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PhD Physics Project Ideas

PhD Physics Project Ideas

PhD Physics Project Ideas

PhD Physics Project Ideas

PhD Physics Project Ideas

We are looking for excellent PhD student candidates, who would like to explore project ideas with us. Examples of ideas in our pipeline are listed below.

These are open to self-funded students and those who want to apply to the DTP programme. We strongly recommend that you contact potential supervisor(s) in advance- contact details can be found within the individual project.

Biomedical physics

Supervisors: Dr Peter Petrov and Prof Peter Winlove (Department of Physics and Astronomy)

Toxins secreted by bacteria are major causes of disease. Usually, the interaction between the toxin and the cell plasma membrane is a complex, multistage process, which may ultimately lead to cell death. Whilst the biochemistry, molecular and cell biology of this process has been extensively studied, little is known about the role of the membrane physical properties in cell susceptibility to toxins. We have pioneered research revealing that electrical and mechanical properties of the cell plasma membrane could determine cell susceptibility to toxin. Membrane physical properties are also altered in disease, thereby influencing cellular susceptibility to toxin. This project will focus specifically on a class of toxins called pore-forming toxins. We shall investigate how membrane physical properties (viscoelasticity, electrical properties and their changes in disease) affect the three stages of toxin-membrane interactions (binding, aggregation and membrane insertion) leading to formation of pores in the membrane and, ultimately, cell lysis. We shall also investigate the effects of elevated oxidative stress, an ubiquitous condition in a number of diseases. This will be achieved through integrated cross-disciplinary approaches accounting for each aspect of toxin-membrane interactions and their interdependence.

This research will have an impact on the growing community of scientists working on the mechanisms of invasion of host cells by bacterial pathogens. It will inform the development of novel therapeutic approaches to combat bacterial infections in humans and domestic animals, major concerns for human health and for farming communities.

This is an exciting interdisciplinary project suitable for a student motivated to work at the boundary between physics and biology.

This project aims to optimise sorting of biological cells according to their mechanical properties by utilising novel Deterministic Lateral Displacement (DLD) devices.

It is now well established that various diseases lead to alteration in the physical properties of the cell plasma membrane such as membrane elasticity, viscosity and electrostatics. This effect, often due to disease-associated factors such as elevated levels of oxidative stress, in turn could compromise a number of biological functions hosted by the plasma membrane.  Sorting of cells according to their physical properties is therefore an important step in understanding the effects of disease on membrane properties and cell function. In this project, we shall focus on novel strategies for cell sorting based on their viscoelastic properties.  Novel DLD prototypes will be based on structured microfluidic devices with carefully controlled geometries, and underpinned by numerical simulations. The concept will be validated using in vitro experiments on human red blood cells, modified to produce cell subpopulations of different viscoelastic properties (membrane bending and shear moduli, membrane and cytoplasmic viscosity) and geometry (volume-to-area ration), all of which are important in setting cell deformability. Independent control of the membrane mechanical properties will be ensured by using additional single-cell techniques such as thermal fluctuation spectroscopy, micropipette aspiration and fluorescence-based methods. Later stages of the project will focus on designing and implementing adaptive microfluidic devices capable of optimising cell sorting depending on particular cell properties in the subpopulations. This is an exciting interdisciplinary project on the boundary between physics, biology and metamaterials.   

Electromagnetic and acoustic materials (EMAG)

Supervisors: Dr Paul Keatley and Prof Rob Hicken (Department of Physics and Astronomy)

With the advent of Big Data and the Internet of Things, demand for data storage is growing exponentially, placing additional strain on the world’s energy resources. As scaling of existing technology, such as the hard disk drive, reaches its physical limits, there is an urgent need to develop new recording paradigms that are ultra-dense, ultrafast, and energy efficient. Switching of magnetic “bits” by ultrafast laser pulses is highly attractive for its potential speed, but the physical mechanisms needed to deliver the required density and energy efficiency are as yet unclear. All-optical “toggle switching” of ferrimagnetic materials has recently been demonstrated [1] but requires heating, full demagnetization, and a significant time for cooling. It has been proposed that switching may also be induced by non-thermal mechanisms that are potentially faster and more energy efficient [2]. Optically induced non-thermal switching will be explored in artificial ferrimagnetic trilayer materials, and van der Waals bonded semiconductor/magnetic bilayer materials, that allow the magnetic parameters of the material to be carefully tuned. The underlying aim is to promote transfer of electron spin angular momentum without significant absorption of energy. The project will make extensive use of the new EPSRC funded EXTREMAG facility.

Diagram to accompany project idea: All-optical magnetic switching for ultrafast data storage

Figure 1. Magnetic switching induced by circularly polarized light [3].

References:

[1] T. A. Ostler et al., Nat. Commun. 3, 666 (2012).

[2] S. Mangin et al., Nat. Mater. 13, 291 (2014).

[3] C.D Stanciu et al., Phys. Rev. Lett. 99, 047601 (2007).

Supervisors: Dr Paul Keatley and Prof Rob Hicken (Department of Physics and Astronomy)

Spintronics seeks to exploit the spin angular momentum that is associated with every electron. A spin-polarized electric current can be used to exert a torque upon a magnet causing it to switch. This effect is already being exploited within magnetic random access memory (MRAM) cells, but the flow of electric current leads to energy dissipation and degradation of the most delicate components of the device. Instead, pure spin currents, in which spin flows without an associated transfer of charge, may be generated from an electric current by means of the spin Hall effect, but with limited efficiency. Following the prediction that spin current can be amplified within an antiferromagnet [1], we recently confirmed that the effect results from the superposition of evanescent antiferromagnetic spin waves [2]. In this project we will use time resolved optical and x-ray probes to explore the character of the underlying spin waves, and then determine the extent of the spin current amplification that may be achieved within a multilayered antiferromagnetic material. The generation of enhanced spin currents could play a vital role in the continued development of MRAM technology. The project will make extensive use of the new EPSRC funded EXTREMAG facility.

Diagram for project idea: Amplification of spin current within antiferromagnets

Figure 1. Schematic representation of time resolved x-ray detection of propagation of spin current s(t) through an antiferromagnetic NiO layer. A spin current is injected from the FeCo source layer and drives precession of the magnetization in the NiFe sink layer, which is detected by a short pulse of x-rays.

References:

[1] R. Khymyn et al., Phys. Rev. B 93, 224421 (2016).

[2] M. Dabrowski et al. Phys. Rev. Lett. 124, 217201 (2020).

