Department of Chemistry

Department of Chemistry University of Oxford
Name:  Dr Carla Sofia Perez-Martinez


I was born in Costa Rica in 1989 to Salvadoran immigrants. Growing up, I always loved maths, and I joined the math Olympiad team at my school when I was 12. The first time I participated it was a disaster; I did not even make it past the first round. But I tried again the next year, and I eventually competed in the Central and Iberoamerican Mathematical Olympiads.

When I needed to decide on a subject at university, I was drawn to engineering. I could apply all the maths I loved to real world problems. I thought I would study aerospace engineering, since my parents’ house is close to the main Costa Rican airport, and I always saw the airplanes flying past as I was growing up. I asked around where was the best place to study aerospace engineering, and somebody told me MIT, in the USA. I applied and I was accepted for my undergraduate studies, so off I went.

At MIT, undergraduates have the opportunity to work as assistants in the research laboratories. In my second year, I joined the Space Propulsion Laboratory (SPL), where I was mentored by Professor Paulo Lozano. I worked on a new miniature thruster technology, based on small needles covered with a very special type of liquid, ionic liquids. I got my bachelor’s degree in 2011. I really enjoyed working in a laboratory so I decided to pursue graduate degrees in the SPL. I obtained my masters in 2013 and my PhD in 2016.

After MIT, I came to Oxford to work as a postdoc to study fundamental properties of ionic liquids with Professor Susan Perkin in the Physical and Theoretical Chemistry Laboratory. I am also a Junior Research Fellow at Trinity College.

Current research

I am currently investigating fundamental properties of liquids using a surface force balance (SFB). In the SFB, we squeeze a liquid in between two atomically smooth surfaces, and by passing light through the experiment, we can determine the exact thickness of the liquid film. We confine the liquid to very small distances, of the order of a few molecular diameters, and investigate several properties of the liquid. For example, we can slide the surfaces past one another, and measure the friction between the surfaces, and so we have a very controlled way of comparing lubrication properties of different liquids.

I am interested in a very special type of liquid called ionic liquids. These substances are mixtures of positively and negatively charged molecules; interest in these liquids has exploded over the past two decades, as they have properties that would make them most attractive for energy storage applications such as batteries and super capacitors. Ionic liquids do not evaporate easily, even under vacuum, so they are remarkably stable substances and can even be used in space. With the SFB, I can study how the ionic liquid molecules would organize themselves in a small space, such as a small pore within a battery. Beyond measuring the nanostructure, the SFB can be used to probe electrostatic interactions in ionic liquids and very concentrated electrolytes, e.g., salt water near the point of saturation. Our recent experiments reveal that interactions in these systems span much longer distances than anticipated by classical theories. Currently I am focusing on studying what happens to confined liquids when they are subjected to electric fields, which should further elucidate the performance of these substances for their intended applications.

A little bit extra

My aim is to become a professor in a research university, so that I can lead a research group and make young people interested in science. The best feeling about doing research in a university is coming to work and thinking that maybe I could make a scientific discovery that day, even if it is something small.

Outside of science, I enjoy walking in the English countryside on weekends with the Oxford University Walking Club.