Wednesday, April 17, 2024

New stretchable skin sensor gives robots and VR a human touch

The virtual aspects of modern virtual reality are constantly improving, but it doesn’t quite match up to the reality label without tactile sensations. As a solution to this, a team of engineers at Cornell University (USA) has created a fiber-optic sensor that combines low-cost LEDs and dyes, resulting in a stretchable “skin” that detects deformations such as pressure, bending, and strain.

The team was inspired by silica-based distributed fiber-optic sensors, which detect minor wavelength shifts to identify multiple properties, such as changes in humidity, temperature, and strain, to make a stretchable lightguide for multimodal sensing (SLIMS).

SLIMS sensors detect deformations such as pressure, pinpoint their exact locations and magnitudes.
SLIMS sensors detect deformations such as pressure, pinpoint their exact locations and magnitudes. Credit: Cornell University

In a prototype glove, each finger has a stretchable lightguide that contains a pair of polyurethane elastomeric cores. One core is transparent, while the other is filled with absorbing dyes at multiple locations and connects to an LED. Each core is coupled with a red-green-blue sensor chip to register geometric changes in the optical path of light.

When you deform the lightguide through bending your fingers or encountering pressure, the dyes serve as “spatial encoders” that light up and register exactly what’s happening and pinpoint their exact locations and magnitudes. The new stretchable sensor uses fairly simple and inexpensive technology. The glove is printed on a 3D printer and is equipped with Bluetooth, so it can transmit data to the basic software that recovers the movements and deformations of the glove in real-time. It also has built-in LED sensors and a lithium-ion battery.

Right now, sensing is done mostly by vision,” said lead researcher Rob Shepherd, associate professor of mechanical and aerospace engineering in the College of Engineering. “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 on our phones. It’s using vision to measure touch. This is the most convenient and practical way to do it in a scalable way.”

According to the researchers, their development can be used to improve virtual reality systems and incorporated into a robot’s hand to give them a sense of touch. The team is also considering the use of new technology in physiotherapy and sports medicine. The material that responds to deformation will give the machines an analog of touch and thus expand their capabilities.