Sensitive riboflavin sensing using silver nanoparticles deposited onto screen-printed electrodes via controlled-energy spark discharges.

In this work, we elaborated the graphite screen-printed electrodes (SPEs) modification with metal nanoparticles formed as a result of spark discharges produced between a metal wire electrode and SPE that are connected to an Arduino board-based DC high voltage power supply. This sparking device allows, on the one hand, the toposelective formation of NPs of controlled dimensions through a direct and liquid-free approach, and on the other hand, controls the number and energy of the discharges delivered to the electrode surface during a single spark event. This way, the potential damage to the SPE surface by the action of heat evolved during the sparking process is considerably minimized compared with the standard setup in which each spark event consists of multiple electrical discharges.

Dynamics of microflow at the plasma-liquid interface.

We study the interaction of microplasma with viscous liquid in a narrow gap. The reduced surface tension and viscosity of the liquid droplet from local plasma-heating induce a radial fingering. The introduced methodology enables spatially and temporally resolved quantification of dissipated power density and of resulting velocity of the advancing plasma-liquid interface.

Viscous droplet in nonthermal plasma: Instability, fingering process, and droplet fragmentation.

The interaction of dielectric barrier discharge plasma and silicone-oil liquid droplet in a Hele-Shaw cell was investigated experimentally employing synchronized optical and electrical time-resolved measurements. Temporal development of the destabilization, stretching, and fragmentation of the plasma-liquid interface was studied for the whole event lifespan. The perturbation wavelength and temporal development of fingering speed, plasma-liquid interface length, mean transferred charge, and fractal dimension of the pattern were determined.

High-resolution measurements of the electric field at the streamer arrival to the cathode: a unification of the streamer-initiated gas-breakdown mechanism.

A time-correlated single-photon counting technique was used to verify the formation of a cathode-directed streamer inside the narrow cathode region following the interpulse phase of regular negative corona Trichel pulses in ambient air. A purely experimental approach was used to determine the spatiotemporal development of the electric field during the Trichel pulse rise with an extremely high resolution of 10 μm and tens of picoseconds. The results confirm the positive-streamer mechanism for Trichel pulse formation and provide supportive evidence for the hypothesis that the formation of a primary cathode-directed streamer occurs always in any streamer-initiated breakdown and prebreakdown phenomena associated with cathode spot formation.