Artist’s depiction of the biodegradable pressure sensor wrapped around a blood vessel with the antenna off to the side (layers separated to show details of the antenna’s structure).
Image: Levent Beker

A sensor, developed by Stanford University researchers, monitors vascular surgery outcomes by tracking blood flow through the artery. The compact, wireless, battery-free, biodegradable sensor could allow doctors to track a healing vessel from afar, enabling earlier interventions since the first sign of trouble often comes too late, resulting in additional surgery.

“Measurement of blood flow is critical in many medical specialties, so a wireless biodegradable sensor could impact multiple fields including vascular, transplant, reconstructive, and cardiac surgery,” says Paige Fox, assistant professor of surgery and co-senior author of a paper on the sensor.

Wrapped snugly around the healing vessel, blood pulsing past the sensor pushes on its inner surface, changing its shape. Shape changes alter the sensor’s capacity to store electric charge, which doctors can detect from a device located outside the body, near the skin, that pings the sensor’s antenna for a reading. In the future, the device could be a wearable patch or be integrated into other technology, such as a smartphone.

Researchers tested the sensor by pumping air through an artery-sized tube to mimic pulsing blood flow. Surgeon Yukitoshi Kaizawa, a former postdoctoral scholar at Stanford and co-author of the paper, also implanted the sensor around a rat’s artery. The sensor successfully reported blood flow to the wireless reader.

The sensor is a wireless version of technology that chemical engineer Zhenan Bao has been developing to give prostheses a delicate sense of touch. (See TMD’s previous coverage of some of Bao’s research at: https://tinyurl.com/ybgynra9 and https://tinyurl.com/ydezrsl8).

Researchers modified the sensor’s material to be sensitive to pulsing blood and rigid enough to hold its shape. They moved the antenna to a location where it would not be affected by pulsation and re-designed the capacitor so it could be placed around an artery.

Making connections

The idea of an artery sensor began when former postdoctoral fellow Clementine Boutry of the Bao lab reached out to Anaïs Legrand, who was a postdoctoral fellow in the Fox lab. Boutry connected those groups, along with the lab of James Chang, the Johnson and Johnson Professor of Surgery.

The collaboration won a 2017 Postdocs at the Interface seed grant from Stanford ChEM-H, which supports postdoctoral research collaborations exploring transformative ideas.

The researchers are now finding the best way to affix the sensors to the vessels and refining their sensitivity.

Stanford University
https://www.stanford.edu

Additional Stanford co-authors include Clementine Boutry (co-lead), Christopher Vassos, Helen Tran, Allison C. Hinckley, Raphael Pfattner, Simiao Niu, Junheng Li, Jean Claverie, Zhen Wang and Yukitoshi Kaizawa. This work was funded by the Swiss National Science Foundation, the European Commission, Stanford ChEM-H, and the National Science Foundation.