Shujie Yang Harnesses Sound to Build the Next Generation of Microrobotic Medicine

As a child, Shujie Yang, Assistant Professor in Mechanical Engineering and Applied Mechanics, was captivated by robots and the idea that intelligent machines could be built, programmed and brought to life. Science fiction novels and robotics films fed his imagination, but it was a televised university robotics competition that left a lasting impression: Watching students design open robotic systems to complete complex tasks planted a dream that would guide his career in mechanical engineering.

At Penn Engineering, Yang’s lab explores an unconventional but powerful medium for engineering and medicine alike: sound. Using precisely controlled ultrasound waves, Yang develops acoustic tweezers — microscale tools that can manipulate cells, viruses and soft materials without physical contact. His work sits at the intersection of mechanical engineering, microsystems and biomedicine, with implications for disease diagnostics, immunology and future cancer therapies.

From Robots You Can See to Systems You Can’t

Yang’s academic path began in mechanical engineering and robotics during his undergraduate studies in China, where he joined a university robotics team. 

“I realized that if I wanted to build truly great robots, I needed to understand mechanics and electronics deeply,” says Yang.

That realization pushed him toward a master’s degree focused on mechanics and electronics fundamentals. But rather than continuing along the well-trodden path of large-scale robotics, Yang found himself drawn in the opposite direction: toward precision micro- and nanoscale systems, where the rules of physics change and intuition must be rebuilt from the ground up.

“At smaller scales, you can’t just miniaturize what works in the macro world,” he explains. “Familiar mechanisms like wheels, gears and even lubricants fail to work as expected because scaling laws reshape how forces and lubrication dominate at the micro- and nanoscale. We have to think differently, and we have to be more creative.”

This fascination led Yang into Micro-Electro-Mechanical Systems (MEMS) and later BioMEMS during his doctoral studies, where he began integrating engineering with biology. A pivotal moment came when he encountered research on acoustic manipulation.

“I started wondering whether ultrasound waves could be programmed to function almost like a human hand, to grab, move or interact with microparticles,” he says. “That idea kept me up all night.”

The question became the foundation of his doctoral work and, ultimately, his research identity.

Fundamental Questions with Transformative Potential

At the heart of Yang’s work is a set of fundamental questions:
Can sound waves be tuned to resonate with specific cells?
Is there a “magic frequency” that selectively affects cancer cells but spares healthy ones?
How does acoustic stimulation alter immune cell behavior?

Yang aims to answer these questions from a strong background of research in the field of acoustic manipulation. Through studies published in Nature Materials, Nature Protocols and Nature Reviews Methods Primers, he has introduced programmable acoustic tweezers, established widely used experimental frameworks and articulated the core principles that enable sound-based control of micro- and nanoscale biological systems — fundamentals that support his current and future work at Penn Engineering.

Acoustic tweezers use sound waves to exert forces on objects ranging from nanometers to millimeters in size. Unlike optical tweezers or atomic force probes, they are non-contact, highly programmable, biocompatible and capable of working deep within tissue. In Yang’s lab, these ultrasound waves become a kind of invisible hand, capable of isolating exosomes for diagnostics, manipulating immune and cancer cells, and probing the mechanobiology of single cells. His long-term vision is ambitious: developing ultrasound-based microrobotic tools precise enough to target individual cancer cells, including those that evade existing therapies and migrate through the bloodstream.

“It sounds like science fiction,” he admits, “but we’re much closer than people think.”

Collaboration and Opportunity at Penn

Now, at the frontier of single-cell acoustic manipulation, an emerging field that blends physics, mechanobiology and medicine, Yang is collaborating closely with researchers across Penn Engineering, the Perelman School of Medicine and Penn Dental Medicine, leveraging strengths in the interdisciplinary research centers CPE4H and CiPD.

“Penn is uniquely positioned for this kind of work,” Yang says. “The collaboration between engineering and medicine here is exceptional, and that is the main reason I chose to bring my work here.”

Building a Lab and a Culture of Resilience

Yang joined Penn Engineering in 2024, and his lab quickly began gaining momentum. Recruitment is ongoing, with an emphasis not just on technical skill, but on creativity and persistence.

“Students here are already smart and hardworking,” says Yang. “What they need in research is patience, support and the freedom to try new ideas.”

Failure, he emphasizes, is part of the process. His first academic paper was rejected nine times before publication, a story he shares openly with his students.

“If you’re not failing, you’re not trying anything new,” he says.

Inspired by advice from Nobel laureate Drew Weissman, Yang structures mentorship around balance: pairing one stable, well-defined project with another that is higher-risk and more innovative. The approach builds confidence while encouraging bold thinking.

Looking ahead, Yang is focused on understanding immune–cancer cell interactions through acoustic manipulation, both to answer basic biophysical questions and to explore therapeutic possibilities.

“Sound has always been part of healing,” he says. “We intuitively understand its power. Now we’re building the science to harness it precisely.”

Learn more about Yang’s work and opportunities on his research website.