IMEC together with its sister company IMEC-Nederland at the Holst Centre realized two new body-monitoring wireless sensor nodes which collect and process data from human body sensors and wirelessly transmit the data to a central monitoring system. The small size and low power consumption of both systems enables non-invasive and ambulatory monitoring of vital body parameters.

IMEC’s two-channel bio-potential wireless sensor node targets the simultaneous monitoring of two vital body signs provided by portable electrocardiogram (ECG, which monitors the heart activity), electromyogram (EMG, which monitors muscle contraction), electroencephalogram (EEG, which monitors brain waves) and electrooculogram (EOG, which monitors eye movement). The second system is an eight-channel wireless EEG system integrated in a cube. The small size and autonomy of the systems increase the patient’s autonomy and quality of life and open up new applications for sports, entertainment, comfort monitoring, and other health and lifestyle products and services.

Both systems use IMEC’s proprietary ultra-low-power bio-potential readout ASIC (application specific integrated circuit) to extract the bio-potential signals produced during the ECG, EMG, EEG or EOG measurements. The ASIC exists in a one-channel and an eight-channel version. The main features of the ASICs are:
- Ultra-low power consumption of only 60µW for the one-channel version and 300µW for the eight-channel version;
- Suitable for a large spectrum of bio-potential signals, including EEG, ECG, EMG and EOG, by an electronic settable gain, electronic settable high cut-off frequency and externally adjustable low cut-off frequency;
- Low noise (60nV/Hz integrated noise for the one-channel and 80nV/Hz for the eight-channel ASIC);
- High common-mode rejection ratio (>120dB) which is required to cope with the large common-mode interference from which the µV-range signals suffer;
- Capable of filtering 50mV DC offset generated by the bio-potential electrodes.

Two-channel bio-potential wireless sensor node </b>
The wireless sensor node integrates two of the one-channel bio-potential EEG, EMG, ECG and EOG read-out ASICs, allowing simultaneous monitoring of two bio-potential signals, a commercial microprocessor and a 2.4GHz radio link. It also includes a human body adapted loop antenna offering a range up to 10m. The system has a power consumption of only 5 to 10mW, depending on the application, allowing 12-24 hours continuous measurement when operated from a prismatic or coin-cell rechargeable battery. Thanks to its small size (49.15mm x 19.35mm x 3mm without battery), it can easily be integrated in a plaster or bandage and worn on the body thus allowing non-invasive and ambulatory multi-modal monitoring of vital body parameters. Potential applications are sleep monitoring, activity and muscle fatigue monitoring and rehabilitation monitoring.

Eight-channel wireless EEG system</b>
The wireless EEG system is a 3D system-in-a-package integrating the eight-channel bio-potential read-out ASIC, a commercial microprocessor and a 2.4GHz radio. The system consumes only 6.6mW power (from which 70% is consumed by the radio) at a sampling rate of 512Hz, resulting in 60 hours energy autonomy when being supplied by a compact 150mAh Li-ion battery. The very compact size of only 1.35cm3 is achieved by using IMEC’s 3D system-in-a-package technology which allows high integration density and double-sided component mounting.

Future research targets the integration of IMEC’s proprietary ultra-low power UWB radio to further improve autonomy. Complete energy autonomy is targeted by integrating energy scavengers such as thermal scavengers which use the heat of the body to generate the required power.

For more information:

Katrien Marent
Corporate Communication Manager
IMEC, Kapeldreef 75
B- 3001 Leuven, Belgium
Tel +32 16 28 18 80 Fax +32 16 28 16 37
Email: Katrien.Marent@imec.be