A PCA-Based Method to Select the Number and the Body Location of Piezoresistive Sensors in a Wearable System for Respiratory Monitoring

Abstract

This work aims at selecting the number and the body location of piezoresistive sensors to instrument wearable systems for respiratory rate (RR) estimation. We tested a novel method based on Principal Component Analysis on 10 healthy male subjects, who were asked to perform six trials on a treadmill (at rest, during walking and low speed running). We monitored RR using both a smart garment composed of six piezoresistive sensors and a flowmeter, used as reference signal. On the basis of the results, we propose the following guidelines: i) breathing assessment at rest requires one sensor, placed on the lower thorax; ii) low speed walking assessment requires three sensors, placed on upper thorax, lower thorax and abdomen; iii) high speed walking and running assessment requires a four-sensor configuration (one sensor placed on the upper thorax, one on the lower thorax and two on the abdomen); iv) an effective assessment can be performed at all speeds using the above-mentioned four-sensor configuration, denoted as General Purpose Configuration.