A new flexible and biocompatible electronic device can produce a more detailed picture of the electrical activity of a beating heart. This high-resolution electrical map could help improve the diagnosis and treatment of heart abnormalities by pinpointing areas of damage or misfiring circuitry.

Today, the best way to map the electrical activity of a person’s heart is to insert a probe tipped with a few electrical sensors through a vein and into the heart. The probe is used to measure activity at different locations in the tissue to slowly build up a picture of electrical activity. An electrocardiogram, which picks up signals from outside the body, offers a less precise picture.

“It can take hours to map where these heart rhythms are coming from,” says Brian Litt, a neurologist and biomedical engineer at the University of Pennsylvania, and one of the senior researchers on the project. “If you map at a very high resolution, it may be possible that you can pick up, in local areas, precursors to arrhythmias before they occur.”

The flexible device can be used to attach multiple sensors to the wall of a beating heart, measuring electrical activity at multiple sites despite the heart’s movement. The electronics needed to record this activity are also built into the device, meaning more data can be collected. The new device is 25 microns thick and covers 1.5 square centimeters. It contains over 2,000 transistors sealed within a flexible coating and is covered with 288 sensor electrodes. So far the device has been tested successfully in pigs.

It is the first time that flexible electronics have been used in such high density in a medical device, says John Rogers, an engineer at the University of Illinois, Urbana-Champaign, who collaborated on the work. “These devices contain more transistors than any previously reported flexible device,” he says.

The flexible device could be used in other kinds of biological sensors, says Litt, including devices for monitoring neurological conditions such a Parkinson’s and epilepsy. The work, which also involved researchers from Northwestern University, is published in the journal Science Translational Medicine.