SEPTEMBER 29, 2008 -- A team of researchers with the European Optical Fiber Sensing Embedded in Textiles for Healthcare project has developed new types of optical sensors that promise to improve patient safety during magnetic resonance imaging (MRI) scans.
Because the patient must lie motionless for as much as an hour or more within the MRI machine, sedatives or anesthetic drugs are sometimes used. Respiration, however, "is constantly at risk of being impaired by anesthetic drugs or by upper airway obstruction," says Mathieu Jeanne of the Centre Hospitalier Régional Universitaire de Lille, one of the partners in the OFSETH project. So patients must be monitored remotely, and conventional electronic sensors aren't appropriate because magnetic fields can interfere with electrical equipment. The EU-funded OFSETH project is pursuing a solution using optical sensors and optical fibers, according to an article in ICT Results. It involves wearable textiles that incorporate optical monitoring systems.
"The light-guiding properties of an optical fiber can change depending on its surrounding environment," explains François Narbonneau of Multitel, an independent research center based in Mons, Belgium, which is coordinating the project. "By measuring the constraints applied to an optical fiber or by analyzing modifications of the signal properties transmitted in an optical fiber, it is possible to measure a lot of parameters."
To monitor breathing, the researchers wove a plastic optical fiber into an elastic bandage to be placed around the chest or abdomen. The bandage expands and contracts as the patient breathes and two types of sensors detect the strains in the fiber to monitor the breathing rate.
The team has also designed a non-invasive blood-oxygen sensor that compares the absorption of red and infrared light to gauge how much oxygen is present in the blood. The sensor fits on a finger-tip and detects reflected light from the skin. It measures pulse rate as well. Although other non-electronic devices can be used to measure vital functions, they can be cumbersome and expensive. And while optical technology is already in use for MRI monitoring, the patient often needs to be switched between two or three different systems as they are moved between different parts of the hospital.
The OFSETH-developed system avoids the need for such changes by incorporating the sensors into a garment worn by the patient. Plastic optical fibers are particularly suitable for such applications as they can be woven into the fabric.
"The main innovation is to use optical fiber sensors embedded into textile during the fabrication process for medical applications," says Narbonneau. "The key idea is to provide a garment which allows monitoring of the patient from arrival at the hospital until departure without changing or disconnecting the monitoring system."
All the hardware components are now ready and the next phase is to integrate them into a prototype garment which will then be tested in clinical trials. The project is due to finish in August 2009.
The ten partners contributed their expertise on health care, optical sensing and textile technology to make the project a reality. The lessons learned can be applied to a much wider range of applications. For example, the team is already planning to use the same sensors to create baby clothes that can be used at home to guard against sudden 'cot deaths'.
OFSETH is part of SFIT, a cluster of projects to develop 'smart' textiles supported by the EU's Sixth Framework Programme for research.