Researchers have developed a wearable sensor that allows users to turn their hand or finger movement into communication without having to say a word or tap a touchscreen. The sensor could open new possibilities for rehabilitation applications and help those with disabilities communicate more easily.

The sensor combines a soft and flexible material called polydimethylsiloxane, or PDMS, with an optical component known as a fiber Bragg grating (FBG). The sensor is designed to be comfortable for long-term wear while having the ability to detect movements with accuracy.

Kun Xiao from Beijing Normal University said the sensors could translate gestures or facial expressions into words or commands, enabling those with severe mobility or speech issues to communicate with others or interact with technology more easily. “For someone recovering from a stroke, these sensors could monitor wrist, finger or even facial movements to monitor their rehabilitation progression,” Xiao said.

The cross-disciplinary team of researchers from Beijing Normal University, Sun Yat-sen University and Guilin University of Electronic Technology described the new sensor in the journal Biomedical Optics Express. The sensor reportedly shows a high level of sensitivity and accuracy during tests involving gesture recognition and communication assistance. Researchers believe that the sensors could be tailored for applications such as monitoring other health indicators like respiratory or heart rate by detecting subtle body movements. They could also be useful for athletes or fitness enthusiasts to monitor and improve their form or technique in real time.

The researchers used PDMS, a type of silicone elastomer that is flexible and skin friendly, to develop the sensor. This enables the sensor to be worn for long periods without irritation or discomfort. To give the sensor its movement-sensing capability, the researchers embedded the PDMS with FBGs, a type of reflector that is etched into a short segment of optical fibre to reflect specific wavelengths while transmitting all the others. The sensor makes it possible to detect slight changes in the way light propagates through the fibre optic during movement, allowing the system to detect specific movements by analysing the alterations in light behaviour.

When developing the sensor, the researchers found that using a thicker PDMS patch caused a more pronounced wavelength shift. Leveraging this sensitivity-enhancing effect of PDMS allowed the optical sensors to detect subtle movements, like the bend of a finger. The sensors can be applied to various parts of the body for a range of applications. The researchers are also developing a calibration method that allows the sensors to be tailored to each user, making them adaptable to various applications.

Image caption: Researchers have developed a wearable PDMS sensor that uses an FBG to sense movements. The sensors could be used to monitor wrist, finger or even facial movements. Image credit: Kun Xiao, Beijing Normal University in China.