A portable multi-sensor system for non-invasive measurement of biometrical data

Abstract

In the last years, the availability of performing personal computing devices, like smartphones, opens new scenarios to the so called Body Area Network, i.e., sensor networks used to monitor physical conditions of the user. Generally speaking, the sensors adopted to monitor physical parameters, like heartbeat or exertion level, are not suitable for runtime measurements. However, the physical performance of athletes may be improved by a continuous monitoring of the body conditions. In this work, a simple, portable and low-cost system for non-invasive measurement of physical parameters is proposed and experimentally characterized. It is based on two different sensors combined in a unique structure to be applied in a clip-like fashion to the earlobe or analogue body part of a person. A photoplethysmographic sensor is used to optically measure the change in volume of blood in the arteries, thus to acquire information about heart beating, blood pressure, and arrhythmias. The second sensor is composed of two electrodes, thus an impedance measurement of the tissue is conducted. The impedance estimation can be used to monitor application-specific parameters, such as blood pH. The structure is compact in size and low-power, making it suitable for portable and battery-operated systems. The experimental characterization of the prototype demonstrates the feasibility of the proposed approach. © 2012 The Authors. Published by Elsevier Ltd.