Supervisor: Prof V. V. Kruglyak (Department of Physics and Astronomy)

In this theoretical (computational, actually) project, you will study wave excitations of the magnetic order - so called spin waves, quanta of which are called magnons. Spin waves have a dispersion relation like no other kind of waves: it is nonlinear, anisotropic and often non-reciprocal. In addition, the spin wave dispersion is very sensitive to the sample’s magnetic properties and micromagnetic configuration, so that spin waves are rarely observed to propagate in uniform media. Using hints from other, more traditional areas of wave physics, you will explore the excitation, propagation and control of spin waves in media with continuously varying properties, i.e. media with a ‘graded magnonic index’ [1,2]. Not only this research is full of exciting fundamental physics questions, but also a new, spin wave based technology for data and signal processing is out there to be grabbed by those who dare to face the challenges!

References:

[1] N. J. Whitehead, et al, “A Luneburg lens for spin waves”, Appl. Phys. Lett. 113, 212404 (2018).

[2] N. J. Whitehead, et al, “Graded index lenses for spin wave steering”, Phys. Rev. B 100, 094404 (2019).

Supervisors: Dr Paul Keatley and Prof Rob Hicken (Department of Physics and Astronomy)

Information is processed within the human brain through the mutual synchronization of a vast 3 dimensional network of neurons that oscillate at a frequency of order 40 Hz. In contrast, spin transfer oscillators (STOs) are nanoscale non-linear oscillators with frequencies that can be tuned within the GHz frequency range. Synchronization of a chain of 4 STOs has been used for recognition of human vowel sounds [1], while mutual synchronization of 8 x 8 arrays of STOs has recently been demonstrated [2]. Exploiting the high frequency and small footprint of STOs, arrays of STOs can be connected together to form powerful devices for high-speed pattern recognition. This project addresses a critical gap in present understanding of STO synchronization, namely the relative phase of oscillation in adjacent STOs. Time resolved scanning Kerr microscopy will be used to directly resolve the GHz oscillations of each STO device so that its relative phase can be determined. Spatial resolution of down to 50 nm will be achieved through the optimization of a plasmonic antenna mounted on the tip of an atomic force microscope [3]. The project will make extensive use of the new EPSRC funded EXTREMAG facility.

Diagram for project idea: Synchronizing spin transfer oscillators for neuromorphic computing

Figure 1. Schematic of an array of nanoscale spin transfer oscillators [2].

References:

[1] M. Romera et al., Nature 563, 230 (2018).

[2] M. Zahedinejad et al., Nature Nanotechnology 15,  47 (2020).

[3] P. S. Keatley et al., Rev. Sci. Instrum. 88, 123708 (2017).

Supervisors: Prof V. V. Kruglyak and Dr P. S. Keatley (Department of Physics and Astronomy)

A stone thrown into water creates waves that propagate in form of circles. An intense and tightly focused ultrashort optical pulse incident on a thin solid film of a magnetic material also launches waves – so called spin waves as well as more familiar acoustic waves. By studying the shape of the excited wave fronts, one can obtain vital information about the waves’ properties, which are in turn inherently related to the interatomic and magnetic interactions in the studied films. These phenomena can be studied using the time-resolved optically pumped scanning optical microscopy (TROPSOM), a unique technique pioneered in Exeter [1] and now to be set up within the EPSRC funded Exeter Time-Resolved Magnetism Facility (ExTReMag). In this experimental project, you will contribute to setting up of the TROPSOM experiment at ExTReMag and then use it to explore magnonic and acoustic metasurfaces. Disentangling optically excited dynamics of their electron, lattice and spin sub-systems is a challenging and exciting task. Yet, a bunch of radically novel functionalities arising from interplay between surface acoustic and spin waves is a prize for those who solve it! When the primary goal of in-depth understanding of the observed dynamics is achieved, you will proceed to exploration of lithographically shaped, optically driven magnonic and acoustic sources that will enable control of the excited waves.

References:

[1] Y. Au, et al, “Direct excitation of propagating spin waves by focused ultrashort optical pulses”, Phys. Rev. Lett. 110, 097201 (2013).

Quantum systems and nanomaterials (QSN)

Supervisor: Dr Luis A. Correa

No quantum system exists in isolation—they all interact with their surrounding environment, which can largely affect their dynamics [1]. Treating the full combined problem of ‘system + environment’ is, in most cases, unworkable. Luckily, an effective theory—the theory of open systems—has been developed to approximately solve such problems. This is able to drastically reduce complexity, albeit at the expense of a number of heavy approximations and perturbation theory. Traditionally, very weak linear dissipation into a linear reservoir is assumed. While much work has been done recently to relax some of these assumptions, considering, e.g., strong dissipation into structured environments [2], the dogma of ‘linear dissipation’ has hardly been questioned. Yet, nearly any real physical open quantum system of interest is highly non-linear. Problems such as energy transport in molecular complexes within biological systems [3], or diffusion of impurities in atomic condensates [4] cannot be fully understood until a new theory of non-linear open quantum systems is put forward. The aim of this project is to develop it and explore its physical consequences.

In this project we will primarily work with continuous-variable open quantum systems connected to non-linear environments through possibly non-linear couplings. In particular, we will explore limits of practical interest, such as weak non-linear dissipation; and the strong but weakly-non linear regime. To do so, we will combine perturbative methods, Markovian embedding techniques [3], quantum master equations [5] and Langevin equations [2,5]. We will then apply our newly developed tools to transport problems, the problem of temperature estimation in atomic condensates [4], or to understand the thermodynamics of quantum systems in the nonlinear regime [1].

Please check out the Exeter Open Quantum Systems group page.

References:

[1] Alicki and Kosloff, “Introduction to quantum thermodynamics: history and prospects”. In: Binder, Correa, Gogolin, Anders, and Adesso (eds) “Thermodynamics in the quantum regime”, Fund. Theor. Phys. 195, Springer (2018).

[2] Correa et al., Phys. Rev. A 96, 062103 (2017).

[3] Garg, Onuchic and Ambegaokar, J. Chem. Phys. 83, 4491 (1985).

[4] Mehboudi et al., Phys. Rev. Lett. 122, 030403 (2019).

[5] González et al., Open Syst. Inf. Dyn. 24, 1740010 (2017).

Supervisor: Dr C. A. Downing (Department of Physics and Astronomy)

In recent years, chirality has been shown to have profound implications in nanophotonics and nanoplasmonics. This asymmetry has given the freedom for phenomena not previously thought possible to be realized, including the unprecedented directionality of emissions in microresonators and photonic crystals. In order to understand the wealth of physics which chirality allows for beyond standard quantum optics, the emerging field of chiral quantum optics has been developed. Recent successes of the field include the discovery of novel quantum many-body states and potential quantum entanglement protocols. Meanwhile, topology continues to play a decisive role in the development of novel phenomena in metamaterials, particularly those with strong light-matter coupling.

