Wireless EEG system self-powered by body heat and light

Apr 09, 2008
Wireless EEG system self-powered by body heat and light
The wearable wireless EEG system with hybrid power supply.

In the framework of Holst Centre, IMEC has developed a battery-free wireless 2-channel EEG (electroencephalography or monitoring of brain waves) system powered by a hybrid power supply using body heat and ambient light. The hybrid power supply 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. The system can provide more than 1mW on average indoor, which is more than enough for the targeted application.

Thermoelectric generators using body heat typically show a drop in generated power when the ambient temperature is in range of the body temperature. Especially outside, the photovoltaic cells in the hybrid system counter this energy drop and ensure a continuous power generation. Moreover, they serve as part of the radiators for the thermoelectric generator, which are required to obtain high efficiency.

Compared to a previous EEG demonstrator developed within Holst Centre, which was solely powered by thermoelectric generators positioned on the forehead, the hybrid system has a reduced size and weight. Combined with full autonomous operation, no maintenance and an acceptable low heat flow from the head, it further increases the patient’s autonomy and quality of life. Potential applications are detection of imbalance between the two halves of the brain, detection of certain kinds of brain trauma and monitoring of brain activity.

The system is a tangible demonstrator of Holst Centre’s Human++ program researching healthcare, lifestyle and sport applications of body area networks. Future research targets 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. Interested parties can get more insight in this research or license the underlying technologies through membership of the program.

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, has an external area of 4×8cm² that is made of high-efficiency Si photovoltaic cells. Further, thermally conductive comb-type structures (so-called thermal shunts) have been used to eliminate the thermal barrier between the skin and the thermopiles that is caused by the person’s hair on the thermoelectric generator.

The EEG system 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 PC via a 2.4GHz wireless radio link. The whole system consumes only 0.8mW, well below the power produced to provide full autonomy.

Source: IMEC

Explore further: Researchers increase the switching contrast of an all-optical flip-flop

add to favorites email to friend print save as pdf

Related Stories

China to send orbiter to moon and back

2 hours ago

China will launch its latest lunar orbiter in the coming days, state media said Wednesday, in its first attempt to send a spacecraft around the moon and back to Earth.

Beijing's focus on coal lost in haze of smog

2 hours ago

The soaring, grimy chimneys of the coal-fired power station have belched the last of their choking fumes into Beijing's air, authorities say—but experts doubt the plan will ease the capital's smog.

Apple issues security warning for iCloud

3 hours ago

Apple has posted a new security warning for users of its iCloud online storage service amid reports of a concerted effort to steal passwords and other data from people who use the popular service in China.

Review: Better cameras, less glare in iPad Air 2

3 hours ago

If I've seen you taking photos with a tablet computer, I've probably made fun of you (though maybe not to your face, depending on how big you are). I'm old school: I much prefer looking through the viewfinder ...

Recommended for you

Intelligent materials that work in space

Oct 23, 2014

ARQUIMEA, a company that began in the Business Incubator in the Science Park of the Universidad Carlos III de Madrid, will be testing technology it has developed in the International Space Station. The technology ...

Using sound to picture the world in a new way

Oct 22, 2014

Have you ever thought about using acoustics to collect data? The EAR-IT project has explored this possibility with various pioneering applications that impact on our daily lives. Monitoring traffic density ...

User comments : 0