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Researchers at Cornell University in New York state developed the fibre-optic device, which uses low-cost LEDs and dyes. The sensor could be added to soft robotic systems or used with augmented reality (AR) technology.
The researchers, led by mechanical and aerospace engineer Rob Shepherd, are working to commercialise the technology for physical therapy and sports medicine.
Co-lead author Hedan Bai drew inspiration from silica-based distributed fibre-optic sensors to develop a ‘stretchable lightguide for multimodal sensing’ (Slims). This long tube contains a pair of polyurethane elastomeric cores. One core is transparent, while the other connects to an LED and is filled with absorbing dyes at multiple locations. Each core is coupled with a red-green-blue sensor chip to register geometric changes in the optical path of light.
The dual-core design increases the number of outputs by which the sensor can detect a range of deformations – pressure, bending or elongation – by lighting up the dyes, which act as ‘spatial encoders’. Bai paired that technology with a mathematical model that can separate the different deformations to pinpoint their exact locations and magnitudes.
The researchers designed a 3D-printed glove with a Slims sensor running along each finger. The glove is powered by a lithium battery and equipped with Bluetooth so it can transmit data to basic software, which Bai designed, to reconstruct the glove's movements and deformations in real time.
Whereas distributed fibre-optic sensors require high-resolution detection equipment, Slims sensors can operate with small optoelectronics that have lower resolution. That makes them less expensive, simpler to manufacture and more easily integrated into small systems. A Slims sensor could be incorporated into a robot’s hand to detect slippage, for example.
“Right now, sensing is done mostly by vision,” said Shepherd. “We hardly ever measure touch in real life. This skin is a way to allow ourselves and machines to measure tactile interactions in a way that we now currently use the cameras in our phones. It's using vision to measure touch. This is the most convenient and practical way to do it in a scalable way.”
Bai and Shepherd are working with Cornell's Centre for Technology Licensing to patent the technology. Physical therapy and sports medicine have incorporated motion-tracking technology but have so far been unable to capture force interactions, the researchers said.
The team is also investigating ways to use Slims sensors in AR and virtual reality (VR) experiences.
“VR and AR immersion is based on motion capture. Touch is barely there at all,” said Shepherd.
“Let's say you want to have an augmented reality simulation that teaches you how to fix your car or change a tyre. If you had a glove or something that could measure pressure, as well as motion, that augmented reality visualisation could say, ‘Turn and then stop, so you don't overtighten your lug nuts.' There's nothing out there that does that right now, but this is an avenue to do it.”
The research paper, “Stretchable Distributed Fibre-Optic Sensors,” was published in Science.
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