Measuring chest movement using an array of unobstusive pressure sensors

The use of unobtrusive sensors for physiological monitoring is growing in popularity. Advantages such as their non-contact nature and their limited cognitive demand on the user can increase acceptance and usefulness in certain populations. Biomedical applications for unobtrusive pressure sensors include the analysis of bed transfer sequences and the extraction of breathing rate during long-term trend analysis and health monitoring. This paper proposes an algorithm to measure chest wall motion using an unobtrusive pressure sensor array in a combined signal format and compare it to measurements derived from respiratory inductance plethysmography bands. The novel contributions are using an unobtrusive pressure sensor array beneath the mattress to determine the duration of inspiration and expiration segments, and to determine the timing of each movement. The cross-correlation was used to align signals for the pressure array. The durations of the movements were statistically similar, and the timing of the identified movements overlapped considerably (>80%) when the signals were aligned using the calculated delay value.