Breaking the Rayleigh-Plateau Instability Limit Using Thermocavitation Within a Droplet

Padilla-Martínez, Juan Pablo; Ramírez-San-Juan, J. C.; Korneev, N.; Banks, Darren; Aguilar, Guillermo; Ramos-Garcı́a, R.

doi:10.1615/atomizspr.2013007155

Cited by 11 publications

(15 citation statements)

References 43 publications

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“…To provide a qualitative demonstration of the efficacy of optical clearing in skin treated with the optimal PG perfusion enhancement protocol, we utilized a thermocavitation technique we reported previously . Briefly, treated ex vivo porcine skin was placed on the outer face of a quartz cuvette containing saturated aqueous copper nitrate solution (CuNO 4 ).…”

Section: Methodsmentioning

confidence: 99%

Optical clearing agent perfusion enhancement via combination of microneedle poration, heating and pneumatic pressure

et al. 2014

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Background and Objective: Optical clearing agents (OCAs) have shown promise for increasing the penetration depth of biomedical lasers by temporarily decreasing optical scattering within the skin. However, their translation to the clinic has been constrained by lack of practical means for effectively perfusing OCA within target tissues in vivo. The objective of this study was to address this limitation through combination of a variety of techniques to enhance OCA perfusion, including heating of OCA, microneedling and/or application of pneumatic pressure over the skin surface being treated (vacuum and/or positive pressure). While some of these techniques have been explored by others independently, the current study represents the first to explore their use together. Study Design/Materials and Methods: Propylene glycol (PG) OCA, either at room-temperature or heated to 458C, was topically applied to hydrated, body temperature ex vivo porcine skin, in conjunction with various combinations of microneedling pre-treatment (0.2 mm length microneedles, performed prior to OCA application), vacuum pre-treatment (17-50 kPa, performed prior to OCA application), and positive pressure post-treatment (35-172 kPa, performed after OCA application). The effectiveness of OCA perfusion was characterized via measurements of transmittance, reduced scattering coefficient, and penetration depth at a number of medicallyrelevant laser wavelengths across the visible spectrum. Results: Topical application of room-temperature (RT) PG led to an increase in transmittance across the visible spectrum of up to 21% relative to untreated skin. However, only modest increases were observed with addition of various combinations of microneedling pre-treatment, vacuum pre-treatment, and positive pressure post-treatment. Conversely, when heated PG was used in conjunction with these techniques, we observed significant increases in transmittance. Using an optimal PG perfusion enhancement protocol consisting of 458C heated PG þ microneedle pre-treatment þ 35 kPa vacuum pre-treatment þ 103 kPa positive pressure post-treatment, we observed up to 68% increase in transmittance relative to untreated skin, and up to 46% increase relative to topical RT PG application alone. Using the optimal PG perfusion enhancement protocol, we also observed up to 30% decrease in reduced scattering coefficient relative to untreated skin, and up to 20% decrease relative to topical RT PG alone. Finally, using the optimal protocol, we observed up to 25% increase in penetration depth relative to untreated skin, and up to 23% increase relative to topical RT PG alone. Conclusions: The combination of heated PG, microneedling pre-treatment, vacuum pre-treatment, and positive pressure-post treatment were observed to significantly enhance the perfusion of topically applied PG. Although further studies are required to evaluate the efficacy of combined perfusion enhancement techniques in vivo, the current results suggest promise for facilitating the translation of OCAs to the clinic.

