How a Low-Cost Soft Robot Is Learning to Perform Surgery Inside a Beating Heart
In a leap for minimally invasive medicine, a soft robot is learning to perform delicate procedures inside a living, beating heart—something no human hand could ever achieve.
For Assistant Professor Tommaso Ranzani (ME, MSE, BME), who leads this project, it’s the culmination of years of design and experimentation.
His team’s latest breakthrough marks one of the first demonstrations of a soft robot operating safely and effectively within a beating heart. The implications stretch far beyond a single research paper. This innovative work could redefine cardiac surgery, making procedures faster, safer, and less invasive.
“It’s a very unforgiving environment,” Ranzani said. “You’re not working on a benchtop model, you’re in a living [porcine model], in the hands of a surgeon who is performing a procedure with it. It has to work.”
That dependability was tested in a paper published in Advanced Robotics Research, in which Dr. Ranzani and his collaborators, including BU PhD student Leonardo Zamora Yañez, demonstrated a soft-robotic guidance system capable of performing intricate maneuvers within a beating heart.
Most traditional surgical robots, while offering enhanced stability, often restrict the high mobility and adaptability required for complex, minimally invasive procedures. Current advanced surgical robots, particularly those used for endovascular approaches that navigate the vascular system to minimize patient invasiveness, are typically designed to reach specific anatomical locations to deliver targeted therapy.
Ranzani’s work, however, is particularly innovative because it pivots the design from this functional constraint to one of high mobility and dexterous manipulation. The device not only enables manipulation within the beating heart but also effectively transmits forces and maintains stable contact with moving anatomical structures. These transformative capabilities enable more complex and advanced procedures within the beating heart without compromising the procedure’s low invasiveness.
Most surgical robots today are built for stability rather than motion. However, Ranzani’s work is particularly innovative because it pivots the design paradigm of surgical robotics from traditional stability to high mobility and adaptability.
“Our goal is to perform procedures trans-catheter,” Yañez said. “All done while the patient’s heart is still beating.”
Ranzani’s team turned to soft robotics—robots built from compliant, flexible materials that can bend and stretch naturally in response to the body.
“Soft robots are perfect for medical use,” Ranzani explained. “They can move with the beating heart instead of fighting it. That means we don’t need very complex control systems to synchronize with every pulse—the materials themselves adapt.”
The project began through the National Institutes of Health Trailblazer Award, a grant designed for unconventional, high-risk ideas. The first phase demonstrated that tasks, such as cannulation, that once took over an hour could be completed in less than ten minutes.
The team’s success led to a new NIH R01 grant exceeding $2 million that expands the scope of the work, in partnership with Massachusetts General Hospital and Boston Children’s Hospital. The goal now is not only to improve existing cardiac procedures but also to enable new ones within cardiology.
“We designed it to be intuitive for surgeons,” Dr. Ranzani said.
The robot’s compliance—its ability to flex and stretch with the heart’s natural movement—allows it to track the valve’s motion even as the heart beats, maintaining contact and precision on a constantly moving target. It eliminates the need to compensate for the target area.
Surgeons can focus on deploying the anchors. The robot handles the precise tracking, making the procedure direct and reliable, as described in another recent paper by Ranzani and his team.
“You just keep turning, and at a certain point, the anchor releases itself into the tissue.”
Safety remains a central concern. To prevent tissue damage, the team has integrated real-time force sensing into the robot’s soft structure, enabling it to consistently monitor and estimate contact pressures via internal measurements, serving as a built-in safeguard.
At the same time, Dr. Ranzani and his students are focused on accessibility. Despite its sophistication, the robot’s materials are inexpensive.
“The robot itself costs well below $100,” he said. “The most expensive part is a stabilizer made from nitinol, the same material used in stents, but it can be sterilized and reused. We want hospitals of all sizes, not just the biggest ones, to be able to use it.”
It will still take years for the system to reach human trials. The team must first scale its studies to larger animal populations, test the robot across different surgeons and operating conditions, and confirm its safety and efficacy.
Dr. Ranzani estimates at least five to six years before the first use in humans.
“If a medical device is released in 15 years from idea to actual use, that’s fast,” Yañez said.
But the trajectory is clear.
From the first fragile prototypes to a robot now operating inside a beating heart, the field of soft robotics in medical applications is moving from theory to practice.
“We’re not just making surgeries faster,” Dr. Ranzani says. “We’re making surgeries possible that couldn’t be done before.”
Because the robot’s compliant, flexible materials allow it to move with the heart’s beating rather than fighting it, the robot has a key advantage over traditional instruments that struggle to maintain precision in such a dynamic, high-stakes environment. The soft robot enables intricate procedures that were previously too risky or technically challenging to attempt.
This soft robotic system does not exert control—it cooperates, offering a small glimpse of a future in which medicine moves as naturally as the body itself.
Tommaso Ranzani is an Assistant Professor in the Department of Mechanical Engineering, Biomedical Engineering, and the Division of Materials Science and Engineering at Boston University. His research focuses on soft and bioinspired robotics with applications ranging from underwater exploration to surgical and wearable devices. He is interested in expanding the capabilities of soft robots across multiple scales to develop novel reconfigurable soft-bodied robots capable of operating in environments inaccessible to traditional robots.
Leonardo Zamora Yañez is a third-year PhD student in the Department of Mechanical Engineering. His research focuses on soft robotic systems for beating-heart procedures. He is interested in advancing the design, modeling, and control of soft robots for applications in minimally invasive surgery.