3D printed micro-scale fiber optic probe for intravascular pressure sensing

Abstract

Small form-factor invasive pressure sensors are widely used in minimally invasive surgery, for example to guide decision making in coronary stenting procedures. Current fiber-optic sensors can have high manufacturing complexities and costs, which severely constrains their adoption outside of niche fields. A particular challenge is the ability to rapidly prototype and iterate upon sensor designs to optimize performance for different applications and medical devices. Here, we present a new sensor fabrication method, which involves two-photon polymerization printing and integration of the printed structure onto the end-face of a single-mode optical fiber. The active elements of the sensor were a pressure-sensitive diaphragm and an intermediate temperature-sensitive spacer that was insensitive to changes in external pressure. Deflection of the diaphragm and thermal expansion the spacer relative to the fiber end-face were monitored using phase-resolved lowcoherence interferometry. Pressure changes of 0.38 mmHg were detectable in the range of 760 to 1060 mmHg (absolute pressure), while a temperature changes of 0.023 °C were detectable in the range 25 to 47 °C using this fiber optic sensor. This method will enable the fabrication of a wide range of fiber-optic sensors with pressure and temperature sensitivities suitable for guiding minimally invasive surgery.

Precision-Microfabricated Fiber-Optic Probe for Intravascular Pressure and Temperature Sensing

“…To enable LCI signal detection at lower illumination power, the sensor element design was modified to enhance coupling of the back-reflected beam from each cavity surface into the core of the SM optical fiber. In contrast, within the case of parallel reflecting surfaces as is the design norm for FP cavities in fiberoptic pressure sensors, [19], [38]- [40] only a small fraction of the reflected interferometric signal can couple back into the SM fiber to be detected by the spectrometer. This is a result of progressive divergence during both the forward and backreflected trajectories within the optical cavity when passing through the extrinsic sensor element.…”

“…These changes in optical path length can be monitored as variations in the complex argument of the inverse Fourier-transformed spectrum at its maxima, as detailed in our previous work. [19], [38].…”