Towards clinical use of a laser-induced microjet system aimed at reliable and safe drug delivery

Abstract

Abstract. An Er:YAG laser with 2940-nm wavelength and 250-μs pulse duration is used to generate a microjet that is ejected at ∼50 m∕s in air. The strength of the microjet depends on the bubble dynamics from the beamwater interaction within the driving chamber as well as the discharging of the drug solution underneath the elastic membrane that separates the drug from the driving liquid. The jet characteristics, such as velocity, volume, and level of atomization, are obtained by high-speed camera images taken at 42,000 fps. The enhancements in jet volume (dosage) and repeated jet generation, which are aimed at making the injector suitable for general clinical applications, are achieved. The generation of repeated microjets is achieved with the help of a stepping motor that provides a uniform pressure within the drug reservoir before an ejection occurs through a micro nozzle. Also, two types of human growth hormones are used for monitoring any potential thermal damage to the drug solution due to a repeated laser ablation when driving the microjet. We provide strong evidence to support that the drugs, as they are injected to porcine skins, are free of the damage associated with the present delivery method. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Toward jet injection by continuous-wave laser cavitation

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These can be classified as impulsive pressure-induced jets, such as compressed gas, spring 6,7 or piezoelectric transducer, [8][9][10] and cavitation-induced jets, such as electric current 11 or laser. [17][18][19][20][21] Particularly, spring and compressed gas systems are now commercially available, which are mostly used for insulin injection. [13][14][15][16] The potential of cavitation-induced jets by lasers was first explored by studying cavitation bubbles near to an elastic boundary.…”

Needle-free delivery of fluids from compact laser-based jet injector

“…Laser-based jet injectors [21][22][23][24][25][26][27][28][29][30] were tested with aqueous solutions. While water is the most common solvent for Fig.…”

“…Laser induced cavitation has been investigated as the driving mechanism for needle-free injection systems. 12,[21][22][23][24][25][26][27][28][29][30] Tagawa et al 28 demonstrated injection with a new type of highly focused liquid microjets generated by a laser pulse focused by an optical objective from the side of a transparent nozzle. In the recent study by Krizek et al 29 this concept was elaborated on hydrogel models mimicking stiffer materials representing mechanical properties of various soft body tissues up to 0.5 MPa (e.g.…”

Skin pre‐ablation and laser assisted microjet injection for deep tissue penetration

“…However, there still remain many unresolved issues such as the potential for cross‐contamination from the jet splash back, poor reliability regarding the delivered dose, and significantly painstaking procedures associated with the injection . As an alternative, the use of microjets generated with Er:YAG lasers to deliver small doses per pulse at 10 Hz with controlled penetration depths have been reported to be quite competitive with previously attempted methods .…”