Non-invasive Acquisition of Blood Pulse Using Magnetic Disturbance Technique
Résumé
Blood pulse is an important human physiological signal commonly used for the understanding of the individual physical health. Current methods of non-invasive blood pulse sensing require direct contact or access to the human skin. As such, the performances of these devices tend to vary with time and are subjective to human body fluids (e.g. blood, perspiration and skin-oil) and environmental contaminants (e.g. mud, water, etc). This paper proposes a novel method of non-invasive acquisition of blood pulse using the disturbance created by blood flowing through a localized magnetic field. The proposed system employs a magnetic sensor and a small permanent magnet placed on the artery (major blood vessel) of the limbs. The magnetic field generated by the permanent magnet acts both as the biasing field for the sensor and also the uniform magnetic flux for blood disturbance. As such, the system is able to operate at room temperature, reliable for continuous long term acquisition, compact (small size) and convenient for daily usage. The heart rate obtained from the proposed system when measured through non-conductive opaque fabric, is found to be highly correlated to commercially available cardiac monitoring system such as ECG and pulse-oximetry.