Wireless sensor systems enable a better sleep

Leuven 02 September 2009At the IEEE EMB Conference in Minneapolis, Minnesota, USA, IMEC and its research affiliate Holst Centre have presented the clinical validation of a wireless sleep staging system. The miniaturized wireless system allows patients to wear the device in the comfort of their home, thus enabling early screening of abnormal sleep profiles outside clinics. The sleep staging system has been validated in the sleep laboratory at the University Hospital Center (CHU) in Charleroi, André Vésale Hospital in Belgium, against a commercially available reference system. With this validation, the technology is ready for product development at industry opening new perspectives for remote and comfortable sleep monitoring.

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Sleep disorder is a major health problem. Ten percent of the population of the United States is affected by sleep apneas, and 1 billion people worldwide experience some kind of chronic nasal congestion during sleep. IMEC's wireless sleep staging system which is light weight, wearable and miniaturized can drastically increase the comfort of sleep disorders tests. The system consists of a head band with three sensor nodes measuring 2 EEG-channels (electro-encephalogram) to monitor the brain activity, 2 EOG-channels (electro-oculogram) to monitor the eye activity and 1 EMG-channel (electro-myogram) to monitor the chin muscle activity.

These 5 signals provide the required information for sleep staging according to the Rechtschaffen and Kales standard. The sensor nodes integrate IMEC's proprietary ultra-low power biopotential read-out application-specific integrated circuit (ASIC) to amplify and filter the 5 different ExG signals. The measured ExG signals are wirelessly transmitted to the recording computer. No additional wires from the head to the body or from the head to the recording device are needed, making the system comfortable to wear. The system is optimized for low power resulting in 12 hours autonomy.

The system has been validated in a controlled clinical environment and benchmarked with state-of-the-art ambulatory monitoring equipment. Twelve healthy volunteers were enrolled in the study, and were monitored for a complete night using the wireless and the reference systems set-up in parallel. At the end of the study, the signals were given to a sleep expert for blind scoring, leading to two hypnograms for each subject. From the hypnograms, sleep statistics such as percentage of sleep time in each stage were deducted, and compared for the two systems. Hypnograms were also compared directly for similarity. The analysis proved the potential of wireless sleep staging systems to replace the current monitoring systems.

Within the Human++ programme, IMEC and Holst Centre aim to develop solutions for an efficient and better health care. Wireless sensor nodes in intelligent body area networks may provide more comfortable health care systems by enabling home monitoring of patients. Home monitoring does not only increase the comfort of the patient, it is also a cost-efficient solution for expensive and time-consuming monitoring in hospitals. Moreover, wireless monitoring systems provide more natural daily life monitoring results. Industry can get access to the technology by joining the Human++ programme as research partner or by licensing agreements for further product development.

Holst Centre is an independent open-innovation R&D centre that develops generic technologies for Wireless Autonomous Transducer Solutions and for Systems-in-Foil. A key feature of Holst Centre is its partnership model with industry and academia around shared roadmaps and programmes. It is this kind of cross-fertilization that enables Holst Centre to tune its scientific strategy to industrial needs. Holst Centre was set up in 2005 by IMEC, Flanders, Belgium and TNO, The Netherlands, with support from the Dutch Ministry of Economic Affairs and the Government of Flanders. It is named after Gilles Holst, a Dutch pioneer in Research and Development and first director of Philips Research. Located on High Tech Campus Eindhoven, Holst Centre benefits from the state-of-the-art on-site facilities. Holst Centre has over 145 employees from 25 nationalities and a commitment from close to 20 industrial partners.

IMEC is an independent research centre in nano-electronics and nanotechnology. IMEC is headquartered in Leuven, Belgium, and has offices in Belgium, The Netherlands, Taiwan, the United States, China and Japan. Its staff of more than 1650 people include over 550 industrial residents and guest researchers. In 2008, IMEC's revenue (P&L) was 270 million euro. IMEC's More Moore research targets semiconductor scaling for the 22nm technology node and beyond. With its More than Moore research, IMEC invents technology for nomadic embedded systems, wireless autonomous transducer solutions, biomedical electronics, photovoltaics, organic electronics and GaN power electronics.

IMEC's research bridges the gap between the fundamental research at universities and R&D in the industry. It has unique processing and system know-how, intellectual property portfolio, state-of-the-art infrastructure, and a strong and worldwide network position. This makes IMEC a key partner for shaping the technology of the future. More IMEC news can be found in the VMW September 2008 article eHealth closer to reality thanks to real-time relevant medical data extraction.


Source: Interuniversity Microelectronics Centre - IMEC

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