Human-Motion Energy-Harvesting PhD | Testing Ferrofluid-Enhanced Linear Machines

Human-Motion Energy-Harvesting PhD | Testing Ferrofluid-Enhanced Linear Machines

Research cut-off: 6 November 2026

Quick Decision

Promising with material uncertainties. This University of Sheffield EPSRC Doctoral Landscape Award project proposes a distinct configuration: ferrofluid in the airgap of a linear electrical machine intended to harvest energy from walking or running. The advertised work joins machine modelling, materials considerations, prototype development and tests under simulated movement. Sheffield has relevant electrical-machine expertise, including Professor Guang-Jin Li's work on ferrofluid cooling, while Dr Jonathan Davidson contributes power-conversion and systems-modelling expertise. The project is also listed in collaboration with Liquids Research Ltd, a ferrofluid manufacturer. Project directory Li profile Davidson profile Company information

The device concept remains a research question. Recent papers demonstrate ferrofluid-assisted harvesters in resonant, sloshing and magnetic-levitation designs, but none reviewed directly validates a ferrofluid-filled linear-machine airgap or confirms wearable-scale durability. The C3.5 project code aligns with Sheffield's standard 3.5-year DLA route, although collaborative DLA awards can be 3.5 or 4 years; the offer letter must confirm the individual award period. The project record displays a £21,805 stipend reference for 2026/27 alongside 2027/28 entry, so the stipend rate at October 2027 is not yet settled. International applicants may be considered, but the DLA has a strict cap and Home applicants are considered first. DLA scheme DLA application rules

The useful next step is to contact the supervisors before applying and ask about the project's performance metrics, facility access, Liquids Research Ltd's committed role, the C3.5 term, 2027/28 funding and International eligibility.

Research Problem and Doctoral Work

Linear machines produce straight-line motion or power rather than rotation. The project description proposes using such a machine to convert movement such as walking or running into electricity for small devices, including wearables and sensors. It identifies two limitations in existing harvesters: modest efficiency and mechanical wear in moving parts. Its proposed approach is to introduce ferrofluid into the machine airgap, with the expectation that the magnetic fluid may strengthen the airgap flux while also damping or lubricating moving components. These are proposed benefits to test, not established outcomes for this particular machine. Project directory

The advertised doctoral work has three main elements:

1. Design and computationally compare different linear-machine configurations with ferrofluid-filled airgaps.
2. Model how ferrofluid interacts with the machine's magnetic field.
3. Build selected prototypes and test them under conditions simulating walking and running.

The project description mentions potential uses such as wearable health monitors, smart textiles, rescue devices and remote sensors. It does not state target power, efficiency, device size, battery-replacement interval, service-life threshold or a commitment to a commercial wearable. Any application beyond the planned simulations and prototypes should therefore be treated as a possible longer-term use, not a promised PhD output.

An important technical question is whether a possible increase in magnetic flux can outweigh fluid-induced damping under variable movement. Recent studies make several useful comparisons, but their results cannot be transferred directly to this project. A 2023 original study reports a multi-frequency planar electromagnetic harvester in which ferrofluid is used around moving magnet poles; it reports 1.3718 mW during walking and 1.4227 mW during jogging. Its moving-magnet resonant arrangement is not a ferrofluid-filled linear-machine airgap. Chen et al. 2023

A 2025 study of ferrofluid sloshing under external magnetic fields reports a maximum mean power of 232.56 nW. It demonstrates that field arrangement and fluid movement can matter, but its container-based geometry is different and its reported output is a proof-of-concept result, not a comparable benchmark for the Sheffield design. A 2026 magnetic-levitation harvester combines variable spacing with ferrofluid damping and reports about a 1.5-times peak-power increase in that configuration. It is another relevant precedent, but it uses a different machine architecture and excitation setup. Rajnak et al. 2025 Nie et al. 2026

Together these papers suggest questions for the research plan: how the design balances flux gain and damping; how performance changes with irregular or different-frequency motion; how fluid retention and moving-part wear will be assessed; and how model predictions will be compared with prototype results. These are evidence-based questions, not additional advertised milestones.

