77th Annual Meeting of the APS Division of Fluid Dynamics (November 24, 2024 — November 26, 2024)

P2620630: The Burning Event

• View Larger
• Download Original

Authors

• Arpit Mishra, Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina
• Pei Zhong, Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina

DOI: https://doi.org/10.1103/APS.DFD.2024.GFM.P2620630

The Thulium Fiber Laser (TFL) offers significant advancements in laser lithotripsy, particularly for kidney stones, but it poses unique challenges when treating hard calcium phosphate stones due to its distinct wavelength. In this work, the intricate dynamics of stone carbonization and cavitation bubble collapse are uncovered during TFL lithotripsy. Millimeter-sized bubbles form with each pulse, creating submillimeter craters that ablate the stone into fine dust. Scanning Electron Microscopy captures 'carbonization or charring' features from intense burning recorded at 50,000 fps. Rounded, dendritic structures result from incipient melting during improper heat treatment. This charring weakens subsequent cavitation bubble collapse, reducing its ability to deepen craters and fragment the stone. Over time, cavitation-induced damage diminishes, limiting the treatment's efficiency despite continued laser irradiation.**The authors extend their gratitude to IPG Photonics for their technical assistance with the TFL system and acknowledge the support of Dornier MedTech for providing the Axis single-use flexible ureteroscope. This project is supported by the National Institutes of Health (NIH) through grants 1P20DK135107-02 and 2R01DK052985-26.