Mr. Aidan R. Restelli Profile

Aidan R. Restelli

at Univ of North Carolina at Charlotte

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Publications (2)

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Proceedings Article | 13 March 2024 Presentation + Paper

Quartz versus sapphire optical chambers for use in infrared laser sealing of blood vessels

Woheeb Saeed, Patrick O'Brien, Jude Yoshino, Aidan Restelli, Alexandria Traynham, Nathaniel Fried

Proceedings Volume 12817, 1281703 (2024) https://doi.org/10.1117/12.3000375

KEYWORDS: Sapphire, Quartz, Infrared lasers, Blood vessels, Tissues, Semiconductor lasers

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Infrared (IR) lasers are being tested as an alternative to radiofrequency (RF) and ultrasonic (US) devices for hemostatic sealing of vascular tissues. In recent studies, a side-firing optical fiber was reciprocated, producing a linear laser beam pattern for sealing blood vessels. Challenges include limited field-of-view of vessel position within the device jaws, and matching fiber scan length to vessel size. A transparent jaw may improve visibility and enable custom treatment. Quartz and sapphire square optical chambers (2.7 x 2.7 x 25mm OD) were tested with a 1470nm laser and 550-μm-core fiber. Peak temperatures and cooling times were recorded on chamber surfaces. Angle polished fiber tips delivered 94% of light at a 90° angle. Porcine renal arteries with diameters of 3.4±0.7mm (n=13) for quartz and 3.2±0.7mm (n=14) for sapphire (P>0.05), were sealed using 30W for 5s. Reflection losses were 3.3% and 7.4% for quartz and sapphire. Peak temperatures on external chamber surface averaged 74±8 °C and 73±10 °C (P>0.05). Times to cool down to 37 °C measured 13±4s and 27±7s (P<0.05). Vessel burst pressures (BP) averaged 883±393mmHg and 412±330mmHg (P<0.05). For quartz, 13/13 (100%) vessels were sealed (BP>360mmHg), versus 9/14 (64%) for sapphire. Quartz provided more consistent seals and shorter cooling times than sapphire.

Proceedings Article | 14 March 2023 Presentation + Paper

A novel flexible ureteroscope design using a saline light guide channel for combined irrigation and illumination

Aidan Restelli, Woheeb Saeed, Nathaniel Fried

Proceedings Volume 12353, 123530A (2023) https://doi.org/10.1117/12.2649036

KEYWORDS: Design and modelling, Waveguides, Simulations, Zemax, Liquids, Fiber optics, Total internal reflection, Laser lithotripsy, Optical simulations, Light sources

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Miniature ureteroscopes (< 2-mm-outer-diameter) may potentially enable less expensive, office-based, laser lithotripsy in the lower urinary tract with patients only requiring local anesthesia. This preliminary study describes a flexible miniature ureteroscope design combining illumination and irrigation channels using a saline liquid light guide (LLG). Teflon AF 2400 is a novel, flexible, biocompatible material with lower refractive index (n = 1.29) than saline (n = 1.33), thus enabling total internal reflection (TIR) of light through an LLG. Irrigation rates were measured through an annulus-shaped LLG, sandwiched between concentric inner (OD = 0.74mm / ID = 0.61mm) and outer (OD = 1.60mm / ID = 1.02mm) Teflon AF 2400 tubing. A flexible plastic fiber optic imaging bundle (7.4k pixels / OD = 0.5mm / NA = 0.5) was placed within the inner Teflon tubing core. Two optical fibers of 0.100-mm / 0.140-mm / 0.170-mm (core/cladding/buffer) were placed between the Teflon layers, as spacers, steering cables, and for energy delivery. Computational fluid mechanics models (ANSYS) and optical simulation software (Zemax) were used to predict irrigation rates and illumination, respectively, over a wide range of Teflon dimensions. Computational models calculated gravitational flow rates up to 12.8 ml/min for a larger annulus with concentric inner and outer Teflon AF tubing dimensions of 0.74-mm-OD and 1.80-mm-ID, with two fiber spacers decreasing annular flow by an additional 10%. Optical simulations predicted optimal illumination out of the annulus-shaped saline light guide of 72-77% of initial input. The LLG flexible ureteroscope design utilized concentric Teflon AF tubing for TIR of light through an annulus-shaped irrigation channel, minimizing cross-sectional area, for a miniature ureteroscope (< 2-mm-OD). With further development, miniature ureteroscopes may enable an office-based approach to laser lithotripsy.

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