Solving complex problems with purpose

Senior Angelica Padilla, who recently completed research through the Laboratory for Research on the Structure of Matter undergraduate summer program, shares her passion for fluid mechanics.

angelica padilla working in a lab on a crowded optics table looking at a computer
Senior Angelica Padilla from San Antonio recently finished her second summer semester working in the lab of Paulo Arratia. Padilla, a chemical and biomolecular engineering major, enjoys solving problems and doing research in Arratia’s complex fluids lab. 

Growing up in San Antonio, senior Angelica Padilla always knew that she liked engineering. “I knew it was problem solving-based, and I liked that part. I liked a bit of pressure, being questioned, and finding different answers to the same question,” she says.

As she completes her second semester of summer research in the lab of Paulo Arratia, most recently as part of the NSF-funded summer undergraduate research program at the Laboratory for Research on the Structure of Matter, the chemical and biomolecular engineering major continues to have a strong desire to solve problems that combine her interests in fluid mechanics, physics, and engineering. 

Padilla reached out to Arratia, a fluid mechanics professor, because of her interest in mechanical engineering and her goal of gaining experience outside of her coursework. “I like physics, energy, heat, and mass. Dr. Arratia did chemical engineering in his undergrad, so I reached out to him because I related to him,” she says.

In Arratia’s Complex Fluids lab, Padilla studies active fluids, ones that contain living organisms like E. coli or algae. In the past 10 years, there’s been a lot of interest in understanding how living organisms influence the dynamics of fluid systems and materials. “It’s very interdisciplinary,” says Arratia about the field. “It takes biology, engineering, physics, chemistry. And that’s the world in which Angelica has been immersed.”

One of the challenges is understanding how cells and organisms influence the material properties of a fluid, like its viscosity and elasticity. This type of information is crucial for future applications that might use E. coli to generate fuel, create vaccines, or clean contaminated sites. 

“For typical fluids, you can measure viscosity, but for active complex fluids, specifically E. coli cells, the viscosity changes and you don’t really know if it’s going to go up or down,” explains Padilla. “It’s incredibly important because viscosity is going to be in every equation.”

padilla working with a petri dish of ecoli inside of a chemical hood
Padilla’s work on the dynamics of active fluids, ones that contain living cells like E. coli or algae, is essential for future applications that might use living cells to generate fuel, create vaccines, or clean contaminated sites. 

Padilla says that some days are straightforward: The cells grow and she runs an experiment and gets the data that she needs. But at other times, Padilla relies on her troubleshooting and engineering skills to solve a problem, with some help from other researchers in the Arratia lab. She says that her ability to adapt to problems as they arise has been instrumental in the lab and is thankful for the opportunity to tap into that skillset. 

“That was one of my strong suits, which is why I’ve always loved engineering so much. But I never really had the chance to do it because in school you can’t sit there for hours and try and figure it out, you have so many other things to do. So it’s nice being able to use your mind and figure out creative solutions,” says Padilla. 

Padilla’s background in chemical engineering has also been a great addition to the expertise of the Arratia group. “She’s very precise with her methods and she continues to develop her skills in the lab,” Arratia says. “The way we talk about flows is different to the way they teach it in other engineering disciplines, and I appreciate what she brings and her way of thinking in trying to unify certain concepts.” 

Working in the Arratia lab also helped Padilla envision what she could do in the future. She’s currently thinking about working in industry after graduation, but pictures herself going to graduate school once she figures out what field of engineering she wants to specialize in. 

“I didn’t know if chemical engineering was for me, and this was the first time that I saw that I could do something that I like. When we sit in lab meetings, people are so excited about what they are studying that it just gets me excited and it makes me want to understand,” she says.  

Arratia also says that Padilla was instrumental at helping their group solve a problem related to a project on flow cells, where she made an important contribution towards getting methods for a new set of experiments up and running. “Angelica is really a joy to work with,” Arratia adds. “Research is a frustrating enterprise, and I can see that she doesn’t get easily defeated by the frustrations of the lab. Her resilience goes a long way.”

padilla adjusting a metal test tube holder that is held inside a cardboard box, working in a lab with tools and a computer in the background
Some days in the lab are straightforward, but sometimes Padilla must rely on her troubleshooting and engineering skills to solve a problem with help from other researchers in the Arratia lab. “That was one of my strong suits, which is why I’ve always loved engineering so much,” she says. 

Providing undergraduates with an authentic research experience is one of the goals of the LRSM Research Experience for Undergraduates program. The program hosts 20-25 students like Padilla from across the U.S. for 10 weeks every summer, along with one student from Penn. Besides research, the program  also includes lectures, networking, and social events. “I want them to go through some of the frustrations of being a graduate student and also to experience the autonomy, freedom, and excitement of diving into a new research area,” says Mark Licurse, LRSM’s director of education and outreach.

Now that her summer of research is winding down, Padilla is enjoying time at home with family and friends while reflecting on her time so far at Penn. In addition to working as an undergraduate a researcher, Padilla also worked as a Senior Peer Mentor for PENNCAP’s Pre-Freshman Program. After participating in the program, where selected students come to campus four weeks before the start of the semester to take courses and meet classmates, Padilla wanted to give back to the program that had meant so much to her. 

“I had an amazing experience. I met the greatest people, and then when they started hiring for peer mentors, I decided to apply,” she says. Padilla worked for the PennCAP program for two years before deciding to focus more on research and gaining the technical skills she would need for a career as an engineer. Padilla is also on the board of Penn’s Chapter of the Society of Hispanic Professional Engineers, which coordinates community outreach, leadership development, and professional development programs. 

Outside of engineering coursework, research, and community outreach, Padilla says that she doesn’t have a lot of free time but is hoping to cross some items off of her Penn “bucket list” before she graduates. She says that being in Philadelphia this summer has allowed her to spend more of her time exploring the city, which she really enjoys, and she hopes to find more time for the “little things,” like cooking and spending time with friends, during her senior year. 

“I think I have a lot left to do at Penn. This place is amazing, and hopefully I can feel satisfied by senior year.” Padilla says that her goals for senior year are reachable, “but I’m just not ready yet!”

Paulo Arratia is a professor in the departments of Mechanical Engineering and Applied Mechanics and Chemical and Biomolecular Engineering in the School of Engineering and Applied Science at the University of Pennsylvania. He is also a group leader of one of the Interdisciplinary Groups in the LRSM’s Materials Research Science and Engineering Center.