Listen to this beat (Image: Adrian Neal/Getty) What are you thinking? (Image: USCD Jacobs)

MIND reading can be as simple as slapping a sticker on your forehead. An “electronic tattoo” containing flexible electronic circuits can now record some complex brain activity as accurately as an EEG. The tattoo could also provide a cheap way to monitor a developing fetus.


The first electronic tattoo appeared in 2011, when Todd Coleman at the University of California, San Diego, Ricardo Gil da Costa at the Salk Institute in La Jolla, California, and colleagues designed a transparent patch containing electronic circuits as thin as a human hair. Applied to skin like a temporary tattoo, these could be used to monitor electrophysiological signals associated with the heart and muscles, as well as rudimentary brain activity.

To improve its usefulness, Coleman’s group has now optimised the placement of the electrodes to pick up more complex brainwaves. They have demonstrated this by monitoring so-called P300 signals in the forebrain. These appear when you pay attention to a stimulus. The team showed volunteers a series of images and asked them to keep track of how many times a certain object appeared. Whenever volunteers noticed the object, the tattoo registered a blip in the P300 signal.

The tattoo was as good as conventional EEG at telling whether a person was looking at the target image or another stimulus, the team told a recent Cognitive Neuroscience Society meeting in San Francisco.

The team is now modifying the tattoo to transmit data wirelessly to a smartphone, Coleman says. Eventually, he hopes the device could identify other complex patterns of brain activity, such as those that might be used to control a prosthetic limb.

For now, the group is focusing on optimising the tattoo for use in conditions such as depression and Alzheimer’s disease, each of which have characteristic patterns of neural activity. People with depression could wear the tattoo for an extended period, allowing it to help gauge whether medication is working. “The number one advantage is the medical ease of application,” says Michael Pitts of Reed College in Portland, Oregon.

Because its electronic components are already mass-produced, the tattoo can also be made very cheaply.

That means it might also lend itself to pregnancy monitoring in developing countries. With help from the Bill & Melinda Gates Foundation, Coleman’s group is working on an unobtrusive version of the tattoo that monitors signals such as maternal contractions and fetal heart rate.

This article appeared in print under the headline “‘Tattoo’ reads your brain and bump”