The most common reason people with lower-limb loss stop using their prosthesis is an ill-fitting socket. Everyday activities such as standing, walking, or stair climbing put enormous pressures on the soft tissues of the residual limb, which are not well-adapted to managing the forces these activities generate.

Engineers at the University of Notre Dame and Purdue University are collaborating to map the location and intensity of complex forces within prosthetic sockets. While previous studies relied on data collected by experts in laboratory settings, these researchers aim to develop a data-collection system that prosthetic users can wear comfortably during their daily activities. The data collected will enable researchers to design sockets better tailored to how users move.

“We’re devising a system that seamlessly combines information from different types of sensors—external, pressure, inertial—with biomechanical models,” said Edgar Bolívar-Nieto, assistant professor in aerospace and mechanical engineering at the University of Notre Dame, “Our system will also account for sheer forces within the socket, which are challenging to measure with existing technology.”

The sensors used in this project communicate through an array of different protocols and formats. Axel González Cornejo, a graduate student in Bolívar-Nieto’s lab, is assisting his advisor by creating a monitoring system in which sensors, controller, and algorithms all “speak the same language.”

A unique component of this complex communication system is an e-textile sock, which will be worn on a

user’s residual limb. Purdue University’s Sticktronics Laboratory, directed by Professor Chi Hwan Lee, creates these textiles by using a spray technique that incorporates tiny sensors into fabric. Bolívar-Nieto’s lab will merge the data collected by the sock’s sensors into the rest of the monitoring system.

This collaborative project is funded by a National Institutes of Health (NIH) Trailblazer R21 Award for New and Early Stage Investigators.