In this theoretical project, we will encounter new effects arising from the interplay of chirality, topology and nonlinearities. In particular, we will study how many-body interactions lead to a new paradigm for topological photonics, and how multi-excitation effects lead to much rich chiral phenomena, which can be exploited for quantum transport at the nanoscale. The results of this research will both be important for the fundamental understanding of topological phases and chirality beyond the single particle limit, and will find future applications in quantum technology, which is currently undergoing an unprecedented revolution.

Figure 1: Evolution of the eigenvalues of a topologically nontrivial many-body system, where
the topological states are displayed in red.

Supervisors: Prof Janet Anders, Dr Simon Horsley and Dr Marco Berritta (Department of Physics and Astronomy)

This is a theoretical physics PhD project at the University of Exeter to start in Autumn 2021.

Quantum thermodynamics is a new research field, where thermodynamics is studied in the small-system size limit where fluctuations become non-negligible, weak coupling between system and environment cannot be assumed, and a fully quantum mechanical description may be needed [1]. This project is concerned with the application of theoretical tools from the fields of quantum thermodynamics and open quantum systems to the problem of modelling the dynamics, the equilibrium state, and the timescale of equilibration, of a collection of interacting spins that are strongly coupled to their environment. The aim of this project is to find analytical equations that describe the spin dynamics when they are driven by a changing magnetic field and exposed to a heated environment (with potentially multiple temperatures). These will then be used to quantify the importance of quantum mechanical and strong coupling effects in the magnetization dynamics and in the long-time steady state of the spins.


The critical components of magnetic hard drives have been continually scaled down in size. Magnetic grains, which store information, are pushing below 8nm and further miniaturization faces new challenges. Magnetically hard materials are required to ensure thermal stability of the information encoded in these small bits. But the magnetic write-fields in recording heads are no longer strong enough to switch them. Heat-assisted magnetic recording (HAMR) has been proposed as a candidate technology that would enable the switching of grains by providing additional energy in form of heat delivered by a laser diode in the recording head. The effective inclusion of such laser diodes in the recording head is actively developed by industry and first prototypes are now available [2].


It is anticipated that this new technology will soon reach the regime where the standard theoretical tools used to model the spin dynamics are insufficient and require a rethink of the theory used. The commonly used phenomenological Langevin equation, the Landau-LifschitzGilbert (LLG) equation, valid for large spin-grains will not describe the dynamics accurately at small sizes [3]. Alternative quantum Langevin equations describing the spin dynamics when undriven and in contact with a heat bath at a fixed temperature T has been derived by Prof Anders’ and her team [4].


You will begin your study with rederiving the standard LLG equation from a microscopic quantum Hamiltonian with the help of your supervisors, and assessing natural modifications of the LLG that include coloured noise rather than the standard flat Gaussian noise commonly assumed in the LLG equation [4]. In addition to quantum effects that arise because of the quantisation of the environmental modes, you will identify quantum effects that arise because of the quantisation of the spins themselves, including any dynamic features caused by quantum coherences and quantum correlations/entanglement. Beyond environments that have a fixed temperature T, you will explore how varying the temperature of the environmental modes, i.e. “heating”, as well as changing the magnetic field affects the spin dynamics. Taking the long-time or steady state limit of the dynamics, you will aim to establish how the spin dynamics becomes equilibrated, on what timescales and assess if the steady state may include strong coupling terms described by a Hamiltonian of mean force [5]. You will identify parameter ranges where any deviations from the standard LLG model could be evident and interact with a modelling group (York) who solve the dynamics numerically, and experimental groups (Exeter) who may be able to test the new predictions.
The derived theory will help clarify how to optimally heat and drive the spin dynamics, and assess when quantum effects become important for the optimisation of the HAMR technology. The research outcomes are potentially world leading, for the first time applying fundamental physics from the emerging theory of quantum thermodynamics to solve a practical problem in magnetic materials research.

References:

[1] S. Vinjanampathy, J. Anders, Contemporary Physics 57, 545 (2016).

[2] Mark Re, https://blog.seagate.com/craftsman-ship/hamr-next-leap-forward-now/ (2018)

[3] R. F. L. Evans, W. J. Fan, O. Chureemart, T. A. Ostler, M. O. A. Ellis and R. W. Chantrell, J. Phys. Cond. Mat. 26 103202 (2013).

[4] S. Horsley, C. Sait, J. Anders, "Versatile three-dimensional quantum spin dynamics equation with guaranteed fluctuation-dissipation" (2020).

[5] H. Miller, J. Anders, Nat. Comm. 9, 2203 (2018).

Supervisors: Prof Janet Anders (Department of Physics and Astronomy, University of Exeter) and Dr Federico Cerisola (Department of Materials, University of Oxford)

External collaborators: Dr Natalia Ares (experimentalist) (Department of Materials, University of Oxford); Prof Juan Parrondo, (Department of Structure of Matter, Thermal Physics and Electronics, Madrid University); Prof Alexia Auffeves, (Department of Quantum Engineering, Grenoble University) and Dr Owen Maroney (Faculty of Philosophy, University of Oxford).

This is a theoretical physics PhD project based at the University of Exeter to start in Autumn 2021.

Landauer showed that information processing tasks are not thermodynamically neutral, quite the contrary: erasure of bits of information when in an environment at temperature T requires thermodynamic work, and this energy is dissipated as heat in the erasure process [1]. The fundamental realization that information is linked to physical laws, such as the laws of thermodynamics, was the starting point for the development of quantum information theory. However, the link between quantum information processing tasks and thermodynamics is only now being fully made. Quantum thermodynamics is a new research field where thermodynamics is studied in the small-system size limit where fluctuations become non-negligible, weak coupling between system and environment cannot be assumed, and a fully quantum mechanical description may be needed [2].

This project is concerned with building theoretical models and predictions to quantify the thermodynamic work needed to perform certain quantum information processing tasks, such as Landauer erasure [1] and work extraction from coherences [3]. The aim of this project is to develop the theoretical understanding of work extraction from coherence for new experimental platforms on which these predictions can be tested, and answering if and when thermodynamic cycles could benefit from making use of coherences. A particular experimental platform that we will focus on is a new nanomechanics experiment that is being built by Dr Natalia Ares’ group [4]. Regular visits of the Exeter theory PhD student to the experimental group in Oxford, as well as visits to the other team members in Grenoble/Madrid, will be part of the PhD project.

The experimental platform being set up in Oxford combines the mechanical motion of a suspended carbon nanotube with the quantum states of an electron in a quantum dot. The pillars over which the carbon nanotube is suspended are electron reservoirs which act as heat baths at different temperatures. The up-down motion of the tube is strongly coupled to the quantum dot state, as recently demonstrated [4]. This setup provides a new, highly controlled platform that is suited to reveal the thermodynamic value of information in the quantum regime for the first time. The mechanical motion can act as a direct probe of the work done on the quantum dot, i.e. work extracted from the quantum dot can be stored in the mechanics and then reused (depicted by the wheel).

