Nano sensor detects forever chemicals hidden in water

We met her just after returning from her third maternity leave, already fully immersed in her work again: coordinating her research group and following the development of a new laboratory under construction. Her work lies at the boundary between fundamental research and concrete applications, with the goal of translating advanced scientific results into technologies useful for society.

Calm and determined, she embraces challenges naturally. Smiling, as she passionately recounts the path that led her from basic research to the development of new nanosensors for PFAS monitoring. And to young women interested in science she offers an invitation: to build a path consistent with their own inclinations, without giving up their ambitions.

Very much. Many of the ideas underlying both the ERC ULYSSES and the Proof of Concept stem from collaborations developed in the United States, in particular with Princeton University and Columbia University. In recent years I have moved from molecular spectroscopy toward nanophotonics and device engineering: being able to change field, while remaining within the same discipline, has been fundamental.

The ability to move across different topics is one of the keys to success in projects, but more generally in research today. At the same time, a distinctive feature of our Department of Physics is openness to collaboration: there is always enthusiasm in bringing in new ideas. This flexibility is important, because it allows ideas to expand and grow.
The METASENSE project originates precisely from this context: from the meeting of different competences and from an established collaboration with colleagues in Chemistry. At a certain point it became clear that this could provide a solid starting point for a Proof of Concept.

They have been decisive. These funds allow not only the development of ideas, but also the creation of the conditions to do so: new laboratories, instrumentation, research groups.

In my case, they are making it possible to set up a laboratory from scratch, with the opportunity to develop new research topics. It also means attracting people and expanding the group. In a context where competitive funding is central, European programmes remain a fundamental reference for supporting ambitious research in the medium to long term, also through the creation of new experimental infrastructures.
Having resources also means having an attractive force and maintaining a high international reputation. Having had the opportunity to see different laboratories, I can say that the quality of the research we do here is very high. It is also the reason why I am very happy to work at the Department of Physics of Politecnico. Of course, starting again from scratch is demanding, but it is natural.
 

The Proof of Concept is designed to push innovative ideas toward concrete validation, in the direction of patents, scalability, and industrial application. It is valuable support for projects that are very risky but also very promising. Compared to a traditional ERC, it is a shorter project — lasting one and a half years — and it is focused on the experimental validation of an idea that has already emerged, rather than on in-depth basic study. For this reason, for me, it is particularly interesting: it allows me to explore a more applied dimension of research, which I had encountered less so far, but which several colleagues in our Department have already learned to pursue very well.

They are synthetic chemical substances widely used in industry for their resistance: for example, they are used to make materials non-stick, or resistant to heat, chemical agents, or wear.

This stability, which represents an advantage from an industrial point of view, becomes a problem when they are released into the environment. They are difficult to eliminate, and they tend to accumulate, particularly in water.

They can be found both in water intended for domestic use, in water used to irrigate fields, and in drinking water. Even at very low concentrations, PFAS represent a risk, because they are toxic substances and can have an impact on health and the environment. For this reason it is essential to develop rapid and effective detection methods that allow intervention within short timeframes.

Today many analyses require complex and not easily transportable instruments, such as mass spectrometers, and lengthy procedures. The objective of METASENSE is to move toward in situ measurements, which are faster and more accessible.

The final goal is to have a small, compact device containing our nanosensor based on metasurfaces. These are structures that are extremely sensitive to changes in the surrounding environment: the optical signals we measure change very rapidly and with high contrast when the sensor is exposed to chemical variations. In practice, if one wants to analyse a water sample, a small amount can be introduced into a fluidic circuit and the variation of the sensor’s optical response can be observed as a function of the concentration of the substance we want to measure.

The higher the concentration, the more evident the change in the signal. The real difficulty, of course, is to push toward very low detection limits: highly sensitive instruments are needed, capable of capturing minimal variations. In this sense optical approaches can be a good solution, although there are naturally other strategies, such as electrochemical ones, each with advantages and limitations.

We aim for a technology that is real-time, portable, compact, and also reusable. Unlike many disposable tests, the idea is to have a sensor that can be cleaned and returned to its initial state, so that it can be used multiple times without having to discard cartridges or supports after each measurement.

Yes. An important aspect is reusability. Unlike many disposable tests, we want to develop a sensor that can be regenerated after each measurement and reused.
We are working on surface functionalization together with chemists, to make the sensor selective toward specific PFAS. This is what enables targeted and effective measurements.

