PORTFOLIO

Die Studie entwickelt Messtechniken zur kontinuierlichen Überwachung von hämodynamischen Parametern (Puls; arterielle Druckschwankungen) von Patienten an Wohnort und Arbeitsplatz sowie in der Freizeit. Schwerpunkt ist die Analyse von nicht-invasiven, optischen Messtechniken am Handgelenk (photonische Migration; interferometrische oder holographische Messtechnik).

Das innovative und interdiziplinäre Projekt zeichnet sich durch eine hohe Wirksamkeit aus. Ein Transferpotential besteht auch ausserhalb der klinischen Anwendung. Die von der Gebert Rüf Stiftung gewährte Initialfinanzierung ermöglicht die Startphase eines technologisch neuartigen und erfolgversprechenden angewandten Forschungsprojektes, dass in der präkompetitiven Phase steht.

A well-known method to measure the heart rate is based on optical devices that track light transmission variations at the fingertip or the earlobe. It is much more convenient to wear a monitoring device at the wrist, but also technically more difficult: the optical signal that can be obtained is much smaller and corrupted by artifacts due to arm and hand motion.
3D low noise accelerometers, giving an accurate motion reference signal, together with multi-channel optical sensing, provide the necessary inputs for the signal processing section. Nonlinear modeling allows removing the motion contributions in the optical signals. A statistical estimation, based on physiological properties of the heart, gives a robust estimation of the heart rate.
Qualitative and quantitative performance evaluation of the performances on real signals clearly show that the proposed system gives a good estimation of the heart rate, even under intense physical activity.
The other part of the project is devoted to the non-invasive measurement of the pressure at the wrist. Continuous monitoring of blood pressure is expected to bring invaluable pieces of information, which are presently missing to the physician. The hypertension peaks may also pass undetected when measured by conventional method such as sphygmomanometer and come to the fore by the complications induced by these peaks such as haemorrhage or brain ischemia. The surveillance of hypertension must therefore be adapted to each patient. A method has been developed for the measurement of the skin movements caused by the arterial pulse. A device has been developed to evaluate non-invasively arterial pressure at the wrist. Miniaturization of the device is presently in progress.

Philippe Renevey, Rolf Vetter, Patrick Celka, Jens Krauss and Yves Depeursinge. Wrist-located pulse detection using IR signals, activity and nonlinear artifact cancellation. In IEEE EMBS, Istanbul, October 2001.
Philippe Renevey, Rolf Vetter, Patrick Celka and Jens Krauss, "Activity Classification Using HMM For Improvement Of Wrist Located Pulse Detection", BioSignal 2002, pages 192-196, Brno, Czech Republic, June 26 - 28, 2002.

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