You will begin with revisiting Landauer’s erasure protocol and deriving protocols for work extraction from coherence [3]. You will gain understanding of key issues such as “where did the work go” and “what entropy should one use” to assess information changes and energetic exchanges in the quantum regime. With the help of your supervisors, you will learn how to theoretically model the nanomechanical platform, see Figure, and adapt Landauer erasure and coherence work extraction protocols for this twolevel system. We will work closely with the experimental group in Oxford to discuss progress and measurement results, as well as the philosophical implications of our findings. It is expected that these first experimental tests of work associated with quantum states/coherences can bring up entirely new perspectives on the thermodynamic cost of quantum information processing, which we hope to explore. We may also explore alternative platforms for the work-from-coherence protocol, including continuous-variable Bose-Einstein condensates that allow highly coherent manipulation and superconducting qubits where coherent interaction between qubit and cavity has been demonstrated [5].

References:

[1] Landauer, R. “Dissipation and heat generation in the computing process”, IBM J. Res. Dev. 5, 148 (1961).

[2] S. Vinjanampathy, J. Anders, “Quantum Thermodynamics”, Contemporary Physics 57, 545 (2016).

[3] P. Kammerlander, J. Anders, “Coherence and measurement in quantum thermodynamics”, Scientific Reports 6, 22174 (2016).

[4] Y. Wen, N. Ares , F.J. Schupp, T. Pei, G.A.D. Briggs, E.A. Laird, “A coherent nanomechanical oscillator driven by single-electron tunnelling’’, Nature Physics (2019).

[5] N. Cottet, et al., “Observing a Quantum Maxwell Demon at Work”, Proc. Nat. Aca. Sci. 114, 7561 (2017).

Reciprocity in the animal kingdom gave rise to the evolution of reciprocal altruism: “you scratch my back, and I will scratch yours”. Aside from mere grooming, the consequences of reciprocity for the sharing of food, medicine and knowledge are profound. However, the breakdown of reciprocity, perhaps fueled by a lack of affinity or obligation, can also lead to certain benefits for the non-reciprocator, who can profit from the nonreciprocal interaction. Introducing the concept of nonreciprocity into metamaterials research also allows one to profit from nonreciprocal interactions, with immediate technological applications. Non reciprocal devices, such as optical circulators and isolators,rely on the directional transfer of energy and information at the nanoscale. Furthermore, the realization of nonreciprocal waveguides will lead to extraordinary propagation lengths, being immune to backscattering. In this project, we will construct theoretical models inducing nonreciprocity in metamaterials, for example those built from nanoscopic lattices of meta-atoms. We will consider how topology, dissipation and various symmetries can be employed to create a new class of nonreciprocal metamaterials with extraordinary transport and directional properties. Our work will be done in close collaboration with the leading experimentalists at the CMRI, where the novel phenomena that we discover can be simulated by, for example, acoustic waves or microwaves. The results of this project should guarantee future applications in wave physics, metamaterials and nanotechnology, particularly via the exploitation of the unidirectional flow of excitations.

Supervisor: Dr C. A. Downing (Department of Physics and Astronomy)


While the eigenvalues of a Hermitian Hamiltonian are always real, the Hermicity condition is more stringent than is strictly necessary. In fact, it was shown by Bender in 1998 that Hamiltonians that obey parity-time (PT) symmetry can both admit real eigenvalues and describe physical systems. The condition of combined space (P) and time (T) reflection symmetry has immediate utility in open quantum systems, where there is balanced loss into and gain from the surrounding environment. The application of the concept of PT symmetry into both classical and quantum physics has led to some remarkable advances and unconventional phenomena, which cannot be captured with standard Hermitian Hamiltonians. Typically, unusual physics occurs near to exceptional points, where the PT symmetry transitions from its broken to unbroken phase. In this theoretical project, we will exploit the rich physics of PT symmetry in order to propose quantum systems which can transport energy and information highly efficiently, combating the pernicious effects of dissipation. We will utilize synthetic magnetic fields to induce chiral currents, and will investigate the effects of ultrastrong light-coupling and strong photon correlations. The results of this research should benefit future photonic technologies, where the unidirectional flow of excitations can be exploited in novel devices.

Centre for Metamaterial Research and Innovation

Nature is a constant source of inspiration for science, and this project will develop 3D metamaterials inspired by curious structures found in the retina of certain shrimp species. These take the form of hollow spheres made of high refractive index plates, structured in a way that produces a much greater refractive index in the radial direction than the tangential (radial anisotropy). This leads to manipulation of the natural resonances of these spheres, which increases their backscatter significantly.

In the course of this project the student will study such anisotropic systems though simulation and theory, and will design demonstrators operating at microwave frequencies to show both maximised scattering and the potential for zero scattering (cloaking) conditions. They will 3D print samples and test them in our specially developed anechoic chamber.

There is also great potential for this technology to be applied to the development of novel dielectric antennas, as well as ample opportunities for engagement and collaboration with industrial partners.

This work will be closely tied to an existing project sponsored by the Royal Academy of Engineering, and the successful applicant will enjoy a close working relationship with the academics on that project.

Acoustic Metamaterials (AM) are regarded as a potential solution as sound absorbers in the previously unattainable low frequency band (<1 kHz). The vast majority of AM consist of arrays of local resonators, mainly membrane based, however their performance is often narrow band.  Our ambition is to push the boundary of AM to address technological challenges of low frequency broadband sound absorption in practical environments. We will draw on our expertise in widening the bandwidth of electromagnetic devices, while also applying our previous work on tuneable vibrational energy harvesters, such as magetically induced non linearity, and closed-loop tracking systems, to provide absorption of ambient acoustic frequencies.

Objectives of this project are to:

  1. design low power mechanisms to tune the resonant frequency for membrane-based AM below 1 kHz.
  2. optimise performance of magnetically induced nonlinear AM below 1 kHz.
  3. develop an autonomous closed-loop frequency tracking system for frequency tuneable AM.
  4. demonstrate sound absorption using the broadband AM.

The Nano Engineering Science and Technology (NEST) group currently researches within a portfolio of awards exceeding £13m. The PI (Zhu) is currently leading development of underwater energy harvesters funded by Innovate UK (103380) and has previously led research into mechanical and electrical methods of tuning the resonant frequency of vibration energy harvesters together with control algorithms.

Existing solutions are either theoretical or have obvious weaknesses such as limited broadband, high power consumption and large dimensions

Optoelectronic devices working in the infrared have a host of important applications in the areas such as communications, security, defense, imaging, medicine etc. Most current infrared devices are however essentially passive - their operating characteristics are fixed by their structure and design. However there is a growing interest in active, i.e. tuneable or reconfigurable, infrared devices and systems, where the operating characteristics can be changed ‘on the fly’ to respond to changing needs. In this project we will develop such active devices by combining the dielectric (optical material property) control offered by switchable chalcogenide phase-change materials with novel optical metasurface concepts. Target applications include LIDAR, multispectral imaging and holographic displays.

