Researchers at Washington State University have developed an electronic skin system that can detect pressure and temperature, a step toward giving amputees a sense of touch through their prosthetics. The work, published in the journal Cell Reports Physical Science, operates at a sensitivity ten times finer 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 paper.
Why current e-skins fall short
Electronic skins already exist, but they come with real limitations. They’re expensive, offer low sensing resolution, and often fit poorly. The more they’re shaped to a custom form, the worse their sensing performance gets. The large volume of data generated by sensing arrays also makes real-time use difficult.
“Often these devices are forced to compromise between comfort and mechanical reliability,” said Shen.
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The WSU team built a customizable system that conforms to the freeform shape of limbs. The sensor modules are thin-layered sandwiches that incorporate both temperature and pressure sensors, allowing for human-like tactile sensing that identifies surface texture and material properties.
The manufacturing method follows a “scan-model-print” process. That means high-density sensing can be combined with personalized 3D fabrication in one step.
A Lego-like approach to sensor assembly
“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, an 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 measure both pressure and temperature at high density across flat or curved surfaces. Instead of relying on adhesives, the modules snap together like Legos.
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“Our main manufacturing method using 3D printing and laser cutting is relatively simple, so it could be relatively low cost and convenient,” Qiu said.
The sensing system’s ability to maintain accuracy while conforming to a custom shape stands out, because past designs often had to sacrifice one for the other. That tension between fit and function has been a persistent problem in wearable medical devices, and the WSU approach sidesteps it entirely by scanning the actual prosthetic first, then mapping sensors to its exact geometry.
What’s next for the bionic skin
The project received partial support from WSU’s National Science Foundation Research Traineeship in Next-Generation Robotics, led by Prashanta Dutta, a professor and director in the School of Mechanical and Materials Engineering. Dutta is also a corresponding author on the paper. Additional funding came from Qiu’s WSU startup and Cougar Cage funds.
The researchers have filed an invention disclosure for a provisional patent with the WSU Office of Research Innovation and Entrepreneurship. They’re now working on an actuator that would convert the sensing signals of the e-skin into stimulation for nearby nerves, letting an amputee know what they’re touching. Haptic stimulation replicates the sense of touch, and providing even partial sensation could substantially improve an amputee’s ability to perform everyday tasks.
