Non-contact measurements of thin catalytic membranes with ultrasonics

Roll-to-roll (R2R) manufacturing is essential for large-scale production of thin membranes needed for green hydrogen and electric batteries. This project will develop advanced non-contact measurements for these membranes using ultrasonic waves, mathematical modelling, and machine learning. By advancing R2R processes and integrating digital methods, this research supports efficient, high-throughput manufacturing of the next-generation of materials for clean energy.

Project Description:

Roll-to-roll (R2R) manufacturing is a continuous process to make thin flexible membranes at highspeed and large-scale production. R2R has enabled large scale production in flexible solar panels and electronics [1], as well as biosensors for diagnostics such as glucose monitoring [2]. Often the alternative to R2R is traditional batch processing which is harder to scale up. The focus of this project is to develop a sensing method for thin membranes during R2R manufacturing that can continuously monitor quality and can be ultimately used in a control loop. These are essential to increase throughput and quality. In this project the focus will be on coated membranes, with one example being catalyst coated membranes.

Catalyst membranes speed up chemical reactions, for example they are used to remove pollutants by breaking them down. For this project, working with Johnson Matthey, the focus will be on catalyst membranes used to split water into hydrogen and oxygen – a key process in water electrolysis and producing green hydrogen fuel. Manufacturing catalyst membranes is a significant part in making the transition to net zero a reality.

There is ongoing research to improve the performance of catalyst membranes based on both their formulation and design. Sensing methods to measure their properties and layers are needed both for research and development, as well as to achieve high throughput, high quality, and exceptional control over the process.

Measuring membranes with ultrasonic waves. In a thin solid membrane, if you shake the membrane you can transmit a vibration that can propagate over a metre or more (depending on the material). If you use a laser to measure this wave, the measured signal will contain information about the integrity of the membrane between the transmitter and measured point. These vibrations are Lamb waves, which produce small displacements throughout the membrane thickness, so the entire thickness of the membrane is interrogated, including surface changes, and changes within such as debonding. Using Lamb waves forms a practical and quantitative way to measure thin structures and has had a significant impact in finding defects in aerospace structures. We plan to adapt these methods for thin coated membranes.

R2R Coated membranes have 3 layers, where the middle layer is a flexible composite, and the top and bottom layer are the coatings. Lamb waves are normally used for single layer structures, which only have two Lamb modes: the symmetric and antisymmetric. For a 3 layered structure, there are more modes and the methods need to be adapted. To precisely excite the correct modes we will use air coupled transducers below and above the membrane, then the Lamb waves will be measured with Laser Doppler Vibrometers, potentially on both sides of the membrane. The type of mode and its speed tell us about the thickness and debonding, whereas the attenuation of the mode tells us about the integrity of the coatings. This project is about high throughput characterization and testing of a range of materials which are essential to reach net zero.

The project will both use a data-based approach, with machine learning, as well modelling and simulations to link the material make up with the Lamb wave characteristics. Finally, measurement (as proposed by this project) is the first step towards digitalisation in materials manufacturing.

Supervisors:

1. Artur Gower ([email protected])
2. Kirill Horoshenkov ([email protected])

If you are interested in this PhD, we encourage you to contact the project supervisor(s) directly.

Application Deadline:

Applications open until successful candidate is recruited (no later than Summer 2025) 

Funding Notes:

This is a fully funded project, part of cohort 2 of the EPSRC CDT in Materials 4.0. CDT. The studentship covers fees (home & international), a tax-free stipend of at least £19,237 plus London allowance if applicable, and a research training support grant.

Candidates of all nationalities are welcome to apply; up to 30% of studentships across the CDT can be awarded to outstanding international applicants. Early applications from interested overseas candidates are encouraged.

The Materials 4.0 CDT is committed to Equality, Diversity and Inclusion. Five countries are represented in cohort 1. We would like to see a more gender-balanced cohort 2, so we strongly encourage applications from female candidates

Enquiries:

For application-related queries, please contact Sharon Brown ([email protected]). Please note that each partner of the CDT in Materials 4.0 will have its own application process. 

Application Webpage:

https://www.sheffield.ac.uk/postgradapplication/login.do

After the personal details, you need to ‘add research course’, and select ‘Doctoral Training Course’, and then ‘Developing National Capability for Materials 4.0’.