Our civilization is defined by the functionalities delivered by devices, ranging from smartphones to airplanes.  These functionalities are however constrained by materials available to engineers, when constructing and indeed even conceiving a device.  Radically new dynamical properties and advanced functionalities can be created by tailor-tuning the spectra of wave excitations in structured media – so-called metamaterials.  Among other waves, ‘surface acoustic waves’ have been investigated for over one hundred years and currently used for a wide and diverse range of functions, e.g. analogue signal processing in mobile phones. Recently, the field of metamaterials research has expanded to acoustic waves. To date, however, there have been very few suggested ways of designing acoustic metamaterials that can be dynamically reconfigured and tuned. Integration with magnetic materials, well known for their ability to store information e.g. in magnetic hard disk drives, offers an exciting route for achieving non-volatile tuning of acoustic metamaterials. We strive to develop a new class of magneto-acoustic metamaterials in which the role of their building blocks (“meta-atoms”) is played by magneto-acoustic resonators [1,2].  Such metamaterials will add magnetic field tunability to structures aimed to control the propagation of surface acoustic waves, opening intriguing opportunities both in fundamental science and technology.  The memory phenomenon inherent to magnetism will enable significant energy savings in non-volatile magneto-acoustic data and signal processing devices.  For instance, they would be instantly bootable and could be more easily integrated with the existing magnetic data storage devices.  From the point of view of fundamental science, the magneto-acoustic metamaterials will serve as an excellent test bed for studying the physics of wave propagation in non-uniform and non-stationary media. 

This research is tightly related to a larger project (just approved for funding by EPSRC) on the same topic, within which we will collaborate with researchers from the University of Sheffield.  

  • Please contact Prof Volodymyr Kruglyak, Prof Geoff Nash, Dr. A. V. Shytov, and / or Dr. S. A. R. Horsley (depending on whether an experimental, theoretical or computational project is preferred) via metamaterials@exeter.ac.uk for more information.

References:

[1] O. S. Latcham, et al, “Controlling acoustic waves using magneto-elastic Fano resonances”, Appl. Phys. Lett. 115, 082403 (2019). 

[2] O. S. Latcham, et al, “Hybrid magnetoacoustic metamaterials for ultrasound control”, arXiv:1911.06774 (2019).

Direct laser writing in glass and polymer substrates can be used to generate strain fields which change the properties of the light passing through them. For example, within polymers, a laser written feature generates a repeatable pattern of birefringence around it (similar to an ‘impulse response’). By careful selection of the size and location of these features it is possible superpose the individual ‘impulse responses’ from each feature to generate a custom three-dimensional pattern of birefringence. Using advanced modelling techniques we can then apply inverse design to determine where to place these features to create a target optical field. We are at the very beginning of determining the full potential of this novel technology.

Quantum thermodynamics is a new research field, where thermodynamics is studied in the small-system size limit where fluctuations become non-negligible, weak coupling between system and environment cannot be assumed, and a fully quantum mechanical description may be needed. This project is concerned with the application of theoretical tools from the fields of quantum thermodynamics and open quantum systems to the problem of modelling the dynamics, the equilibrium state, and the timescale of equilibration, of a collection of interacting spins that are strongly coupled to their environment. The aim of this project is to find analytical equations that describe the spin dynamics when they are driven by a changing magnetic field and exposed to a heated environment (with potentially multiple temperatures). These will then be used to quantify the importance of quantum mechanical and strong coupling effects in the magnetization dynamics and in the long-time steady state of the spins.

Spin waves (elementary excitations of magnetically ordered materials) may be excited by electromagnetic waves at frequencies from a few to hundreds of GHz. This is however not easy, due to a huge mismatch between the wavelength (and therefore momentum) of electromagnetic and spin waves at the same frequency. We are tackling this challenge by exploring spin wave excitation and control in media with translational symmetry broken by compositional, geometrical or micromagnetic non-uniformities, which may either naturally exist (they are ubiquitous, in fact) or be artificially created. The interaction (‘coupling’) between propagating waves (spin or electromagnetic) and localised non-uniformities is often enhanced at specific discrete frequencies, giving rise to a rich variety of phenomena often referred to as ‘Fano resonances’ or ‘Fano physics’. We explore such Fano resonances as a platform for creation of novel spin-wave devices and metamaterials with unseen functionalities, such as re-programmability and non-reciprocity, and use them to address new physics that is inaccessible for other waves.

References:

[1] Y. Au, et al, “Resonant microwave-to-spin-wave transducer”, Appl. Phys. Lett. 100, 182404 (2012).

[2] Y. Au, et al, “Nanoscale spin wave valve and phase shifter”, Appl. Phys. Lett. 100, 172408 (2012).

Textiles have been at the heart of human progress for thousands of years, with textile developments closely tied to key inventions that have shaped societies. A new revolution is currently underway, where the most widely used material by humankind has gained new functionality with the incorporation of electronic components. The invention of electronic textiles is set to push boundaries again in sports, defence, medicine, and health monitoring. Seamless integration of electronics into fabrics represent the ultimate form of electronic textiles and the most ambitious challenge for longer-term innovation. This project addresses novel ambitious research aimed at new approaches in nanoscale Materials Science that will pave the way for the next-generation electronic textiles for personalised healthcare, specifically, sweat diagnostic devices, enabling sensing of biomarkers for the prevention, early diagnostic and management of chronic diseases.


Sweat analysis has recently attracted attention due to progress in wearable technologies and driven by the prospect of providing real-time information on metabolism and physiology. Applications include drug abuse detection, athletic performance improvement, and disease diagnosis. Ultrathin 2D materials with only few-atom thickness, resulting in extreme flexibility and high fracture strengths, have attracted great interest due to their potential to achieve ultimate mechanical robustness in flexible electronic devices. 2D materials hold great potential for sweat sensing due to their ultralow thickness, electrical conductivity and mechanical flexibility. Compared to their 0D, 1D, and 3D analogues, the large surface-to-volume ratio of 2D materials ensures tremendous surface area available for interactions between the sensing material and biomarkers. This is of great importance for realizing high sensitivity at extremely low concentrations of biomarkers, as it is expected in the case of biomarkers for chronic diseases in sweat. We will explore a new class of sensing materials, the 2D atomically thin transition metal dichalcogenide (TMDC) materials, which have emerged as a promising platform for sweat sensing. 2D-TMDCs are a family of materials with a chemical formula of MX2, where M is a transition metal ion and X is a chalcogen (e.g. sulphur). In contrast to graphene, TMDCs display a wide range of polymorphs, have a richer surface chemistry, manifested by the presence of active sites, which we will explore to achieve effective and selective interaction with the targeted biomarkers. These materials also exhibit a rich variety of electrical properties, which can be altered by fine structural and compositional tuning, enabling efficient signal transduction due to a molecular binding event. The charge transport in these materials is strongly confined in the 2D plane, leading to remarkable changes in their electronic properties upon biomarker binding.


