Innovation
Recently, researchers at Stanford University developed a new type of sensor that can be used to monitor blood flow through arteries, making it easier for doctors to monitor the success or failure of vascular procedures. The sensor is biodegradable, battery-free, and wireless. It is small and portable and does not need to be removed, alerting the patient's doctor even when there is a blockage in blood flow.
The sensor is described in detail in a paper published January 8 in the journal Nature Biomedical Engineering.
The sensor wraps tightly around a blood vessel that is in the process of healing. In a blood vessel, blood flows through rhythmically, squeezing the inner surface of the vessel. As the shape of the inner surface of the blood vessel changes, so does the capacity of the sensor to store an electrical charge. With a device located outside the body near the skin, the doctor is able to monitor this change remotely. This device is connected to the sensor's antenna for communication and obtains a reading, similar to an ID card scanner. In the future, this device is expected to evolve into a patch form or be integrated into other technologies, such as wearables or smartphones.
First, the researchers created an artificial model by injecting air into a tube like an artery to mimic blood flow. The researchers tested the sensor in this artificial model. Surgeon Yukitoshi Kaizawa, one of the paper's co-authors and a former postdoctoral visiting scholar at Stanford, also implanted the sensor around an artery in a mouse. Despite the scale being so small, the sensor successfully reported blood flow information to a wireless reader. For now, while they are only interested in detecting complete blockages, they also recognize that future versions of the sensor promise to identify more subtle fluctuations in blood flow.
One of the senior authors of the paper, Zhenan Bao, a chemical engineer and professor in the College of Engineering, has been developing a technology that gives prosthetics a subtle sense of touch. This sensor is a wireless version of that technology," says Bao. "This sensor has a history. We're always interested in how these sensors should be utilized in medicine, but it does take time to find the right ones."
The researchers had to modify the existing sensor material to be sensitive to pulsating blood flow but stiff enough to hold its shape. They also had to move the antenna to a safe location, unaffected by pulsation, and redesign the capacitor so that it could be placed around the artery.
Value
"Measuring blood flow is important in many medical specialties," said Paige Fox, Assistant Professor of Surgery and a fellow senior author of the paper***. As a result, wireless, biodegradable sensors will impact multiple fields, including vascular, graft, prosthetic and cardiac surgery. As we try to care for patients throughout the Bay Area, Central Valley, California, and beyond, this technology allows us to expand our care without the need for face-to-face visits or lab tests."
The Future
The researchers are looking for the best way to attach the sensor to blood vessels and increase its sensitivity. They also hope that other new ideas will emerge as interest in this interdisciplinary field grows.
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