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Mike Bailey

Senior Principal Engineer

Associate Professor, Mechanical Engineering and Adjunct Assistant Professor, Urology





Research Interests

Medical Ultrasound, Acoustic Cavitation


Dr. Bailey's current research focuses on the role of cavitation in lithotripsy (kidney stone treatment) and ultrasound surgery. He is the lead APL-UW researcher on two collaborative programs among the Laboratory, Indiana University, Moscow State University, and the California Institute of Technology to optimize acoustic waves to exploit bioeffects due to cavitation. Previously, he was one of the designers of a shock wave lithotripter developed at APL-UW to concentrate cavitation and damage on the kidney stone and not on the kidney tissue. Dr. Bailey joined APL-UW in 1996.


B.S. Mechanical Engineering, Yale University, 1991

M.S. Mechanical Engineering, The University of Texas at Austin, 1994

Ph.D. Mechanical Engineering, The University of Texas at Austin, 1997


Ultrasonic tweezers: Technology to lift and steer solid objects in a living body

In a recent paper, a CIMU team describes successful experiments to manipulate a solid object within a living body with ultrasound beams transmitted through the skin.

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15 Jul 2020

A collaborative, international research teams developed and tuned an ultrasound transducer to create vortex shaped beams that can trap, grab, levitate, and move in three dimensions mm-scale objects. The team is working to apply this technology to their all-in-one kidney stone treatment system that, in clinical trials, uses ultrasound to non-invasively break, erode, and move stones and stone fragments out of the kidney so that they may pass naturally from the body.

Mechanical Tissue Ablation with Focused Ultrasound

An experimental noninvasive surgery method uses nonlinear ultrasound pulses to liquefy tissue at remote target sites within a small focal region without damaging intervening tissues. A multi-institution, international team led by CIMU researchers is applying the method to the focal treatment of prostate tumors.

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19 Mar 2020

Boiling histotripsy utilizes sequences of millisecond-duration HIFU pulses with high-amplitude shocks that form at the focus by nonlinear propagation effects. Due to strong attenuation of the ultrasound energy at the shocks, these nonlinear waves rapidly heat tissue and generate millimeter-sized boiling bubbles at the focus within each pulse. Then the further interaction of subsequent shocks with the vapor cavity causes tissue disintegration into subcellular debris through the acoustic atomization mechanism.

The method was proposed at APL-UW in collaboration with Moscow State University (Russia) and now is being evaluated for various clinical applications. It has particular promise because of its important clinical advantages: the treatment of tissue volumes can be accelerated while sparing adjacent structures and not injuring intervening tissues; it generates precisely controlled mechanical lesions with sharp margins; the method can be implemented in existing clinical systems; and it can be used with real-time ultrasound imaging for targeting, guidance, and evaluation of outcomes. In addition, compared to thermal ablation, BH may lead to faster resorption of the liquefied lesion contents.

Characterizing Medical Ultrasound Sources and Fields

For every medical ultrasound transducer it's important to characterize the field it creates, whether for safety of imaging or efficacy of therapy. CIMU researchers measure a 2D acoustic pressure distribution in the beam emanating from the source transducer and then reconstruct mathematically the exact field on the surface of the transducer and in the entire 3D space.

11 Sep 2017

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2000-present and while at APL-UW

Development of a burst wave lithotripsy system for noninvasive fragmentation of ureteroliths in pet cats

Maxwell, A.D., G.W. Kim, E. Furrow, J.P. Lulich, M. Torre, B. MacConaghy, E. Lynch, D.F. Leotta, Y.-N. Wang, M.S. Borofsky, and M.R. Bailey, "Development of a burst wave lithotripsy system for noninvasive fragmentation of ureteroliths in pet cats," BMC Vet. Res., 141, doi:10.1186/s12917-023-03705-1, 2023.

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2 Sep 2023

Upper urinary tract stones are increasingly prevalent in pet cats and are difficult to manage. Surgical procedures to address obstructing ureteroliths have short- and long-term complications, and medical therapies (e.g., fluid diuresis and smooth muscle relaxants) are infrequently effective. Burst wave lithotripsy is a non-invasive, ultrasound-guided, handheld focused ultrasound technology to disintegrate urinary stones, which is now undergoing human clinical trials in awake unanesthetized subjects.

In this study, we designed and performed in vitro testing of a modified burst wave lithotripsy system to noninvasively fragment stones in cats. The design accounted for differences in anatomic scale, acoustic window, skin-to-stone depth, and stone size. Prototypes were fabricated and tested in a benchtop model using 35 natural calcium oxalate monohydrate stones from cats. In an initial experiment, burst wave lithotripsy was performed using peak ultrasound pressures of 7.3 (n = 10), 8.0 (n = 5), or 8.9 MPa (n = 10) for up to 30 min. Fourteen of 25 stones fragmented to < 1 mm within the 30 min. In a second experiment, burst wave lithotripsy was performed using a second transducer and peak ultrasound pressure of 8.0 MPa (n = 10) for up to 50 min. In the second experiment, 9 of 10 stones fragmented to < 1 mm within the 50 min. Across both experiments, an average of 73–97% of stone mass could be reduced to fragments < 1 mm. A third experiment found negligible injury with in vivo exposure of kidneys and ureters in a porcine animal model.

These data support further evaluation of burst wave lithotripsy as a noninvasive intervention for obstructing ureteroliths in cats.

Phase holograms for the three-dimensional patterning of unconstrained microparticles

Ghanem, M., A.D. Maxwell, D. Dalecki, O.A. Sapozhnikov, and M.R. Bailey, "Phase holograms for the three-dimensional patterning of unconstrained microparticles," Sci. Rep., 13, doi:10.1038/s41598-023-35337-8, 2023.

