Nanotechnology at Northwestern

Meet William Gaviria, a PhD student in the Hersam Group

By Mark Heiden

June 23, 2020

William Gaviria is a PhD student in Prof. Mark Hersam’s group, which focuses on hybrid hard and soft nanoscale materials for applications in information technology, biotechnology, nanotechnology, and alternative energy.

Where are you originally from?

I was originally born and raised in Colombia, but lived my teenage years in South Florida. These are my two homes.

Where did you complete your undergraduate degree?

I got my BS in electrical engineering at MIT in 2013.

When did you first become interested in engineering?

Cliché answer here, but it started when I was about 9 years old and my parents bought a desktop computer. I would fiddle with both hardware and software for the next 8 years or so, which is why my original goal at MIT was to study computer science.

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

I always use the TV analogy. It goes like this:

Think back to the very first TVs that came out. Big, bulky, round screen, etc. Now think about where we are today. TVs were able to first go “flat” by abandoning tube technology and adopting plasma technology. Then they got thinner by adopting liquid crystal display (LCD) technology. Then even thinner and better by adopting LED technology. Now think about the future of where we are going: TVs that are transparent and flexible like a poster you hang up on your wall.

Sounds crazy right? But think about how crazy the TVs we have now must have been to someone 40 years ago. The common thread in this evolution of TVs was the adaptation of new materials that enabled new functionality.

My graduate research is in this cutting edge of flexible electronics using a material called ‘carbon nanotubes.’ However, my research did not focus on display technologies. It focused on wearable devices that will enable a future where people will carry/wear flexible phones and electronics without a second thought – much like you stream and watch 1080p videos on a portable tablet in bed today without realizing how mind-blowing this would have sounded to someone 40 years ago.

Can you tell me about some potential applications for your work?

My research work focused on demonstrating novel application for carbon nanotube electronics. In particular, my work focused in applications for Internet of Things (IoT) electronics. For example, we developed the first solution-processed (i.e. compatible with printing and roll-to-roll manufacturing) random number generator for applications in IoT security. This represents an important milestone since this is a crucial building block of most (if not all) security hardware. Similarly, we developed a novel transistor that addresses a key performance bottleneck in printed electronics: sensor signal amplification. Overall, the end-goal is to prove that amongst different next-generation semiconductors (e.g. pentacene, graphene, III-Vs, nanowires, etc), carbon nanotubes are ideal for future flexible and printable electronics.

Besides this work, I also led efforts to simulate the how a neural network could learn (think AI) using neuromorphic devices developed by others in the Hersam group. This work serves as a proof of concept for future AI hardware that mimics some functions of neurons in our brain. As this technology matures and is adopted, we will see leaps in training efficiency and deployment of AI, especially in applications where it is currently constrained by energy consumption.

What has been a highlight of your time at Northwestern?

Working within the Hersam group. It has taught me the value of being in the right environment under the right leadership. The recipe that makes the group so special is the right combination of smart people, strong leadership, relaxed atmosphere, and a hint of silliness – this allows for the unique kind of place where people are striving to be the best in the field, yet are humble and quick to help others.

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

Semiconductor fabrication. Because of how we worked in the Hersam group, I was in charge of taking a blank silicon wafer and turning it into a working nano-electronic device. This multi-step process is fairly complex and requires significant sweat equity to master. However, I found it really humbling as an engineer because it taught me the value of experimental design, statistical inference, and experience. The upside is that when the universe aligned such that things worked for the first time, it led to some fun ‘Eureka!’ moments.

Congratulations on recently defending your PhD! What are you hoping to do next, and what directions would you like to explore in your future research?

I am really excited to start my career as I am the first PhD in my family. My PhD projects taught me the value of data, as most of our breakthroughs were made possible by data-driven decisions. With this in mind, I want to apply my technical creativity and diverse experiences to define the future of how we apply data to complex, open-ended problems. I will most likely start in the field of data science and AI today, but my role might rapidly change given the fast pace of this field.

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

During my PhD, I was lucky to experience both mentoring junior students and being mentored by senior researchers. Although my mentors were key in my professional development, mentoring other students was extremely rewarding. Overall, I cannot stress enough how important it is to network and find mentors for yourself, as their guidance is invaluable in your career. This is particularly true during your transition years (i.e. first and last year as a grad student).

What are your hobbies outside of the lab?

I am lucky enough to have a beautiful wife and awesome cat at home, so I spend most of my free time having quality time with them. Outside of this, volunteering, cooking, lifting and playing strategy games were key to keeping my sanity and mental health during my PhD experience.