A centimeter-square wearable patch could one day monitor a patient's medication levels and deliver drugs automatically, and the UC San Diego engineering lab behind it is now testing the technology on real patients.

The microneedle sensor patch, developed over 15 years by Joseph Wang's lab in the Jacobs School of Engineering, is in preliminary clinical trials at UC San Diego for real-time sensing of interstitial fluid, the body's fluid layer sitting less than one millimeter beneath the skin, according to a UC San Diego Health Sciences article published Aug. 18.

"We are developing a lab just under the skin," Wang said in the university's Discoveries magazine.

Wang holds the SAIC Endowed Chair in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering and co-directs the Center for Wearable Sensors.

Each microneedle on the patch functions as its own sensor, coated with enzymes that bind to a specific biomarker or medication and generate an electrical signal proportional to its concentration. Because the needles access fluid shallower than pain nerves, the patch causes no pin-prick sensation. Patients feel only slight pressure.

That contrasts sharply with today's continuous glucose monitors, which use a guide needle penetrating 5 to 6 millimeters into fatty tissue and measure only one substance. Wang's patch can track multiple biomarkers simultaneously.

Parkinson's trial underway

Neurologist Irene Litvan, the Tasch Endowed Professor of Neurology and director of the Parkinson and Other Movement Disorders Center at UC San Diego School of Medicine, is leading a pilot clinical trial evaluating the device's accuracy, tolerability and safety in Parkinson's patients. Katherine Longardner, a neurologist at UC San Diego Health, is collaborating on the study.

The trial targets levodopa, the most effective symptomatic treatment for Parkinson's disease. Dosing is notoriously difficult because patients' responses shift as the disease progresses, causing unpredictable symptom swings. Current adjustments rely on brief clinic visits that may miss those fluctuations, and traditional blood-plasma monitoring is costly and rarely used in practice.

Litvan said continuous, real-time tracking of levodopa could help clinicians fine-tune dosing for individual patients rather than relying on snapshots from occasional office visits.

Sepsis detection in the ICU

A separate UC San Diego study published in 2026 in ACS Sensors found that microneedle-based continuous lactate sensors were highly accurate compared with standard blood tests in intensive care and emergency department patients. Rising lactate signals oxygen deprivation in the blood, an early marker of sepsis or shock.

Atul Malhotra, a professor at the School of Medicine and research chief of Pulmonary, Critical Care, Sleep Medicine and Physiology at UC San Diego Health, is leading that clinical work. He said the lactate microneedle electrode "has the strong potential to allow us to risk stratify patients in real time and to assess their responses to therapy."

Currently, each lactate check requires a separate blood draw, which can cause anemia in hospitalized patients and adds to health care costs.

Wang, who holds 60 patents and has authored more than 1,300 research papers, said his team's long-term vision is a closed-loop system where solid sensing microneedles work alongside hollow microneedles that deliver medication stored in reservoirs outside the body into interstitial fluid, where it enters the bloodstream. No timeline has been announced for that next phase.