News and events - Tampere University of Technology

Emfit mattress sensor detects increased respiratory effort during sleep

The doctoral dissertation of PhLic Mirja Tenhunen explores the detection and evaluation of prolonged partial upper airway obstruction during sleep. The Emfit mattress sensor provides an affordable tool for screening large groups of patients for sleep-disordered breathing problems.
Mirja Tenhunen was born in Varkaus, Finland, in 1963 and works as a medical physicist at Tampere University Hospital. Photo: Petri Heino
Mirja Tenhunen was born in Varkaus, Finland, in 1963 and works as a medical physicist at Tampere University Hospital. Photo: Petri Heino

As sleep-disordered breathing (SDB) problems are quite common, they are putting an increasing strain on our healthcare system. Especially obstructive sleep apnea (OSA) and its health consequences, such as different cardiovascular diseases, are nowadays well recognized. In addition to OSA, attention has recently been paid to another SDB: prolonged partial obstruction. However, it is often under-diagnosed and left untreated because of the low number of respiratory events during polysomnography (PSG) recording. This patient group has been found to display more atypical subjective symptoms than OSA patients.

Polysomnography (PSG) is recognized as the gold standard for the assessment of SDB. The use of esophageal manometry is recommended for the measurement of respiratory effort. This recording method is demanding and uncomfortable and is usually not used with ordinary sleep laboratory patients.

“There is a long tradition in Finland of using mattress sensors in SDB diagnostics. Smaller electromechanical film transducer (Emfit) mattresses have recently replaced the old Static Charge-Sensitive Bed (SCSB) mattresses, but a proper clinical validation of Emfit mattresses in SDB diagnostics has not been carried out,” Tenhunen says.

In her dissertation, PhLic Mirja Tenhunen evaluates the use of Emfit recording in the detection of sleep apneas, hypopneas, and prolonged partial obstruction with increased respiratory effort. In addition, she estimates the usability of compressed tracheal sound signal scoring in SDB screening. The goal was to develop and improve the diagnostic methods for sleep-related breathing disorders. Tenhunen’s results demonstrate that the Emfit signal and the use of tracheal sound reveal increased respiratory effort as well as apneas/hypopneas.

Currently the analysis of sleep recordings is still based on a doctor’s subjective and visual estimation. To date, no generally accepted and sufficiently reliable automatic analysis method exists. Robust, automatic quantification methods with easier techniques for non-invasive sleep recording would also allow the use of the analysis methods for screening purposes. In today’s technology-orientated world, people could take more responsibility and take better care of themselves by monitoring their biosignals and changing their unhealthy habits earlier. The need for good sleep as a necessity for good life and health is widely recognized.

Public defence of a doctoral dissertation on 4 September 2015

The doctoral dissertation of MSc, PhLic Mirja Tenhunen titled ‘Detection and Assessment of Sleep-Disordered Breathing with Special Interest of Prolonged Partial Obstruction’ will be publicly examined in the Faculty of Computing and electrical Engineering of Tampere University of Technology (TUT) in Auditorium TB109 in the Tietotalo building (address: Korkeakoulunkatu 1, Tampere, Finland) on Friday, 4 September 2015 at 12:00.  

The opponent will be Professor Tapio Seppänen (Department of Electrical and Information Engineering, University of Oulu). Professor Jari Hyttinen from the Department of Electronics and Communication Engineering at TUT and BioMediTech will act as Chairman.

Further information: Mirja Tenhunen, tel. +358 3 3116 4196,

The dissertation is available online at:


News submitted by: Sara Riihimäki
Keywords: science and research