November 03, 2025
The breakthrough invention could help introduce viscosity as a new vital sign of human health.
For years, doctors have relied on familiar vital signs — heart rate, blood pressure, temperature and oxygen levels — to monitor someone’s health. But researchers at the University of Missouri believe one key metric has been overlooked: blood viscosity, or how thick or sticky blood is as it flows through the body. And they’ve developed a breakthrough technology to monitor it non-invasively and in real time.
Viscosity plays a hidden but crucial role in health. It’s linked to six of the top 10 leading causes of death in the United States, including heart disease, cancer and stroke.
Thick, sluggish blood forces the heart to work harder and can raise the risk of clots or tissue damage, Nilesh Salvi, a research scientist in Mizzou’s College of Agriculture, Food and Natural Resources and lead author on the project, said.
“Blood pressure tells us what’s happening to the vessel walls,” he said. “But it doesn’t tell us about the blood itself. Viscosity could be that missing piece.”
The first-of-its-kind device uses ultrasound waves to measure blood viscosity in real time — but the true innovation lies in its software. The system works by gently vibrating blood with a continuous sound wave — meaning it sends a steady sound wave through the blood while simultaneously sensing its response. Then, a powerful algorithm analyzes how the sound moves through the body.
At its core, the invention is driven by advanced math and signal processing. This approach improves accuracy and, for the first time, enables the simultaneous measurement of both blood density and viscosity using the same signal.
From motor engines to human health
This innovative tool wasn’t originally designed for medicine.
Salvi, who earned his master’s degree and PhD at Mizzou Engineering, initially designed the system to monitor oil quality in engines. Building on that invention, he founded a startup company developing engine sensors to monitor lubricants in real time.
With guidance from his mentor, Jinglu Tan, a professor of chemical and biomedical engineering, Salvi began exploring how the same sensing principles could be used to study biological fluids. Tan’s expertise helped him refine and strengthen the science behind this new direction.
Seeing the medical potential, William Fay, a professor of medical pharmacology and physiology in Mizzou’s School of Medicine, was one of the first people to encourage Salvi to explore the technology’s clinical uses. His guidance helped Salvi and his team link their engineering work to biomedical research.
“Measuring blood viscosity has always been a challenge,” Fay said. “Specialized lab equipment is needed, and most hospitals don’t have it. This new device could be a game changer — it allows accurate, real-time viscosity readings without ever drawing blood.”
Traditionally, blood viscosity is determined by taking blood samples — a process that can alter the blood’s natural properties. By contrast, the Mizzou device measures viscosity inside the body, thus capturing its true behavior.
“Blood is a living organ,” Tan, who also serves as director of strategic initiatives at the College of Agriculture, Food and Natural Resources, said. “You can’t take it out and expect it to behave the same way. Measuring it in the body — in situ — is what makes our approach so powerful.”
The work could revolutionize how doctors manage diseases such as sickle cell anemia, where irregularly shaped blood cells increase viscosity and threaten organ health. Continuous monitoring could help tailor transfusions or medications to each patient’s real-time needs, instead of relying on scheduled intervals.
A new look inside the body
Researchers are continuing their studies in hopes of preparing for human trials. Salvi’s long-term goal is to make blood viscosity a standard vital sign — alongside heart rate and oxygen levels.
Since the invention is mostly software-based, it can operate on inexpensive hardware, Salvi said. A prototype could also be built with readily available parts, opening the door to affordable, portable devices — and possibly future wearable health technology.
“This isn’t just a new device,” he said. “It’s a new way of thinking about the human body. Once we can see viscosity in real time, we’ll understand blood flow and disease progression in ways we never could before.”
The study, “A model-based method for in situ viscosity measurement with continuous-wave ultrasound,” is published in the Journal of Dynamic Systems, Measurement, and Control.