Brain-machine interfaces (BMIs) have taken a breakthrough thanks to the creation of a graphene sensor that allows precise control of a robot just by thinking about it. The use of this technology not only has positive implications in the field of health, but can also have applications in other industries.

ICMs allow a person to operate a device using brain waves. As hands-free and voiceless interfaces, ICMs have great potential for use in robotics, bionic prosthetics, and driverless cars.

An ICM is made up of three modules: an external sensory stimulus, a sensing interface, and a unit that processes neural signals. Of the three, the sensing interface is crucial because it senses electrical activity generated by the brain’s outer layer, the cerebral cortex, which is responsible for higher-level processes, including motor function.

But it is the visual cortex, the part of the cerebral cortex that receives and processes information sent from the eyes, that is critical for ICMs that rely on visual stimuli. The visual cortex is located at the back of the brain, in the occipital lobe.

Problems in the detection of brain waves

Implantable or wearable sensors, such as electroencephalography (EEG) electrodes, are used to record brain waves. The problem with using EEG electrodes and other non-invasive biosensors on the back of the head is that it is typically a hair-covered area.

Wet sensors rely on the use of conductive gel on the scalp and hair, but this can cause the sensors to move when the person moves. Dry sensors can be an alternative, but they also have challenges; they are less conductive than wet sensors and, due to the rounded shape of the head, may have difficulty in maintaining proper contact.

The solution: graphene sensors

Researchers at the University of Technology Sydney have addressed these issues by developing a dry biosensor containing graphene. Graphene is an atom-thick layer of carbon arranged in a hexagonal lattice that is 1,000 times thinner than a human hair and 200 times stronger than steel.

Graphene is an optimal material to create dry biosensors due to its thinness and high electrical conductivity. On the other hand, it is resistant to corrosion and the effects of sweat, which makes it perfect for use on the head. We have talked about the advantages of graphene on dozens of occasions in the corresponding category.

The point is that the researchers found that combining graphene with silicon produced a more resistant dry sensor. The graphene layer in the sensors they developed is less than a nanometer thick.

Results and applications

The researchers experimented with different sensor patterns, including squares, hexagons, pillars, and dots, and found that the hexagonal-patterned sensors had the lowest impedance on the skin. They then tested their new sensor with an ICM.

Hexagonal-patterned sensors are placed on the scalp at the back of the head to detect brain waves from the visual cortex, and the user wears an augmented reality lens that displays white squares. By concentrating on a particular square, brain waves are created that are picked up by the biosensor. A decoder translates the signal into a command.

Australian Army soldiers conducted a real test of the graphene-sensor BMI, using a four-legged robotic dog. The device allowed the robot to be controlled hands-free, with up to 94% accuracy..

“Hands-free and voiceless technology works outside of laboratories, anytime, anywhere,” said Francesca Iacopi, corresponding author of the study. “It makes interfaces like consoles, keyboards, touch screens, and hand gesture recognition redundant.”

However, the researchers do not consider this to be the final version of their design. More research and testing is needed to find a balance between the total area of ​​graphene available, the ability to accommodate the presence of hair, and the ability to maintain sensor contact with the scalp.

future applications

This technological advance can be of great benefit for people with disabilities when operating a wheelchair or prosthesisas well as having broader applications in the fields of advanced manufacturing, defense, and aerospace.

It is important to note that this technology raises ethical issues, such as the privacy and security of data collected from users’ brain waves. Proper regulation and an ethical approach are needed to ensure that this technology is used responsibly and does not cause harm.

It certainly has the potential to improve the quality of life for people with disabilities and have broader applications in various fields, let’s hope it’s not just used in the military.

Learn more at uts.edu.au