Associate Professor Sarah Guerin is a lecturer and Principle Investigator in the newly established Actuate Lab in the Department of Physics, and is an SSPC Funded Investigator in the Faculty of Science and Engineering and Bernal Institute. Her research focus is working on computationally-guided crystal engineering of organic crystals for pharmaceutical and energy harvesting applications. The energy that is being harvested as part of Sarah’s research is generated by squeezing molecules that exist in the human body and this research formed the basis of her PhD in UL from 2015-2018.
“My PhD was the bedrock for my current research. One of my supervisors, Syed Tofail, who is currently the head of the Physics Department, was looking at why human proteins were showing a property that if you squeeze them, they generated electricity and he wanted to understand why. For my PhD, I started to use computer models to study the building blocks of those proteins. Every protein is just a long chain of these smaller molecules called amino acids. I wanted to investigate the hypothesis that if a protein has this property, do all the little pieces that make up a protein have this property too. If so, is there any way that we can use them as sensors?”
The property that Sarah was looking at is called piezoelectricity which translates from Greek to mean pressing electricity and is usually found in ceramics or polymers. To discover its existence in small human protein molecules was understudied and unexpected.
“I was looking at those smaller pieces that make up the proteins and discovered that they have these massive piezoelectric responses that could be used for technological applications currently filled by environmentally-damaging ceramics or polymers. So, we decided to go in a completely different direction and develop these crystals as a new class of material—one that could be used in medical devices or consumer electronics”.
During Sarah’s PhD she grew crystals in the lab based on a computer model she developed and made them into devices that could be used in this manner; modelling became an important part of the process.
“Part of my research at this stage was developing predictive computer models. These models can calculate how much electricity a biological material is going to generate when you squeeze it, allowing us to predict their properties before we make them in the lab or make a device out of them. There are hundreds of thousands of biomolecules and the models allow us to identify how much electricity they will generate, and more importantly, how strong they are. By knowing how hard we can squeeze a crystal before it breaks, we can identify what molecules are suitable for different types of devices.”
There are many real-world applications for this research, but the one area that Sarah believes this research can make a real impact is sensor technology.
“Anything that can interconvert electrical and mechanical energy can be used as a sensor. There are billions of them in use currently around the world in everyday items like your phone, your laptop, and in light switches. The sensors we are developing are unique because they are biocompatible, in that they are made from biological materials and won’t produce a negative reaction from the body. They are also cheap to produce and very good for the environment compared to materials that are currently being used as sensors.”
One of the materials currently in use in the sensors that Sarah is referring to is lead, and her research has the potential to have a significant environmental impact should biocompatible protein crystal sensors become the technology of choice for manufacturers.
“There are EU regulations around the use of lead, but piezoelectrics are one of the last remaining mainstream technologies that is allowed to contain this substance because there is no high-performance alternative. There are about 4,000 tons of lead-based electronic waste generated from these sensors every year, and this research has the potential to remove this waste from the manufacturing process.”
Sarah went on to complete a postdoctoral fellowship in UL, continuing the research she had started in her PhD while expanding her computer model’s impact into pharmaceuticals through the SSPC Research Centre. It was during this period that she produced a protein crystal sensor for the first time and could begin to see the implications of her research and its practical applications.
“I started collaborating with a team in UCD that was investigating damage detection. An example of what they were looking at is detecting leaks in pipes in Third World countries to improve water access, because if there is a leak in a pipe, then the water dripping out of the pipe generates little vibrations that can also be converted into electricity. I sent my sensors up to Professor Vikram Pakrashi in UCD to see how they performed in this scenario and the results showed that the sensors were out performing other materials.”
This moment led Sarah to apply for the European Research Council Starting Grant, which she was awarded in January 2022. The grant has allowed her to start up the ‘Actuate Lab’ in the Department of Physics, so named after the actuating devices that they are developing. The lab currently has a team of eight full-time researchers who are involved in computer modelling, making the eco-friendly crystals in the lab, and developing them for medical devices or for self-powered electronics applications.
“I’m really enjoying leading our research team. To know that six people moved to Limerick to work on my project and see them get that love and spark for research is really rewarding; I love it.”
Outside of her research, Sarah is involved with the SOPHia Project, a primary and secondary school programme, taught by undergraduate students to encourage more female participation in Physics.
“It's really about getting rid of all those stereotypes about physics. The project was set up by Dr Grainne Walshe and has been running for about five years now. We have seen a 40% increase in women taking Applied Physics in UL from local Limerick schools since the programme started.”