Bubble dynamics and speed of jets for needle-free injections produced by thermocavitation

Nancy Elizabeth González-Sierra; José Manuel Perez-Corte; Juan Pablo Padilla-Martinez; Samuel Cruz-Vanegas; Silvio Bonfadini; Filippo Storti; Luigino Criante; Rubén Ramos-García

doi:10.1117/1.JBO.28.7.075004

21 July 2023 Bubble dynamics and speed of jets for needle-free injections produced by thermocavitation

Nancy Elizabeth González-Sierra, José Manuel Perez-Corte, Juan Pablo Padilla-Martinez, Samuel Cruz-Vanegas, Silvio Bonfadini, Filippo Storti, Luigino Criante, Rubén Ramos-García

Author Affiliations +

Journal of Biomedical Optics, Vol. 28, Issue 7, 075004 (July 2023). https://doi.org/10.1117/1.JBO.28.7.075004

Abstract

Significance

The number of injections administered has increased dramatically worldwide due to vaccination campaigns following the COVID-19 pandemic, creating a problem of disposing of syringes and needles. Accidental needle sticks occur among medical and cleaning staff, exposing them to highly contagious diseases, such as hepatitis and human immunodeficiency virus. In addition, needle phobia may prevent adequate treatment. To overcome these problems, we propose a needle-free injector based on thermocavitation.

Aim

Experimentally study the dynamics of vapor bubbles produced by thermocavitation inside a fully buried 3D fused silica chamber and the resulting high-speed jets emerging through a small nozzle made at the top of it. The injected volume can range from ∼0.1 to 2 μL per shot. We also demonstrate that these jets have the ability to penetrate agar skin phantoms and ex-vivo porcine skin.

Approach

Through the use of a high-speed camera, the dynamics of liquid jets ejected from a microfluidic device were studied. Thermocavitation bubbles are generated by a continuous wave laser (1064 nm). The 3D chamber was fabricated by ultra-short pulse laser-assisted chemical etching. Penetration tests are conducted using agar gels (1%, 1.25%, 1.5%, 1.75%, and 2% concentrations) and porcine tissue as a model for human skin.

Result

High-speed camera video analysis showed that the average maximum bubble wall speed is about 10 to 25 m/s for almost any combination of pump laser parameters; however, a clever design of the chamber and nozzle enables one to obtain jets with an average speed of ∼70 m / s. The expelled volume per shot (0.1 to 2 μl) can be controlled by the pump laser intensity. Our injector can deliver up to 20 shots before chamber refill. Penetration of jets into agar of different concentrations and ex-vivo porcine skin is demonstrated.

Conclusions

The needle-free injectors based on thermocavitation may hold promise for commercial development, due to their cost and compactness.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Nancy Elizabeth González-Sierra, José Manuel Perez-Corte, Juan Pablo Padilla-Martinez, Samuel Cruz-Vanegas, Silvio Bonfadini, Filippo Storti, Luigino Criante, and Rubén Ramos-García "Bubble dynamics and speed of jets for needle-free injections produced by thermocavitation," Journal of Biomedical Optics 28(7), 075004 (21 July 2023). https://doi.org/10.1117/1.JBO.28.7.075004

Received: 20 February 2023; Accepted: 2 June 2023; Published: 21 July 2023

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