A team of engineers and cardiology experts at Johns Hopkins School of Medicine and Children’s Center have teamed up to develop a fingernail-sized biosensor that could alert doctors when serious brain injury occurs during heart surgery. By doing so, the device could help doctors devise new ways to minimize brain damage or begin treatment more quickly.

In lab tests, this small biosensor successfully detected a protein associated with brain injuries. They say that the testing would happen while surgery is going on, using a drop of the patient's blood on the sensor, which could activate a sound, light, or numeric display if the protein is present.

The project centers around children undergoing surgery, because their brains are still developing. Recent studies found that after heart surgery, about 40 percent of infant patients will have brain abnormalities that show up in MRI scans. The damage is most often caused by strokes, which can be triggered and made worse by multiple events during surgery and recovery, when the brain is most susceptible to injury. These brain injuries can lead to deficiencies in the child's mental development and motor skills, as well as hyperactivity and speech delay.

To create a biosensor that responds to glial fibrillary acidic protein, a biomarker linked to brain injuries, they turned to an organic thin film transistor design. These transistors are attractive due to their low cost, low power consumption, biocompatibility, and ability to detect a variety of biomolecules in real time.

The sensing area is a small square, 3/8ths-of-an-inch on each side. On the surface of the sensor is a layer of antibodies that attract GFAP, the target protein. When this occurs, it changes the physics of other material layers within the sensor, altering the amount of electrical current that is passing through the device. These electrical changes can be monitored, enabling the user to know when GFAP is present.

The team is looking for industry collaborators to conduct further research and development of the device, which has not yet been tested on human patients. But with the right level of effort and support, they believe the device could be put into clinical use within five years.