Session 17 at this year’s International Solid-State Circuits Conference (ISSCC) focused on the diagnostic and therapeutic technologies for health, leveraging the recent advances in sensor and semiconductor technologies. Topics covered included:
• SoC solution for continuous electroencephalography (EEG) monitoring in epilepsy patients;
• chaos processor utilizing body channel communication interface for mental health monitoring;
• multimodal sensor with adaptive stimulator IC for compact electro-acupuncture (EA) system;
• battery-less energy harvesting system for body area sensor networks (BAN);
• IEEE 801.15.6/Bluetooth-compliant solution for biotelemetry in wireless body area network (WBAN);
• millimeter-scale remote-controlled wireless-powered implantable biomedical device;
• and CMOS impedance Cytometer single cell analysis in three dimensional flow real time analysis.
In the article, more details are presented on continuous monitoring of EEGs enabled by a SoC that has an excellent potential for implementation in clinical and nonclinical settings with applications in body area networks.
SoC solution for continuous EEG monitoring
EEG, which is the recording of electrical activity along the scalp, measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. It is a non-invasive recording of the brain's spontaneous electrical activity over a short period of time (a few tens of minutes) recorded from multiple electrodes placed on the scalp. Diagnostics are made based on the spectral content of EEG. To diagnose cases of epilepsy, physicians look for signs of abnormalities in comparison to a baseline EEG. EEGs are also the first line of diagnostic tools for coma, encephalopathies (disorder or disease of the brain) and brain death. One of the advantages of EEGs is the millisecond-range temporal resolution not possible with CT or MRI scans.
The existing solution for recording EEGs is clinical, requiring a patient to visit a medical facility to be interviewed, "wired-up" and recorded for 10 to 20 minutes in the presence of a technician. Most often this yields baseline data and variations thereof for the diagnosing physicians. The recording of an actual seizure (i.e., an ictal recording) which has more diagnostic value than an inter-ictal (period between seizures) recording of a probable epileptic patient can give better information about whether or not a seizure is an epileptic one and the location in the brain from which the seizure activity emanates.
A few data points about the scale of epilepsy and the associated costs: the worldwide prevalence of epilepsy according to the World Health Organization (WHO) is upwards of 50 million, 80 percent of which live in developing economies. In the U.S. alone, according to the Epilepsy Foundation, upwards of 3 million people of all ages suffer seizures and epilepsy every year at an approximate cost of $17.6 billion in direct and indirect costs. There is ample justification for early diagnosis and diagnosis and profiling for proper treatment enabled by a solution that provides an ictal recording.