Mr. Patrick J. O'Brien Profile

Patrick J. O'Brien

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 transparent quartz laparoscopic jaw design for infrared laser sealing of vascular tissues using a reciprocating, side-firing fiber

Patrick O'Brien, Woheeb Saeed, Nathaniel Fried

Proceedings Volume 12355, 1235504 (2023) https://doi.org/10.1117/12.2650462

KEYWORDS: Quartz, Tissues, Infrared lasers, Laparoscopy, Thermography, Optical fibers, Blood vessels, Reflection, Temperature metrology, Thermal imaging cameras

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Infrared (IR) lasers are being tested as an alternative to conventional radiofrequency and ultrasonic surgical devices for rapid hemostatic sealing of vascular tissues. During previous studies, a reciprocating, side-firing optical fiber delivered a linear laser beam across compressed vessels, simulating pressure from laparoscopic device jaws. However, technical challenges include limited field-of-view of vessel position within the jaws, and matching the fiber scan length to variable vessel diameters (2-7 mm). Use of transparent laparoscopic jaws may improve the surgeon’s visibility and enable customized treatment. Transparent quartz square tubing (with dimensions of 2.7 x 2.7 x 25 mm, compatible with a standard 5-mm-outer-diameter laparoscopic port) was sealed on its distal end with a black resin plug for absorbing residual forward directed light. Optical transmission studies were conducted using an infrared (IR) diode laser (1470 nm / 30 W). Razor blade scans and an IR beam profiler were used to acquire side-firing fiber (550-um-core / 0.22 NA) spatial beam profiles. Thermocouples (TC) and a thermal camera recorded peak temperatures and cooling times on the inside and outside surfaces of the quartz jaw, respectively. Side-firing fibers polished at a 50° angle delivered 94% of the light radially (90°) and 2.3% in the forward (0°) direction at powers ≤ 34 W. Total reflection losses for the two quartz-air interfaces measured 6% with 94% of side-firing light transmitted through the quartz tubing wall. Peak TC temperatures on the external surface of the jaw measured 85 ± 14 °C with 23 ± 8 s to cool to body temperature (37 °C). Optical and thermal measurements were conducted on a transparent laparoscopic device jaw for IR laser sealing of vascular tissues. Further development and improved visibility may enable customization of fiber scan length to match variable compressed vessel widths during placement within device jaws.

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