Tiny Printed Sensors Could Transform Healthcare Through Sweat

Scientists at Caltech have developed a breakthrough technology that could revolutionize healthcare monitoring: printable nanoparticle sensors that can continuously track everything from vitamins to cancer drugs through a person’s sweat. The innovation brings us one step closer to truly personalized medicine, where treatments can be precisely tailored to each patient’s needs.

“These are just two examples of what is possible,” says Wei Gao, a professor of medical engineering at Caltech and corresponding author of the study published in Nature Materials. “There are many chronic conditions and their biomarkers that these sensors now give us the possibility to monitor continuously and noninvasively.”

The technology has already proven effective in monitoring metabolites in patients with long COVID and tracking chemotherapy drug levels in cancer patients at City of Hope in Duarte, California. The key innovation lies in special nanoparticles that can be printed like ink to mass-produce flexible, wearable sensors.

The researchers describe the nanoparticles as core-shell cubic structures. These tiny cubes are formed in a solution containing the specific molecule they want to track. As the particles form, they create precise molecular “holes” that can later capture and measure those same molecules in a person’s sweat.

“This core is critical. The nickel hexacyanoferrate core is highly stable, even in biological fluids, making these sensors ideal for long-term measurement,” explains Gao, who is also a Heritage Medical Research Institute Investigator and a Ronald and JoAnne Willens Scholar.

The versatility of the technology was demonstrated when researchers created sensors to simultaneously measure multiple amino acids, metabolites, hormones, and drugs in sweat by simply using different nanoparticle “inks” in a single array. The sensors can also be implanted just below the skin for even more precise monitoring.

“Demonstrating the potential of this technology, we were able to remotely monitor the amount of cancer drugs in the body at any given time,” says Gao. “This is pointing the way to the goal of dose personalization not only for cancer but for many other conditions as well.”

The research was supported by the National Science Foundation, National Institutes of Health, American Cancer Society, Office of Naval Research, Army Research Office, NASA, Heritage Medical Research Institute, and the Caltech-City of Hope Biomedical Initiative.