Sensors developed to respond to jaw movement can be wirelessly connected to different devices for hands-free control.
Hands-free control is a technological breakthrough. Not only does it make our lives easier and safer – consider asking Siri to make a call so you don’t have to fiddle with your phone while driving or asking Alexa to turn on your kitchen light because your hands are full groceries – for many with accessibility issues, hands-free devices can also make it easier to manage daily activities.
In a recent study published in Advanced intelligent systemsa University of Glasgow team led by Ravinder Dahiya reports the development of an ultra-thin pressure sensor that they incorporated into a set of goggles to monitor and respond to simple facial movement.
“Our device shows promise for restoring self-sufficiency,” Dahiya said. “We incorporated a pair of identical micron-sized pressure sensors into a pair of goggles. When worn, the sensors come into contact with the temporal muscles on the side of the head that lift the lower jaw.
The sensors can be connected wirelessly to different devices, such as a kitchen appliance, an electronic door or even a wheelchair, allowing their control thanks to the flexion and relaxation of this facial muscle obtained by opening and closing the jaw.
The sensor is a pressure-sensing field-effect transistor based on crumpled graphene flakes made from a modified graphene oxide-chitosan composite material. “Chitosan is usually derived from natural sources, such as shrimp shell waste, which makes the sensors non-biocompatible and ‘skin-safe’, but also biodegradable,” said Ambarish Paul, another of the authors of the study.
In lab tests, when the sensors were thrown into the ground, they were broken down by microorganisms or bio-assimilated by fungi in just six months.
The “crumpled” nature of the graphene flakes is what gives the sensor its sensitivity to subtle facial movements. The crumpled structure led to a sufficient band gap in the material, which allows the device to have separate electronic “ON” and “OFF” states with a low threshold between them.
“The sensors are prepared with ultra-thin chitosan composites, which can adapt to a curvy surface,” Dahiya explained. “The sensors are prepared with cost-effective materials and processes with a minimum of electronic components and circuits so that the control unit can be integrated on a pair of glasses.”
Dahiya’s team demonstrated hands-free control of a robotic toy vehicle, where the device allowed the user to move the car forward, right, left and stop simply by asking the user to move their temporal muscles against the handles of the glasses.
The implications for this will be significant. The team says they also plan to explore more complex scenarios where more than two sensors can be applied. But before this is possible and commercialization can be achieved, more research and testing is needed, according to Dahiya.
“At this point, we need an easy method for uniform crumpling over a large area,” he explained. “This will allow good control of the bandgap level [and the sensor’s sensitivity]. With demonstrated proof of concept, [these sensors] could possibly be made available within 2-3 years with dedicated efforts.
Reference: Ambarish Paul, et al., Pressure Sensitive Ultra-Flexible Biodegradable Field-Effect Transistors for Hands-Free Robot Motion Control, Advanced Intelligent Systems (2022). DOI: 10.1002/aisy.202200183
Featured Image: Kimson Doan on Unsplash
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