Inconspicuous Measurements of Cardiac Function: Shielding (ECG) and Radiating (ICG) Approaches
Inconspicuous Measurements of Cardiac Function: Shielding (ECG) and Radiating (ICG) Approaches, Proc Portuguese Physics for Health Summer School - PPHSS, Covilhã, Portugal, Vol. I, pp. 1 - 1, July, 2010.
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Accompanying a patient’s state without his knowledge in an unobtrusive form is very profitable. It minimizes involuntary psycophysiological responses, and allows regular and long-term monitoring, without quality of life reduction. Aging and the prevalence of cardiac maladies in society has motivated an increase in research of homecare technologies, aiming at continuous and unremarkable subject monitoring.
The most suitable way of non-invasively assessing the cardiovascular activity is by using electrophysiological signals. Also because they are the most well-known, it is important to adapt the traditional acquisition systems to permit unobtrusive monitoring. Using implanted sensors, it has been made possible in recent years to acquire the electrocardiogram (ECG), while the first steps are being taken in robust measurements of bioimpedance (BIOZ).
The ECG acquisition is passive, since electrodes are placed to gather the signal. The BIOZ measurement is active, because a 100 kHz sinusoidal current is emitted. Therefore ECG’s approach is labeled shielding approach, because the measurement process aims at isolating the leads from power line interference and any other noise sources. The BIOZ approach is labeled radiating approach, because a very weak single-frequency current is radiated in two electrodes, and the objective is to capture, in other two electrodes, the changes around that part of the spectrum.
Our group has been able to unobtrusively acquire both ECG and BIOZ signal. The measurements are taken by embedding the sensors in pieces of furniture. Given the paramount knowledge brought by these two measurements, an insightful characterization of the inconspicuously monitored subject is provided.