MRI compatible fiber optic multi sensor platform for real time vital monitoring
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Microsystems sensors are implemented on a fiber optics based platform towards use in magnetic resonance imaging assisted interventions. The presented platform offers real-time and in-situ pressure, temperature and localization feedback during imaging assisted surgical procedures. This multi-sensor platform fits into an interventional medical device with a diameter of 2.5 mm. A polymer cap with perforation is utilized for circulation of blood in the vessel to allow correct monitoring of the temperature and pressure in real time. Graded Index (GRIN) lenses were utilized at the tip of the fiber cables improved optical signal collection efficiency. Three light sources having different wavelengths were utilized each for one sensor; a 637 nm laser, a 780 nm laser and a 875 nm LED (50 nm bandwidth) for pressure, localization and temperature sensors, respectively. Pressure sensing is performed by a released polymer metal hybrid membrane having a diffraction grating interferometer readout scheme. Temperature sensing is accomplished based on the change of absorption and transmission in semiconductors (i.e.GaAs) due to variations of energy bandgap with temperature. Localization of the medical device is acquired based on magneto-optical Kerr effect where Iron Oxide magnetic material is employed. The sensor chip revealed a temperature precision of ±0.22°C, a pressure resolution of 1 mmHg and a localization resolution of 3 mm, where all values are relevant to medical practice. Integration of the sensors developed in this study helps medical devices such as catheters and stents, allow a new horizon in interventional surgery.