Washington State University (WSU) researchers developed an electronic skin that can detect pressure and temperature, which could help people gain feeling in their prosthetic devices. The e-skin can sense at ten times a finer scale than current commercial glove sensors.
“This approach democratizes the production of medical-grade e-skins, making advanced tactile feedback viable for widespread clinical adoption,” said Hongyi Shen, a graduate student in the School of Mechanical and Materials Engineering and first author on the related paper. “This work lays a crucial foundation for a full bionic skin with both sensing and haptic stimulation functions on prosthetics.”
Haptic stimulation replicates the sense of touch. The researchers said that e-skins available now are expensive, have low sensing resolution, often don’t fit well, and can only cover small regions. In fact, the more that e-skins are made to a custom shape, they say, the worse they perform in sensing ability and the large amount of data generated from the sensing arrays also prevents them from working well in real time.
“Often these devices are forced to compromise between comfort and mechanical reliability,” said Shen.
The WSU researchers developed a customizable sensing system for prostheses that conforms to the freeform shape of limbs and better mimics real human skin in its sensing abilities. The sensor modules they created are thin-layered sandwiches that incorporate temperature and pressure sensors. The elements allow human-like tactile sensing, enabling reliable identification of surface texture and material properties.
The researchers used a “scan-model-print” manufacturing method that allows for high-density sensing at the same time as the personalized, 3D fabrication.
“The scanner basically scans the prosthetic and then, based on the geometry, we map our sensors as a multimodal sensing system with that geometry,” said Kaiyan Qiu, PhD, assistant professor in the School of Mechanical and Materials Engineering and corresponding author on the paper. “This enables our sensing system to have seamless coverage over the freeform region on the prosthetics.”
The sensors are accurate and reliable and can measure both pressure and temperature at a high density across a flat or curved surface. Rather than requiring adhesives, modules of sensors snap together like Legos.
“Our main manufacturing method using 3D printing and laser cutting is relatively simple, so it could be relatively low cost and convenient,” said Qiu.
The researchers have submitted an invention disclosure for a provisional patent with the WSU Office of Research Innovation and Entrepreneurship team. They are also working on an actuator that will eventually convert the sensing signals of the e-skin to communicate what the prosthesis user is touching. That would entail converting the sensing signals to stimulation and signaling of nearby nerves.
Editor’s note: This story was adapted from materials provided by WSU.
The open-access study, “A geometry-aware and customizable multimodal sensing system for texture and material identification in prosthetics,” was published in the journal Cell Reports Physical Science.
