Customized optoelectronic in-ear sensor approaches for unobtrusive continuous monitoring of cardiorespiratory vital signs
Vladimir Blazek, Boudewijn Venema, Steffen Leonhardt, Paul Blazek
Customization of diagnostic and therapeutic pathways in medicine and personalization of medical devices are currently major trends in biomedical engineering together with miniaturization, digitalization and increasingly ambient and unobtrusive sensor strategies. This article presents a novel optoelectronic sensor: its concept is based on simple, easy-to-use classical photoplethysmography technology, but is attached to the ear. Via the ear channel or the inner tragus, the sensor detects diagnostically relevant parameters from peripheral arterial and venous blood volume movement (including heart rate, heart rate variability, respiratory activity, blood oxygen saturation and other subdermal blood phenomena). The diagnostic system consists of customizable i) sensor forms, ii) biodata mining, and iii) communication protocols sent to the medical control center. This article describes novel possibilities for cardiorespiratory monitoring with these sensors characterized by enhanced customization features. In contrast to established art sensor applications on fingers or toes, this optical in-ear sensor technology offers additional physiological and technological advantages by mining vital signs in the ear channel. Since the optical in-ear sensor is comfortable, noninvasive and unobtrusive, it is recommended not only for patients at high cardiovascular risk but also (potentially) for homecare application and the monitoring of physical activities, e.g. during high altitude climbing. Preliminary results demonstrate that vital signs can be assessed with sufficient robustness and accuracy and that, due to the customized sensor application, patient comfort is higher compared with the classical wearable (non-customized) sensors.