Artery sensor measures blood flow

In searching for a topic for this week’s blog post, I came across an article that reminded me of the March, 2018 Ask the Experts column, Calculating Medical Flow Measurement, in which Béla Lipták answers a reader who asks if blood flow can be measured to determine whether a stent should be installed inside of a blood vessel.

Although Liptak recommends using optical fiber pressure sensors, Stanford University researchers had a different idea. A Stanford Engineering Magazine article by Taylor Kubota, titled “A new sensor could make it easier to monitor blood flow after surgery,” explains that the researchers developed a sensor to monitor blood flow within a healing blood vessel.

The researchers published a paper detailing the innovation in Nature and Biomedical Engineering, Jan. 8. The paper is titled, “Biodegradable and flexible arterial-pulse sensor for the wireless monitoring of blood flow.”

The sensor wraps around a blood vessel so that as blood pumps through the vessel, the vessel pushes on the inner surface of the sensor. When the shape of the surface changes, the sensor’s capacity to store an electric charge is altered, which can be remotely detected by a doctor with a wireless device located near, but outside, the body, the article explains.

The researchers used the technology in development by Zhenan Bao, K. K. Lee Professor in the School of Engineering and co-author of the paper, which was designed to give prostheses a delicate sense of touch. They modified the existing sensor’s antenna, redesigned the capacitor, and adjusted its materials to make it both rigid and sensitive.

“This one has history,” Bao said in the article. “We were always interested in how we can utilize these kinds of sensors in medical applications, but it took a while to find the right fit.”

In order to test their innovation, the researchers used air pumped through an artery-sized tube to mimic blood flow in a blood vessel. Then, taking their research further, Surgeon Yukitoshi Kaizawa, a former post-doctoral scholar at Stanford and co-author of the paper, tested the device in a rat, the article explains.

The tests found that the sensors detected and reported blood flow to the wireless reader, successfully monitoring for complete blockages. The researchers reported indications that the sensors could evolve to detect more subtle fluctuations in blood flow.

Continuing their research with the device, the team is now searching for the best method of attaching sensors to vessels while also making them more sensitive to flow changes, the article reports.

“Using sensors to allow a patient to discover problems early on is becoming a trend for precision health,” Bao said in the article. “It will require people from engineering, from media school and data people to really work together, and the problems they can address are very exciting.”