A brain aneurysm is a bulge or ballooning in a blood vessel in the brain. The condition can be fatal; it can leak or rupture, causing bleeding into the brain (hemorrhagic stroke). There are treatments available, but even after treatment, a cerebral aneurysm can continue developing and how it heals cannot be predicted.
Monitoring the progress of cerebral aneurysms through imaging technique is costly and has potential negative effects. However, a sensor placed in a blood vessel could allow more frequent evaluations without the use of imaging dyes. Now, researchers at Georgia Tech have developed a sensor that could help clinicians evaluate the healing of aneurysms. The wireless sensor is small enough to be implanted in the blood vessels of the human brain, reports Georgia Tech.
To reduce costs and accelerate manufacturing, fabrication of the stretchable sensors uses aerosol jet 3D printing to create conductive silver traces on elastomeric substrates. The device is believed to be the first demonstration of aerosol jet 3D printing to produce an implantable, stretchable sensing system for wireless monitoring.
“The beauty of our sensor is that it can be seamlessly integrated onto existing medical stents or flow diverters that clinicians are already using to treat aneurysms,” said Woon-Hong Yeo, an assistant professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering and the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “We could use it to measure an incoming blood flow to the aneurysm sac to determine how well the aneurysm is healing, and to alert doctors if blood flow changes.”
The six-layer sensor is fabricated from biocompatible polyimide, two separate layers of a mesh pattern produced from silver nanoparticles, a dielectric and soft polymer-encapsulating material. The sensor would be wrapped around the stent or flow diverter, which must be less than two or three millimeters in diameter to fit into the blood vessels, the report said.
The sensor has a coil to pick up electromagnetic energy transmitted from another coil located outside the body. Blood flowing through the implanted sensor changes its capacitance, which alters the signals passing through the sensor on their way to a third coil located outside the body. In the laboratory, Yeo and his collaborators have measured capacitance changes six centimeters away from a sensor implanted in meat to simulate brain tissue.
“The flow rate is correlated really well with the capacitance change that we can measure,” Yeo said. “We have made the sensor very thin and deformable so it can respond to small changes in blood flow.”
Because the sensor can be fabricated in a single step without costly cleanroom facilities, it could be manufactured in higher volume at lower cost.