School, Programme and Field Context

The University of Sheffield is the named university and degree-awarding institution; the project is placed in its School of Electrical and Electronic Engineering. Sheffield's Faculty of Engineering lists its address in the United Kingdom and describes four academic schools and three interdisciplinary programme areas. The Faculty reports 6,700 students and annual research income above £89 million. Faculty of Engineering

The University reports that Electrical and Electronic Engineering ranked joint third in the Guardian University Guide 2024 and joint fifth in The Times and Sunday Times Good University Guide 2024. These are 2024 UK subject-guide rankings and are best read as dated student/teaching signals. They are not current research rankings and do not independently establish the quality of this PhD. EEE ranking announcement

The School's Electrical Machines and Power theme covers permanent-magnet machines and drives, power electronics, power systems and energy storage, with applications in automotive, aerospace, renewable energy, power grids and consumer products. The theme lists six industry-funded research centres and two government-funded hubs. This indicates a broader research and industrial environment; public information does not confirm which centre or equipment will be available to this student. Electrical Machines and Power theme

The EPSRC DLA provides the University's Doctoral Development Programme, milestone support, conferences and symposia, knowledge-exchange training, optional teaching-related development, careers guidance and thesis-writing support. The scheme describes standard awards as 3.5 years and collaborative awards as 3.5 or 4 years. Since the title code is C3.5, the likely expectation is a 3.5-year studentship; the formal duration and registration limit should be checked in the offer. Sheffield's general PhD fee-period guidance says full-time fee-paying periods range from 3 to 4 years, with 3.5 years recommended for most full-time PhDs; the offer specifies the applicable period. DLA scheme and training PhD fee periods

Supervisor and Lab Assessment

Professor Guang-Jin Li is a Professor in Electrical Machines and belongs to the Electrical Machines and Drives Research Group. His profile covers permanent-magnet and switched-flux machines, reluctance machines and drives, fault modelling, renewable-energy and EV/HEV applications, and thermal management including ferrofluid cooling. This is the clearest direct supervisor connection to both electrical machines and ferrofluids. Li profile

Dr Jonathan Davidson is a Senior Lecturer in the School. His profile emphasizes electrical power conversion, resonant converters, impedance sensing and system modelling. Those interests can complement the machine design and electromagnetic work, although the public profile does not identify ferrofluid or human-motion linear harvesting as a specific research focus. Davidson profile

Three recent Li-group publications indicate relevant adjacent capability:

• The 2024 IEEE Access study compares ferrofluid cooling in permanent-magnet machines using coupled electromagnetic, fluid and thermal models, with a motorette used for validation. It is the closest recent supervisor paper on ferrofluid in an electrical machine, but it studies cooling rather than energy harvesting. Zhang, Li and Qin 2024
• A 2025 IET Electric Power Applications paper uses 3D computational fluid-dynamics modelling and thermal experiments to study forced-air cooling in modular permanent-magnet machines. It supports experience with machine modelling and model-to-test validation, but does not use ferrofluid. Zhang and Li 2025
• A 2026 paper compares self-cooling permanent-magnet machines using computational fluid-dynamics analysis and experimental validation. It adds evidence of current machine-design work, but not of a human-motion harvester. Li and Li 2026

Liquids Research Ltd says it manufactures ferrofluids and magnetic nanoparticle systems for engineering and biomedical applications. That public capability is relevant to the proposed materials work. The project record names the collaboration, but the reviewed sources do not establish a placement, company-funded stipend enhancement, material-supply commitment, day-to-day co-supervision or guaranteed facility access. Liquids Research Ltd

Funding, Application, and Living Cost

The project listing calls the opportunity fully funded under the EPSRC DLA and states that the funding covers tuition at the UK rate, research costs and a tax-free UKRI-rate stipend currently shown as £21,805 for 2026/27. It labels the academic year as 2027/28. The current DLA scheme page states that the award covers full tuition, a UKRI-rate stipend currently at £21,805 for 2026/27 and a Research Training and Support Grant of £4,500 total. It also says industry-collaborative awards may include extra research funding or a stipend enhancement, but neither is confirmed for this project. The 2027/28 stipend rate, project research budget and exact fee enhancements remain unconfirmed. Project directory DLA scheme UKRI student support

For the School of Electrical and Electronic Engineering PhD, Sheffield lists Home fees of £5,238–£10,238 for 2026/27 and says Home fees for 2027/28 are to be confirmed. It lists Overseas fees of £30,790–£35,790 for 2026/27 and £31,870–£36,870 for 2027/28. The University notes that research/support-element enhancements may apply by project. The DLA page says Sheffield will fund the fee difference for successful International candidates, but individual project availability and the exact EEE fee treatment should be confirmed. EEE fee lookup

The DLA application page sets a 5pm UK-time deadline on Wednesday 13 January 2027 and a start date of 1 October 2027. It requires the dedicated EPSRC DLA form; a standard PhD application is not eligible. The form asks three questions, each capped at 300 words, and permits up to two project preferences in ranked order. Applicants are strongly encouraged to contact supervisors before applying. Applications for collaborative projects may be shared with the partner, and applicants must disclose AI use according to the competition's recruitment statement. The University anticipates a maximum of 10 International places within the EPSRC-wide 30% cap and considers Home candidates first; shortlisted Home interviews are expected in mid-February 2027 and International interviews in late March. DLA application rules

