7 October 2021

PhD researcher publishes first paper

Alice Kirvin's paper ‘Rotating ellipsoidal catalytic micro-swimmers via glancing angle evaporation’ focuses on introducing advantageous rotational motion to chemically active Janus micro-swimmers.

Alice Kirvin

The paper was written in collaboration with Andrew I. Campbell (University of Sheffield CBE), David Gregory (University of Sheffield Materials Science and Engineering) and Andrew Parnell (University of Sheffield Physics and Astronomy).

Why is this paper important?

The paper combines a recent push for research into non-spherical Janus micro-swimmers with a desire to achieve rotational motion for micro-stirring and cargo-capture applications. Ellipsoidal micro-swimmers which are anisotropic in shape can be easily manipulated during coating to achieve asymmetric catalyst coatings which produce the desired rotational motion. Ellipsoids are especially beneficial for such purposes as their increased surface area when compared to a sphere will lead to more fluid interactions and more potential for cargo capture.

How did you do the research? 

The ellipsoidal colloids were produced in the department of Physics and Astronomy in collaboration with Dr. Andrew Parnell whist the catalyst coatings and testing were conducted in CBE labs. Using a coating method previously optimised for spherical swimmers by former PhD student Richard Archer, Ellipsoidal colloids were coated via electron beam evaporation at a ‘glancing angle’ to induce shadowing and non-symmetrical catalyst coatings. The swimmer’s motion was then observed in fuel and custom software was used to quantify the amount of spin achieved.

What is the potential impact of the study? 

The results of the study show that enhanced rotational motion can be achieved in ellipsoidal swimmers with a simpler synthesis route than the previously studied spheres. The differing geometry also leads to more defined circling trajectories and increased fluid interactions due to the increased effective hydrodynamic radius.

Tell us more about yourself. 

Prior to moving to Sheffield, I completed my undergraduate and MSC degrees in Chemistry and Advanced chemical sciences at the University of Liverpool. I was lucky to find a PhD project at Sheffield that complimented my previous research experience in Catalytic active swimmers and have enjoyed the new skills I have learned during the transition from a Chemistry background to joining the Engineering department.