
Begoña Parias Moreno de los Rios (l) and Helen Barr (r) pictured at graduation

Innovative research on soft matter engineering featured in Nano Letters.
Begoña Parias Moreno de los Rios and Helen Barr, final year undergraduate students with the Department of Chemical Engineering, extended their final year research project into a publication in a leading international journal.
Crack formation
The research, entitled “Thermal Conduction Suppresses Cracks in PDMS Wrinkling by Plasma Oxidation”, took an innovative approach to a hitherto unresolved challenge.
For over two decades, surface wrinkling of soft materials has fascinated researchers, leading to a range of technological applications from tuneable wetting and spreading, to antimicrobial or photonic properties. Cracks, compete with wrinkles, disrupt these undulated, highly periodic structures, and restrict their practical use.
Using a combination of high heat transfer coefficient (HTC) of the substrate and low film thickness (typically, polydimethylsiloxane, PDMS) they demonstrated that consistently crack-free surface wrinkling could be achieved. Employing optical and atomic force microscopy, light scattering, thermal measurements, and heat transport and stress calculations, they were able to demonstrate findings that hold for a range of glass, plastic, metal, and layered support materials and plasma processing conditions.
Professor João Cabral, lead academic, said: “In this paper, we employ plasma oxidation of a polymer elastomer (rubber) to create a thin, stiff, skin. Normally the skin cracks, but Begoña, Helen and Zain (PhD student supervising) ingeniously show that by modelling and designing the thermal profile of these films (employing concepts from heat & mass transfer classes), they could entirely suppress cracks. The impact is significant as it paves the way for large area, defect-free patterning at the nano- and microscales."
From undergraduate research to journal paper
This research was initiated by the undergraduate students as part of their final year research project on the MEng Chemical Engineering programme. In partnership with PhD student Zain Ahmed, Begoña and Helen extended their project, working after lectures and over weekends to take the work to a leading publication, which was eventually featured on the cover of the journal.
What stood out to me was the commitment of Begoña and Helen—even after submitting their project report (awarded best project in the year), they made time to continue the experiments, balancing this with their demanding final-year design projects and hockey practices. Zain Ahmed PhD lead
Zain Ahmed, who worked closely with the undergraduate students, said: “What stood out to me was the commitment of Begoña and Helen—even after submitting their project report (awarded best project in the year), they made time to continue the experiments, balancing this with their demanding final-year design projects and hockey practices. Although the experimental observations were puzzling at start, with meticulously gathered data across different process parameters, we were able to rule out competing hypotheses and narrow down the underlying mechanism. Finally, we developed a theoretical model to describe the governing process, compiling and validating experimental results against it."
On their achievement, Begoña and Helen stated: It was brilliant working with João and Zain on this project. Their enthusiasm and passion for research made the long days in the lab fly by. Not only are we now filled with fond memories of our final year in the lab together, but we were also able to produce a paper together which we hope will shape (or at least contribute to!) the future of surface wrinkling."
Article text (excluding photos or graphics) © Imperial College London.
Photos and graphics subject to third party copyright used with permission or © Imperial College London.