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6 Jun 2023

Acoustic radiation forces can remotely manipulate particles. Forces from a standing wave field align microscale particles along the nodal or anti-nodal locations of the field to form three-dimensional (3D) patterns. These patterns can be used to form 3D microstructures for tissue engineering applications. However, standing wave generation requires more than one transducer or a reflector, which is challenging to implement in vivo. Here, a method is developed and validated to manipulate microspheres using a travelling wave from a single transducer. Diffraction theory and an iterative angular spectrum approach are employed to design phase holograms to shape the acoustic field. The field replicates a standing wave and aligns polyethylene microspheres in water, which are analogous to cells in vivo, at pressure nodes. Using Gor'kov potential to calculate the radiation forces on the microspheres, axial forces are minimized, and transverse forces are maximized to create stable particle patterns. Pressure fields from the phase holograms and resulting particle aggregation patterns match predictions with a feature similarity index > 0.92, where 1 is a perfect match. The resulting radiation forces are comparable to those produced from a standing wave, which suggests opportunities for in vivo implementation of cell patterning toward tissue engineering applications.

Quantitative assessment of boiling histotripsy progression based on color Doppler measurements

Song, M.H., G.P.L. Thomas, V.A. Khokhlova, O.A. Sapozhnikov, M.R. Bailey, A.D. Maxwell, P.V. Yuldashev, and T.D. Khokhlova, "Quantitative assessment of boiling histotripsy progression based on color Doppler measurements," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 69, 3255-3269, doi:10.1109/TUFFC.2022.3212266, 2022.

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1 Dec 2022

Boiling histotripsy (BH) is a mechanical tissue liquefaction method that uses sequences of millisecond-long high intensity focused ultrasound (HIFU) pulses with shock fronts. The BH treatment generates bubbles that move within the sonicated volume due to acoustic radiation force. Since the velocity of the bubbles and tissue debris is expected to depend on the lesion size and liquefaction completeness, it could provide a quantitative metric of the treatment progression. In this study, the motion of bubble remnants and tissue debris immediately following BH pulses was investigated using high-pulse repetition frequency (PRF) plane-wave color Doppler ultrasound in ex vivo myocardium tissue. A 256-element 1.5 MHz spiral HIFU array with a coaxially integrated ultrasound imaging probe (ATL P4-2) produced 10 ms BH pulses to form volumetric lesions with electronic beam steering. Prior to performing volumetric BH treatments, the motion of intact myocardium tissue and anticoagulated bovine blood following isolated BH pulses was assessed as two limiting cases. In the liquid blood the velocity of BH-induced streaming at the focus reached over 200 cm/s, whereas the intact tissue was observed to move toward the HIFU array consistent with elastic rebound of tissue. Over the course of volumetric BH treatments tissue motion at the focus locations was dependent on the axial size of the forming lesion relative to the corresponding size of the HIFU focal area. For axially small lesions, the maximum velocity after the BH pulse was directed toward the HIFU transducer and monotonically increased over time from about 20–100 cm/s as liquefaction progressed, then saturated when tissue was fully liquefied. For larger lesions obtained by merging multiple smaller lesions in the axial direction, the high-speed streaming away from the HIFU transducer was observed at the point of full liquefaction. Based on these observations, the maximum directional velocity and its location along the HIFU propagation axis were proposed and evaluated as candidate metrics of BH treatment completeness.

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In The News

Kidney stone breakthrough procedure at UW called 'game changer' for patients (video)

KOMO News, Preston Phillips

A groundbreaking medical procedure for those with kidney stones will soon be offered at the University of Washington after more than two decades of research. It will also give astronauts the go ahead they need from NASA to travel to Mars.

10 May 2023

NEJM Study Suggests If Having Kidney Stone Surgery, Treat All the Stones

Medical Research .com, Marie Benz

Mike Bailey is interviewed about the recently published paper, saying, "When getting stone surgery, treat all stones."

11 Aug 2022

Leaving small kidney stones behind causes problems later

UW Medicine Newsroom, Barbara Clements

When surgeons remove patients' kidney stones, they typically leave behind small stones that appear not to be causing problems.

A new randomized controlled study showed, however, that leaving these asymptomatic stones behind significantly increases the risk of a patient's relapse in the following five years.

11 Aug 2022

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Noninvasive Fragmentation of Urinary Tract Stones with Focused Ultrasound

Patent Number: 11,583,299

Adam Maxwell, Bryan Cunitz, Wayne Kreider, Oleg Sapozhnikov, Mike Bailey


21 Feb 2023

Confinement or Movement of an Object Using Focused Ultrasound Waves to Generate an Ultrasound Intensity Well

Patent Number: 11,580,945

Adam Maxwell, Oleg Sapozhnikov, Wayne Kreider, Mike Bailey


14 Feb 2023

Method and System for MRI-based Targeting, Monitoring, and Quantification of Thermal and Mechanical Bioeffects in Tissue Induced by High Intensity Focused Ultrasound

Example embodiments of system and method for magnetic resonance imaging (MRI) techniques for planning, real-time monitoring, control, and post-treatment assessment of high intensity focused ultrasound (HIFU) mechanical fractionation of biological material are disclosed. An adapted form of HIFU, referred to as "boiling histotripsy" (BH), can be used to cause mechanical fractionation of biological material. In contrast to conventional HIFU, which cause pure thermal ablation, BH can generate therapeutic destruction of biological tissue with a degree of control and precision that allows the process to be accurately measured and monitored in real-time as well as the outcome of the treatment can be evaluated using a variety of MRI techniques. Real-time monitoring also allow for real-time control of BH.

Patent Number: 10,694,974

Vera Khokhlova, Wayne Kreider, Adam Maxwell, Yak-Nam Wang, Mike Bailey


30 Jun 2020

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center