First Biodegradable Bioactive Glass-based Humidity Sensor

Monitoring changes in edema-associated intracranial pressure that complicates trauma or surgery would lead to improved outcomes. Implantable pressure sensors have been explored, but, these sensors require post-surgical removal leading to risks of injury to brain tissue. Biodegradable implantable sensors would eliminate the risks while providing sensing when needed. Here, we demonstrate a bioactive glass (BaG)-based hydration sensor. A fluorine (CaF2) containing BaG (BaG-F) was produced using a melting manufacturing technique. The structure and electrical properties of the resulting constructs were evaluated to understand the electrical behaviors of this BaG-based sensor. The synthetic process of producing the BaG-F-based sensor was validated by assessing the electrical properties. We demonstrated that this BaG-F chemical composition is highly sensitive to hydration, and that electrical activity (resistive-capacitive) is induced by hydration and reversed by dehydration. These properties make BaG-F suitable for use as a humidity sensor to monitor brain edema and consequently provide an alert for increasing intracranial pressure.