do feel that they missed the in-person experience and the chance to meet different researchers from all around the world. On the other hand, think that they have learnt some valuable skills with regards to presenting their work in an online format compared to in-person. The good news for in-person conferences is that according to our researchers their future is safe, they are just having a needed break for now.

Elizabeth says:

The virtual conference was obviously very different to that of the in-person conference, I enjoyed the experience and obviously I’m thrilled to be awarded a best poster award. I did miss the in-person experience and the chance to meet/catch-up with different researchers from all around the world, talking/messaging online is not the same, but this is the way things are at the moment. One of the benefits was that the presentations were in an “on-demand” format, meaning we were able to watch any presentation at any time we wanted because they were pre-recorded (another benefit was that this year none of us experienced jetlag).

The presentations from the conference are available to view on the conference online platform (for registered conference attendees only), until 30th November 2020. Other presenters from University of Exeter included Prof Feodor Ogrin, Elizabeth’s supervisor, and Dr Maciej Dabrowski, David Newman’s supervisor.

 

Elizabeth in avatar form at the conference’s social networking session

Ioannis Leontis gives oral presentation at Graphene 2020

Last month, fourth year PGR Ioannis Leontis gave an oral presentation virtually at Graphene 2020.  The event ran online from 19th-23rd October, including presentations, poster sessions and an industrial forum.

Ioannis says of the experience:

Last month, I contributed an oral presentation at the virtual conference Graphene 2020. The conference was really interesting as its programme presents very big names in the field including Nobel Laureates, such as Andre Geim, one of the fathers of graphene, and F. Duncan M. Haldane, one of the founders of the theory about topological phase transitions and the topological phases of matter. My presentation was on “Room temperature ballistic graphene p-n junctions defined by Zn metal doping”. In my talk I presented a new method for the fabrication of ultra-sharp ballistic graphene p-n junction using metal doping of graphene and a new simple characterization method of the metal induced graphene p-n junctions. My research work in this field may give a new push in the fabrication of room temperature graphene electron optic devices. In overall, my participation in such a high-level conference help me a lot in the deeper scientific understanding of my field and gave me the opportunity to make new connection as well.