Wireless microsensors system for monitoring breathing activity

André, Nicolas [UCL] Gérard, Pierre [UCL] Drochmans, Philippe [UCL] Kezai, Tahar [UCL] Druart, Sylvain [UCL] Moreno Hagelsieb, Luis [UCL] Francis, Laurent [UCL] Flandre, Denis [UCL] Raskin, Jean-Pierre [UCL]

A portable, non-invasive and easy to operate wireless system has been developed for monitoring the breathing activity of patient. The system is composed of a capacitive microsensor (airflow-humidity sensor) integrated on a silicon chip and of a Negative Temperature Coefficient thermistor; both are coupled to a Radio Frequency wireless link. The sensitive part of the microsensor is an array of interdigitated metallic electrodes covered by 100 nm-thick dense anodized aluminum oxide layer. The breath water vapor is adsorbed over the interdigitated electrode and changes the sensor characteristic capacitance. This modulated signal is then digitized and either stored in a memory or directly transmitted to a monitor through the short distance RF link. Full size of the microsensor is less than 1 cm/sup 2/ and can be easily implemented in a classical adhesive bandage. This microsystem is proposed for monitoring sleep-disordered breathing as well as breathing rhythm of athletes during effort.