Wearable Sensors for Non-Invasive Way to Track Parkinson’s Drug Levels

But getting the dose right is not always simple. Response to treatment can vary from patient to patient and often changes as the disease progresses, leading to motor fluctuations. Long-term use and higher cumulative doses can also contribute to complications such as dyskinesia.

In clinical practice, treatment response is usually assessed using rating scales and patient reports. Those approaches are useful, but they can miss short-term changes and do not always capture how symptoms shift through the day.

Blood or plasma L-DOPA measurement remains the standard for pharmacokinetic monitoring, but it is invasive and requires costly equipment and complex sample preparation, making frequent testing difficult.

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Sweat sensing is a non-invasive alternative that could allow repeated sampling in more practical settings. Earlier studies suggested that sweat L-DOPA measurements may correlate with blood levels, although direct paired validation in the same patients is still needed.

Rather than trying to prove sweat can replace blood testing, the researchers demonstrated that a wearable sweat sensor could perform reliably in a clinical setting and produce useful data alongside symptom measurements.

Conducting the L-DOPA Sensing Study

The team developed wearable electrochemical sweat sensors for L-DOPA detection and tested them in 32 patients with Parkinson’s disease at Taichung Veterans General Hospital in Taiwan.

The study combined sweat sensing with tremor assessment using inertial measurement units, physiological monitoring through a smartwatch, physician evaluation, 10 clinical movement metrics, and standard MDS-UPDRS scoring.

Patients were taking standard oral L-DOPA formulations, including Madopar and Sinemet.

The sensor used a three-electrode Metrohm 220AT gold system chosen for robustness and inter-sensor uniformity. Gold dendrites were grown on the working electrode to increase surface area. Thione acetate salts were then deposited by cyclic voltammetry, followed by tyrosinase, glutaraldehyde, bovine serum albumin, and Nafion. Scanning electron microscopy confirmed the dendritic structure.

Before the clinical testing, the researchers also assessed the sensor’s analytical performance in buffer and human sweat, including linearity, reproducibility, temperature effects, and selectivity against common interferents such as uric acid, ascorbic acid, and glucose.

Clinical Testing

Patients stopped taking L-DOPA for 12 hours before testing to allow for drug washout, in line with the drug’s roughly 30-minute to 2-hour half-life. The full session lasted about two hours and included four rounds of measurements.

In each round, hand tremor was measured using IMUs during resting and postural tasks, followed by a circle-drawing task. Sweat sensors were attached to the upper back, and participants also wore a Garmin smartwatch during physiological monitoring. Clinical motor assessments and a gait task were then carried out.

To help collect enough sweat, the protocol also included hand cycling, stationary biking, and the use of a heating pad. After the first round, patients took their usual L-DOPA dose. Follow-up measurements were collected at 30, 60, and 90 minutes.

Results of the Study

Among the 24 patients who produced sufficient usable sweat data, 19 (79 %) showed moderate to strong negative Spearman correlations (−1.0 < ρ < −0.4) between sweat L-DOPA profiles and hand tremor intensity.

In other words, higher sweat L-DOPA levels were often associated with lower tremor intensity. That suggests the sensor may be capturing not just drug presence, but a clinically relevant relationship between drug exposure and symptom change.

The findings support the potential of wearable sweat sensors as non-invasive tools for monitoring L-DOPA exposure and possibly informing future treatment adjustment. But the study does not show that the technology is ready for routine clinical dose management.

The main correlation analysis was limited to patients with usable sweat data, not the full enrolled group. The authors point to possible timing mismatches between sweat L-DOPA levels and symptom relief, the effects of co-administered drugs such as carbidopa, the difficulty some older patients had completing the tasks, and the practical issue of insufficient sweat production.

Just as importantly, the study did not directly compare sweat and blood or plasma L-DOPA measurements in the same patients. That kind of validation will still be needed before sweat sensing can be treated as a reliable substitute for standard pharmacokinetic monitoring.

Even with those limitations, the study offers a strong early case for wearable biochemical monitoring in Parkinson’s disease. It suggests that drug exposure, movement data, and clinical assessment could eventually be integrated in a more continuous and objective manner.

Journal Reference

Guo, YJ. et al. (2026) Wearable sensors for monitoring drug pharmacokinetics in patients with Parkinson’s disease. Scientific Reports. DOI: 10.1038/s41598-026-43825-w

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