The aim of this proposal is the creation of new experimental approaches for developing the thinnest possible, textile-based sweat sensing technology. The research objectives are to:
1) Develop novel experimental approaches for the seamless incorporation into textiles of atomically thin two-dimensional (2D) materials that are conformal and lightweight by nature, offering the ideal interface with textiles.
2) Understanding fundamental material science aspects related to the use of 2D-materials dyed textile as sweat sensors for biomarkers of chronic diseases.

Spin orbit torques (SOTs) result from the spin Hall and Rashba effects within multilayered thin film magnetic materials. An injected charge current generates a spin current that can transfer angular momentum to local magnetic moments, thereby exerting a torque upon them. SOTs have the advantage that charge current may be passed within the plane of the film, rather than through a delicate tunnel barrier, so that larger current densities, sufficient to change the magnetic state of the sample, may be used.  It is expected that SOTs will be exploited in future generations of magnetic random access memory (MRAM) device, and within new data storage and processing paradigms that harness topological structures such as domain walls vortices and skyrmions.

Existing measurement methods rely on magnetoresistive response to characterise spin-orbit torques.  However this approach does not sense the magnetization directly, provides a null response in certain geometries of interest, and lacks spatial resolution.  Direct optical detection of the magnetization overcomes all of these difficulties and, together with the detection of the resulting dynamics in candidate MRAM and spin transfer oscillator devices. The proposed project is intended to provide the theory and modelling needed to extract the values of the torques reliably and understand how they induce dynamic response within devices where the magnetization undergoes quasi-uniform precession.  This theory will then be extended to more complicated topological objects such as skyrmions.  Specifically, the means by which skyrmions move within thin films will be explored, with particular focus upon whether the internal dynamics of skyrmions affect their translational motion and interaction with defects and pinning sites, such as those found at the edges of nanowires that are used to guide their motion.

Molecular aggregates are an important and interesting class of materials particularly in the context of optical (pigmented) materials, both in nature and in synthetic materials, for example in semiconducting polymers for solar cells and light emitting diodes (Spano, Ann Rev Phys Chem (2014) 65 p477).

However, there is a serious sub-wavelength problem in studying such aggregates. Typically inter-molecular separations are very much smaller than the wavelengths associated with the optical transitions of the pigments so that the interactions between the molecules in an aggregate are dominated by near-field interactions, typically of a dipole-dipole character. Despite the near-field nature of the inter-molecular interactions involved, optical investigations are almost universally based on far-field optical spectroscopy techniques, making, for example, the role of disorder and noise very difficult to investigate in a systematic way. This project will explore an alternative approach, one that involves making cm-scale analogues of molecular aggregates based on microwave-domain metamaterials.

In the future, billions of devices connect through the internet of things (IoT) will mediate environmental information, human-machine and machine-machine interactions, but energy sources that can provide local power to these IoT devices are required. Solar fabrics, i.e. photovoltaic (PV) devices integrated into textiles harvesting ambient light, provide a new generation of energy sources that can help make our buildings smart and our portable devices independent from electricity grids.

E-textiles, including solar fabrics, refer to either electronic textiles or electrically integrated textiles. These technologies are currently very much in infancy because their manufacturing is a hard challenge. To endow textiles with PV capability, it is essential to integrate the functionality while maintaining the soft, stretchable properties of the textile, and the look and feel the end-user expects. However, this is vastly different from fabrication of PV devices on the flat surfaces of glass or plastic flexible substrates due to the porous, 3D structure of woven fabrics.

2D materials have been used to demonstrate devices with photovoltaic effects. In most cases these were proof-of-concept devices reporting the basic feasibility of photovoltage generation. The semiconducting transition metal di-chalcogenide (TMDC), with a bandgap ranging from visible to near infrared part of the spectrum and high absorption coefficient per unit thickness are extremely suitable for highly absorbing ultrathin photovoltaics. While stable semiconducting TMDCs are available since 2011, most of the scientific progress was achieved with manually exfoliated layers, allowing only small prototype devices to be realized. This manufacturing method is not scalable to areas of relevance for photovoltaics. Significant effort has also been devoted to larger area synthesis via chemical vapor deposition, but few manufacturing approaches are available for integration into functional devices, and even fewer are cost-effective and scalable. For using 2D TMDC in solar fabrics, fabrication approaches for 2D semiconductors need to be developed that are compatible with textile substrates.

The goal of this research is to develop a novel scalable methodology for coating textiles with 2D materials, and use it to advance state of the art in solar fabrics manufacturing. The objectives are:

Objective 1: To develop a new process for the coating of textile fabrics with 2D-TMDC materials and with 2D/2D heterostructures. The focus will be on the deposition of 2D-TMDC semiconductors and fabrication of 2D heterostructures for photovoltaic devices on textiles. Novel material and device manufacturing will be developed based on techniques suitable to textiles in order to easily translate from prototyping to production.

Objective 2: To optimize the performance of solar fabrics comprising textile coated with 2D-materials. To date, the use of high performance photoactive materials on textiles has provided power conversion efficiency approaching 10%. PVs based on 2D materials using 2D/2D heterojunctions as active layers are emerging as promising candidates, exhibiting external quantum efficiencies exceeding 50% and absorbance exceeding 90%. Achieving high power conversion efficiencies on textiles, above 10% is a key achievement for the investigations pursued here.

Over the last 10 years the world around us has become ever more densely populated by a host of autonomous machines. Although these technologies open up a vast array of opportunities, they also create significant problems around the area of detectability: machines are getting smaller, while the electromagnetic environment is becoming increasingly congested. Detecting and identifying small objects such as remote drones and small ‘picosat’ satellites via conventional radar is difficult due to their small radar cross section (RCS). For technologies such as self-driving vehicles, the problem is inverted, and it is the vehicle that must accurately identify small RCS targets such as cyclists in order to avoid collisions.

This project will address this challenge by designing 2D and 3D metamaterial structures to improve or otherwise dictate the RCS of small objects. The project will start at a quite fundamental level, examining novel highly scattering structures through simulation and experiment, and will later have the potential for collaboration with industrial partners to integrate these materials into an low cross section technology such as drones or picosats. This work will be closely tied to a 5-year project sponsored by the Royal Academy of Engineering, and the successful applicant will enjoy a close working relationship with the academics on that project.

  • Please contact Dr Alex Powell via metamaterials@exeter.ac.uk for further details and any questions about this project.

