Evolution on Fast Forward: Grace Gu Engineers AI-Optimized, Bioinspired Materials

However, as Gu says, “Nature has answers to nature’s problems, which aren’t necessarily the same problems that we face in our modern world.” She is using AI to identify what configuration of the denticles will best suit human needs, within human manufacturing limitations.

She compares this bioinspired, computationally optimized design process to figuring out how to build a house with a pile of toy building blocks of different shapes and sizes, without any instructions. Brute-forcing a solution could take years, but AI can theoretically fast-track evolution and find a solution in a much shorter period of time.

Gu and her research team “translate” material structures into the binary code that computers can understand and then put them through an optimization algorithm to determine the best structure for given usage requirements, such as lower air drag or higher heat resistance, as well as manufacturing constraints, such as 3D-printer resolution. 

This machine learning technology is similar to how AI can be trained to decipher whether an image shows a cat or a dog by detecting patterns in color and texture, except that it is now designing three-dimensional models by recognizing structural features.

The team has been working to reshape shark denticles to a configuration that is well suited to cover the panels of commercial airplanes. Then, under Robinson’s guidance, they test the materials and validate their prototypes in the UC Davis aeronautical wind tunnel. 

“The CITRIS Seed Funding program really helped to catalyze this collaboration,” Gu said.

While the Seed Award focuses on applications in aviation, she notes that denticles could also be designed to coat automotive vehicles, wind turbine blades, gas pipelines, even swimsuits — anything that would benefit from reduced drag.

Beyond her CITRIS-supported efforts, Gu’s group is pursuing several other research avenues with biological underpinnings. One area of investigation, supported by the UC Berkeley Bakar Fellows Program, integrates Gu’s interests in additive manufacturing and biomedical applications. As a Bakar fellow, she is working to help people heal from ligament ruptures by “bioprinting” custom replacement parts from collagen. She aims to produce a prototype within three years.

The wings of owls have also offered inspiration. Unique among birds for their silent flight, which helps them approach prey without detection, owls have serrated feathers that break down air turbulence to reduce noise. Gu is hoping to apply lessons learned from these feathers to the design of drone propellers for use in urban settings.

“If you’re thinking about delivering packages, you don’t want the noise to disrupt the neighborhood, right?” she said.

In a collaboration with MIT Lincoln Laboratory, Gu and team are planning to combine features from both shark denticles and owl wings in uncrewed underwater vehicles, or UUVs, to lessen drag, reduce noise and thus optimize their ability to operate in stealth.

She is also working on a multi-university project funded by the National Science Foundation’s Designing Materials to Revolutionize and Engineer our Future (DMREF) program to combine structural features from octopuses, chemical properties from mussels and AI to engineer adhesive devices that can be easily removed and reapplied. This switchable adhesive technology could help make prosthetics fit better, robots grip better and pick-and-place manufacturing processes run more efficiently.

Although numerous and wide-ranging, Gu’s efforts in the laboratory maintain focus on applications that improve people’s lives.

“For research, it’s important to think about why you’re doing it, and what steps you have to take in order to achieve the goals you’ve set,” said Daniel Lim, a doctoral student in Gu’s group. “Professor Gu mentored me well on how to define my research process. I’m very lucky to have her as my advisor.”

Gu is also dedicated to making her research more accessible in the hopes of inspiring the next generation of scientists and engineers. 

She has created outreach activities for elementary and middle schoolers with UC Berkeley Girls in Engineering (GiE) and the Society for Women Engineers. In January 2023, Gu and her group organized a hands-on workshop for a dozen high school and undergraduate students. The students built a 3D printer from scratch, sharpened their computer-aided design (CAD) skills and tackled a challenging design project that made use of the new machine. 

Gu is also a mentor for the UC Berkeley Transfer-to-Excellence (TTE) Summer Research Program, a nine-week research internship that brings California community college students into the labs of UC Berkeley science and engineering professors. 

Here she made use of another CITRIS resource: A recent TTE intern completed his research project with the help of the CITRIS Invention Lab, which allowed him to quickly manufacture 3D-printed prototypes. With the assistance of Daniel Lim, a former Invention Lab superuser, 2022 intern and Fullerton College student Jacob Lopez was able to create physical models of semiconductors — something almost unheard of given the short timespan of the program.

“It’s hard to achieve physical outcomes in that period of time, but thanks to Chris Myers and Dan Chapman, Jacob was able to actually use the equipment to fabricate a complete experimental setup,” Lim said. “It really boosted up the thought process behind prototyping in research.”