Smart mat system with pressure sensor array for unobtrusive sleep monitoring

To improve the unobtrusiveness and comfortableness of sleep monitoring, we proposed the design and implementation of a smart mat which utilized flexible pressure sensor array and printed electrodes to monitor physiological and behavioral data during sleep. With the proposed novel soft seven-layer structure, the smart mat system can measure pressure distribution images and calculate respiratory rate of subjects. The function of this system was realized with pressure acquisition circuit controlled by Arduino processor. Experiments for pressure distribution tests and respiratory rate measurements were carried out to validate the performance of the proposed system. The experimental results demonstrated that the smart mat could be a viable option for unobtrusive sleep monitoring in the future.

I. Introduction

Sleep is considered as an important state which exerts significant effects on human both physically and mentally. In sleep medicine, polysomnography (PSG) is considered as the standard method for the assessment of sleep quality [1]. PSG is conducted in a specialized sleep laboratory, and consists of continuous, simultaneous and multiple monitoring of several physiological parameters including electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), airflow, oxygen saturation (SpO2) and respiratory efforts. However, the unfamiliar environment of the sleep laboratory as well as the equipment and wired sensors attached to the subject can cause mental stress and bad influence to the subject during sleep. So it is inevitable to interfere the sleep quality due to its complexity and inconvenience of obtaining the PSG signals in sleep laboratory. Hence developing a noninvasive sleep monitoring system can contribute to more convenient and accurate sleep assessment. For example, for neonatal sleep monitoring, noninvasive system is necessary due to the sensitive skin and developmental needs [2].