Localizing Seizure Activity in the Brain Using Implantable Micro-LEDs with Quantum Dot Downconversion

Current methods for high resolution imaging of neural activity, such as functional magnetic resonance imaging and penetrating electrode arrays, are not well suited for chronic patient monitoring in clinical settings. The ability to locally monitor neural activity in the brain would benefit doctors and surgeons treating and diagnosing neurological diseases such as epilepsy. Measurement of the intrinsic optical signal offers a high resolution (better than 100 mu m) for the localization of brain activity. The localized detection of seizures in rats using an implantable optical sensor is demonstrated. The implantable optical sensor is fabricated on a 25 mu m thick, flexible polyimide substrate and uses micro-LEDs to measure localized changes in reflectivity due to cerebral blood flow when attached to the surface of the brain. Quantum dot coatings are applied directly to the micro-LEDs via pneumatic printing for wavelength conversion by photoluminescent re-emission.