Electronic face tattoos can tell when your brain is overloaded

By Stephen Beech

Electronic face tattoos can warn when someone's brain is working too hard.

The non-permanent wireless forehead e-tattoos decode brainwaves to measure mental strain, without the need for bulky headgear, say American scientists.

They believe the state-of-the-art technology could be used to track the mental workload of workers, such as air traffic controllers and HGV drivers, whose lapses in focus can prove catastrophic.

Study leader Professor Nanshu Lu, from the University of Texas at Austin, said: "Technology is developing faster than human evolution.

"Our brain capacity cannot keep up and can easily get overloaded.

“There is an optimal mental workload for optimal performance, which differs from person to person.”

She explained that humans perform best in a cognitive "Goldilocks zone" - neither overwhelmed nor bored - and finding that balance is key to optimal performance.

But current mental workload assessment relies on the NASA Task Load Index, a lengthy and subjective survey that participants complete after performing tasks.

But, unlike EEG caps that are bulky with dangling wires and lathered with squishy gel, the wireless e-tattoo consists of a lightweight battery pack and paper-thin, sticker-like sensors.

The sensors feature "wavy" loops and coils, a design that allows them to stretch and conform seamlessly to the skin for comfort and clear signals.

Lu said, “What’s surprising is those caps, while having more sensors for different regions of the brain, never get a perfect signal because everyone’s head shape is different.

“We measure participants’ facial features to manufacture personalised e-tattoos to ensure that the sensors are always in the right location and receiving signals.”

The research team tested the e-tattoo on six participants who completed a memory challenge that increased in difficulty.

As mental load rose, the participants showed higher activity in theta and delta brainwaves, signalling increased cognitive demand, while alpha and beta activity decreased, indicating mental fatigue.

The results, published in the journal Device, suggest that the device can detect when the brain is struggling.

The researchers said the device could also predict mental strain.

The team trained a computer model to estimate mental workload based on signals from the e-tattoo, successfully distinguishing between different levels of mental workload.

The results show that the device can potentially predict mental fatigue, according to the research team.

Traditional EEG equipment can exceed $15,000, while the e-tattoo’s chips and battery pack cost just $200, and disposable sensors are about $20 each.

Study author Professor Luis Sentis said: “Being low cost makes the device accessible.

“One of my wishes is to turn the e-tattoo into a product we can wear at home.”

While the e-tattoo only works on hairless skin, the research team is working to combine it with ink-based sensors that work on hair.

They say that will allow for full head coverage and more comprehensive brain monitoring.

As robots and new technology increasingly enter workplaces and homes, the researchers hope their technology will enhance understanding of human-machine interaction.

Sentis added: “We’ve long monitored workers’ physical health, tracking injuries and muscle strain.

“Now we have the ability to monitor mental strain, which hasn’t been tracked.

"This could fundamentally change how organisations ensure the overall well-being of their workforce.”