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A novel system for the research and reduction of motion artefact

In his doctoral thesis MSc Alper Cömert developed novel methods to investigate motion artifact and the susceptibility of biopotential electrodes to motion artifact.

As part of his research he also developed motion artifact resilient electrodes used, e.g., to measure cardiac signals enabling more reliable cardiac monitoring.

With the ageing of the population and rising obesity rates, the health care system is quickly becoming overloaded. Not only does the increasing number of patients pose a problem, but also the reduced mobility of these patients. The Economist estimates the rise in health care costs to be from 8% of the GDP of EU countries to 14 percent in the next 20 years. It is clear that this will be a problem for the already stretched budgets of EU countries.

The widespread use of mobile monitoring devices for disease prevention, early diagnosis, recovery and rehabilitation would reduce the load on the health care system by freeing up personnel and resources for more acute issues. These mobile devices would allow patients to complete their medical checks in the comfort of their home or workplace.

The electrocardiogram (ECG) is one of the most widely used biosignal in medicine, and electroencephalograms (EEG) and electromyograms (EMG) also have considerable implementation areas.

“While important steps have been taken to enhance related devices, for example, in terms of processing power, battery life, storage and communication, there is still one area that holds immense potential for improvement: the signal detector itself; the electrode,” Cömert says.

As the electrode is the interface between the body and the measurement system, it can be considered as the generator of the input signal for a given monitoring system. The better the quality of the signal, the more reliable, accurate and useful the information given by the monitoring system will be.

These mobile monitoring systems are intended for daily use, and even during rigorous activity. Due to reusability, user comfort and other factors, so called “dry electrodes” made, for example, from textiles are the most preferable.

“However, unlike medical electrodes that are glued to the skin, these dry electrodes are susceptible to motion artefact, which is the electrode noise originating from patient movement. At present, the noise hampers the reliability of mobile monitoring systems and is the bottleneck in the development and widespread use of such systems,” Cömert explains.

In his thesis Cömert introduces a novel system for testing the electrode for motion artifact in response to motion applied directly to the electrode.

“This motion is programmable, accurate, repeatable, and maybe most importantly, known, so that a thorough analysis of the electrode is possible. The method is promising and provides new, reliable and robust measures of the electrode characteristics,” Cömert states.

 The developed methods also enabled him to clarify issues regarding the use of skin-electrode impedance for the detection and reduction of motion artifact.

The electrode design tools and guidelines Alper Cömert presents can be used to design new electrodes with considerably reduced susceptibility to motion artifact just by improving the structural design of electrodes. These improved electrodes can make way for the wider implementation of wearable monitoring systems.


Public defence of a doctoral dissertation on 10 September 2015

The doctoral dissertation of MSc. Alper Cömert titled ‘The Assessment and Reduction of Motion Artifact in Dry Contact Biopotential Electrodes’ 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 Thursday, 10 September 2015 at 12:00.  

The opponent will be Professor Jens Haueisen (Institut für Biomedizinische Technik und Informatik, Ilmenau University of Technology). Professor Jari Hyttinen from the Department of Electronics and Communication Engineering at TUT and BioMediTech will act as Chairman.

The dissertation can be found at: http://URN.fi/URN:ISBN:978-952-15-3575-8

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News submitted by: Sanna Kähkönen
Keywords: science and research