There’s growing interest in prostheses that simulate a sense of touch. With rare exceptions, prosthetic limbs are controlled to move as intended by the wearer but do not return any feedback through the sensation of touch. We recently wrote about brain implantation to enable a sense of touch with a robotic arm, ongoing research at the University of Pittsburgh Medical College, which is one of the rare exceptions.
Researchers from the University of Applied Sciences Upper Austria, Hagenberg, Austria report a different approach. They realized that cost, accessibility, and other health issues would put sensing prosthetics out of reach for many if not most patients. Cost alone can be a prohibitive factor with prosthetic legs, which are priced at $5,000 to $50,000 and need replacing every couple years. Rather than embedding sensors within prosthetics, the Austrians have conceived a prosthetic wearable, a sock that a user puts on over a prosthetic foot.
“We present a novel concept and prototype of a prosthetic-sensing wearable that offers a non-invasive, self-applicable and customizable approach for the sensory augmentation of present-day and future low to mid-range priced lower-limb prosthetics,” the researchers wrote in a report published in the UIST ’16 Proceedings of the 29th Annual Symposium on User Interface Software and Technology.
The proCover was developed in consultation with eight lower-limb amputees. The design concept research studied smart textiles for user-directed sensory mapping of regions of the foot based on wearable haptic feedback actuators in the cover. Researchers tested a sock with as many as 221 sensors. The proCover includes a sensor sock, electronics including wiring and microcontrollers, and a vibrotactile band. Rather than using brain implants to deliver tactile sensation, the band delivers the stimulus. When worn on the upper arm, users learn to “feel” sensations from their foot on their arm.
The system is still under development and study, and would require retraining people to respond to sensations in new parts of their bodies. User motivation levels would necessarily need to be high for the sensory re-training, but the promise of relatively low cost, self-customized tactile sensation could be sufficient motivation itself.