Waves propagating in quasicrystals are at a curious point where neither Bloch’s theorem (applicable to periodic media), nor the diffusion approximation (applicable to random media) are appropriate. While quasicrystals can be constructed from a deterministic rule, they do not exhibit the translational invariance that allows propagation to be understood in terms of a single unit cell. However, it has been known for some time that diffraction from photonic quasicrystals exhibits similar sharp peaks as are observed for true periodic crystals, due to the presence of long range order.  This project explores the propagation of electromagnetic waves on the surface of 2D quasicrystals. Such lattices (e.g. those generated using the Fibonacci sequence in particular) have an interesting link to topology via Chern numbers, and fractals.  Although little experimental work has been done to explore these aperiodic structures, our fabrication and characterisation techniques for exploration in the microwave domain naturally lend themselves to this project, and to accompany this experimental strand, there will be a challenging programme of numerical and analytical modelling work for the student to undertake.

  • Please contact Prof Roy Sambles, Dr Simon Horsley, and Prof Alalstair Hibbins via metamaterials@exeter.ac.uk for more information.

Magnetic steels and alloys are widely used in infrastructure systems and industrial equipment and processes. They are used in on-shore and off-shore oil and gas pipes, in coiled-tubing pipes for oil and gas well services and drilling equipment, in bridge and crane cables, and in rail tracks, to name a few. These structures experience different and extreme forms of stress, and mechanical and environmental damage as part of their manufacturing and deployment processes, and during their operation. It is therefore critical that these structures are regularly inspected and monitored to ensure safety of operations, for maintenance, and to predict their remaining life to avoid the risks of unexpected failure and for efficient management of their operations.  

Non-destructive inspection is used to detect defects and abnormalities in magnetic structures, and estimate the extent and severity of these defects to end users and operators. This research project focuses on the theoretical and experimental development of novel techniques and algorithms to enhance the detection sensitivity and resolution of two non-contact inspection methods: magnetic flux leakage (MFL), and electromagnetic-acoustic inspection (EMAT). The development will be applied to the inspection and characterisation of coiled tubing steel pipes in the oil and gas well services industry, working closely with an industrial partner. The theory will include the development of multi-physics finite-element models of the electromagnetic inspection heads and models of the magnetic material. The experimental development will involve the construction of an experimental test apparatus in close collaboration with the industrial partner who will also supply the test samples.

Supervisor: Dr C. A. Downing (Department of Physics and Astronomy)

Reciprocity in the animal kingdom gave rise to the evolution of reciprocal altruism: “you scratch my back, and I will scratch yours”. Aside from mere grooming, the consequences of reciprocity for the sharing of food, medicine and knowledge are profound. However, the breakdown of reciprocity, perhaps fueled by a lack of affinity or obligation, can also lead to certain benefits for the non-reciprocator, who can profit from the nonreciprocal interaction. Introducing the concept of nonreciprocity into metamaterials research also allows one to profit from nonreciprocal interactions, with immediate technological applications. Non reciprocal devices, such as optical circulators and isolators,rely on the directional transfer of energy and information at the nanoscale. Furthermore, the realization of nonreciprocal waveguides will lead to extraordinary propagation lengths, being immune to backscattering. In this project, we will construct theoretical models inducing nonreciprocity in metamaterials, for example those built from nanoscopic lattices of meta-atoms. We will consider how topology, dissipation and various symmetries can be employed to create a new class of nonreciprocal metamaterials with extraordinary transport and directional properties. Our work will be done in close collaboration with the leading experimentalists at the CMRI, where the novel phenomena that we discover can be simulated by, for example, acoustic waves or microwaves. The results of this project should guarantee future applications in wave physics, metamaterials and nanotechnology, particularly via the exploitation of the unidirectional flow of excitations.

The crystal – a lattice made of atoms plays the fundamental role in science. Its properties are defined by the geometry, interactions, and potentials, and are typically difficult to control. One possible way to change it is to consider artificial lattices made of optical resonators, where optical engineering and coupling to optically active medium can turn into versatile tool for simulating crystals. For instance, this research direction has brought two highly intriguing fields of physics. First, the precise control of coupling and effective spin orbit interaction allows to study topologically nontrivial lattices with emergent chiral states of polaritons – hybrid light-matter quasiparticles [S. Klembt et al., Nature 562, 552 (2018)].  Second, when light in the optical lattice is coupled to nonlinear medium, this potentially allows to reach the physics of strongly correlated polaritons [A. Greentree et al., Nature Physics 2, 856 (2006)]. Bringing the two directions together is an exciting possibility, which is yet to be explored, and serves the basis for the project. In particular, the unique combination of chiral edge states, multicavity system, and nonlinearity at the level of few quanta, can become a building block for spatially distributed quantum devices even in the presence of noise and dissipation.

This project will quantitate the physical interactions between individual bacteria such as Escherichia coli and Pseudomonas aeruginosa with commonly employed antimicrobials such as antibiotics or phages. This will be done via a novel approach for single-cell analysis relying on a combination of microfluidics, microscopy and mathematical modelling. This novel knowledge will inform on how cell-to-cell differences within a bacterial population impact antimicrobial resistance that is a major societal problem. Therefore, this project will be paramount for repurposing existing antimicrobials as well as rationalising the design of the next generation of therapeutics against infections caused by gram-negative pathogens.

Quantum computing represents a paradigm-shifting approach to perform calculations, where a genuine quantum setup is used as a processor. From the theoretical perspective, foundations of quantum information science were laid down by proposals for quantum algorithms which can run exponentially faster than classical versions (e.g. Shor’s algorithm). More recently, the problems of quantum chemistry and simulation of materials were considered as the most prominent application for quantum computing, leading to a huge economic impact in the future. This serves as a great motivation for the field. However, to implement them in practise two key ingredients are needed: 1) quantum hardware of sufficient size and quality, where noise level is reduced; 2) quantum software suitable to be run on existing hardware and solve industrially relevant problems. For the first point, the important step was made by achieving quantum supremacy [Google AI group, Nature 574, 505 (2019)] and increasing size of processors. To improve on the second point, novel strategies for quantum simulation of molecules shall be proposed, and shall represent the core goal of the project.

Within the doctoral studies, we will use the best state-of-the-art quantum computing techniques, and merge easy-to-implement variational approaches with novel ways to represent a system Hamiltonian. This shall allow to create efficient algorithms for tackling wide range of problems and advance the field of quantum chemistry, materials, and machine learning. The project requires both the background in theoretical physics and mathematics, and the desire to challenge existing state of the art in computational science.

Precision measurement underpins science and technology, and novel sensors that push the fundamental limits of accuracy and precision are required for applications ranging from nano-electronics to medical imaging. Colour centres have atom-like electronic transitions that can be probed with optical and microwave techniques, and thanks to a spatial extension on the scale of the atomic lattice, they can provide an exquisite probe of their local environment. In this project, you will develop an integrated microwave and photonic platform to control and investigate spins in 2D materials, with the ultimate aim of building a new generation of sensors with the highest possible sensitivity and spatial resolution.

