This article presents a miniature shock wave driven micro-jet generator to deliver liquid drugs into human skin, to a controlled depth, with minimal invasion. The device can release the vaccine/drug to the depth of dermal blood vessels, without breaching much of the microcirculation system of dermis. The drug delivery technique is needle-free, which can reduce pain, trauma, and contamination besides minimal dosage and systemic exposure. The device can also be used to deliver liquid or colloidal drugs into soft tissues in human. The mechanical analyses of the device were carried out by analyzing the strength of the impulse of the shock wave, measuring the velocity of the generated jet and capturing the pressure exerted by the jet on the target. The penetrating ability of the jet was investigated by delivering it into sample of human skin and gelatin slabs. Theoretical analyses were carried out on the physics of the delivery and the predicted results had a close agreement with the experimental observations. The development can offer an important cost-effective solution to needle-free health care worldwide. Biotechnol. Bioeng. 2016;113: 2507-2512. © 2016 Wiley Periodicals, Inc.

A shock wave assisted biolistic (biological ballistic) device has been developed to deliver DNA/drug-coated micro-projectiles into soft living targets. The device consists of an Nd:YAG laser, an optical setup to focus the laser beam and, a thin aluminum (Al) foil (typically 100 µm thick) which is a launch pad for the micro-projectiles. The DNA/drug-coated micro-particles to be delivered are deposited on the anterior surface of the foil and the posterior surface of the foil is ablated using the laser beam with an energy density of about 32×109 W/cm2. The ablation launches a shock wave through the foil that imparts an impulse to the foil surface, due to which the deposited particles accelerate and acquire sufficient momentum to penetrate soft targets. The device has been tested for particle delivery by delivering 1 µm size tungsten particles into liver tissues of experimental rats and in vitro test models made of gelatin. The penetration depths of about 90 and 800 µm have been observed in the liver and gelatin targets, respectively. The device has been tested for in vivo DNA [encoding β-glucuronidase (GUS) gene] transfer by delivering plasmid DNA-coated, 1-µm size gold (Au) particles into onion scale, tobacco leaf and soybean seed cells. The GUS activity was detected in the onion, tobacco and soybean cells after the DNA delivery. The present device is totally non-intrusive in nature and has a potential to get miniaturized to suit the existing medical procedures for DNA and/or drug delivery.

Atmospheric-pressure microplasma jets with long and fine torches have recently been used in industrial and medical applications, such as local dental treatment, inner surface treatment of capillaries, stimuli of microorganisms, and local cleaning of semiconductor devices. The final torch appearance is greatly dependent on both the plasma between electrodes and the gas flow that is also dominated by the configuration of the nozzle. In this study, the mechanisms of torch appearance in a dc-driven capillary microplasma jet using atmosphericpressure air have been investigated. Experimentally measured visible torch lengths are analyzed on the basis of fluid mechanics using a fluid simulation code. The time evolution of the plasma torch is visualized with a high-speed camera, and the length and propagation velocity of the torch are presented.

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