Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

This paper presents a novel process for the fabrication of out-of-plane hollow microneedles in silicon. The fabrication method consists of a sequence of deep-reactive ion etching (DRIE), anisotropic wet etching and conformal thin film deposition, and allows needle shapes with different, lithography-defined tip curvature. In this study, the length of the needles varied between 150 and 350 micrometers. The widest dimension of the needle at its base was 250 μm. Preliminary application tests of the needle arrays show that they are robust and permit skin penetration without breakage. Transdermal water loss measurements before and after microneedle skin penetration are reported. Drug delivery is increased approximately by a factor of 750 in microneedle patch applications with respect to diffusion alone. The feasibility of using the microneedle array as a blood sampler on a capillary electrophoresis chip is demonstrated.

Several application fields can benefit from solar-hydrogen technologies via specific short-term and long-term pathways.

When a droplet impacts upon a surface heated above the liquid's boiling point, the droplet either comes into contact with the surface and boils immediately (contact boiling), or is supported by a developing vapor layer and bounces back (film boiling, or Leidenfrost state). We study the transition between these characteristic behaviors and how it is affected by parameters such as impact velocity, surface temperature, and controlled roughness (i.e., micro-structures fabricated on silicon surfaces). In the film boiling regime, we show that the residence time of droplets impacting upon the surface strongly depends on the drop size. We also show that the maximum spreading factor Γ of droplets in this regime displays a universal scaling behavior Γ ∼ We^3/10, which can be explained by taking into account the drag force of the vapor flow under the drop. This argument also leads to predictions for the scaling of film thickness and velocity of the vapor shooting out of the gap between the drop and the surface. In the contact boiling regime, we show that the structured surfaces induce the formation of vertical liquid jets during the spreading stage of impacting droplets.