Wearable lithium sensor could help people with bipolar disorder track medication levels through sweat: Study

The research appears in the journal Device, a new flagship publication from Cell Press, highlighting cutting-edge innovations in electrical engineering, materials science and bioengineering.

As easy as a fitness tracker

Khan’s team identified sweat as an ideal alternative to blood samples because sweat can be collected noninvasively and reflects lithium concentrations in real time. To simplify the process even further, the wearable includes a skin-safe, iontophoresis-based system to induce sweat without requiring physical exertion. In just minutes, the device collects data, which is transmitted directly to a smartphone app, allowing patients to track their lithium levels from the comfort of their own homes.

Behind this is a powerful innovation: the use of organic electrochemical transistors (OECTs) specifically designed for lithium detection. OECTs are electronic devices that respond to ionic signals in liquid, converting them into readable electronic data. Unlike conventional OECTs, which rely on complex fabrication steps and are not optimized for lithium, the sensor developed at USC features a fully printed OECT using a novel material formulation tailored to detect lithium ions specifically.

“We developed the entire lithium monitoring system — from the OECT-based sensor patch and on-demand sweat induction to the readout electronics and smartphone app — using a simple, scalable and cost-effective fabrication process,” said Mohammad Shafiqul Islam, the first author of the study and a doctoral student in the Khan Lab. “Our goal was to make lithium tracking as easy and comfortable for patients as checking a daily fitness tracker.”

This makes it the first OECT-based lithium sensor to be entirely printed — a critical advancement that paves the way for affordable, scalable production.

Patients liked using the tracker

The sensor’s potential extends far beyond the lab. In partnership with psychiatrist Adam Frank at Keck School of Medicine, the device has already been tested by his patients. “This is one of the biggest benefits of being at USC,” Khan said. “We have clinical collaborators right across campus.” During pilot trials, Khan’s team worked directly with Frank and his patients to test the sensors in individuals taking lithium.

Sweat samples were collected using the wearable device, and lithium measurements were successfully matched against values derived from bulky commercial sensors. Participating patients responded positively, expressing relief at the prospect of monitoring their health without repeated hospital visits.

“The ability to noninvasively monitor lithium levels will improve care for patients taking lithium, who typically require regular blood draws to assess lithium levels,” Frank said. “Being able to track these levels continuously over time will improve safety by allowing for medication dose adjustments that avoid side effects and potential medication toxicity.”

Next, the team plans to develop more advanced wearable systems powered by artificial intelligence to automatically adjust lithium dosage and achieve optimal therapeutic benefits without causing lithium toxicity.

Reference:

Mohammad Shafiqul Islam, Wearable organic-electrochemical-transistor-based lithium sensor for precision mental health, Device, DOI: 10.1016/j.device.2025.100862