A current cost illustration is useful but not a forecast for 2027/28. Sheffield's student-cost page lists monthly survey-based items of £155 for groceries, £73 for transport, £60 for going out, £45 for takeaways/eating out, £33 for clothes/shopping, £15 for a mobile phone and £14 for subscriptions: £395 in selected costs, excluding housing and other expenses. University postgraduate halls for 51 weeks in 2026/27 include bills, contents insurance and internet. Listed examples range from £7,939.68–£8,839.32 for shared-bathroom rooms at Endcliffe Crescent/Oakholme to £9,178.47 at St Vincent's Place and £9,910.32 at Allen Court for en-suite rooms. Sheffield living-cost estimates 2026/27 rent list

Adding the selected £395 monthly items to rent annualized across 12 months gives an illustrative total of about £1,057–£1,221 per month. The current £21,805 annual stipend is about £1,817 per month, leaving roughly £596–£760 before omitted spending. This comparison does not include laundry, personal purchases, travel, dependants, visa/IHS or relocation, and it does not use a confirmed 2027/28 stipend. GOV.UK currently requires students studying outside London to show £1,171 per month for up to nine months plus first-year fees, generally held for 28 consecutive days. This is a visa evidence threshold, not a full living-cost budget, and may change before a 2027 application. Student visa financial requirement

Applicant Fit and Preparation

Formal conditions stated by the project: The project description does not specify a degree class, exact required subject, English-language score, programming language or prior lab experience. These requirements should be checked with the supervisors or DLA team rather than inferred from other Sheffield projects.

Competition requirements: Use the dedicated EPSRC DLA form, select up to two projects in preference order, choose 1 October 2027 as the start date, complete all form sections by 5pm UK time on 13 January 2027, and answer the three questions within their 300-word limits. The common assessment uses core competencies. The application form includes an AI-use disclosure; read and follow the DLA statement. DLA application rules

Suggested preparation, not stated prerequisites: The advertised research spans electrical-machine design, electromagnetics, computational modelling, ferrofluid/material behavior, prototype development and interpretation of tests. Prior examples that show careful problem-solving, connecting a model or design choice to evidence, and learning from an experimental or computational challenge would be relevant to the DLA's questions. Do not present every research method as an admission requirement.

The National Careers Service describes electrical engineers as designing, building and maintaining electrical systems and machinery across several sectors. It lists £27,000 for starter roles and £58,000 for experienced roles and identifies possible pathways in engineering research and development, design, project management and consultancy. These figures are broad occupation-level context, not a PhD-specific salary or employment forecast. Electrical engineer career profile

Next Actions and Questions to Verify

Before Applying

• Contact Prof Guang-Jin Li and Dr Jonathan Davidson to discuss the research question, relevant preparation and whether another project preference is appropriate.
• Confirm whether C3.5 means a 3.5-year award for this collaborative project and ask for the 2027/28 stipend, exact fee coverage, research budget and any enhanced fee or stipend details.
• If applying internationally, confirm that this specific project is available to International candidates and how Sheffield's fee-difference policy applies; factor visa and IHS costs separately.
• Ask whether the programme has academic, subject-background or English requirements not included in the project description.

At Interview

• Ask how the team plans to compare magnetic-flux benefit against damping and how performance and durability will be evaluated under variable movement.
• Clarify which modelling and prototype facilities are available, what training/access is needed and what role Liquids Research Ltd will play.
• Distinguish confirmed activities from potential industry engagement or placement.

Before Accepting an Offer

• Check the written offer for funded duration, total registration limit, start and end dates, stipend schedule, Home/International fee coverage, research/support enhancements and research-cost budget.
• Obtain written details of the company role and any placement, co-supervision or additional stipend before treating those items as part of the package.

Evidence and Sources

Project, programme and school

• Sheffield PhD project directory
• EPSRC DLA scheme and training
• EPSRC DLA application process
• Sheffield PhD fee periods
• EEE postgraduate research fee lookup
• EEE 2024 ranking announcement
• Faculty of Engineering
• Electrical Machines and Power research theme

Supervisors, company and research papers

• Professor Guang-Jin Li
• Dr Jonathan Davidson
• Liquids Research Ltd
• Zhang, Li and Qin, 2024
• Zhang and Li, 2025
• Li and Li, 2026
• Chen et al., 2023
• Rajnak et al., 2025
• Nie et al., 2026

Funding, cost and careers

• UKRI support for funded students
• Sheffield living-cost estimates
• University accommodation rents for 2026/27
• GOV.UK Student visa financial requirement
• National Careers Service: Electrical engineer