A new type of smart fabric that can sense pressure and light up in response could help make prosthetic limbs more comfortable and reduce the risk of injury.
Researchers at Purdue University and the University of Notre Dame have developed an embroidered textile sensor that measures the complex forces between a person’s residual limb and a prosthetic socket.
The technology can monitor these forces in real time and even display pressure levels using illuminated sections of fabric.
The research, published in Science Advances, could address one of the biggest challenges faced by people who use prosthetic limbs: getting the socket to fit properly.
More than 50 million people worldwide are estimated to have lost a limb. For those using prosthetics, the area where the residual limb meets the socket is especially important.
Standing, walking and changing posture create forces in multiple directions. If these forces are uneven or excessive, they can cause discomfort, skin damage and other injuries.
Existing sensors have limitations. Some optical systems require electronic components to be installed inside the socket, where space is extremely limited. Other sensors may require changes to the socket itself, while some can measure only direct pressure and cannot detect sideways, or shear, forces.
The new system is designed to overcome these problems using flexible embroidered electronics.
The researchers created a textile sheath containing an array of sensors that fits inside the prosthetic socket. Each sensor uses conductive threads and an ionic gel to detect changes in force. Its design includes four smaller electrodes arranged beneath a larger electrode.
When pressure pushes straight down, all four sections respond in a similar way. When sideways forces are also present, the sections respond differently. By comparing these signals, the system can determine both the strength and direction of shear forces.
The information is collected by a small electronic module and transmitted through Bluetooth to a portable device, where the forces can be digitally mapped. The researchers also created an embroidered electroluminescent display that provides immediate visual feedback by illuminating textile pixels.
In testing, a person with a below-the-knee amputation wore the system while performing everyday activities. The sensors successfully monitored changing pressure and shear forces in real time.
The textile system can also be customized. Its size, sensor arrangement and sensitivity can be adjusted for different people, socket shapes and expected levels of force. Snap-button connections make it easier to attach or remove the electronic components.
Importantly for something designed to be worn regularly, the sensors are washable. Researchers protected them inside a water-permeable covering and put them through more than 30 complete cycles in a standard washing machine using ordinary detergent.
The team hopes the technology will eventually provide prosthetic users and clinicians with detailed information about how a socket behaves throughout daily life.
Instead of relying mainly on how a prosthetic feels during a fitting appointment, future users could have continuous information showing exactly where potentially uncomfortable or harmful forces are developing—helping create prosthetic limbs that are safer, more personalized and more comfortable to wear.