Supervisor: Dr Luis A. Correa (Department of Physics and Astronomy)

The lowest temperatures in the universe—of just a few nanokelvins—are nowadays within reach in many labs [1]. Ultracold gases loaded in optical lattices stand out as an ideal platform for quantum simulation, which could help to crack long standing condensed-matter physics problems, and assist in the design of new metamaterials or drugs. Precise temperature control is indispensable to run reliable simulations and yet, measuring extreme temperatures with high accuracy still remains a formidable open challenge [2]. Thermometry with atomic impurities immersed in Bose–Einstein condensates is a promising route to sense such extreme tem- peratures in practice [1]. However, up to now, the interpretation of measurement results has relied on the “classical” assumption that impurities thermalise with the condensate. Modelling the problem from first principles within the theory of open quantum systems, however, tell us otherwise—while this assumption works perfectly well at temperatures ~100 μK, it breaks down in the ~1 nK range. There, quantum correlations start to build up between probe and sample, which may radically change the way data should be interpreted [3,4]. A better theoretical understanding of this quantum-thermodynamic problem is, therefore, indispensable.

The newly-developed field of quantum thermometry aims to upgrade current technologies for high-precision low-temperature measurements [2]. To do so, it combines the toolbox of quantum metrology with that of the theory of open quantum systems. The most common theoretical open-system models rely on crude simplifying assumptions (weak and linear dissipation) that become inappropriate to model thermometric setups in the ultracold regime. There, the effects of strong, structured, and/or non-linear dissipation and the build-up of quantum correlations are likely to play a major role [3,4]. In this PhD project, we will develop and apply new methods to model quantum dissipative systems under strong, structured, and/or non-linear dissipation beyond the current state of the art. We will also devise new computationally efficient techniques in quantum metrology, to help us design novel data-analysis and measurement protocols that can maximise the sensitivity of quantum thermometers at ultra-low temperatures.

Check out Exeter Open Quantum Systems group page.

References:

[1] Olf et al., Nat. Phys. 11, 720 (2015).

[2] Mehboudi, Sanpera, Correa, J. Phys. A 52, 303001 (2019).

[3] Correa et al., Phys. Rev. A 96, 062103 (2017).

[4] Mehboudi et al., PRL 122, 030403 (2019).

This project aims to optimise graphene-based conductive inks and fabricate coils on textiles for wearable wireless power transfer (WPT) applications.

There is increasing demand for embedding electronics into fabrics for wearable applications. Most wearable electronic devices are battery-powered and require regular recharging. Nowadays, more and more wearable electronic devices are rechargeable using inductive WPT techniques. It operates based on the near-field electromagnetic coupling of coils. This concept can be applied to body-worn textiles by integrating a transmitter coil into upholstery, and a receiver coil into garments. This is of particular interests in healthcare applications, including the growing market of remote healthcare, as wearable medical devices can be charged whenever the patients rest without any external interference.

In this project, conductive polymer-based or graphene-only inks will be developed for improved conductivity and durability, and for easy and textile industry-compatible deposition methods. Coils will be designed and fabricated directly onto textiles. Different types of graphene (liquid-exfoliation and redox) will be employed for the preparation of conductive inks that can be easily applied onto textiles and flexible substrates. Different solvents, polymeric matrices, and processing methods (spray-coating, optical lithography, etc.) will be investigated and optimised.

Objectives:

  1. Develop graphene-based conductive inks
  2. Optimise coil design for textile applications
  3. Fabricate optimised coils on textiles using solution-processing methods
  4. Demonstrate wireless power transfer capability using fabricated coils

This project aims to optimise sorting of biological cells according to their mechanical properties by utilising novel Deterministic Lateral Displacement (DLD) devices.

It is now well established that various diseases lead to alteration in the physical properties of the cell plasma membrane such as membrane elasticity, viscosity and electrostatics. This effect, often due to disease-associated factors such as elevated levels of oxidative stress, in turn could compromise a number of biological functions hosted by the plasma membrane.  Sorting of cells according to their physical properties is therefore an important step in understanding the effects of disease on membrane properties and cell function. In this project, we shall focus on novel strategies for cell sorting based on their viscoelastic properties.  Novel DLD prototypes will be based on structured microfluidic devices with carefully controlled geometries, and underpinned by numerical simulations. The concept will be validated using in vitro experiments on human red blood cells, modified to produce cell subpopulations of different viscoelastic properties (membrane bending and shear moduli, membrane and cytoplasmic viscosity) and geometry (volume-to-area ration), all of which are important in setting cell deformability. Independent control of the membrane mechanical properties will be ensured by using additional single-cell techniques such as thermal fluctuation spectroscopy, micropipette aspiration and fluorescence-based methods. Later stages of the project will focus on designing and implementing adaptive microfluidic devices capable of optimising cell sorting depending on particular cell properties in the subpopulations. This is an exciting interdisciplinary project on the boundary between physics, biology and metamaterials.   

This project explores the role of metasurfaces loaded with magnetic materials in manipulating electromagnetic waves in the RF and microwave bands. In particular, we will identify metasurface designs that allow for instant switching of the operation of devices, such as steering beams or tuning the frequency of filters, absorbers or sources.  The research will be undertaken using a full electromagnetic wave solver that takes into account both electric and dynamic magnetic response of materials.  Developed in-house, and unavailable commercially, our state of the art software solves Maxwell and Landau-Lifshits-Gilbert equations simultaneously. It can be utilised to explore the use of magnetisation dynamics of highly structured magnetic configurations (e.g. vortices, domain walls).  Although the project primarily aims at numerical modelling, it is anticipated that some (successful) models will be verified experimentally.

Metallic ferromagnetic materials exhibit high magnetic moments and therefore offer high operating frequencies and magnetic permeabilities. These unique properties make them prime candidates for applications in telecommunications, electromagnetic wave absorption, noise suppression and in microwave devices. They are also compatible with CMOS fabrication methods and are hence attractive for spintronic and magnonic devices and systems.

The resonance mechanism and corresponding frequencies in confined metallic magnetic nano-structures are complex and dependent on the shape, size, magnetic and dielectric properties of the material and strength and polarization of the incident waves. Understanding this dependence enables the design and engineering of light-weight, compact, high-frequency and tuneable magnetic metamaterials and composites with interesting properties for a wide range of applications.

In this project, we will develop a novel numerical approach that models both electromagnetic wave propagation and nonlinear magnetic nano-structures within the finite-difference time-domain method. We will use this coupled numerical approach to study wave transmission and absorption in individual and arrays of 3D magnetic structures in the nano- and micro-scale, for the purpose of designing high-frequency, tuneable metamaterials and composites.