A personalized electronic facial tattoo that wirelessly monitors the brain can tell when the organ is being overworked and can use the data it collects to predict mental overload, according to a new study. The tech could help us maintain the productivity sweet spot.
Air traffic controllers, pilots, healthcare workers, truck drivers, police and first responders, and military personnel. These are just some of the high-pressure jobs that require a person to concentrate fully at all times, or risk catastrophic, potentially fatal consequences.
Researchers led by the University of Texas at Austin (UT Austin) may have made performing these jobs a whole lot easier, thanks to their new technology. Their temporary electronic face tattoo, or e-tattoo, can read brain waves and not only detect when the ol' gray matter is overworked, but also predict when exhaustion is approaching.
“Technology is developing faster than human evolution,” said co-corresponding author of the study, Professor Nanshu Lu, PhD, the current Carol Cockrell Curran Chair in Engineering at UT Austin. “There is an optimal mental workload for optimal performance, which differs from person to person.”
The trick, according to the researchers, is to find that cognitive Goldilocks zone, the sweet spot between overwhelmed and bored. So, they set about developing a wireless way of measuring and analyzing the brain’s electrical activity without an electroencephalography (EEG) device, which requires dozens of bulky, wired electrodes usually attached to a cap.
“What’s surprising is that those caps, while having more sensors for different regions of the brain, never get a perfect signal because everyone’s head shape is different,” Lu said. “We measure participants’ facial features to manufacture personalized e-tattoos to ensure that the sensors are always in the right location and receiving signals.”
The researchers’ disposable wireless e-tattoo electrode spans the width of the forehead and extends down to the cheekbone on each side of the face. A ground e-tattoo is attached behind one ear. The device records four channels of EEG on the forehead and two channels of electrooculography (EOG), which measures eye movements, across the eyes.
They tested their e-tattoo on six participants while they undertook a dual N-back task, a cognitive training exercise used to measure working memory and fluid intelligence. During the N-back task, streams of auditory and visual stimuli are presented simultaneously, and participants are asked to keep track of both and indicate when the current stimulus (either auditory or visual) matches the one that was presented N steps earlier in the sequence. The more steps back in the sequence the participants need to remember (e.g. 3-back, 4-back), the more difficult the task.
The researchers analyzed the signals collected from each subject, which included delta, theta, alpha, beta, and gamma EEG band powers. “EEG band powers” refers to the strength or intensity of brain wave activity in those frequency ranges. They found that as mental workload (N) increased, participants’ delta- and theta-band powers increased, signaling an increased cognitive load, while alpha-, beta-, and gamma-band powers decreased, indicating mental fatigue.
Theta waves (4 – 8 Hz). Theta waves are linked to light sleep, drowsiness, and deep relaxation. They also appear during meditative states and are often associated with creativity, intuition, and emotional processing.
Alpha waves (8 – 12 Hz). Alpha waves are associated with calm, relaxed but alert states. They’re often observed during meditation, daydreaming, or when you’re closing your eyes but still aware of your surroundings.
Beta waves (12 – 30 Hz). Linked to active thinking, focus, and problem-solving, beta waves are dominant when you’re awake and concentrating on a task, making decisions, or engaging in active mental work.
Gamma waves (30 – 100 Hz). The fastest brain waves, gamma waves, are associated with higher-level cognitive functions, such as learning, memory, and information processing.
Not only did the e-tattoo detect when the brain was overworked, but it could also predict when it might happen. Using a machine learning model, the researchers demonstrated that the EEG and EOG data collected by the device provided sufficient information to estimate the mental workload that a dual N-back task would produce in each study participant.
Despite its capabilities, the disposable facial e-tattoo is remarkably affordable. Depending on how fancy you want to go, a traditional EEG machine can set you back between US$20,000 and $150,000. Whereas the researchers estimate that each disposable tattoo would cost less than $20, with a cost of $200 for the computer chips and battery pack.
“Being low cost makes the device accessible,” said the study’s other corresponding author, Luis Sentis, PhD, a professor in UT Austin’s Department of Aerospace Engineering and Engineering Mechanics. “One of my wishes is to turn the e-tattoo into a product we can wear at home.”
The researchers are currently working on ways to make the e-tattoo work on parts of the body that have hair. Being able to place the device on someone’s head would allow for more comprehensive brain monitoring. They see huge potential in their device.
“We’ve long monitored workers’ physical health, tracking injuries and muscle strain,” Sentis said. “Now, we have the ability to monitor mental strain, which hasn’t been tracked. This could fundamentally change how organizations ensure the overall well-being of their workforce.”
The study was published in the journal Device.
Source: UT Austin
