Nanotechnology at Northwestern

Meet Nicolas Alderete, a graduate student in the Micro and Nanomechanics Laboratory

By Mark Heiden

July 19, 2021

Nicolas A. Alderete is a graduate student in Prof. Horacio Espinosa’s Micro and Nanomechanics Laboratory, which focuses broadly on two goals: understanding the behavior of materials across scales, from nano to macro, and developing novel engineered devices for both materials research and biological applications.

Where are you originally from?

I come from Buenos Aires, the capital city of Argentina.

Where did you complete your undergraduate degree?

I obtained my Mechanical Engineering Degree (5-Years), with a 2-year focus in Material Science, from the Buenos Aires Institute of Technology (ITBA), located in the heart of the city.

When did you first become interested in theoretical and applied mechanics?

My interest in theoretical and applied mechanics was cultivated at two particular periods of my life. First, while I was in high school and became exposed to the beauty of physics and the elegance of math. This is what led me to pursue a career in engineering, particularly in mechanics.

Then, during the last two years of my undergraduate degree, I was exposed to advanced topics in continuum mechanics, computational modeling of materials, and nanocomposites, which fascinated me and sealed the deal. That led me to work in research & development in the industry in applied mechanics projects, which continued to foster my passion for the field and led me to seek further theoretical mechanistic understanding of the processes I was working on. The degree in theoretical and applied mechanics at Northwestern was extremely appealing to me due to its unique interdisciplinary nature.

How do you explain what you study to non-scientists?

In general, I would say my field of study is in multiscale multifunctional materials, which can have many facets. In my case, this has taken the form of two distinct classes of materials and their intersections: biomaterials (materials found in natural structures) and origami/kirigami mechanical metamaterials (materials that derive their mechanical properties not only from their chemistry but also from their structural/geometry arrangement).

While seemingly disparate, these two types of materials share some common design principles: for example, multiscale arrangements, hierarchical structures, functional gradients, and size effects, which endow them with remarkable mechanical properties like strength, toughness, and stability. Understanding how the interplay of the different design principles produces those extraordinary properties, both in static and dynamic regimes, can be leveraged to design new advanced materials facing broadened environmental windows, like the ones experienced by modern structures and materials.

To gain such understanding we typically employ a combination of experimental and modeling approaches. On the experimental side, we employ multiscale material characterization techniques (microscopy and spectrometry) and in-situ testing, which give us direct visualization of the deformation and failure mechanisms occurring in the material. Later, we try to create physical models, which we solve in the computer, to make sense of the observed phenomena and get further insight.

To illustrate the above, we were recently able to show how nature deals with the issue of scaling (how common multiscale structures, with the same building-block materials, are adapted in large and small animals) to maintain the same level of biomechanical functionality. These same principles can be used to design scalable synthetic composites. In another example, we showed how changes in the arrangement of origami tilings can lead to nanoscale structures that are foldable in some directions and rigid in others, which can open the way for the design of soft-actuators with different stiffness requirements.

Your research interests include computational modeling and mechanical characterization of biomaterials. What inspired you to focus on that, and what are you finding that you’re excited about?

Nature has been the greatest inspiration for me to enter the field of biomaterials. The fact that a process like natural selection, through millions of years of evolution, resulted in the development of remarkable mechanical structures — each one superbly fulfilling its biomechanical functionality — is fascinating to me. Even today, building materials from the bottom-up, like nature does, and attaining multifunctionality remains a challenge for the engineering community.

Currently, we are looking into the dynamics of biomaterials, particularly the way the hierarchical multiscale structures, the interfaces, and phases affect the propagation of elastic waves traveling through them (like in phononic metamaterials). Most of the studies in biomaterials have dealt with effects in the quasi-static regime, but we believe there is still a lot to learn from a dynamic point of view in biomaterials that exhibit remarkable impact properties.

What has been a highlight of your time at Northwestern?

It is hard to pinpoint a single highlight of my time here at Northwestern because there have been so many. I would say that the possibility to work side-by-side with great professors and researchers who are thought leaders in their fields and being exposed to that atmosphere is definitely at the top. I would also highlight those small but sweet moments when you successfully complete an experiment, get a model working, or get a paper accepted.

What has been the most challenging aspect of your work or your time at Northwestern?

Undoubtedly, the most challenging aspects of my work have been how to deal with uncertainty and with setbacks. But at the same time, these are the experiences that I learn the most from. In an undergrad or course-based masters, we usually face problems with known solutions, and we can rely on certain sources to complete the work. However, during a PhD, we are dealing with open problems, where the validity of our solutions must come from the process itself (e.g., an experiment that matches a computational prediction), which in turn entails a continuous process of learning and discovery.

At the same time, particularly in experimental research, many things can go wrong, and the desired outcomes may not come at the first, second, or even at the nth try. (Hopefully at the nth+1!) This can be extremely demotivating at times, especially after long hours in the lab, but this is also what makes it so interesting and challenging. Coping with these two issues has been and still is the toughest aspect of my time at Northwestern.

Can you tell me about your experiences either being mentored or mentoring others?

During my time at Northwestern, I had the opportunity to do both. Naturally, my first and most important mentoring relationship has been, and still is, with my advisor Prof. H. Espinosa. Being a person with an invaluable experience in conducting research and a vast knowledge in nanomechanics, every interaction I have had with him has taught me something. This can go from how to approach a problem, how to troubleshoot when things go wrong, how to present my research, and how to network.

The collaborative nature of my research, and my lab in general, means that I have been indirectly mentored by senior students, postdocs and professors from Northwestern and other universities as well. This is an invaluable asset, that has taught me a lot from the experiences and backgrounds of other people. Recently, with a colleague from the theoretical and applied mechanics program, we have started organizing meetings of students with professors invited to the TAM seminars. These meetings have been extremely useful resources for students to learn from highly accomplished researchers and mentors.

Fortunately, I had the experience to mentor younger students in the lab and via my interactions as a teaching assistant in the Experiments in Solid Mechanics course, led by Prof. Espinosa. What I have learned from those interactions is that you can be mentoring someone without being aware of it, which means that we have to be very aware of what we say/do and how that may impact a person. In other words, simple things, like sharing professional experiences, giving feedback on an exam or task, or just listening to the other person’s concerns/issues can mean a lot to that person.

While I still have a lot more to grow and develop professionally, I really welcome the possibility of mentoring, and I hope I can continue doing so at Northwestern.

What are your hobbies outside of the lab?

When I am not in the lab I enjoy reading, road-tripping across the US, going to the philharmonic, and checking out new venues in Chicago with my girlfriend and friends. In keeping with the old adage of “healthy mind in a healthy body”, I also enjoy doing CrossFit.