A few tears may someday reveal important clues about a person’s neurological health. Researchers reporting in ACS Omega have developed a low-cost electrochemical sensor designed to detect dopamine, a neurotransmitter involved in movement, learning, motivation, and emotional regulation — and tested it successfully using artificial human tears.
By creating the sensor, the researchers aim to “facilitate the ultra-early detection of neurological disorders, creating opportunities for clinical” intervention before symptoms emerge, according to corresponding author Neftalí Lênin Villarreal Carreño.
Why Tears?
Changes in dopamine levels are associated with a range of neurological and psychiatric conditions; in Parkinson’s disease, for instance, dopamine concentrations tend to decrease. Current monitoring methods — blood samples, urine analysis, or implanted devices — are time-consuming or invasive. Tears, by contrast, can be collected quickly and painlessly, making them an appealing alternative source of health information.
To build the sensor, the researchers used a laser to convert portions of a thin plastic film into electrically conductive graphene. The resulting device, about the size of a postage stamp, produces an electrical signal when dopamine reacts with the graphene. In lab tests, the team added dopamine to artificial human tears and measured the sensor’s performance — it accurately detected dopamine levels, including concentrations similar to those previously reported in tears from people with Parkinson’s disease, and it maintained its accuracy even in the presence of other compounds commonly found in tears.
“Our sensor can detect dopamine from levels well below the healthy baseline and up to three times higher. This capability ensures that a person’s initial dopamine drop can be identified early on, which is crucial to enabling timely, proactive therapeutic interventions.”
Lucas Minghini Gonçalves, co-author
The researchers say their findings lay the groundwork for future studies using real human tear samples, and will help them develop point-of-care devices capable of monitoring neurological biomarkers through a simple tear sample.
The research was funded by Brazil’s Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, the Rio Grande do Sul Research Foundation, the National Council for Scientific and Technological Development, and the AgroHealth project through the Center for Embedded Devices and Research in Digital Agriculture.
The study was published June 8, 2026, in ACS Omega (DOI: 10.1021/acsomega.6c03287).