What if a pair of sticker-like sensors could transform your earbuds into a powerful health monitor capable of flagging brain or mood disorders, and treating them with sounds or electrical pulses in real time?

Engineers at the University of California, San Diego, are developing flexible sensors, small enough to fit on earbuds, that can record electrical brain activity and lactate levels in sweat. Someday, the sensors could monitor and treat conditions in the here and now, playing sounds or using electrical stimulation to influence brain activity, an emerging type of therapy known as electroceuticals.

“We can hijack the auditory signal to drive brain states towards more desirable outcomes,” said Gert Cauwenberghs, PhD, a head engineer involved in developing the sensors and a professor of bioengineering at UCSD Jacobs School of Engineering. “Those things are possible now that we can close the loop between producing sounds and measuring brain activity.”

In a study published in NatureBiomedical Engineering, the sensors proved just as effective as traditional monitoring methods like electroencephalogram (EEG) headsets for brain activity and blood samples for lactate levels. But unlike those methods, the sensors could be worn continuously outside the clinic as patients go about their lives. The sensors are “spring-loaded” to maintain tight contact with the ear and covered with a hydrogel film to absorb sweat. They can send data to the earbuds, which then transmit it to a smartphone or laptop via Bluetooth.

Using in-ear devices to track health is not new. But this is the first to combine brain and body sensors, opening the door for all kinds of research and clinical advances.  The researchers say this technology could be used to help diagnose and treat a long list of conditions, from brain-related diseases like Parkinson’s, Alzheimer’s, and epilepsy to mood conditions like posttraumatic stress disorder, anxiety, and depression. It could also detect and treat strokes, tinnitus, sleep apnea, and traumatic brain injuries.

Plenty of research has explored wearables for remote patient monitoring, but in-ear wearables could be especially useful for conditions that impact the brain. Patients being tested for epilepsy, for example, could be monitored remotely, even wearing the sensors at night to catch seizures that may have gone undetected, said Erik Viirre, MD, PhD, a professor of neurosciences at UCSD who was not involved in the research.