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    Öğe
    A stacked multi-sensor platform for real-time MRI guided interventions
    (Elsevier, 2023) Zolfaghari, Parviz; Erden, Oğuz K.; Tümer, Murat; Yalçınkaya, Arda D.; Ferhanoğlu, Onur
    We present a stacked temperature, pressure, and localization platform, targeted for minimally invasive surgical and diagnostic applications under Magnetic Resonance Imaging. The platform comprises a micro-fabricated three-layer (Titanium-Parylene-Titanium) membrane pressure sensor, a Gallium Arsenide band-gap temperature sensor, and a magnetic material on double prism retro-reflector that benefits from Magneto-Optic Kerr effect as a magnetic field sensor, to provide localization feedback under Magnetic Resonance Imaging. All sensors can be addressed with a single fiber optic cable, where the collected light is directed to a spectrometer and a polarimeter. For the three-layer microfabricated membrane sensor, an analytical formulation is derived, linking the pressure to optical intensity. Moreover, finite-element simulation results are provided, verifying analytical findings. Wavelength division multiplexing is exploited to address the sensors simultaneously. We measured sensitivities of 0.025 millidegree/Gauss rotation of polarization, 1.5 nm/mmHg displacement (in agreement with simulation results and analytical findings), 0.36 nm/degrees C. bandgap wavelength shift for magnetic field, pressure, and temperature sensors; respectively. With further development, the proposed device can be adapted to a clinical setting for use in Magnetic Resonance assisted surgical procedures.
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    Öğe
    MRI compatible fiber optic multi sensor platform for real time vital monitoring
    (Institute of Electrical and Electronics Engineers, 2021) Zolfaghari, Parviz; Erden, Oğuz Kaan; Ferhanoğlu, Onur; Tümer, Murat; Yalçınkaya, Arda Deniz
    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.