Wireless EEG System Powered by Body Heat and Light

A new electroencephalography (EEG) system powered by a hybrid power supply based on body heat and ambient light can be used to monitor brain waves after a head injury.

Researchers at The Interuniversity Microelectronics Center (IMEC, Leuven, Belgium) developed the battery-free wireless 2-channel EEG system, which is powered by a hybrid power supply that combines a thermoelectric generator that uses the heat dissipated from a person's temples and silicon photovoltaic cells. The entire system is wearable and integrated into a device resembling headphones, and can provide more than 1 mW on average indoor light, which is more than enough for the targeted application. The thermoelectric generator is composed of six thermoelectric units made up from miniature commercial thermopiles; each of the two radiators, on left and right sides of the head, is made of high-efficiency silicone photovoltaic cells. Thermally conductive comb-type structures (so-called thermal shunts) were used to eliminate the thermal barrier between the skin and the thermopiles caused by hair adjacent to the thermoelectric generator.

The EEG system itself uses IMEC's proprietary ultra-low-power biopotential readout application-specific integrated circuit (ASIC) to extract high-quality EEG signals with micro-power consumption. A low-power digital-signal processing block encodes the extracted EEG data, which are sent to a computer via a 2.4 GHz wireless radio link. The whole system consumes only 0.8 mW, well below the power produced to provide full autonomy. Potential applications of the system are detection of imbalance between the two halves of the brain, detection of certain kinds of brain trauma, and monitoring of brain activity. Future research targets of the system include further reduction of the power consumption of the different system components of the body area network, as well as a significant reduction of the production cost by using micromachining.


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The Interuniversity Microelectronics Center