A low-cost electrochemical sensor that measures dopamine in tears has shown promising performance in laboratory testing, offering a potential route toward noninvasive monitoring of neurological biomarkers that currently require more invasive sampling methods.
Researchers developed the experimental sensor using laser-induced graphene modified with nickel nitrate and urea, creating a porous surface designed to improve the detection of dopamine. Abnormal levels of dopamine have been linked to conditions including Parkinson’s disease, schizophrenia, Alzheimer's disease, and depression.
Current approaches to measuring dopamine typically rely on blood, urine, or implanted devices. The new study, published in ACS Publications, instead focuses on tear fluid, which offers a readily accessible sample that could eventually support repeated monitoring with minimal discomfort for patients.
The laser fabrication process produced a graphene structure with a large active surface area that was further enhanced by the addition of nickel and nitrogen-containing groups. According to the authors, these modifications improved electron transfer and increased the number of sites where dopamine could be detected, resulting in stronger and more selective sensor responses than unmodified graphene electrodes.
The study highlights continuing advances in electrochemical biosensors aimed at point-of-care testing rather than conventional laboratory assays. The disposable sensor demonstrated repeatable and reproducible performance in bench testing and maintained stable function for at least one week after fabrication, suggesting potential compatibility with practical diagnostic workflows if future studies confirm its clinical utility.
Importantly, the device was evaluated not only in buffered laboratory solutions, but also in synthetic tear fluid and recovery experiments designed to mimic real-world testing conditions. The sensor maintained a reliable response across clinically relevant dopamine concentrations in synthetic tears and achieved recovery values close to 100 percent, indicating that common tear components did not substantially interfere with measurement under the conditions tested.
The work remains an early-stage proof of concept. The sensor has not yet been validated in patient samples, and additional studies will be needed to determine whether tear dopamine measurements correlate reliably with neurological disease status or treatment response. Nevertheless, the findings suggest that inexpensive, laser-manufactured graphene sensors could contribute to future noninvasive diagnostic strategies by enabling biomarker monitoring from easily collected tear samples rather than invasive specimens.
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