Getting under your skin for better health

The next frontier of continuous health monitoring could be skin deep.

Biomedical engineers at the University of Cincinnati say interstitial fluid, the watery fluid between and around cells, tissues and organs in the body, could provide an excellent medium for early disease diagnosis or long-term health monitoring.

A U.S. National Science Foundation-supported paper published in the journal Nature Biomedical Engineering outlines the potential advantages and technological challenges of using interstitial fluid. The reason the researchers see it as a valuable diagnostic fluid is continuous access. With blood, they said, you can't easily take continuous readings.

Researchers are looking for alternatives to monitor a person's health and wellness. Blood is the gold standard for health monitoring. But people also have liters of interstitial fluid that make up as much as 15% of their body weight. Interstitial fluid contains many of the same chemicals in the same proportions as blood, offering a potential alternative to costly and time-consuming lab work.

The study outlined the ways doctors can sample interstitial fluid, from applying suction to the skin to deploying microdialysis. In Jason Heikenfeld's lab at the University of Cincinnati, researchers are developing sensors to measure hormones and other chemicals in interstitial fluid. They use microneedles less than 1 millimeter in length that pierce the skin through a tiny patch.

They said that interstitial fluid holds promise for monitoring health through wearable technology. This could help doctors track the efficacy of drugs to ensure proper dosage or provide early diagnosis of illness by monitoring the immune system. "One day," said Usha Varshney, a program director in NSF's Directorate for Engineering, "continuous monitoring of health will be performed by a wearable skin device that will replace bloodwork with testing of interstitial fluid."