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Sensors (Basel). 2014 Aug 20;14(8):15371-86. doi: 10.3390/s140815371.

An ultrasonic contactless sensor for breathing monitoring.

Author information

1
Laboratoire PROTEE EA3819, Université de Toulon, Avenue de l'Université, BP 20132, La Garde Cedex, France. arlotto@univ-tln.fr.
2
Laboratoire PROTEE EA3819, Université de Toulon, Avenue de l'Université, BP 20132, La Garde Cedex, France. grimaldi@univ-tln.fr.
3
Clinical Research Unit, Centre Hospitalier Intercommunal de Toulon La Seyne. 54, rue Henri Sainte Claire Deville, BP 1412, 83056, Toulon Cedex, France. roomila.naeck@gmail.com.
4
Laboratoire LSIS CNRS UMR 7296, Université de Toulon, Avenue de l'Université, BP 20132, La Garde Cedex, France. ginoux@univ-tln.fr.

Abstract

The monitoring of human breathing activity during a long period has multiple fundamental applications in medicine. In breathing sleep disorders such as apnea, the diagnosis is based on events during which the person stops breathing for several periods during sleep. In polysomnography, the standard for sleep disordered breathing analysis, chest movement and airflow are used to monitor the respiratory activity. However, this method has serious drawbacks. Indeed, as the subject should sleep overnight in a laboratory and because of sensors being in direct contact with him, artifacts modifying sleep quality are often observed. This work investigates an analysis of the viability of an ultrasonic device to quantify the breathing activity, without contact and without any perception by the subject. Based on a low power ultrasonic active source and transducer, the device measures the frequency shift produced by the velocity difference between the exhaled air flow and the ambient environment, i.e., the Doppler effect. After acquisition and digitization, a specific signal processing is applied to separate the effects of breath from those due to subject movements from the Doppler signal. The distance between the source and the sensor, about 50 cm, and the use of ultrasound frequency well above audible frequencies, 40 kHz, allow monitoring the breathing activity without any perception by the subject, and therefore without any modification of the sleep quality which is very important for sleep disorders diagnostic applications. This work is patented (patent pending 2013-7-31 number FR.13/57569).

PMID:
25140632
PMCID:
PMC4179033
DOI:
10.3390/s140815371
[Indexed for MEDLINE]
Free PMC Article

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