Purdue and Notre Dame Engineers Develop Embroidered Textile Sensors for Prosthetic Socket Fit

Engineers at Purdue University, collaborating with researchers from the University of Notre Dame, have engineered a machine-embroidered textile sensor system capable of mapping real-time pressure and shear stress inside lower-limb prosthetic sockets. As first reported by TechXplore, the novel wearable platform integrates flexible force-sensing fabric with a light-emitting display and wireless data transmission, offering a practical approach to continuous biomechanical monitoring. The technology has been disclosed to the Purdue Innovates Office of Technology Commercialization, which is moving to secure patent rights for the system.

An estimated 50 million people globally, including roughly two million individuals in the United States, live with limb loss. For those utilizing artificial limbs, maintaining a proper fit where the residual limb meets the prosthetic socket remains a key physiological challenge. During daily routines such as standing, walking, or adjusting body posture, the interface encounters complex multidirectional dynamic forces. Failing to accurately monitor these force interactions can lead to discomfort, skin breakdowns, and secondary injuries over time.

Existing mechanical approaches to evaluating internal socket pressures present several operational limits. Optical sensing setups depend on embedding chips and signal processors into tight socket cavities, where space is severely constrained. Meanwhile, strain gauge-based transducers typically require physical alterations to the socket's geometry, and many available sensors measure only perpendicular pressure rather than lateral friction. "Optical systems rely on integrating signal processing and chip components within the socket—difficult to do in such a tight space," said Chi Hwan Lee, corresponding author and professor in Purdue's Weldon School of Biomedical Engineering and School of Mechanical Engineering. "Strain gauge-based transducers often require modification of socket geometry. Other solutions are limited to pressure sensing alone."

To address these physical and mechanical barriers, the research team constructed a fully embroidered, multiaxial sensing setup using specialized threads and capacitive structures. "This called for novel materials and fabrication techniques," said Tianhao Yu, first author of the study and a Ph.D. candidate in mechanical engineering at Purdue. "We met this challenge with a fully embroidered, multiaxial sensing system to detect forces at the limb-socket interface." The sensing elements are fabricated using a standard polyester top thread combined with a silver-plated conductive bobbin thread stitched directly into a fabric substrate.

The architecture relies on ionic gel-based electric double-layer capacitors paired with machine-embroidered electrodes arranged in a four-quadrant pattern. "The embroidered sensor forms a multilayered capacitive structure with a large common top electrode and four smaller bottom electrodes arranged in a quadrant configuration," Lee explained. "The sensor detects differential capacitance changes. Under normal compression, all four quadrants exhibit similar capacitance increases. Combined normal and shear loading induces asymmetric changes, revealing both the magnitude and direction of shear."

The broader system relies on a modular layout featuring a textile sleeve worn inside the prosthetic socket. Snap-button connectors bridge the fabric sensors to a Bluetooth-enabled data acquisition module, which streams capacitance signals to a portable device for digital force mapping. Simultaneously, the onboard microcontroller powers a textile-based electroluminescent display built into the user's garment sleeve, activating illuminated embroidered pixels that offer real-time visual indications of localized pressure distribution.

The practical feasibility of the platform was evaluated with a transtibial amputee patient performing daily functional movement tasks, demonstrating its capability to capture both normal forces and shear stress under dynamic real-world conditions. Furthermore, the researchers verified the garment's durability through rigorous laundering tests. Encased in a water-permeable protective bag, the embroidered sensors maintained full functionality after undergoing more than 30 complete wash, rinse, and spin cycles in a standard home washing machine using commercial liquid detergent.

The multidisciplinary research effort included Purdue faculty Hyeonseo Joo, Ziheng Wang, and Yumin Dai, alongside Notre Dame researchers Axel Gonzalez Cornejo and Edgar Bolivar-Nieto from the Department of Aerospace and Mechanical Engineering. The findings were detailed in a Science Advances paper titled "Embroidered textile sensors for real-time multiaxial force mapping in prosthetics." "The pressures of the prosthetic limb interface are very intricate and complex," Yu noted. "We want to deliver the most granular, most customizable data for patients to give them the best possible experience with their artificial limbs across their daily lives."

Because the underlying textile architecture can be adjusted in size, electrode arrangement, and mechanical sensitivity, the system can be customized for diverse socket geometries, sheath designs, and user weight profiles. "This work represents a step forward in developing practical, wearable solutions for continuous biomechanical monitoring in lower-limb prosthetic users," Lee said. The disclosure to Purdue Innovates marks the preliminary phase toward commercializing the platform, with the university seeking patent protection to support potential medical device licensing.