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Wearable Robots for Human Assistance and Rehabilitation

Adapted from Tommaso Lenzi’s “Building Bionics: How technologies are going to enhance the human body and end physical disability,” this year’s William R. and Erlyn J. Gould Distinguished Lecture on Technology and the Quality of Life, delivered at University of Utah’s J. Willard Marriott Library on March 29, 2023. 

The University of Utah has a long history of medical breakthroughs. The first bionic arm was created at the U in the 1970s. And the first artificial heart was implanted at the University of Utah in the early 1980s. Today, we continue this legacy of life-changing technologies.

From a very young age, I knew I wanted to be an engineer. I’ve always had a drive to understand how things work and how to fix them. I discovered the true power of engineering in college and graduate school. Engineers are problem solvers. With millions of people living with physical immobility, I can’t think of a more important problem to solve.

The Utah Bionic Leg

I believe everyone should be able to live without disability if they want to. We have the technology that empowers us to do that. My goal as an engineer is to build technologies to help people stay mobile, active, and free.

The Utah Bionic Leg was born in the HGN Lab for Bionic Engineering at the University of Utah. It is the lightest and strongest robotic leg prosthesis that has ever been created. This device is the result of many years of work in collaboration with my students and generous donors. Millions of dollars in funding from the National Institutes of Health, National Science Foundation, Department of Defense, and many other supporters have made this project a reality.

How Does the Utah Bionic Leg Work?

Engineers have been using batteries and electrical motors in prosthetics for more than 20 years. But this approach has been unsuccessful. The Utah Bionic Leg is fundamentally different from any prosthesis to date. It has a lightweight, variable transmission system with a tiny motor and battery that provide a wide range of torque and speed to match that of the biological knee. It also has an artificial tendon that connects the toe and ankle of the prosthesis. The knee and ankle of the prosthesis articulate together to provide a better, more natural gait.

With this leg, we hope people will be faster, stronger, and achieve better mobility and stability.

Because the ankle and toe of the prosthesis give the user more lift and mobility while walking, the rest of the body doesn’t have to compensate as much. Over time, this makes for better walking habits and better overall health. Uneven terrain is also easier to navigate, as the ankle adapts easily to different surfaces. The leg also allows users to walk up stairs, something that isn’t possible with prescribed prostheses.

How Does the Leg Know What to Do?

Among the many sensors in the Utah Bionic Leg, two are essential. One tells us the position of the thigh—where it is in space, which direction it’s swinging, and how fast it’s moving. The other sensor detects if the foot of the prosthesis is in contact with the ground. Data from these sensors are captured and updated thousands of times per second. Based on this data, the prosthesis emulates what the biological leg would do.

Additional sensors, attached to specific areas of the residual limb, capture the voltage that is generated when the leg muscles contract. When the user thinks about extending or flexing the prosthesis knee, the small muscle contractions trigger the prosthesis to extend or flex. With this system, we achieve a more natural way of controlling the prosthesis by merging the biological nervous system with technology.

Science Robotics Magazine
The Utah Bionic Leg featured on the cover of Science Robotics, November 2022.

Expanding Research

Thanks to countless donors, our technological research is expanding.

In October 2022, we partnered with Ottobock, the largest and oldest prosthetics and orthotics company in the world. Ottobock licensed our technologies and donated funding for research and development. Thanks to Ottobock and other generous donors, we are now one of the best equipped labs in the world to develop and validate assistive technologies for people with disabilities.

We have also expanded our research program to include powered exoskeletons. For patients who still have both their legs but have lost strength or mobility (for example, individuals who have survived a stroke), powered exoskeletons can be life changing. Our powered exoskeletons are lightweight devices that provide external stability and powered assistance. Our powered knee exoskeleton can help people stand up easier. Our powered hip exoskeleton helps users lengthen their stride and walk faster, improving mobility.

Clinical Trials

Within the walls of the Bionic Engineering Lab, I see technology that can really change the lives of many people. For me, it’s not so much about ability or disability. It’s about developing technology that can help people achieve the level of mobility they want and need to live a full life.

Over the past five years, patients with mobility challenges have tested our technologies. Their feedback and input are critical to our success. Clinical trials are the next step in bringing these technologies to as many patients as possible. Only through clinical trials can we provide endorsement for the technology and show the efficacy of these devices.

Tommaso Lenzi Amputee
Tommaso Lenzi, PhD, (left) helps Alec McMorris put on an experimental exoskeleton that Lenzi developed for lower-limb amputees.

What Is Disability?

Disability is not black and white—it’s a spectrum. We all move slowly down the spectrum with age, and we can also move suddenly down the spectrum after injury. Amputation moves people down the spectrum of disability, and current prosthetic technologies only help a little. In fact, if you were to have an amputation today, you’d be given a technology that is 70 years old. So, when I see a person struggling to walk with their passive prosthetic leg, I don’t see a disabled person—I see bad technology. I see our failure to provide people with the technology they need to thrive and achieve their goals.

Bionics Will Change the Future of Rehabilitation

We have the power to move people up the spectrum of disability. That’s why my lab has been working so hard to bring our technologies to market and prove how much they can help people in the real world. We don’t want our devices to stay in the lab; we want to bring them to as many people as possible.

I believe bionics will give people the mobility they need to pursue their life goals. Technology will free people and empower them to live without disability if they want to.

Tommaso Lenzi

Tommaso Lenzi, PhD, MS

Tommaso Lenzi gave the 2023 William R. and Erlyn J. Gould Distinguished Lecture on Technology and the Quality of Life at the University of Utah. Lenzi’s main research interests include robotics, mechatronics, and rehabilitation medicine with a major emphasis on the design and control of wearable robots for human assistance and rehabilitation. He is an associate professor of mechanical engineering and director of the Bionic Engineering Lab at the U. Lenzi received a PhD in biorobotics at Scuola Superiore Sant’Anna and an MS in biomedical engineering at the University of Pisa. He completed a postdoctoral fellowship at Northwestern University. 

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