Designing and Developing Novel Bionic Limbs

Exploring innovative technology to promote optimal comfort and eradicate disability

In the U.S. alone, millions of people suffer from a loss of functionality to their limbs. These disabilities can be caused by stroke, spinal cord injury, peripheral nerve damage, cerebral palsy, multiple sclerosis, or amputation. Dr. Hugh Herr, Associate Professor of Media Arts and Sciences at Massachusetts Institute of Technology (MIT), advances fundamental science and technology by developing bionic devices that not only emulate biological function, but augment human physicality. He explores the interplay between biological science and design, developing biohybrid "smart" bionic limbs that are significantly more powerful than current human rehabilitation technologies.

Dr. Herr’s biomechatronics group of research scientists, postdocs, graduate and undergraduate students has authored more than 150 peer-reviewed manuscripts and patents, highlighting Dr. Herr’s many scientific and technological innovations. They collaborate with other research labs—including researchers at the University of Michigan and the University of Colorado—to pioneer novel research in the fields of biomechanics and biological motion control. 

Their novel research results accelerate the merging of body and machine, significantly improving the quality of life for persons having limb conditions. Two of their commercialized technology includes a prosthetic ankle-foot prosthesis called the BiOM, and a knee prosthesis called the Rheo. Compared to typical prostheses, their bionic systems are more powerful, intelligent, sentient, and adaptive to the human user. Through a comprehensive understanding of human morphology and dynamics, their designers are better able to fabricate unique synthetic and biologic interventions for the eradication of limb disability. They currently have multiple projects, with research and development time frames spanning from 6 months to 5 years. 

The main themes of their bionic design and development research include:

  • Mechanical Interface: Dr. Herr and his team are looking at how to attach wearable devices onto the human body in a comfortable and healthy manner, while still providing adequate mechanical support. They’re looking at all devices that interact with the body—from bionic limbs to broader devices like bras and shoes—to achieve individualized optimality and comfort. They first image the anatomical region of interest using MRI and robotic indenters. and then develop a biomechanical model of that anatomical region.  Such a mathematical model describes how the biological segment responds to outside forces and pressures. Next, they derive an optimal interface shape and stiffness and then digitally fabricate the interface using 3-D printing technology. They perform optimizations with the model, minimizing pressures and large tissue strains by varying the design of the synthetic skin, iterating over hundreds of designs. Dr. Herr and his team want to create a world that eradicates discomfort from all devices. Their vision is that everyone will one day have a digital representation of their body stored on a computer. If you want shoes, for example, you will be able to send in the digital data of your foot and ankle, and then receive the perfect customized pair with absolutely no discomfort.
  • Electrical (Neural) Interface - Dr. Herr and his team are developing technology that enables the human peripheral nervous system—composed of nerves and muscles—to communicate neurally with a bionic device. They design small electronic packages that interface with a person’s nervous system, recording an individual’s movement desires and using that information to directly control the synthetic motors in a bionic limb. They also take sensory information from a bionic limb and reflect that onto a person's nerve endings, enabling them to feel different positions, forces, and touch. The user is able to volitionally control the device, as well as receive sensory information from the device into the nervous system.  
  • Dynamic Interface - Dr. Herr and his team are exploring how a designed synthetic prosthesis or orthosis can be fabricated with the same weight, volume, and dynamics as its biological counterpart. They developed a computer-controlled knee prosthesis, the Rheo Knee, which is currently used by thousands of people worldwide who have an above-knee amputation. Outfitted with a microprocessor, the device continuously senses the joint's position and the loads applied to the limb, allowing it to naturally move like a biological knee. Another of their innovative devices is a powered ankle-foot prosthesis called the BiOM. It is currently the first leg prosthesis in history to enable individuals with leg amputation to walk with normal levels of speed and metabolism, as if they had biologically operating legs. All other commercial devices are human powered, in which only a person’s remaining musculature powers their movement, similar to riding a bicycle. The BiOM—much like a car—adds to the energy and power of its user as they move, emulating lost muscle functions in a natural way. They have fitted more than 1,200 patients with this device, half of which have been wounded U.S. soldiers. 


Dr. Herr started mountain climbing when he was 7 years old. By age ten, he was considered a child prodigy in the climbing world. At age 16, he was considered one the top climbers in the U.S. During a mountain climbing outing in January of 1982, he became stranded on Mount Washington in New Hampshire for nearly four days in –20o F temperatures and blizzard conditions. He suffered severe frostbite damage to his lower legs, and two months later the efforts to save his biological legs had be terminated. Both of his limbs were amputated six inches below the kneecap. 

After the accident, Dr. Herr dreamed of being able to climb again. In early June of that year, he received his first pair of artificial limbs. Still in the rehabilitation process, he began climbing again that same month. He continued to climb at a more advanced level than he achieved prior to the accident.

He went on to design and develop artificial limbs specifically for climbing, enhancing advantages and mitigating areas of disadvantage. The specialized prosthetic feet he created allowed him to stand on small rock edges, and his titanium-spiked feet assisted his ascensions on steep ice walls. He made his height adjustable—five to eight feet tall—avoiding awkward body positions and enabling him to grab hand and foot holds previously out of reach.

That life-changing experience after his climbing accident was very inspirational for Dr. Herr, because he quickly realized the extraordinary capacity of technology to heal, rehabilitate, and—in cases such as his own—extend human physiology beyond natural boundaries, enabling superhuman capabilities. These realizations convinced Dr. Herr to pursue a career in science and engineering so that he could be in a better position to advance human rehabilitation and augmentation technologies. He went from being a poor high school student with little interest in academics to a straight-A college student. He completed his undergraduate degree in physics at Millersville University, his master's degree in mechanical engineering at MIT, and a Ph.D. in biophysics from Harvard University.

He currently leads the Biomechatronics research group at the MIT Media Lab, and co-directs MIT’s new Center for Extreme Bionics. Their mission is to advance the fundamental science and technology that will ultimately eradicate disabilities impacting the mind and body.

When he’s not in the classroom or lab, Dr. Herr tries to climb on a weekly basis at a local gym. His latest outdoor mountain climbing trip was to the Italian Alps, which tower vertically thousands of feet high. 


Design and testing of a bionic dance prosthesis


Clutchable series-elastic actuator: Implications for prosthetic knee design


Volitional Control of Ankle Plantar Flexion in a Powered Transtibial Prosthesis during Stair-Ambulation


A clutchable series-elastic actuator: design of a robotic knee prosthesis for minimum energy consumption


Continuously-Variable Series-Elastic Actuator


Proportional EMG Control of Ankle Plantar Flexion in a Powered Transtibial Prosthesis


A variable impedance prosthetic socket for a transtibial amputee designed from MRI data



Blouin Creative Leadership Award
, 2015

41st Annual Inventor of the Year Award

R&D Magazine’s Innovator of the Year, 2014

Smithsonian American Ingenuity Award in the Technology Category, 2014

Prince Salman Award for Disability Research, 2014

Spirit of Da Vinci Award, 2008

Action Maverick Award, 2008