The possible applications are many. We are also testing the device on real samples, such as tap water, and the first results indicate that we can be competitive with respect to the limits required by European regulations.

If validated, the device could be used for environmental monitoring, remediation, control of industrial discharges, or even in contexts closer to everyday use. The idea is to provide a rapid tool to make informed decisions about water use.

Yes, the Proof of Concept is designed precisely for this: to validate an idea and verify its potential for technology transfer.

METASENSE originates from a platform developed in basic research, that of metasurfaces, which in my ERC we use to study and modify ultrafast chemical reactions. During these studies we realized how sensitive these structures were to the environment. From there the idea emerged: if this sensitivity is so high, then there is a whole class of problems that these nanostructures can address, and among these is also the detection of chemical substances in water. Essentially, METASENSE was born in this way: from a platform developed in basic research that opens up to a concrete and high-impact application.

Exactly. Metasurfaces are the basis of the project. They are nanostructures that I began working on here in the Department and then with collaborators at Columbia and Princeton, who created the first structures for us and allowed us to understand them in depth from an optical point of view. From there we arrived at imagining possible applications. It is a vast and highly competitive field, but precisely for this reason extremely stimulating.

As far as basic research is concerned, we are absolutely competitive. The ability to characterize complex phenomena in depth is one of our strengths.
Where we are less structured is perhaps in the phase of industrial transfer, where other ecosystems are more consolidated. But in terms of scientific quality and fundamental research, the international comparison is there and it is very solid.

Yes, certainly. Every career or experience transition also involves moments of crisis or redefinition. The Marie Curie at Princeton was the first strong and continuous experience abroad, which allowed me to work independently.

I had already been to Harvard during my master’s, so I had already had a glimpse of the American environment, certainly very competitive and less oriented toward mutual support compared to what I feel is closer to our European approach. I greatly appreciate the collaborative approach, because in my opinion it makes everyone faster. Individualism can be useful, but it must be used well.

A second important moment was returning to Italy and moving to a more autonomous role, with the creation and coordination of a research group. This also involved a change in the way of working: from individual research to managing people, projects, and infrastructures, also accepting spending less time directly in the laboratory.

For me, being a mother is a very important part of my life, which I did not want to give up. This has obviously changed the way I work: I had to learn to trust others, to train people, to delegate. This too is an important test, to understand whether one is truly able to do this job.

There is also very high scientific competition, and developing new ideas requires time, study, and continuous updating on the literature. When one is younger, it is possible to focus everything on a single topic; then, as one progresses in their career, responsibilities multiply. For this reason it is essential to work with people with different backgrounds. Today, for example, we need more chemistry expertise for the functionalization of structures, or biophysicists for other projects, such as those on artificial photosynthesis. Multidisciplinarity is a word that is often used, but in our case it is real and helps us grow.

Building a laboratory means creating a research environment, a shared space that grows over time. It is a demanding process, not without unforeseen events, but also very rewarding. 
Currently there are about ten people between postdocs, PhD students, and thesis students working directly with me. Then in the broader ultrafast optical spectroscopy group there are many of us, always well guided by Professor Giulio Cerullo.

It has also been nice to see how in recent years some postdocs have then applied for and won Marie Curie funding to continue their academic careers, others have changed field or taken different paths. I also like this mentoring aspect very much; I have been fortunate to have great mentors, both at work and in my personal life.

It is not simple, but I try to organize myself as best as possible, both at work and on a personal level. External support is fundamental. Consider that the METASENSE project was submitted just a few days after the arrival of my third child; it brought us luck!

From those who live these situations firsthand there is great esteem for all the women researchers who try to pursue this kind of life, which from the outside may seem taken for granted, but is not at all. There are examples of women who manage research and family together, and having these models to look up to helps.

Yes. At the student and PhD levels, the numbers are good, but they decrease at more advanced stages of the career. There are measures that try to compensate for some difficulties, such as flexibility in European funding calls for those who have had interruptions related to maternity. With ULYSSES, for example, which lasts five years, I received an extension due to my maternity-related interruptions. These are important signals, but the gap still exists. 

Yes, it happens, for example at conferences or scientific boards. One always works in a professional way, but it is a fact that representation is not yet balanced.

There is no single path, and one should not try to adhere to a predefined model. It is important to build a path consistent with one’s own inclinations, without giving up one’s ambitions.
Priorities change over time: at the beginning one may experience the laboratory in a totalizing way, then other responsibilities come into play.
Flexibility, adaptability, and also a support network are needed.

See also the interview with Margherita Maiuri from March 2022.