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Section: Methodsmentioning

confidence: 99%

Optical clearing agent perfusion enhancement via combination of microneedle poration, heating and pneumatic pressure

et al. 2014

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“…CW thermocavitation has been observed to produce bubbles that collapse in a toroidal shape when formed near a solid boundary [16]. When a bubble collapses near a heated solid boundary, the microstream jet will be comprised of colder liquid from outside the heated layer near the boundary.…”

Section: Introductionmentioning

confidence: 99%

Planar laser induced fluorescence for temperature measurement of optical thermocavitation

Banks

Robles

Zhang

et al. 2019

Experimental Thermal and Fluid Science

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Pulsed laser-induced cavitation, has been the subject of many studies describing bubble growth, collapse and ensuing shock waves. To a lesser extent, hydrodynamics of continuous wave (CW) cavitation or thermocavitation have also been reported. However, the temperature field around these bubbles has not been measured, partly because a sensor placed in the fluid would interfere with the bubble dynamics, but also because the short-lived bubble lifetimes (∼70-200 µs) demand high sampling rates which are costly to achieve via infrared (IR) imaging. Planar laser-induced fluorescence (PLIF) provides a non-intrusive alternative technique to costly IR imaging to measure the temperature around laser-induced cavitation bubbles. A 440 nm laser sheet excites rhodamine-B dye to fluoresce while thermocavitation is induced by a CW 810 nm laser. Post-calibration, the fluorescence intensity captured with a high-speed Phantom Miro camera is correlated to temperature field adjacent to the bubble. Using shadowgraphy and PLIF, a significant decrease in sensible heat is observed in the nucleation site-temperature decreases after bubble collapse and the initial heated volume of liquid shrinks. Based on irradiation time and temperature, the provided optical energy is estimated to be converted up to 50% into acoustic energy based on the bubble's size, with larger bubbles converting larger percentages.

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“…The use of a continuous wave (CW) laser focused into a hemispherical droplet of highly absorbing liquid has proven to be an alternative technique to produce liquid jets, eliminating the use of nozzles, capillaries, or microcavities. The liquid jets produced by this method are driven by an acoustic shock wave (ASW) emitted at the collapse of a vapor bubble within the droplet contrary to short-pulsed laser-induced cavitation whose dynamic is determined by the bubble [32]. It was shown that the bubble produced by CW lasers is always in contact with the substrate (glass) due to the large optical absorption of the overlaying droplet.…”

Section: Introductionmentioning

confidence: 99%

“…It was shown that the bubble produced by CW lasers is always in contact with the substrate (glass) due to the large optical absorption of the overlaying droplet. The propagation of the ASW was simulated using a ray tracing model as point source originated at the substrate [32]. The simulation shows that the ASW is reflected by the droplet's surface due to an acoustic impedance mismatch (R 99.99) between the solution and air; i.e., the interface acts as a perfect mirror, reflecting the ASW toward the point where it was emitted.…”

Section: Introductionmentioning

confidence: 99%

Controllable direction of liquid jets generated by thermocavitation within a droplet

et al. 2017

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A high-velocity fluid stream ejected from an orifice or nozzle is a common mechanism to produce liquid jets in inkjet printers or to produce sprays among other applications. In the present research, we show the generation of liquid jets of controllable direction produced within a sessile water droplet by thermocavitation. The jets are driven by an acoustic shock wave emitted by the collapse of a hemispherical vapor bubble at the liquid-solid/substrate interface. The generated shock wave is reflected at the liquid-air interface due to acoustic impedance mismatch generating multiple reflections inside the droplet. During each reflection, a force is exerted on the interface driving the jets. Depending on the position of the generation of the bubble within the droplet, the mechanical energy of the shock wave is focused on different regions at the liquid-air interface, ejecting cylindrical liquid jets at different angles. The ejected jet angle dependence is explained by a simple ray tracing model of the propagation of the acoustic shock wave inside the droplet.

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Breaking the Rayleigh-Plateau Instability Limit Using Thermocavitation Within a Droplet

Cited by 11 publications

References 43 publications

Optical clearing agent perfusion enhancement via combination of microneedle poration, heating and pneumatic pressure

Optical clearing agent perfusion enhancement via combination of microneedle poration, heating and pneumatic pressure

Planar laser induced fluorescence for temperature measurement of optical thermocavitation

Controllable direction of liquid jets generated by thermocavitation within a droplet

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