TIME has selected the Utah Bionic Leg as one of the best inventions of 2023, naming it in its “Experimental” category. TIME’s annual list of the best inventions features 200 innovations with the capacity to change people’s lives. To compile the list, TIME’s editors solicit nominations and accept applications describing groundbreaking work in key fields and evaluate each contender on several factors including originality, efficacy, ambition, and impact.
The Utah Bionic Leg was developed by Tommaso Lenzi, PhD, an associate professor in the Department of Mechanical Engineering at the University of Utah, and his students in the HGN Lab for Bionic Engineering.
“The ‘passive’ joints in traditional prostheses can’t fully replicate the biomechanical functions of a biological leg,” Lenzi said. “This makes walking substantially harder, especially on inclines or when climbing stairs. It also leads to users compensating for their prostheses’ deficiencies with other parts of their bodies, which can cause secondary complications, such as back pain and osteoarthritis.”
While motorized leg prostheses have existed for more than 30 years, many users have found them to be too heavy and inefficient to be worn every day.
Lenzi and his colleagues’ actuation technology allowed them to achieve power and torque densities that were previously impossible. Thanks to a lightweight, variable transmission, the Utah Bionic Leg replicates the full range of speed and torque of the human knee with smaller motors and batteries than previous powered prostheses. An artificial tendon that connects the toe and ankle joints also regenerates mechanical energy, allowing the Utah Bionic leg to provide more power despite its lighter weight.
Editor’s note: This story was adapted from materials provided by the University of Utah.
